MixPre User Guide
Contents
1. Two color LED illuminates green when the unit is powered and changes to red when bat teries require changing For external DC the power LED is always green page 4 Input Panel Connectors and Controls SOUNDSDEVICES 14 15 16 17 MIC INPUTS Transformer balanced XLR inputs accepts microphone level signals Pin 2 hot pin 3 cold pin 1 ground PHANTOM Power Three position switch selects either 48 volt or 15 volt phantom power for both inputs Center position turns phantom power off Phantom positions reduce input sensitivity by 10 dB High Pass Filter Switch Three position switch selects 80 Hz or 160 Hz corner frequency filters 6 dB per octave Filters affect both inputs Center position of switch removes filters from the signal path Tape Output 3 5 mm TRS stereo output unbalanced can be used to feed consumer level DAT Mini Disc and CD recorders Tip left ring right sleeve ground 15 16 18 19 20 19 20 Tape Return Level Control Recessed potentiometers adjust Tape Return level feeding the Headphone Monitor Limiter Switch Activates input peak limiter ON position functions as a dual mono limiter with each input signal controlling its own limiter LINK functions as a stereo limiter with both left and right inputs controlled simultaneously Center position of switch turns limiter off Limiter Threshold Level Control Recessed2. bandwidth gain control set at 50 or higher phantom power off 10 dBu minimum phantom off 0 dBu minimum phantom on Line 22 dBu minimum with 100k ohm load 20 dBu minimum with 600 ohm load Tape 8 dBu 2 0 V RMS minimum with 100k ohm load 110 dB minimum 0 05 maximum from 50 Hz 22 kHz 4 dBu output level 46 dB gain setting 100 dB minimum at 80 Hz 60 dB minimum at 10 Hz Greater than 80 dB at 1 kHz gain controls set to 50 Transformer balanced 2k ohm input impedance Tape In to Headphone Output Unbalanced 1 meg ohm input impedance XLR Active balanced 120 ohm output impedance Tape 3 5 mm Unbalanced tip left ring right sleeve ground 2 1k ohm output impedance 80 Hz or 160 Hz switch selectable 6 dB per octave 15 V through 680 ohm resistors or 48 V through 6 8k resistors switch selectable Thresholds independently adjustable from 6 dBu to 18 dBu 10 1 limiting ratio 5 mS attack time 100 mS release time Amber Red LED indicates limiting clipping dual mono or stereo linked 15 V regulated High efficiency peak responding 7 segment GaN Gallium Nitride meter with 3 brightness levels Internal 2 AA alkaline batteries 6 hours life typical with 4 dBu signal into 600 ohms no phantom External Isolated external DC input jack 5 18 V on locking 4 pin Hirose connector pin 4 pin 1 Use gold Hirose HR10A 7P 4P or silver Hirose HR10 7P 4P for locking mating DC connector voltages abo
3. especially at low frequencies while keeping distortion to a minimum Be cause of their inherently high common mode impedance transformers are unrivaled by any other type of input for common mode noise rejection Output Circuitry and Tape Output Each line level XLR output of the MixPre uses an active balanced output stage The circuit provides robust line driving capability To drive unbalanced inputs pin 3 should not be connected When unbal ancing the connection the output level will be reduced by 6 dB The Tape Output is designed to feed consumer level devices such as computer sound cards DAT or MiniDisc recorders and cassette recorders A cable wired with 3 5 mm TRS to 3 5 mm TRS or 3 5 mm TRS to Left Right phono RCA connectors is useful when directly connecting the MixPre to portable consumer audio electronics The Mix in MixPre The MixPre pan switches assign each input channel to an output bus With this feature the MixPre can be used as a two channel microphone preamplifier and as a simple mixer As a mixer many applica tions are possible such as page 6 SOUNDSDEVICES e Quickly reversing the stereo image of a recording without reconnecting inputs or outputs e During set up checking for mono compatibility by assigning both inputs to the same output e Recording dialog in mono By routing input 1 to Center and input 2 to Right a summed mono signal of both inputs appears at the Right output while only inp
4. on an individual basis THE WARRANTY AND REMEDIES SET FORTH ABOVE ARE EXCLUSIVE SOUND DEVICES LLC DISCLAIMS ALL OTHER WARRANTIES EX PRESS OR IMPLIED INCLUDING WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE SOUND DEVICES LLC IS NOT RESPONSIBLE FOR SPECIAL INCIDEN TAL OR CONSEQUENTIAL DAMAGES ARISING FROM ANY BREACH OF WARRANTY OR UN DER ANY OTHER LEGAL THEORY Because some jurisdictions do not permit the exclusion or limita tions set forth above they may not apply in all cases For all service including warranty repair please contact Sound Devices for a return authorization num ber RMA before sending the unit for service Service returns should be sent to Sound Devices LLC Service Repair RMA Sound Devices assigned 300 Wengel Drive Reedsburg WI 53959 USA telephone 1 608 524 0625 page 10 SOUNDSDEVICES CE Declaration of Conformity According to ISO IEC Guide 22 Sound Devices LLC 300 Wengel Drive Reedsburg WI 53959 USA declares that the product MixPre is in conformity with and passes Document Number Description 89 336 EED EMC Directive EN55103 1 1997 Emissions standard for product family audio devices for professional use EN55103 2 1997 Immunity standard for product family audio devices for professional use EN55022 1995 Radiated and Conducted emissions Class B CISPR 22 1997 EN61000 4 2 1995 ESD 6kV contact 8kV air discharge TEC1000 4
5. 2 1995 EN61000 4 3 1995 Radiated RF Immunity 10 V m 80 1 kHz amplitude modulation IEC1000 4 3 1995 EN61000 4 4 1995 EFT Burst I O lines 25 kV to 1 0 kV TEC1000 4 4 1995 EN61000 4 6 1996 Conducted RF immunity 10 V m 80 1 kHz amplitude modulation IEC1000 4 6 1996 Tested by L S Compliance Inc Cedarburg Wisconsin December 16 1999 M Matthew Anderson Director of Engineering Sound Devices LLC page 11 SOUND DEVICES MixPre Compact Mixer User Guide and Technical Documentation
6. SOUNDSDEVICES MixPre Portable Mixer User Guide and Technical Information Sound Devices LLC 300 Wengel Drive Reedsburg WI 53959 USA Voice 1 608 524 0625 Fax 1 608 524 0655 www sounddevices com Copyright 2001 2007 Sound Devices LLC MixPre Compact Mixer User Guide and Technical Documentation General Description The MixPre is a studio quality two channel portable stereo microphone preamplifier mixer With its pan switches built in slate microphone 1 kHz tone oscillator and headphone monitoring the MixPre is a flexible portable mixer The MixPre has impressive audio performance and comprehensive fea tures making it ideal for the front end of any studio or field production system Radio television and film production engineers value its compact size and ability to withstand environmental extremes The MixPre combines rugged mechanical and electrical construction compact size and high quality compo nents for no compromise performance for any application Features High Performance Microphone Inputs e Maximum of 66 dB of gain per input e Premium Lundahl input transformers e Sealed conductive plastic potentiometers e High pass filters with 80 or 160 Hz corner 6 dB per octave e Input panning to Left Center or Right outputs Audio Performance Dynamic range exceeding 110 dB 10 Hz to 50 kHz audio bandwidth Exceptionally low distortion characteristics Discrete 6 transistor balanced outp
7. bient noise levels The 80 Hz position is appropri ate when recording general speech music and ambient sound The 160 Hz position is useful to enhance speech clarity The MixPre high pass circuit topology is unique in that the filters are placed immediately after the input transformer before any active gain circuitry This gives the MixPre higher headroom with low frequency signals as the low frequency signals are not amplified before they are removed as in most other designs The high pass filter is a single pole design slope of 6 dB per octave and uses high quality film capacitors for very low distortion The high pass filter switch controls both inputs The center position of the switch removes the filter from both audio paths When possible attempt to equalize at the sound source with microphone selection use of windscreens shock mounts microphone placement and onboard microphone filtering Multiple high pass filters filters on microphones and on the MixPre will give an additive effect increasing the slope of the filter Headphone Monitoring Tape Return Headphone monitoring is an essential need in production audio The MixPre enables monitoring of pro gram mixer audio or a second audio source In normal operation the headphones monitor the output bus directly Using the Tape Return input a second audio source can be monitored in the headphones This is useful to verify that signal is reaching cameras and tape machines The three po
8. fe of batteries Lithium batteries are significantly better than alkaline batteries at lower temperatures Current Draw The MixPre can vary significantly in the amount of current it draws Several functions of the MixPre directly affect current draw in different ways The following list highlights the larger current drawing functions listed from highest to lowest current draw 1 Phantom power the main source of extra MixPre current draw See Phantom Power 48V Phantom can draw copious amounts of current out of the batteries depending on what model microphone is used Two phantom powered microphones draw twice as much current as one Microphones vary widely in their current draw depending on type and phantom voltage applied 2 Headphone output circuit high headphone output levels increase current draw 3 Meter illumination intensity higher meter brightness increases current draw The meter can be switched to low for battery conservation 4 Output drive level higher output drive levels into low impedance inputs increases current draw Experimentation is recommended to determine battery life for each individual setup and application The chart below can be used as a starting point to estimate battery life Battery Type Microphone Type Battery Life Eveready AA No L91 2 dynamic handheld microphones low meter no head 11 hrs lithium phones Duracell AA MN 1500 2 dynamic handheld microphones low meter low head 6
9. hrs alkaline phones Duracell AA MN 1500 2 condenser 12 volt phantom powered microphones 4 hrs normal meter intensity normal headphone drive level Duracell AA MN 1500 2 studio condenser 48 volt phantom powered micro 2 hrs phones super bright meter intensity cranking head phones Test conditions 70 F 42 dB gain with acoustic music source 600 ohm load 4 dBu output page 9 MixPre Compact Mixer User Guide and Technical Documentation FCC Statement This device has been tested and found to comply with the limits for a class B digital device pursuant to part 15 of the FCC rules These limits are designed to provide reasonable protection against harmful interference in a residential installation This equipment generates uses and can radiate radio fre quency energy and if not installed and used in accordance with the instructions may cause harmful interference to radio communications However there is no guarantee that interference will not occur in a particular installation Warranty Sound Devices LLC warrants the MM 1 Microphone Preamp with Headphone Monitoring against defects in materials and workmanship for a period of ONE 1 year from date of original retail purchase This is a non transferable warranty that extends only to the original purchaser Sound Devices LLC will repair or replace the product at its discretion at no charge Warranty claims due to severe service conditions will be addressed
10. iable gain stage If the audio signal clips anywhere this LED will show it When the limiter is activated the input LED s illuminate amber in proportion to limiting action Headphone Clip LED Above the headphone level control the headphone clip LED shows when either channel of the headphone circuit is nearing clipping level The headphone clip LED also shows when either channel of the tape return audio is nearing clipping level Between these three clip indicators any clipping anywhere in the mixer will be seen before it is heard Output Meter The MixPre has a highly visible seven segment LED output meter The meter is peak responding showing the instantaneous output level in dBu Peak readings are essential when the out puts feed digital devices The meter uses red and green Gallium Nitride GaN LED s These premium LED s allow for excellent viewing with minimal current draw under all lighting conditions including direct sunlight The front panel Meter Brightness switch controls the meter brightness low normal or super bright The meter indicates a signal range of 46 dB From left to right the first three LED s are separated by 15 dB and the next four LED s are separated by 4 dB This calibration provides a large dynamic range with good resolution in the critical signal level range Power Sources The MixPre is designed to operate from two internal AA alkaline cells for approximately 6 hours with typical signal levels with
11. ocking and the right position is clipping illuminates amber to indicate limiter momentary activity 9 Headphone Connector Pan Switches Input Assignment Accepts stereo and mono headphones with Three position switch pans inputs to Left Cen 1 4 inch connectors ter both left and right or Right outputs 10 Headphone Volume Control Slate Microphone Adjusts the level in the headphones Condenser microphone with AGC controlled by momentary Slate Microphone Switch Slate 11 Headphone Peak LED Microphone output appears at all outputs Illuminates 3 dB before clipping of either chan nel of the headphone circuit Also illuminates Tone Oscillator Slate Microphone Switch 3 dB before clipping of either channel of Tape Toggle switch activates a 1 kHz tone oscillator Return audio when switched to the left position and acti vates the slate microphone when in the right 12 POWER Switch momentary position Microphone inputs are Three position switch selects the power source muted when tone or slate are activated The unit is powered from internal batter ies when in the left position powered from Output Level Meter external DC source when in the right position Indicates peak output level in dBu appearing Center position is off at the left and right outputs 13 POWER LED Meter Brightness Control Three position switch adjusts the intensity of illumination of the output meter low illumi nation normal illumination or super bright illumination
12. out phantom power External DC sources such as AC to DC transformers and external battery supplies can also power the MixPre Because of its regulated power supply circuitry audio performance does not change depending on battery or external DC voltage The external DC input supply is galvanically isolated floating from the chassis and the rest of the circuitry The isolation provides trouble free interconnection to other pieces of equipment sharing the same DC power source The pin 2 of the locking Hirose DC connector is positive and pin 1 is negative As the external DC supply is floating the positive or the negative can be connected to the chassis with no adverse effects page 8 SOUNDSDEVICES Battery Life Two factors determine battery life battery power and current draw Battery Power For internal power the MixPre uses two AA LR6 1 5 volt batteries Different batteries have different power capacities depending on their chemistry age operational temperature and amount of current be ing drawn Alkaline cells are a popular and cost effective battery type Lithium cells have higher power per cell with higher current draws and yield significantly longer battery life at a cost premium AA carbon cells and AA nickel cadmium cells are not recommended battery types in the MixPre since these batteries have lower power capacity than other types and will result in very short service life Tempera ture has a significant effect on the li
13. potentiometers adjust peak level of limiter activation Can be independently con trolled for each input page 5 MixPre Compact Mixer User Guide and Technical Documentation Output Panel Connectors 21 22 23 Strap Slot Attachment point for camera straps Tape Return Input Connector 3 5mm TRS stereo unbalanced connector al lows external audio sources to be monitored in the MixPre Headphone circuit Tip left ring right sleeve ground Left and Right Line Level Outputs Active balanced XLR line level outputs 22 dBu peak output level Pin 2 hot pin 3 cold pin 1 ground To unbalance use pin 2 as signal and pin 1 as ground pin 3 should not be grounded Operational Notes 25 BATTERY Compartment MixPre operates on two AA batteries Insert positive end of batteries first External DC Power Input Accepts external DC power source battery supply or AC to DC transformer from 5 18 VDC Locking 4 pin Hirose pin 4 pin 1 Input Circuitry The isolation characteristics of transformers are superior to other balancing techniques for the adverse and uncontrolled environments of field production Transformers provide complete galvanic isolation from the driving source meaning there is no direct electrical connection Signals are transformed magnetically Both the transformers in the MP 1 use premium magnetic core material to achieve high signal handling capability
14. sition Tape Return switch on the front panel selects the audio source being monitored The left and right positions monitor the tape return audio Left is locking and right is momentary The center position monitors the Left and Right outputs of the MixPre Because the MixPre can drive headphones to very high levels care should be exercised when monitoring and adjusting levels Limiters The MixPre has two built in peak responding limiters one for each input channel The three position LIMITER switch on the input panel activates both channels limiters Each limiter in the MixPre is a two stage circuit the first stage keeps the input gain stage from clipping the second stage limits the variable gain stage to the level set by the Limiter Threshold control This unique two stage topology limits the gain stage directly after the mic input transformer to make the front end virtually unclippable but does not change the input impedance as other at the mic limiters do The circuit enables the MixPre page 7 MixPre Compact Mixer User Guide and Technical Documentation to limit when necessary in excess of 50 dB making it very difficult to clip the unit no matter the gain setting The three position Limiter switch can be set to operate in either dual mono or stereo linked operation Dual mono operation ON switch position allows each input to limit independently responding only to its input signal Stereo linked operation LINK swi
15. tch position connects both limiters ensuring that the limiters control both channels identically This linking is important for stereo operation to maintain a proper stereo image When the limiters activate the Peak Limiter LED on the front panel illuminates amber in proportion to the amount of limiting for each channel Tone Oscillator and Slate Microphone The switch labeled 1 kHz SLATE controls two functions The 1 kHz position left locking activates a 0 dBu level 1 kHz sine wave calibration tone sent to both outputs Inputs are muted when the tone oscillator is activated The tone oscillator is useful during setup to verify connections and to set nominal levels to recording and transmission equipment The SLATE position right momentary of the switch activates the built in slate microphone located behind the front panel The Slate Mic circuit contains an AGC automatic gain control to keep the slate level relatively constant regardless of the acoustic level Slate microphones are convenient to document takes right at the mixer location when microphones are on talent or away from the production mixer Slate microphone audio is present at all outputs and inputs are muted while the slate mic is active Metering Input Clip LEDs Above each input gain control is a two color LED that illuminates red when the input approaches clipping 3 dB before clipping This clip circuit monitors both the front end gain stage and the var
16. ut 1 appears at the Left output This is useful for postproduction processing of input 1 audio Phantom Power Microphones requiring phantom power should use the lowest voltage acceptable to maximize MixPre battery life Condenser microphones that can operate on phantom voltages from 11 52 volts will not have a performance benefit with 48 volt phantom therefore 15 volt phantom is appropriate The 15 volt setting will increase battery life versus the 48 volt setting Microphones requiring 48 volt phantom will not operate or may operate with lower headroom and increased distortion at the 15 volt setting therefore use 48 volt phantom for these mics Consult your microphone documentation Dynamic microphones do not require phantom power A properly connected balanced dynamic micro phone will not be affected by the presence of phantom power nor will it draw any current However it is good practice to turn phantom power off when not needed Poor or incorrectly wired microphone cable can cause audible artifacts in microphone signals Some wireless receivers outputs are adversely affected by the presence of phantom power therefore consult the wireless receiver documentation High Pass Filter The two position high pass low cut filter in the MixPre is useful for removing excess low frequency energy in audio signals This excess energy can be caused by multiple sources including wind noise vibration unidirectional proximity effect or high am
17. ut drivers Headphone Monitoring e High current headphone monitor circuit e Headphone level control and peak indicator Level Metering e Sunlight readable seven segment GaN LED output meters e 3 position LED brightness switch e Two color clip limiter activity LEDs per input channel Audio Limiters e Unclippable input peak limiters via two stage opto isolator circuit with adjustable limiter threshold per input e Dual mono or linked stereo limiter operation Flexible Powering e Internal battery power from two AA batteries e Chassis isolated 5 to 18 VDC external power input e Power LED indicates low battery power page 2 Specifications SOUNDSDEVICES Gain Frequency Response Equivalent Input Noise Input Clipping Level Output Clipping Level Dynamic Range THD Noise Common Mode Rejection Ratio Channel Seperation Input XLR Input Outputs High Pass Filters Phantom Power Limiter Internal Voltage Rails Metering Powering Power LED Polarity Operating Temperature Range Dimensions Weight unit only Weight packaged Certification Mic Input to Output per channel continuously variable Output _ Gain Range Line Off 66 dB Tape Off 52 dB 20 Hz 30 kHz 0 2 0 5 dB 1 dB at 5 Hz 50 kHz relative to 1 kHz level with 150 ohm source gain controls set at 50 126 dBu 128 dBV maximum 150 ohm source flat weighting 22 22 kHz
18. ve 18 VDC cause no damage to unit but will open an internal poly fuse Poly fuse will reset when voltage is removed Green indicates power and good battery Red indicates power and low battery LED turns red when approximately 1 hour of battery life remain phantom off Green with external DC power All inputs to all outputs non inverting pin 2 of XLRs hot to unbalanced inputs and outputs 0 to 70 C 32 to 160 F 43 mm x 94 mm x 140 mm h x w x d 1 7 x 3 7 x 5 55 0 8 kg 1 6 lbs 1 2 kg 3 0 Ibs Meets FCC Part 15 Class B Eligible to bear CE mark see conformance statement page 3 MixPre Compact Mixer User Guide and Technical Documentation Front Panel KOR SaR Owtitir oa e IC Mix A L 000 r 1 3 5 TI 30 15 0 4 8 12 16 f ra DE 0000000 N y 1kHz METER i a Gi Ce 1 e IPHONES a 4 7 8 9 10 12 Gain Controls 8 Tape Return Switch Adjusts the input gain via sealed conductive Toggle switch allows external audio to be plastic rotary potentiometers monitored in the headphones The center posi tion is MixPre program audio The left and Input Peak Limiter LED right positions monitor tape return audio the Two color LED illuminates red at 3 dB below left position is l
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