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Fostex 250 User's Manual

1. Rewind the tape Release the RECORD TRACK button for safety Set the appropriate MONMIX to scale 7 position MON MIX in this case Set ali other MONMIX to full CCW and bring down all input FADERS to avoid confusion from the other tracks Press the PLAY button if you prefer to make changes simply repeat steps 1 through 9 of the previous procedure Once satisfied you are free to record new program on the original tracks which no longer needed e g tracks 1 and 2 in this example SECTION7 STEREO RECORDING Stereo recordings involve 2 channels of information that are integrally related when monitored with a pair of stereo head phones or a stereo speaker system such recordings create an acoustic image known as the stereo panorama stereo perspective There are two general methods to creating a stereo record ing A purist stereo recording method places a pair of microphones in the midst of a performance assigning each mic to its own track and then recording the program essen tially in one take Fig 12 A second approach to stereo recording utilizes several microphones locating each mic close to an individual sound source and panning each to a location in the stereo perspective when recording the two tracks Fig 13 In this case the recorded perspective may or may not be true to actual sound source locations With either method of stereo
2. ON3S 10 1 0 100 0 E LNG 21400 ziom 2100 i inoa 5118 35 2 ZNI 6 OVIH Ad 334 36743 OVER 35753 Av Zary 35 1 23 7 BROS SECTION 12 INPUT X4 Mic impedance Input impedance Nominal Input level Minimum input level Maximum input level 4 CHAN REC 4 input impedance Nominal Input level Maximum input level AUX IN 2 input impedance Nominai minimum input level Maximum input level AUX SEND MONMIX OUT Output load impedance Nominal output level Maximum output level DIRECT OUT 4 Output load impedance Nominal output levei Maximum output level TAPE CUE OUT X4 Output load impedance Nominal output level Maximum output bevel HEADPHONE OUTPUT Stereo Load impedance Maximum output EQUALIZER 4 KHz 300 Hz RECORDING TAPE RECORD TRACKS RECORD CHANNELS PLAYBACK CHANNELS NORMAL TAPE SPEED PITCH CONTROL RECORDING TIME HEADS MOTORS FAST WIND TIME SPECIFICATIONS FREQUENCY RESPONSE Mixer section Recorder section 10K or less 5 Mic 60dBY Line
3. right tracks 1 and 2 to emulate or artificially create a stereo panorama A typical Model 250 setup for this recording is shown Artificial Panorama monitor amp Recorded Lett Center InstrumentD 2 Right Instrument 4 17 to R If close mic or direct instrument inputs are used these can be panned to any position in the stereo perspective but during the initial setup pan fully to one track 7 Initially set all input FADERS all the way down 0 Then one channel at a time perform the following steps the channels with new signals raise the FADER to nominal 7 8 Then with signal present at the input adjust the TRIM control for a VU METER indication of approximately 3 to 0 VU b On these same channels adjust the EQ as desired then set the 4 CHAN BUSS to OFF position 8 Press the PLAY button to begin playback of the existing tracks to balance these levels with the new inputs a If the channel 1 amp 2 INPUT selectors are in TAPE posi tion only 1 or 2 new inputs is being added raise the 1 amp 2 INPUT FADERS to nominal position and check the VU METER levels Playback from track 1 will be monitored on the TRK 3 meter and can be adjusted with the channet 1 input FADER Playback from track 2 is seen on the TRK 4 meter and adjusted with the channel 2 input FADER The channel 1 amp 2 trim controls have no effect h
4. The appliance has been exposed to rain or D The appliance does not appear to operate normally or exhibits a marked change in performance or E The appliance has been dropped or the enclosure damaged Servicing The user should not attempt to service the appliance beyond that described the operating structions All other servicing should be referred to qualified service personnel WARNING To avold possible electric shock hazard do not expose this appliance to rain or molsture There are no user serviceable parts Inside Refer servicing to qualified service personnel PAGE 11 13 15 17 21 24 27 1 CONTROLS INDICATORS amp CONNECTORS Figure 1 Model 250 Panel Features i Se ae yl cot 2 lt 4 T AUT MIT 6 i Glo i 55 2 ee Front Panel 25 26 MAIN PANEL FEATURES Input Channel same features for channels 1 through 4 1 INPUT FADER This slide fader controls the signal level from either of two sources the channel s input jack or playoack from the built in cassette recorder depending on the position of the INPUT selector LINE MIC TAPE switch 3 To ensure low distortion and preserve an optimum signal to noise ratio the Input Fader should b
5. record ready made 7 Turn the channel 1 4 CHAN BUSS PAN pot fully clock wise to R position assigning all the input signal to the 4 record buss IMPORTANT NOTE The PAN pot should be fully panned to assign all signal to the designated record buss 4 in 7 this instance The object at this point is to record on only one track of the tape at a time If the PAN pot is set in some mid position part of the signal is being assigned to an unused buss which serves only to degrade the signal to noise ratio on the track being recorded part of the signal is wasted In some cases it is possible one could hear a signal in the headphones or monitor speakers even though that signal is not actually being recorded 8 Set the METER function switch to RECORDER position so that VU METER 4 will monitor the signal level from input channel 1 as assigned to record buss 4 NOTE order to adjust the TRIM LINE MIC control it wili be necessary to provide an average level signal at the channel input It is for you to sing talk or play an in strument although during setup it will be easier to have a friend do this as you adjust the Model 250 controls Alter natively use a radio phonograph record played over speakers a continuous organ note or any convenient sound that wili stimulate a microphone at approximately the level of the ultimate sound source After the setup is achieved and the actual performance
6. successfully be played on those regular format cassette decks having a tape speed of 3 3 4 ips a tape recorded at 3 3 4 ips can be put in the Model 250 for overdubbing or a control signal can be recorded on one track for audio visual applications USE THE PROPER TYPE OF CASSETTE TAPE Fostex has engineered the Model 250 to operate with just one specific type of cassette the tape should have a gam maferric oxide emulsion and should be rated for high bias 6 and 70 microsecond equalization This is the type of tape that uses the chrome position many recorders although not a chrome tape There are several benefits in standardizing on one type of tape Fostex is able to deliver the utmost performance and high reliability at a moderate price Also the user saves time when setting up to record or play a tape because there are no routinely required bias EQ or level alignment procedures Moreover the majority of pro fessional recording engineers choose to standardize on one tape so that they obtain consistently predictable results Metal tape was rejected because it would greatly increase operating costs without any major benefit metal tape was first developed to extend high frequency response at low tape speeds but the Model 250 is already running at twice normal speed Metal tape also requires significantly higher record and erase bias which would compromise track to track separation and erasure depth both critical
7. such extremes in dynamics have already been compressed by a variety of signal processing This is why consumer tape recorders can yield acceptable results even though they offer limited dynamic range When making live recordings however the ability to handle wide dynamics is far more critical For this reason Fostex engineers have given special attention to maximizing the dynamic range of the cassette recorder and of the mixing electronics The result is excellent audio performance with wide band width wide frequency response low distortion and low noise To improve tape record play performance new track speed format has been adopted Standard cassettes are utilized but the tape head configuration and running speed are modified for optimum four channel operation HOW 250 RECORDINGS DIFFER FROM STANDARD STEREO CASSETTES The tape records or plays all 4 tracks in the same direction at 3 3 4 ips 9 5 cm s two times conventional cassette speed providing extended high frequency response and wider dynamic range Additional dynamic range is afforded by the built in Dolby Type C noise reduction system an updated version of Dolby processing that yields approximately 20 dB of noise reduction and headroom extension The Model 250 track format is designed with consideration to improving sync crosstalk while maintaining interchangeability with the standard Phillips cassette format A tape recorded on tracks 1 and 2 of the Model 250 can
8. 100 0 3 66 0 5mvV 12dB 4 TOTAL HARMONIC DISTORTION Mixer section Recorder section 10dBY 0 3 S N 8d BV 2 5V Mixer section 109 0 3 Recorder section 2008 10V CROSSTALK Mixer section 10 8 more 5kQ minimum Recorder section 104 0 3 159 5 6 ERASURE POWER REQUIREMENTS 10K2 or more minimum 10dBV 0 3 150BV 5 6V 10KR more SKB minimum 10dBV 0 3 8d BY 2 5 DIMENSIONS 80 or 42 minimum WEIGHT 100mW at 80 Variable 12 dB peaking Variable 12 dB shelving Compact cassette C 60 or 90 Use a gamma ferric oxide tape that requires high bias level and 70 microsecond EQ TDK SA MAXELL XL It or equivalent 4 track one direction Special format 4 with Dolby NR C type in encode mode throughout encode decode switchable 4 with Dolby NR C type in decode mode throughout encode decode switchable 3 3 4 ips 1 10 of normal tape speed 15 minutes for C 60 4 channel erase ferrite 4 channel record playback FG servo controlled DC capstan motor and one DC 20Hz 20 000Hz 1dB 20Hz 18 000Hz 40Hz 14 000 2 20 at 0 VU 0 05 at 1 000Hz nominal level 1 5 at 315Hz 0 VU level Overall One overall 65dB weighted 629 unweighted One line overall 75dB weighted 72dB unweighted 7548 weigh
9. MONMIX signal will be either the record input signal 4 CHAN BUSS in record mode or tape out signal in play mode The MONMIX signal is used for cue feed to the musicians with an external amplifier or may be used for echo send 32 DIRECT OUT JACKS applies to 1 through 4 These jacks carry the output from cor tespondingly numbered input channel equalizer just ahead of the 4 CHAN BUSS PAN control They can be used to drive external effects devices and the return from such devices can be brought to the AUX IN jacks 28 another 5 INPUT jack 25 or a RECORD IN jack 33 Any DIRECT OUT jack can be patched directly to any RECORD IN jack 33 thus bypass ing the 4 CHAN BUSS selector switch 6 and PAN control 5 33 RECORD IN REC IN JACKS applies to 1 through 4 These jacks apply signals to the cor respondingly numbered tracks of the cassette recorder 34 REMOTE FOOT SWITCH PUNCH IN PUNCH OUT JACK This phone jack accepts the cable from the unit s REMOTE FOOT PUNCH IN PUNCH OUT SWITCH When the unit is in play mode pressing the FOOT SWITCH once will cause it to enter record mode if any RECORD TRACK button 14 is engaged or record ready mode no RECORD TRACK button is engaged The FOOT SWITCH makes it possible for a performer to play an instrument or handle music while oper ating the recorder even if the person is not simultaneously performing the foot switch can free a
10. for best results Before loading a cassette into the Mode 250 we recommend gently tapping the cassette on a flat hard surface This packs the tape uniformly against the bottom of its case Hold the cassette so the side facing up is the same side that will face up when the cassette is loaded To be ex tra certain of a uniform tape pack fast wind a new cassette fully to one end then rewind prior to use 1 Plug a signal source such as a microphone or electric in strument into channel INPUT jack 1 on the front panel 2 Turn on the POWER open the cassette well cover grip the cover at the cutout on the right edge of the case and lift and insert a blank cassette Set the channel 1 INPUT selector switch to LINE MIC position on all other channels set it to OFF position 4 Set the channel 1 input FADER and the MASTER 1 2 FADER to the nominal zone between 7 and 8 on the scale NOTE it is now necessary to decide which of the four tracks is to be recorded this instance we will record the signal from input channel 1 onto track 4 5 Set the 4 CHAN BUSS selector switch to assign the in put to the desired pair of tracks in this example use 3 4 position On all other channels set the selector to OFF position Depress the appropriate RECORD TRACK button for this example engage the 4 button NOTE red LED above the 4 RECORD TRACK but ton will now blink on and off indicating that the track is in
11. set RCV 1 2 as required 12 HEADPHONE LEVEL The headphones are OFF when the knob is at center 12 o clock CCW rotation of the control allows monitoring of the MONMIX signal the left and right headphones at equal levels The 4 CHAN BUSS signals can be monitored in stereo by rotating the con trol clockwise Mixed signals of buss 1 and 3 are heard in the left headphone and buss 2 and 4 in the right headphone 13 MASTER 1 2 FADER This MASTER FADER simultaneously controls the levels of both BUSS OUT 1 amp 2 of the 4 CHAN BUSS This FADER affects the following circuits the LINE OUT 1 jack 29 b the LINE OUT 2 Jack 29 the 1 and 2 meters 9 when the METER selector 10 is set to MIXER position Tape Transport Features 14 RECORD TRACK SELECTOR BUTTONS 1 4 AND INDICATORS These four push buttons and LEDs are numbered to correspond with the four tracks on the cassette tape When a button is depressed its track is record ready as indicated by a blinking LED above the RECORD TRACK button Recording wiil not actually begin until either a the RECORD button 16 and PLAY button 18 are simultaneously press ed or the PLAY button 18 is pressed and then the REMOTE FOOT SWITCH actu ated There is one exception when depress ing a RECORD TRACK selector button immediately results in recording when the RECORD and PLAY buttons have alre
12. strong alternating magnetic field created by a demagnetizer near the head area then withdrawing the field slowly It is very important that this procedure be done carefully and that no tapes be within 6 feet 2 meters of the demagnetizer when it is operating It is also important to turn off the Model 250 during the time the demagnetizer is turned on CAUTION Demagnetizers are not dangerous devices per but if used improperly they can instantly erase valuable tape and can permanently magnetize metal parts the opposite of the desired result NEVER TURN ON OR EVEN PLUG IN A DEMAGNETIZER UNLESS IT IS AT LEAST 3 FEET 1 METER AWAY FROM THE 250 ALSO NEVER TURN THE DEMAGNETIZER OFF UNTIL IT IS WITHDRAWN TO AN EQUAL DISTANCE OF AT LEAST 3 FEET the demagnetizer should be turned on or off nearby the Model 250 it may impart a magnetic charge to the heads or tape guides which is too strong to be removed by the same demagnetizer There is no rule as to how often demagnetization must be done but we recommend it be performed at feast once for every 10 hours of Model 250 record play operation We sug gest observing the following procedure step by step NOTE Some demagnetizers do not have on off switches and must be plugged and unplugged This design may be safer because it avoids accidental switching when near the recorder in these instructions we assume that switchable demagnetizers are always turned on and
13. the sound is very noisy or hissy the Modet 250 output level is probably too low raise the MASTER 1 2 FADER and if necessary lower the record level control on the stereo master recorder 20 Press ZERO RETURN to rewind the Model 250 multi track master cassette to the beginning of the program 21 Place the stereo master recorder in record mode 22 Press the Model 250 PLAY button The mixdown is now being accomplished the resuit will be a stereo master tape NOTE if you plan to fade out at the end of the program it is best to do this with the record level controls on the MASTER 1 2 FADER rather than with the stereo master recorder 23 monitor the stereo master tape use headphones connect the line or play output of that recorder to the monitor amp If using a stereo preamp integrated amp or receiver there is probably a separate input that can be used without having to disconnect the Mode 250 from the amp but be sure to switch the amp s input selector SEcTION6 COMBINING TRACKS PING PONG Track combination involves moving program material from more tracks to another track transfer and combi nation in order to make room for additional program material During the track combination also known as additional live sounds can be added NOTE There are practical limits as to how many times a track can be transferred since some background noise is inevitably add
14. to drive that accessory to full output level this is not necessarily a problem although some additional noise may be introduced If the 4 dBm rated accessory has a gain volume or level control that can be increased as many do then it will operate normally when driven by the Model 250 output NOTE Many power amplifiers are rated at 4 dBm 8 dBm 1 23 to 2 volts input sensitivity While it might not be apparent such amplifiers can be driven to full power by the Model 2505 10 outputs Power amplifiers are ex ception to the rule the input sensitivity specification of a power amplifier is the level required to drive the amplifier to its maximum rated output power To avoid clipping distor tion on peaks nominal input levels to the amp should be 10 dB to 20 dB below the rated amplifier sensitivity Given that the Mode 250 outputs 10 dBV nominal and allowing 2 dB approximate correction for dBV to dBm conversion the Model 250 output level is about 12 dB below 4 dBm just right At times it may be desirable to lower the Mode 250 output level bring down the MASTER 1 2 FADER a surprise if one had casually compared the 10 dBV nominal output to the 4 amplifier input sensitivity IMPEDANCE IN GENERAL Impedance abbreviated 2 can be defined as the total opposition to the flow of alternating current an electri cal circuit In this context alternating current ac refers to
15. 0 RECORD IN and AUX IN jacks are meant for connection to equipment having 10 dBV nominal output levels Since the RCV 1 2 control can lower the AUX IN sensi tivity higher input levels can be accommodated Some sound equipment outputs are rated at 4 dBm nominal This equals 1 23 volts which in turn equals about 1 8 dBV 12 dB above the Model 250 5 line input sensitivity The Model 250 specifications show that the unit is rated for maximum input levels of 12 dBV MIC LINE and RECORD inputs and 20 dBV AUX IN This might appear to accom modate a 4 dBm nominal signal yet such a signal may have peaks of 18 dBm to 24 dBm about 16 to 22 Thus unless a 4 dBm nominal output is reduced tevel or attenuated with an external pad the Madel 250 input still may be overdriven on peaks causing audible distortion MODEL 250 OUTPUT LEVELS Modet 250 outputs are rated at 10 dBV 0 3 volts nominal level with a maximum output of 15 dBV 5 6 volts signal that would tend to cause higher than 15 out put levels wiil merely create distortion clipping The VU METERS are helpful in avoiding distortion due to excess levels Since most consumer tape recorders tuners stereo equip ment and so forth utilize tine levels of approximately 20 to 10 dBV the Model 250 outputs should be compati ble If an accessory has a rated input level of 4 dBm nominal the Mode 250 output may not be adequate
16. 0 dB mic to 10 dB tine depending on the setting of the channel s LINE MIC trim control 21 The jack is live only when the channel s INPUT selector switch 3 is set to LINE MIC position 26 HEADPHONE JACKS two stereo phone jacks Two stereo HEADPHONE jacks are provided parallel wired so that two pair of phones may be used at once Rated for 8 ohm or higher impedance phones these outputs carry the signal from the MONMIX The operator can use one jack to monitor the mix and a performer can use the other for cues during over dubs and inserts REAR PANEL FEATURES Rear Panel NOTE All rear panel input and output jacks except the REMOTE PUNCH OUT foot switch phone jack are unbalanced phono jacks RCA type pin jacks They operate at nominal 10 levels 0 3 Vrms inputs accept low or high impedance sources outputs are intended to drive high impedance loads These levels and im pedances are compatible with most line level mixers tape recorders power amplifiers and signal processors or effects devices Refer to Section 9 for additional interface information 27 TAPE OUT JACKS applies to 1 through 4 These jacks carry an output corre sponding to the tape track of the same number e g track 3 appears at jack 3 These output signals will be the record input signals 4 CHAN BUSS OUT when the transport is in record mode and tape out signals sync when in the play mode I
17. 10 volts 5 volt increase the level increases by the same 6 dB By the same rules if the voltage goes up by a factor of 10 the level increases 20 dB The same relationship applies to sound pressure level doubling the number of dynes is an increase of 6 dB SPL dBV values be converted to specific voltages and vice versa a special slide rule or scientific calculator is usually employed In simple terms however the key to the conver sion is the reference value for dBV The large V in dBV means that the 0 dB value is related to a specific Voltage 1 volt in this instance Given that 1 volt is 0 dBV the following table can be readily constructed plus dB over 1 volt minus dB under 1 volt 2vols 6dBV 05 500 6dBV 4volts 12dBV 0 25 volts 250 mV 12 volis 18dBV 0 125 volts 125 mV 18 10 volts 20dBV 01 volts 100mV 20 dBV NOTE Some equipment is rated using a different 0 dB reference value 0 dBV equals 0 775 volts so a given voltage rated in dBV will be 2 2 dB higher than the operating 0 dBm is referenced to 1 miliwatt power not voltage but in 600 ohm circuit the dBm number is identical to the dBV number so a conversion can be approximated by assuming 600 ohms Bear these differences in mind when comparing specified levels in different equipment NOMINAL LEVELS Except in the case of a test signal such as the output of a tone oscillator or a continu
18. 15 accessible only by means of the MONMIX control of the channel numbered to correspond the track 0 4 Initially set the HEADPHONE control at center OFF and plug a pair of 8 ohm or higher impedance stereo head phones into either HEADPHONE jack on the Model 250 front panel then advance the knob CCW to obtain com fortable listening level NOTE Assuming that the AUX INPUT jacks are not being used during this operation it is good idea to set RCV 1 2 at minimum 0 to eliminate any hiss from the unused inputs 1 _ 12 There is another method to HEADPHONE monitoring for obtaining the most pleasing sound by passing the playback signal through the equalizer The INPUT selector of channel 4 is set to TAPE position The INPUT fader is set at nominal position PAN pot at center the 4 CHAN BUSS at 3 4 position not at 1 2 posi tion as it will oscillate the MASTER 1 2 fader at nominal position and the HEADPHONE control is gradually ad vanced CW from its OFF position until the 4 CHAN BUSS signal is heard at a comfortable level 13 Press the RESET button to zero the index counter so that after the recording the ZERO RETURN button can be used to automatically rewind to this point on the tape 14 Check the PITCH CONTROL to make sure it is centered so that tape records at normal 3 3 4 ips speed 9 5 cm s NOTE Recording can be done at faster or slower speeds for certain special effects but for normal recor
19. 7 Steps to evaluate a stereo transfer cae ac NOTE jumper cable was connected from TAPE OUT to REC IN and the transferfoverdub is completed discon nect that jumper cable sections INSERTS PUNCH IN RECORDING Inserts are useful for replacing portions of an otherwise satisfactory recording e g re recording one stanza of a lead vocal track without affecting the others Inserts are essentially the same as an overdub they are recordings of new material made in synchronization with one or more previously recorded tracks The difference is that while an overdub is made on a different track the insert or punch in is made on the same track as previously recorded material Thus wherever the insert is located previous material is erased For this reason one cannot layer new material on top of an existing track during the insert combin ing tracks or ping pong would be required to obtain this result refer to Section 6 When one is listening to the existing track s ready to begin the insert it is obvious that precise timing is essential If the person operating the Model 250 is also the performer it might be difficult to press the RECORD and PLAY buttons and to also be ready to perform Fortunately the Model 250 has a foot switch jack for remote punch ins One need simply place the unit in play mode with the appropriate RECORD TRACK selector depressed then s
20. BUSS selector at 1 2 position b PAN pot fully clockwise at R position Set the 4 CHAN BUSS selector of inputs not being used 2 3 amp 4 to OFF center position 3 Depress the RECORD TRACK button corresponding to the track on which the overdub will be made 2 in this case to make the track ready for recording CAUTION Make sure no other RECORD TRACK button is depressed since this could lead to inadvertent erasure of a previously recorded track 4 Identify the channel numbers corresponding to those tracks which either are about to be recorded or which have already been recorded channels 2 and 4 in this example Then Set INPUT channel 2 s MONMIX to scale 7 This ensures that the track 4 playback and track 2 recording signals will be fed to the MONMIX buss 5 The METER function switch should be set to RECORDER position so the recording level and track 4 playback level can be monitored by the HEADPHONE outputs 6 On the channel with the live sound source channel 1 a Set the INPUT selector switch at LINE MIC position b Set the channel FADER at nominal 7 to 8 Adjust the TRIM control for a suitable level indication on the TRACK 2 VU METER peaks approx 3 VU to 0 VU 7 Set the HEADPHONE control for the desired listening level NOTE The sound heard in the headphones does not necessarily reflect the level balance that will exist in the final mix Initially the tracks are each being record
21. MMENTS NOTES TO REVERS RETORNA aie REVERE LER RIGHT 22 On Quad Comh af A 7357 SECTION 4 SYNC RECORDING OVERDUBBING Sync recording also known as overdubbing is one of the major benefits of multi track recording It permits complex musical arrangements to be assembled one element at a time sometimes by a single performer The performer listens via headphones to previously recorded tracks while record ing one or more additional tracks on the same tape The Model 250 has special capabilities that enable it to playback and record synchronously sync recording Recording in sync making an overdub is a naturat extension of the process used to record the original track The unit must be set for syne playback If the performer is other than the person operating the Modet 250 then a second set of head phones should be worn by the performer MAKING THE OVERDUB Figure 5 Steps for sync recording with Model 250 coin 1 Connect mic or instrument to an input channel Since mic already is connected to channel 1 from the instruc tions in Section 3 it can be used However it will be assigned to record on a different track 2 Choose the track on which the overdub is to be made In this case an overdub will be made on track 2 and set the input channel s 4 CHAN BUSS selector and PAN pot accordingly 4 CHAN
22. Model 250 RECORDER MIXER Owner s Manual The ideal self contained recording studio for todays performing artist TABLE OF CONTENTS SECTION SECTION SECTION SECTION SECTION SECTION SECTION SECTION SECTION SECTION 10 SECTION 11 SECTION 12 SAFETY INSTRUCTIONS WARNING READ BEFORE OPERATING 1 Read nstructions All the safety and operating instruc tions should be read before the appliance is operated Retain Instructions The safety and operating instruc tions should be retained for future reference Heed Warnings Al warnings on the appliance and the operating instructions should be adhered to Follow Instructions All operating and use instructions should be followed Water Moisture The appliance should not be used near water for example near a bathtub washbow kitchen sink laundry tub in a wet basement or near a swimming pool etc Ventilation The appliance should be situated so that its location or position does not interfere with its proper ven tilation For example the appliance should not be situated on a bed sofa rug similar surface that may block the ventilation openings or placed in a built in installation such as a bookcase or cabinet that may impede the flow of air through the ventilation openings Heat The appliance should be situated away from heat sources such as radiators heat regis
23. NPUT phone jack and a preamplifier The 1 INPUT jack front panel goes to the 1 input FADER etc OFF No signal is applied to the input FADER so the channel is effectively shut off TAPE Tracks 1 through 4 of the built in cassette recorder are connected to the corres pondingly numbered input channels as follows a When the track is not recording the playback signal is applied to the input FADER b When a given track is actually recording record input signal is present at the input FADER 4 EQUALIZER 300 Hz amp 4 kHz The channel s two EQUALIZER knobs 300 Hz amp 4 kHz provide approximately 12 dB of the shelf type boost or cut at a turnover of 300 Hz and boost or cut at a center frequency of 4 kHz Center position 12 o clock provides a flat re sponse The 300 Hz knob controls bass frequencies while the 4 kHz knob affects mid range to higher frequencies 5 4 CHAN BUSS PAN POT L R The input signal after the FADER and EQUALIZER is applied to this PAN pot labelled L R PAN then applies the signal to a pair of record tracks either 1 and 2 or 3 and 4 based on the setting of the 4 CHAN BUSS selector 1 2 3 4 switch 6 Center PAN position 12 o clock rota tion applies equal signal to both selected tracks As the PAN pot is ro tated counterclockwise it applies about 3 dB more signal to track 1 3 and virtually eliminates the signal applied to track 2 or 4 The opposite occu
24. P BUTTON Depressing the STOP button cancels any transport function and stops tape motion Whether tape is moving due to ZERO RETURN REWIND F FWD RECORD or PLAY tape motion wili stop 18 PLAY BUTTON Depressing the PLAY button places the transport in play mode advancing tape onto the takeup reel from left to right at a constant speed of 3 3 4 ips 9 5 cm s plus or minus any deviation set with the PITCH control 22 19 FAST FORWARD BUTTON FWD gt gt Depressing this button cancels any other transport function and causes the tape to wind onto the takeup reel from left to right at high speed If the transport had been in rewind or ZERO RETURN mode tape will first stop mo mentarily then begin forward winding 20 REWIND BUTTON lt lt Depressing this button cancels any other transport function and causes the tape to wind onto the supply reel from right to left at high speed If the transport had been in fast forward or play mode tape will first stop momen tarily then begin rewinding 21 ZERO RETURN BUTTON Depressing this button cancels any other transport function and causes the tape to wind onto the supply reel from right to left at high speed until the INDEX COUNTER 15 displays 0000 4 at which point the tape automatically stops If the transport had been in fast forward or play mode tape will first stop momentarily then begin rewinding to 0000 If the transport had been in rewi
25. X 3 to scale 7 and HEADPHONE control to MONMIX position This enables you to monitor the active record buss and avoids confusion from other signals no other record buss is being used Depress the RECORD TRACK button for the track onto which the transfer will be made so it is ready for recording track 3 in the example If you are simultaneously adding one or two live sources during the transfer use either of the channels whose number does not correspond to the tracks from which existing program is being derived In the example since the program is taken from tracks 1 and 2 use channel 3 and or 4 for live inputs To add a live vocal overdub via input channel 4 for example a Set the channe 4 INPUT selector switch to LINE MIC b Set the channet 4 CHAN BUSS selector switch to 3 4 position and the PAN Pot fully CCW to assign the mic to track 3 Set the channel 4 input FADER one index higher than nominal 88 89 and with sound present at the mic or while playing the instrument adjust the channel 4 TRIM control for a normal indication on the 3 VU meter e g peaks 3 to 0 Later the FADER will be set at nominal reducing the contribution of a given channel to allow for the additional signal from the transferred track Set at top of channel 4 to scale 7 e Make any desired EQ adjustments on channel 4 NOTE if two live sources are being added follow steps through abo
26. ady been pressed so that the trans port is rolling tape and the red LED left of the RECORD button is blinking then depressing a RECORD TRACK Selector switch will cause the track to enter record mode LEDs show the status of the associated tape tracks as follows UNLIT Track is in safe mode and will not record even if RECORD and PLAY buttons are pressed BLINKING Track is in record ready mode and will record as soon as the RECORD and PLAY buttons are pressed or PLAY and then REMOTE PUNCH IN STAYS ON Track is recording 15 TAPE INDEX COUNTER AND RESET BUTTON 4 digit display accurately indicates relative tape position means of a photo interrupter circuit on the trans port takeup spindle Pressing the ad jacent RESET button sets the display at To take advantage of the ZERO RETURN function 21 it is recommend ed that the RESET button be pressed at the beginning of a take especially when overdubbing or making inserts 16 RECORD BUTTON ANDINDICATOR The effect of pressing the RECORD but ton will vary depending upon the status of certain other controls The adjacent LED helps to signal the status as ex plained below you press RECORD while tape is stopped The RECORD MODE LED adjacent to the RECORD button blinks Should any of the four RECORD TRACK selector buttons 14 be depressed TAPE OUT and MONMIX from that channel automatically change from the r
27. an audio signal not to the power mains impedance and resistance are similar both being expressed in ohms However resistance is the opposition to de current flow not 2 and seldom are equal a given circuit in fact impedance changes with frequency If the frequency at which a rated impedance has been measured is not specified it is probably a typical value which is generally measured at 1 000 Hz Input impedance is also known as load impedance the greater the load the lower the impedance If an input has a higher impedance it offers more opposition to the flow of audio than would a lower impedance input Consequently high impedance inputs do not draw as much power from the signal source which feeds they are less of a load on the signal source For example if a given output has adequate power to drive just one low impedance input it may be capable of driving five or more high impedance inputs Outputs impedance is also called source impedance most cases an output can be connected only to an input whose load impedance is equal to or higher than the output s source impedance For example an output having a 600 ohm source impedance could be connected to an input having a 600 ohm load impedance or a 20 000 ohm or higher load impedance When the input impedance equals the output source im pedance the input is said to be matching the output When the load is approximately ten times the sou
28. d quality When ready rewind again and pro ceed COMPLETION OF THE MIXDOWN RECORDING THE STEREO MASTER Figure 9 Steps 17 through 23 of mixdown process 21 18 Semon AUXIN OUT gt olo 9 6 o o 17 Place the stereo master recorder in record ready mode Press record pause or whatever mode permits the record levels to be adjusted without rolling tape NOTE Steps 17 18 and 19 enable the proper record level to be set The Model 250 controls are adjusted so the 1 amp 2 VU METERS indicate a suitable output level and the monitor speakers or phones level may appear to be cor rect yet none of this ensures proper recording levels these are set on the stereo master recorder 18 Press the Model 250 PLAY button and observe the record level meters on the stereo master recorder If necessary adjust the record level on that unit so the levels fall within the manufacturer s specified optimum range 19 Check the sound quality at the stereo master recorder by plugging in a set of headphones to that unit s phones jack if it has none skip this step In rare cases a level mismatch may cause excess noise or distortion usually this can be remedied as follows If the sound is very distorted the Model 250 output level is probably too high lower the MASTER 1 2 FADER and raise the record level control on the stereo master recorder b If
29. d the heads together and if spilled can mar or deform plastic parts Wipe the heads tape guides pinch roller and capstan with a common cotton swab moistened with the head cleaning fluid or alcohol Allow the parts to air dry before installing a cassette The process should be repeated until the swab no longer shows evidence of the reddish brown oxide and until the heads are shiny and clean NOTE We do not recommend the use of so called head cleaning cassettes These products typically use an abrasive tape which can prematurely wear the heads and which does little to clean the capstan or pinch roller The exterior of the Model 250 can be wiped with a cloth that is moistened with a weak detergent and water solution Do not use solvents oils waxes or spray on cleaners DEMAGNETIZATION When a recording is made the record play head applies a powerful magnetic field to the tape Iron oxide or similar magnetic particles in the recording tape store a portion of that magnetic field this is the recording It is a necessary law of physics that as the recorded tape is subsequently played some of the tape s magnetic field will be transferred to near by metal parts This residual magnetism is undesirable because it in turn can partially erase a tape The purpose of demagnetization degaussing is to neutralize residual mag netism in the vicinity of the tape path 24 Demagnetizing also called degaussing is accomplished by bringing a
30. dance in these cases we offer a simplified method Assume that a Model 250 output is being connected to more than one high impedance input and that each of those inputs has the same impedance for example 20 kohms Divide the input impedance 20 kohms by the number of inputs to figure the actual load on the Model 250 output Thus if the output is driving two 20 kohm inputs the load is 10 kohms 20 2 If it is driving three 20 kohm inputs the load is 6 7 kohms 20 3 If it is driving four 20 kohm inputs the load is 5 kohms 20 4 Since the maximum load minimum impedance recommend ed for the Model 250 is 5 kohms the practical limit would be a 4 way split if driving 20 kohm inputs Higher input impedances would allow more inputs to be driven lower impedances would lessen the number of inputs that could be driven by a single Model 250 output CAUTION Do not connect two Model 250 outputs together Also except as specifically noted for track reassignment do not connect Model 250 outputs directly to Model 250 inputs as this could cause feedback THE RELATIONSHIP BETWEEN IMPEDANCE AND LEVEL We have discussed signal level and impedance separately yet are they related Yes but not directly Outputs which are rated at nominal 4 dBm line levels usually are capable of driving low or high impedance inputs e g they can be matched or bridged Outputs which are rated at nominal 10 line levels usually are capable of driving o
31. ding PITCH should be centered 15 When ready to begin recording simultaneously depress the RECORD and PLAY buttons Confirm that tape is win ding at constant speed onto the right hub The LED above the 4 RECORD TRACK button now should stay on in stead of blinking and the record mode LED adjacent to the RECORD button should also turn on NOTE Check the VU METER and peak LED occasionally ensure they are in the proper range if level ad justments are necessary while recording USE THE PUT FADER NOT THE TRIM control 16 When the recording is completed press the STOP button which cancels recording and stops the tape PLAYING BACK THE INITIAL TRACK JUST RECORDED Figure 3 Steps for playback of the initial track __ ofooofjoo __ 010 Press ZERO RETURN Assuming the index counter was zeroed before the recording was done the tape will re wind to the beginning of the take index 0000 Otherwise press REWIND and then STOP when the index counter displays the appropriate reference number or when the end of the reel is reached Disengage the 4 RECORD TRACK button so that the track is in safe mode and cannot be accidentally erased Set input channel 4 s MONMIX knob at scale 7 so that playback can be applied to the MONMIX output It is not necessary to move the 4 CHANNEL BUSS PAN pot The HEADPHOKE control
32. e set in the range between 7 and 8 the scale nominal position When the INPUT selector switch 3 is in LINE MIC position the LINE MIC preamp trim control 2 also affects the channel level 2 LINE MIC PREAMP TRIM CONTROL This rotary control continuously adjusts the preamplifier gain over a 50dB range In LINE position the preamp has 0 dB gain unity which means the channel input is suitable for use with nominal 100B 0 3 Vrms line levels such as the output of electronic musical instru ments and tape recorders As the con trol is rotated toward MIC position the gain increases by 50 dB making the input suitable for use with nominal 60 1 mV rms levels such as the output of a dynamic microphone Inter mediate settings are suitable for such signal levels that might be obtained from condenser microphones guitar pickups and so forth This control has no effect when the INPUT selector LINE MIC OFF TAPE switch 3 is set in TAPE position NOTE Each feature in this section is referenced by a numbered callout and a correspondingly numbered description When a feature is mentioned its callout number may be cited in brackets e g the LINE MIC contro 2 3 INPUT SELECTOR LINE MIC OFF TAPE SWITCH This 3 position lever type switch selects the signal which is applied to the input FADER as explained below LINE MIC Signal is applied to the FADER line to mic level via the front panel I
33. ection to the 250 Connect the LINE OUT 1 and 2 jacks of whatever stereo tape recorder you wish to use for making the stereo master tape to the other side of the Y cable conventional cassette or reel to reel NOTE An alternative connection involves connecting the 250 LINE OUT to the preamp integrated amp preamp receiver and then connecting the tape output jacks from that unit to the stereo recorder This may be an easier ap proach if your sound system is already connected to a stereo recorder The drawback is that the output from the Model 250 must go through additional electronics before it is re recorded and thus may be degraded unnecessarily The MASTER 1 2 FADER controls the level at both the LINE OUT 1 2 jacks so level changes affecting the recording will be heard in the monitor speakers This FADER should be set to obtain the optimum recording monitor levels can be trim med using the volume control on your preamp amplifier integrated or receiver You may wish to do severat trial refining the mix prior to making the transfer to the stereo recorder SET UP AND PROCEDURE FOR MIXDOWN Figure 8 Equipment set up amp steps 1 16 of mixdown procedure see Fig 9 for remaining steps NOTE To begin the monitor amplifier should be connected its power turned on and its volume set very low near minimum The stereo ma
34. ed at the optimum level for high signal to noise ratio and low distortion During remix they can be precisely level balanced 8 Assuming that the AUX INPUT jacks are not being used during this operation it is a good idea to set RCV 1 2 at minimum 0 to eliminate any hiss from the unused inputs Also check the PITCH CONTROL to make sure it centered so that tape records at normal 3 3 4 ips speed 9 5 cm s 9 When ready to begin recording simultaneously depress the PLAY and RECORD buttons Confirm that tape is winding at constant speed onto the right hub The LED above the 2 RECORD TRACK selector button now should stay on instead of blinking and the record mode LED adjacent to the RECORD button also should turn on NOTE if the operator requires both hands free use the remote foot switch Place the transport in play mode then Step on the switch at the instant you wish to initiate recording 10 When the recording is completed press the STOP button 11 PLAYING BACK THE ORIGINAL TRACK AND THE OVERDUB Figure 6 Steps for playing back the initial and overdubbed tracks 1 Press ZERO RETURN to rewind the tape to the beginning of the take 2 Release all RECORD TRACK buttons 2 in this example to prevent inadvertent erasure by placing the tracks in safe mode 3 Bring down the input FADER on the channel used for the overdub mic or instrument While not mandatory this step avo
35. ed during the process we recommend no more than two rounds of ping pong for a given original track HOW TO COMBINE TWO TRACKS INTO ONE NOTE The following steps are expressed in general form However for clarity we will use an example where pro gram is being transferred from tracks 1 and 2 onto track 3 citing this example parentheticaily 1 Set the INPUT selector switches to TAPE on the channels numbered to correspond with the tracks from which the transfer will be made 9 when program is being transferred from tracks 1 and 2 to track 3 set the channel 1 and 2 switches to TAPE position 2 On the same channels you just switched to TAPE mode set the 4 CHAN BUSS selector switches and PAN pots so that signal is assigned to the track onto which the transfer will be made All other 4 CHAN BUSS selectors should be in the center OFF position e g since the transfer is made onto track 3 the channel 1 and 2 4 CHAN BUSS switches should be in 3 4 position and their PAN pots should be fully CCW to L Set the METER switch to RECORDER position so you can monitor the level being applied to the track on which Figure 10 Steps for combining two tracks to one 00 7 recording will be made The meters also will deflect on those tracks from which program is being derived but since this is ahead of the INPUT FADERS such meter indications are not particularly useful Set MONMI
36. edances of 600 ohms to kohms whereas high impedance refers to load impedances of 10 kohms to 100 kohms Speaker impedances typically vary from 3 to 16 ohms The actual source impedance of a power amplifier s speaker output is often in the order of 1 10 of an ohm or less SECTION 10 CLEANING AND DEMAGNETIZATION CLEANING Magnetic recording tape no matter how good in quality will always shed some of its oxide coating as it travels past the tape guides and head assembly Whenever a small particle of oxide dust dirt hair etc comes between the head and the tape audible performance can be degraded especially at high frequencies Regular cleaning of the tape heads and guides will avoid such losses and restore full fidelity If the oxide should be scraped off a portion of the tape back ing there will be a momentary loss of sound a drop out Drop outs are permanent flaws in the tape and must be avoided Clean guides and heads are less apt to scratch the tape This is another reason for routine cleaning Standard tape head cleaning solvents are available from most Fostex dealers An ideal solvent consists of 100 pure isopropyl alcohol Rubbing alcohol should not be used even though it is isopropyl it usually contains water and oils which will leave an unwanted residue after cleaning CAUTION Never use organic solvents such as methyl ethyl ketone MEK lacquer thinner acetone etc These can dissolve the materials that bin
37. eproduce amplifier to the record input signal Then as soon as either the PLAY or STOP button is de pressed the LED turns off and the SYNC signal returns to the repro duce amplifier you press RECORD and PLAY at the same time If none of the four RECORD TRACK selector buttons 14 is depressed the RECORD MODE LED adjacent to the RECORD button blinks and tape is transported in play mode The unit is record ready however and should any RECORD TRACK selector button be depressed its track will immediately enter record mode If one or more RECORD TRACK se lector buttons is already depressed when the RECORD and PLAY buttons are pressed the corresponding track or tracks will enter record mode The RECORD MODE LED next to the RECORD button will be illumi nated as will be the RECORD TRACK LED for any track that is recording you press PLAY on the control panel and subsequently press the REMOTE FOOT SWITCH PUNCH IN PUNCH OUT Until the first time the REMOTE FOOT SWITCH is actuated which puts the unit in the RECORD mode the transport will be in play mode after the second actuation of the switch the unit returns to this mode After the REMOTE FOOT SWITCH has been actuated once the transport will behave as though the RECORD and PLAY buttons had been pressed simultaneously as in 6 above and sequentially alternate between RECORD and PLAY modes with each depressing of the FOOT SWITCH 17 STO
38. ere b Bring up the input FADERS on the channels with new signals and balance these with the previously record ed tracks f 3 or more new inputs are being added and the TAPE OUT 1 amp 2 jacks are patched directly to RECORD IN 3 amp 4 then there is no way to adjust the transfer level instead adjust the input FADERS for the new signals to achieve the desired balance with the tracks being transferred 9 Rewind the tape by pressing ZERO RETURN 10 Depress the RECORD TRACK 3 amp 4 buttons to make these tracks ready for recording 11 When ready to record press the PLAY and RECORD but tons Alternatively press PLAY and use the REMOTE PUNCH IN FOOT SWITCH to initiate recording be sure to begin recording before the original tracks start TO PLAYBACK AND EVALUATE THE STEREO TRANSFER 1 Press ZERO RETURN to rewind the tape 2 Release the RECORD TRACK buttons for safety 3 the appropriate INPUT selectors to TAPE position channels 3 and 4 in this case 4 Set the other INPUT selectors channels 1 amp 2 to OFF to avoid confusion from any previously recorded tracks or live inputs 5 Press the PLAY button 6 Adjust headphone level with the HEADPHONE control 7 you prefer to make changes simply repeat steps 1 through 11 of the previous procedure Once satisfied you are free to record new program on the original tracks which are no longer needed e g tracks 1 and 2 in this example Figure 1
39. g and remixing can become more complicated than necessary A simple system of noting the signals which are recorded on each track and some basic control settings will simplify future operations An informal note pad or a system of log sheets may be kept A sample fog sheet track sheet is shown in Figure 4 along with a blank form Fig 19 for you to reproduce in quan tity for your own use Figure 4 Recording sample log form NOTE ALL TAPE No SONGITITLE START DATE END DATE PERFORMERS ON BACK OF 3 LOTE TO LEARN 2 25 21 3 2 89 THIS SHEET INITIAL TAKE amp OVERDUBS PROGRAM ON EAGH TRACK OF TAPE TRACK 2 TRACK 3 COMMENTS NOTES TRACK 1 TRACK 4 RECORD TRACK SELECTOR SETTINGS FOR INITIAL TRACK ASSIGNMENT RAY THEM OVITAR Foe OW Gustave PATCH 0 Te Dedeg UAT oro 277 TRACK fom Chatt BEAD LEAD TRANSFERS TRACK COMBINATION PROGRAM TRANSFERRED ONTO EACH TRACK OF TAPE TRACK 1 TRACK 2 TRACK 3 TRACK 4 Rayon BE TATI 22 RY amp ba ERASER 2 Voc 6 rit 222 a se LEAD gas 4 lmp 2 45 To THACK 4945 22 SETUP FOR REMIX TO STEREO OR MONO EFFECTS PATCH AUX OUT AUX AUX RCV COMMENTS CO
40. hand to operate a fader EQ or other controls when record ing initial tracks or doing inserts and overdubs 35 AC POWER CORD First make sure the unit s POWER switch 24 is off Then plug this cord into a suitable AC power outlet check the specifications for the proper line voltage and frequency INTRODUCTION The Fostex Model 250 incorporates 4 input x 6 output mixer and a 4 track 4 channel cassette tape recorder a com plete recording system less microphones moniter amp and speakers in a lightweight compact housing With the very portable Model 250 setting up an instant recording studio easy in hotel room or at a friend s place as it is at home The system is ideal for making original multi track recordings overdubbing and mixing down to stereo The Mode 250 provides many alternate signal flow paths thanks to a variety of assignment switches pan pots and auxiliary in out jacks This not only provides creative flexibility it also enables the unit to serve as a back up mixer for simple sound reinforcement applications SECTION 2 Live instruments and vocals tend to generate high instan taneous peak levels and sometimes low average levels both of which tax the limits of the mixing and recording equipment These extremes the difference between maximum un distorted recording level and the noise floor constitute the dynamic range of the program In commercial recordings and broadcasts
41. iate the insert in this case 6 To end the insert either a Press the STOP button or b Step on the REMOTE foot switch a second time 21 INTERFACE DETAILS This section of the manual is written for the non engineer who may have only vague idea of the meaning of levels whether expressed in dBV volts or millivolts and who prob ably understands even less about impedance expressed ohms kilohms The following subsections are written to impart a greater understanding of level and impedance with specific regard to the Model 250 SECTION 9 LEVELS AND DECIBELS 48 Level is a term loosely used to describe the amplitude of a signal or a sound More precisely level is the value of a sound or signal relative to a given reference and usuaily ex pressed in dB SPL DeciBels Sound Pressure Level dBV DeciBels Volts The relationship between dB and volts or dynes when discussing sound pressure is not a 1 1 because the dB value expresses a ratio one which is based on logarithms NOTE An understanding of the following few paragraphs can be very helpful but is not necessary for connecting the Modei 250 to other equipment We have avoided formulas and highly technical language to the extent possible If the voltage level is doubled the number of is not doubled it is increased by 6 This means that whether the voltage goes from 30 millivolts to 60 millivolts a 30 mY in crease or from 5 volts to
42. ids distraction from live inputs before or after playback the input is dead during actual playback 4 Press the PLAY button If necessary adjust HEAD PHONE level TO OVERDUB ADDITIONAL TRACKS Repeat the preceeding overdub steps Input channel 1 may continue to be the live channel assign it to tracks 1 and 3 by switching the 4 CHAN BUSS selector and adjusting the PAN pot below that selector Also press the 1 or 3 RECORD TRACK button to make the appropriate track ready for recording When setting level with the TRIM control observe the VU METER corresponding to the track on which the live program is being overdubbed VU METERS for the other tracks tracks 2 and 4 will be inactive until the unit is placed in record mode at which time they display the previously recorded signal levels 12 You may wish to combine two or three previously recorded tracks on to another track which tracks for addi tional overdubbing This process is known as combining tracks a ping pong and is described in Section 6 SUGGESTION When the recording and overdubbing pro cess is completed and no further recordng is contemplated it is a good idea to protect the cassette against any inadver tent erasure Do so by punching out BOTH safety tabs on the rear edge of the cassette Do not assume one safety tab will offer protection Since the Model 250 records all four tracks on one side of the casse
43. is set at the same position used for initial track recording NOTE There is an alternate approach to headphone monitoring where the INPUT selector is set to TAPE posi tion This allows use of channel EQ track to track balance via FADERs but the added complexity is unwar ranted during this reference playback Reduce the HEADPHONE level setting as a precaution Then press the PLAY button to commence playback and readjust HEADPHONE level as required To check the recorded level leave the METER switch in RECORDER position and observe the active VU METER 4 in this example It should indicate about the same level as shown prior to recording that is peaks of to 0 VU A large discrepancy in playback level suggests that the tape is not of the proper oxide formulation or that the record play electronics require alignment 6 When the playback is completed press the STOP button NOTE if you are satisfied with the first take you can con tinue the recording process by following the steps for sync recording overdubbing in Section 4 if you prefer to erase and re record the first take proceed as follows a Press ZERO RETURN to rewind to the beginning of the take b Press the 4 RECORD TRACK SELECT button to ready track 4 for recording Press RECORD and PLAY simultaneously and record the take again The first take will automatically be eras ed as the new one proceeds SUGGESTION Multi track recordin
44. is under way the levels can be retrimmed slightly as may be required 9 Begin with the TRIM control set fully CCW at LINE posi tion Then with a typical signal present at the channel in put adjust the trim control until the METER pointer peaks at from VU to 0 VU 4 meter in this example The peak indicating LED in the meter face should flash only occasionally if at all Do not record at too low a level 0 20 VU as this will cause excess noise If the peak LED flashes regularly with the VU meter topping at 3 10 0 VU the sound source has a very high peak to average signal ratio 0 forte piano or plucked guitar To avoid distortion readjust the trim to reduce LED flashing and accept the somewhat lower average VU level It may be desirable to use a compressor NOTE The system is now adjusted for proper signal levels from the channel input through the record elec tronics and onto the tape It is now appropriate to set up the monitor section adjustments of HEADPHONE level do not affect the recording or VU levels 10 The MONMIX knob is set at 7 This knob is located at top of channel 4 the other MONMIX knobs set full W NOTE Observe that the MONMIX controls associated with channel 4 are used not channel 1 This is because the recording is occuring on track 4 Any one or more in put channels can be assigned to track 4 channel 1 was used here but the playback from track 4
45. levels respectively depending on the setting of the METER function switch 10 10 METER FUNCTION SWITCH RECORDER MIXER All four meters will monitor the signals determined by the METER selector switch as explained below RECORDER Indicates recorder s out put levels as follows the Record input of those channels in the record mode and the tape output of those channels in the play mode Indicates 4 CHAN BUSS OUT levels from the mixer section Although all four channel buss outputs are applied to the recorder channels 1 and 2 are also fed to the rear panel LINE OUT 1 2 jacks and there fore meters 1 and 2 also monitor the LINE OUT s Aux Receive 1 2 and Headphone Level 11 AUXILIARY RECEIVE LEVEL CONTROL RCV 1 2 This control simultaneously adjusts the level from both the LEFT and RIGHT AUX IN Jacks 28 The signals are then applied to BUSS CHAN 1 and BUSS CHAN 2 of the 4 CHAN BUSS ahead of the MASTER 1 2 fader 13 When AUX IN is used for effects return this control adjusts the proportion of effect 0 reverb or echo to dry signal When AUX IN is used as a sub input from another mixer or remote feed the RCV 1 2 control serves as a sub master for the remote mix If possible it is recom mended that RCV 1 2 initially be set at 7 and the output level from the effects unit or other mixer be set for proper balance and low distortion if it is not practical to adjust the incoming level MIXER
46. n other words the playback signals are output here when the RECORD TRACK button is depressed then change to the record input signal when the transport is put in the record mode 28 AUX IN JACKS AUX 1 and 2 These jacks apply a stereo signal to RCV 1 2 ahead of the MASTER 1 2 FADER 13 The signal levels applied to CHAN 1 and CHAN 2 of the 4 CHAN BUSS are adjustable by means of the RCV control 11 29 LINE OUT JACKS LINE OUT 1 2 These jacks carry the output from the BUSS CHAN 1 and BUSS CHAN 2 of the 4 channel buss The LINE OUT signal level is adjustable by means of the MASTER 1 2 FADER 13 The LINE OUT jacks can be used during remix for transferring the mixed program to a stereo recorder They also are useful for driving a control room monitor amplifier during recording or overdubbing 30 AUX SEND JACK monophonic This jack carries a mono mix of the four input channel signals as determined by the setting of their AUX SEND controls This output is a post EQ and post input fader controlled signal and can be sent to external auxiliary signal processing equipment such as a compressor a graphic equalizer an echo or delay unit or a reverb 31 MONMIX JACK monophonic This jack carries the mono mix signals of the recorder s four channel outputs which are individually level set by the four MONMIX controls before being mixed into mono Depending on whether particular track is in record mode or play mode the
47. nd mode it will continue rewinding until the counter displays 0000 22 PITCH CONTROL This control can be used to vary the constant tape winding speed by 10 during record or play modes For nominal 3 3 4 ips 9 5 cm s tape speed center the control it will into position Turning the knob CCW decreases tape speed and turning it CW increases tape speed 23 CASSETTE WELL AND COVER A transparent plastic cover protects the cassette during operation To insert or remove a cassette open the cover by placing a finger under the recess on the right edge of the main panei and lifting up Observe that the raised edge of the cassette where the tape is visible should face the front of the cassette well NOTE Use C 60 or C 90 cassettes not 120 The bias and tape equalization are Suitable for gammaterric oxide tape that requires high bias level and 70 microsecond EQ For optimum results use only this type of tape e g TDK SA MAXELL UD 1 equivalent 24 POWER SWITCH Actuating this switch located at right of the rear panel turns on the power to the mixer electronics and the tape trans port The VU meter faces will be illumi nated if power is on and the unit is plug ged into a tive AC outlet FRONT PANEL FEATURES Front Panel 25 CHANNEL INPUT MIC LINE JACKS applies to 1 through 4 This standard phone jack accepts any low or high impedance unbalanced input from nominal 6
48. nly high impedance inputs they must be bridged This impedance level relationship is not always the case it is merely a com mon design practice Insofar as actual engineering design there is no set relation ship between high and low impedances and high and low levels However the maximum level available from a given output may be reduced when that output is connected to a low impedance input compared to the level it will deliver to high impedance input For example consider an output rated at 15 dBV maximum into 10 kohms or more Such an output might be useable with a 3 kohm load although with such a oad it might be reduced to a maximum level of 8 Be careful though the same 3 kohm load could cause another similarly rated output circuit to fail altogether How many ohms constitute a high impedance A low im pedance These terms are relative and depend on the nature of the equipment and whether an input or output is 23 being described The ranges cited below are approximate With microphones iow impedance refers to 50 fo 250 ohms whereas high impedance refers to 1 kohm or higher actual source impedance With line level outputs on mixers and accessory equip ment jow impedance refers to actual source impedances of 10 ohms to 600 ohms whereas high impedance refers to 2 kohm or higher source impedance With line level inputs on mixers and accessory equip ment impedance refers to actual load imp
49. or improve separation from other channels by accenting or minimizing paris of the frequency spectrum 13 Set the 4 CHAN BUSS selector of channel 1 to OFF posi tion and that of channel 2 to 1 2 and bring up the fader of channel 2 Repeat steps 11 and 12 for channel 2 and for each of the remaining channels thus creating a stereo panorama of the various acoustic images 14 Bring up all four channel input FADERS to nominal set ting then move them down or up as required to balance the level between tracks Observe the VU METERS to ensure that the level peaks between 3 VU and 0 VU in both the 1 track 1 and 2 track 2 meters the red peak indicator LEDs should flash only once in a while NOTE The 3 and 4 meters will be inactive in this mode only the 2 channels are being monitored 15 If necessary adjust the MASTER 1 2 FADER to obtain the correct VU indications with these exceptions a lf the MASTER FADER must be set below 6 instead reset it at 7 and lower all four input FADERS suffi ciently to obtain the optimum level b If the MASTER FADER must be set between 9 and 10 instead reset it at 8 and raise all four input FADERS sufficiently to obtain the optimum level NOTE If the speakers are too loud or too quiet adjust the monitor amplifier volume or if phones are used adjust HEADPHONE volume 16 Rewind the tape press ZERO RETURN or REWIND then STOP if desired press PLAY and recheck the balance and soun
50. ous organ note signal levels aimost always vary up and down as the sound itself changes from very loud to very quiet For this reason the term 22 nominal level is used to describe the approximate operat ing level of a given circuit expressed in dB or voltage Remember that minimum levels quietest passages are below the nominal level and maximum levels loud pas sages are above the nominal level With regard to the Model 250 and related equipment there are several nominal levels involved the most significant of which microphone level iine level Nominal mic level 60 dBY 1 millivolt Nominal line tevel 10 dBV 300 millivolts 0 3 volts MODEL 250 INPUT LEVELS When connecting mics to the Model 250 MIC LINE INPUTS remember that some microphones have higher output levels than others a given mic wilt have a higher level when it is nearer to the sound source or when the sound is louder Hence a microphone s nominal level may be higher than 60 dBV sometimes as high as 30 dBV Instruments such as electric guitars and pianos may have nominal levels higher than 60 dBY but perhaps lower than 10 dBV Most consumer tape recorders tuners stereo equipment and so forth utilize line levels of approximately 20 to 10 This is why the TRIM LINE MIC control is provided it allows the input sensitivity to be adjusted to suit the actual input source The Model 25
51. p during the remix if desired working from several Model 250 master tapes C 120 cassettes are not recommended because they use a thinner tape backing 1 2 mil and the many record play operations necessary to create a master tape will tend to wear out or the more delicate tape 15 it worth risking the hours of work spent creating a tape only to have it break wear or jam in the final stages Use only premium quality 90 or shorter tapes to be safe USING THIS MANUAL The balance of this manual is presented in a sequence of the basic steps one would follow to create a master tape from recording the original tracks to syne recording overdubbing and then mixdown remixing After that combining tracks ping pong stereo recording and other peripheral topics are covered If the reader is quite familiar with hooking up elec tronic systems a look at the electronic specifications and block diagram in Section 11 will suffice Otherwise we recommend reading the front and rear panel descriptions in Section 1 and also the interface information in Section 9 Most procedures are organized so they can be followed step by step Accompanying diagrams are labelled to show those features associated with the numbered steps SECTION3 INITIAL RECORDING CUTTING ORIGINAL TRACKS PREPARING TO RECORD THE FIRST TRACK Figure 2 Steps for initial recording with Model 250 NOTE Cassette tapes must be smoothly and evenly wound
52. rce impedance or higher the input is said to be bridging the output This distinc tion is not critical except in certain cases where the output must be bridged to avoid overloading or distortion some passive equalizers matching not bridging is required to preserve proper frequency response A typical example of a bridged output is a case where the source imped ance is 2 000 ohms yet the minimum load impedance is 20 000 ohms One kilohm abbreviated kohm equals 1 000 ohms Loudspeakers are an exception there is no standard frequency at which impedance is measured a speaker is usually rated close to its minimum impedance Do not connect a high Z output to a low Z input Sometimes an output can be operated into a load of equal im pedance matching it is seldom that an output can be operated into a load of lower impedance that the output s source impedance For example an output with 2 kohm source impedance should not be connected to an input hav ing a 600 ohm actual load impedance distortion and possi ble overheating and failure of the output circuit could occur FIGURING IMPEDANCE WHEN ONE OUTPUT DRIVES TWO OR MORE INPUTS When Y adapter is used to feed two inputs from a given output the combined input impedance seen by the output is actually jess than the rated load impedance of either input alone This places a greater load on the output Rather than explain the formula to calculate actual impe
53. recorder output signal fed to the summing amplifier All four recorder output channels are mixed into mono by the summing amplifier for feed to the MONMIX jack This mono MONMIX signal is generally used as a cue signal to the musicians The recorder s four channel outputs will be derived from the tape out signal when in the play mode and record input signal when in the record mode VU Meters and Meter Selector 9 VU METERS The four VU meters identical illuminated meters with standard VU ballistics meter levels relate to the perceived loudness A red LED in the corner of each meter illuminates when the instantaneous peak level ap proaches the clipping point providing a better means to avoid distortion than the slower responding meter Typical meter readings should peak at from 3 VU to 0 VU although per cussive or plucked instruments may require lower average readings in order to avoid distortion during the initial high level transient As a rule occa sional flashes of the LEDs are accept able but levets should not be so high as to cause frequent flashing or continu ous LED illumination Meters 1 through 4 monitor record and playback levels on their respective tracks when the METER selector is set to RECORDER position However the four meters monitor the 4 CHAN BUSS OUT s when the METER selector is set to MIXER position The 1 and 2 meters can also monitor the LEFT and RIGHT of LINE OUT
54. recording 2 mic purist or panned multiple mics the recording can be completed in one Figure 12 Stereo recording using 2 microphones one assigned to track track 1 and one to a right track track 2 to capture the stereo panorama a purist approach A typical Modet 250 setup for this recording is shown Si Soles Stereo Panorama Center Right take or it may be augmented in subsequent overdubs To overdub the original pair of stereo tracks are transferred 1 1 to a second pair of tracks and at the same time are mixed with any new sound sources stereo mic or otherwise The term stereo often has been used imprecisely to describe 2 track or 2 channel recordings 2 track record ings a pair of tracks contain related sounds whether record ed at the same time or via an overdub but each track has a discrete sound source so that playback does not create a coherent stereo panorama In this instance remixing and panning each track somewhere from left to right will be required to obtain a stereo image In practice the distinction between stereo and 2 track recording is primarily a matter of mic placement and pan pot position For this reason both techniques are discussed together in this section of the manual Figure 13 Stereo recording using multiple microphones each panned at some location between the and
55. rs when the PAN pot is rotated clockwise NOTE 4 CHAN BUSS pot may be bypassed and the input can be applied directly to one or more record tracks by connecting a cable from the chan nel DIRECT OUTPUT to the desired RECORD INPUT s and setting the 4 CHAN BUSS selector 1 2 OFF 3 4 6 to OFF position NOTE When recording or overdubbing one track at a time it is recommended that this pan pot be set fully to one side or the other in order to apply the channel s signal to a single track Pan ning to intermediate positions is general used during mixdown at which time two tracks are assigned as a stereo pair 9 tracks 1 and 2 and the pot then pans the signal left right or anywhere between This can also be done when recording original stereo tracks or when overdubbing in stereo 6 4 CHAN BUSS SELECTOR 1 2 4 SWITCH This lever type switch determines whether the channel s 4 CHAN BUSS PAN pot 5 applies signat to recording busses 1 and 2 or to busses 3 and 4 The switch is off in mid position which means that no signal from the PAN pot is applied to any recording buss 7 AUX BUSS This control feeds the input channel s post fader and post equalizer signals to a summing amplifier that mixes the Aux Sends of all four input channels for feed to the Aux Send jack This mono mix may be used to feed external auxiliary signal processing equipment 8 MONMIX This controls the
56. ster tape recorder should also be connected and ready 1 Rewind the cassette press ZERO RETURN or REWIND amp STOP 2 Set the METER function switch to MIXER position 3 Make sure alt RECORD TRACK buttons are released in record safe position to preclude accidental erasure of the multi track master cassette 13 Set all INPUT selector switches to TAPE position Initially set all input FADERS at nominal 7 to 8 ne NOTE The TRIM controls have no effect when the unit is operated in this configuration Initially set 4 CHAN BUSS PAN pots at center Set the MASTER 1 2 FADER at nominal 7 to 88 Press the PLAY button causing tape to roll Gradually bring up the monitor amplifier volume until the desired level is heard Alternately if listening with head phones adjust the HEADPHONE volume control CW from OFF position 0 NOTE Both channels will have the same program mono and relative balance probably will be incorrect at this point 10 Set the 4 CHAN BUSS selector to 1 2 of channel 1 and those of other channels 2 through 4 to OFF position and the channel 1 fader to nominal position 11 Adjust the 4 CHAN BUSS PAN pot on channel 1 to place the program from track 1 anywhere from left to right in the stereo perspective 12 Adjust the channel 1 EQ controls as desired to a obtain the most pleasing sound quality b reduce leakage of unwanted sound in the channel
57. ted 65 dB unweighted 650 at 1 000Hz 50dB at 1 000Hz 70dB at 1 000Hz 120V AC 60Hz 35W U S A Canada models 220V AC 50Hz 35W European models 240V AC 50Hz 35W UK Australian models 100 120 220 240 50 60 2 35W general export models 430 x 80 x 355mm 17 x 3 148 x 14 Net 85 Kg 19 Ibs Shipping 9 5 Kg 21 165 motor 80 seconds for C 60 Specifications subject to change without notice Dolby is the registered trademark of Dolby Laboratories inc San Francisco CA 27 FOSTEX FOSTEX CORPORATION 560 3 Miyazawa cho Akishima Tokyo Japan FOSTEX CORPORATION OF AMERICA 15431 Blackburn Ave Norwalk CA 90650 U S A PRINTED IN JAPAN DEC 1984 8288 0040 00
58. tep on the foot switch at the moment the insert must begin a second actuation of the foot switch ends the insert returning the unit to play mode Figure 18 Steps for making an insert 5a 600000000000 Te 1 or instrument to an input channel and assign that channel so its signal goes to the track on which the insert will be made use the 4 CHAN BUSS selector and PAN pot 2 Depress the RECORD TRACK button for the track onto which the insert will be made 3 Set all MONMIX to scale 7 4 Set the METER function switch to RECORDER position 5 Press PLAY monitoring the existing track s in the head phones At the moment you wish to begin the insert either a Press PLAY and RECORD simultaneously or b Step on the REMOTE PUNCH IN PUNCH OUT foot switch NOTE We recommend beginning an insert at a time when no signal is present on the track to be used 0 between notes or during rest if possible also begin the insert in synchronization with a drum beat on another track These procedures will help avoid or mask any audi ble click that might be created by the insert NOTE An alternate method to begin the insert is to leave aif RECORD TRACK button switches disengaged and to initially press the PLAY and RECORD buttons Then to begin the insert depress the appropriate RECORD TRACK bution The REMOTE FOOT SWITCH cannot be used to init
59. ters stoves or other appliances including amplifiers that produce heat Power Sources The appliance should be connected to power supply only of the type described in the operating instructions or as marked on the appliance Power Cord Protection Power supply cords should routed so that they are not likely to be walked on or pinched by items placed upon or against them paying particular attention to cords at plugs convenience recep tacles and the point where they exit from the appliance Controls Indicators amp Connectors Introduction Initial Recording Cutting Original Tracks Sync Recording Overdubbing Mixdown Remixing Combining Tracks Ping Pong Stereo Recording Inserts Punch In Recording Interface Details Cleaning and Demagnetization BLOCK DIAGRAM Specifications 10 11 appliance should be cleaned only as recommended by the manufacturer Nonuse Periods The power cord of the appliance shouid be unplugged from the outlet when left unused for a long period of time Object and Liquid should be taken so that objects do not fall and liquids are not spilled into the enclosure through openings Damage Requiring Service The appliance should be serviced by qualified service personnel when A The power supply cord or the plug has been damaged or Objects have fallen or liquid has been spilled into the appliance or C
60. that power is controlled by plugging in or unplugging the unit from the AC mains 1 Turn off the Model 250 and remove any cassette tapes to a distance of at least 6 feet 2 meters 2 Before plugging in the demagnetizer hold it at least 3 feet 1 meter from the 250 Then plug it in 3 Gradually move the demagnetizer toward the recorder until the tip is about 1 8 inch 3 mm from the heads 4 Slowly pull the demagnetizer away from the heads to a distance of about 3 inches 75 mm then back to within 1 8 inch of nearby metai parts tape guides capstan etc Con tinue this process until the demagnetizer has been waved near all parts in the tape path but DO NOT TOUCH ANY OF THE PARTS WITH THE DEMAGNETIZER PROBE 5 Gradually withdraw the demagnetizer until it is at least 3 feet 1 meter from the Model 250 Then unplug the demagnetizer This completes the demagnetization process Figure 19 Blank log sheet for reproduction NOTE ALL TAPE No SONG TITLE START DATE END DATE PERFORMERS ON BACK THiS SHEET INITIAL TAKE amp OVERDUBS PROGRAM ON EACH TRACK OF TAPE COMMEN OTES TRACK 2 TRACK 3 TRACK 4 RECORD TRACK SELECTOR SETTINGS FOR INITIAL TRACK ASSIGNMENT TRANSFEARS TRACK COMBINATION PROGRAM TRANSFERRED ONTO EACH TRACK OF TAPE TRACK 2 TRACK 4 SETUP FOR REMIX TO STEREO MONO EQUAL 2 PRAN AN 1 2 EFFECTS PATCH 300 4K AUX QUT AUX BLOCK DIAGRAM SECTION 11 auod
61. to overdubs Chrome tape was not chosen because it can cause premature tape head wear and because gamma ferric oxide formulations afford virtually identical performance The gamma ferric oxide tape specified is widely available e g TOK SA Maxell UDXL II It yields high output low noise and extended high frequency response While other tapes will function in the Mode 250 performance will be degraded the noise floor will be higher maximum record levels may be lower and frequency response may be uneven We recommend using only C 60 or C 90 cassettes which normally run 30 and 45 minutes a side respectively Since the Model 250 runs twice speed and the tapes cannot be turned over the usable time is 1 4 that suggested by the tape label as shown on the following chart Running time in 250 at nominal 3 3 4 ips Pitch control centered 1 2 minutes Cassette Running time in length standard recorder at 1 7 8 ips 15 minutes per side 30 minutes total 22 5 minutes per side 45 minutes total 45 11 1 4 minutes C 60 30 minutes per side 15 minutes 60 minutes total 90 45 minutes per side 22 112 minutes 90 minutes total C 120 60 minutes per side NOT RECOMMENDED FOR 120 minutes total USE WITH Model 250 If the running times seem short remember these are master tapes one side of an LP aloum seldom runs more than 22 1 2 minutes Longer recordings can be built u
62. tte with only one safety tab removed it would be possible to insert the cassette upside down and inadvertently record over your valuable program Figure 7 Punching out the record safe tabs to prevent erasure of or recording over an existing program Side B safety tab Side safety tab SECTIONS MIXDOWN REMIXING During the initial recording and overdubbing stages tracks are recorded at near maximum levels Also it is probable that each sound source has been recorded on only one track not panned between tracks The final stage in creating a stereo program requires that track to track levels be balanced and that each track be panned somewhere from left to right in the stereo perspective Some touch up equalization may also be done at this time The final process is known as mixdown or remixing In previous steps you monitored the program using head phones and the Model 250 MONMIX buss signal came directly from the reproduce amplifiers Monitoring is more critical during the mixdown and hence loudspeakers are preferable to headphones although phones can be used Any good stereo high fidelity sound system wilt do the job Simply connect a pair of cables from the Model 250 LINE OUT 1 and 2 jacks to the auxiliary or line inputs on the stereo integrated amplifier or receiver or to the power amp inputs by set of Y cables As precaution turn off the stereo amplifier and set its volume at minimum before conn
63. ve using the remaining free input channel 3 in this case The only trick involved in using the same channel for a live input and to assign the record track is the headphone monitoring set channel 835 to scale 7 when first adjusting the live source 50 you can listen to the input to the recorder and thus monitor the previously recorded program and the live SOUrCeS Press the PLAY button and adjust the input FADERS on those tracks being combined Balance this sound with any live inputs 100 NOTE The VU meter corresponding to the track on which the recording is being made track 3 should show normal levels peaking at to 0 VU if not retain the relative balance by adjusting the INPUT FADERS on channels contributing to the recording pre recorded and five Remember that the MONMIX contro has no effect here the HEADPHONE control affects only the listening volume not the recording level The system is now ready for the actual recording Press ZERO RETURN or REWIND then STOP to get back to the beginning of the program Simultaneously press PLAY and RECORD and the tracks are combined onto one For greater convenience when adding a new input press PLAY and use the REMOTE PUNCH IN foot switch to initiate recording be sure to begin recording before the original tracks start TO PLAY BACK AND EVALUATE THE TRACK COMBINATION Figure 11 Steps to evaluate a combination ping pong

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