User`s Manual
Contents
1. NIV aad XIW van XIW 712970105 o uy Tuv agg 25 Freusiosasa 22 21 frounsicos ES E wen nu d UIT 1 01 NoIssy 47016 476105 291 oiv TT tans Tans 201 Tans le oNOW 1421 ee P Tuy Tus XD V 03318 mm c IT vu 5 im t 5 1 1 eS man AA 3 en ae eS d oNOW 1431 910108 15 4 1 Wai 9 310106 ioni 1 uv 91 a NAJ NA gt i owowa XDVO3u31S 01 Yaa 4 5 5018 1 gt 2 8 o LL ug T lt d uy oNOW 1431 Xn V 034313 roe 29 02 61 81 415 HO West OEH STINNYHO LNANI 03818 bs 4 51 73 ANYA 2171 1 4 o oNOW 1431 594 518 13912. 0 9 PHONES CTRL ROOM SUB 3 4 MAIN MIX 5 1 2 Rotate these knobs to adjust the stereo CO 27 level of CTRL ROOM and PHONES outputs 5 2 30 separately which can be varied from to RIGHT RIGHT RIGHT RGHT 1 MAX SUBGROUPS ASSIGN TO MAIN MIX OUTPUT LEVEL Master AUX SENDS The four switches are used to determine the master AUX SEND levels which can be varied from to 15dB When the external effect unit connected to mixer has no input gain control you can get a further 15dB gain available form these AUX SEND outputs As to the AUX4 it can also provide the lovable level adjustment for the internal effect signal SOLO The function of these SOLO buttons are the same as the channel SOLO button they can also be affected by SOLO MODE switch Press the SOLO button the corresponding AUX send will be routed to CTRL ROOM PHONES outputs and METERS display Master STEREO AUX RETURNS These four controls set the level of effects that received from the stereo AUX RETURN connectors which can be varied from to 15dB They are used to provide the further gain for low level effects AUX SEND1 2 The both rotary knobs assign the AUX RETURN signals to their respective AUX SEND outputs The AUX SEND1 assign the signal from AUX RETURN 1 to AUX SEND1 bus and TO AUX SEND2 assign the signal from AUX RET
3. Fe wm o o 3 53 IH i 5 O sey n oe of 1 1 sl wav 3 J 10795 1 imoroyo arsr ENG Tuv aporises spoz wri WOINVHd 1 2 vo 1 AV OO FEHR ZXnv 9 10 8 5 5 TA 19755 OL TVOLLNAG LASNI mE gt NI Andino LI NE Spo9 0 NIVO IH 2 o Tung lt lt j v anas Noa Tans j T onos z anas D Tomum gt ia anas EST at i 27 cdi 5 wvuovid yaota aaa thw 8 3 8 m 06 1 OLIV 3 E E z 8 TECHNICAL SPECIFICATION Mono input channels Microphone input electronically balanced discrete input configuration Frequency response 10Hz to 55kHz Distortion THD amp N 0 005 at 4dBu 1kHz Gain range OdB to 60dB MIC SNR Signal to Noise Ratio 115dB Line input electronically balanced Frequency response 10Hz to 55kHz 3dB Distortion THD amp N Sensitivity range 0 005 at 4dBu 1kHz 15dBu to 45dBu Stereo input channels Line input Frequency response Balanced unbalanced 10Hz to 55kHz 3
4. User s Manual 20 CHANNEL COMPACT INTEGRATED LIVE SOUND MIXER WITH DIGITAL EFFECTS L 20 ai Lu T Pits 585133 ng LII AL LIEN LLL MELLE Bre 878884 etg 93333 Sg Bees esas tg ttg LIU LE at trt ag ILIUM 45754 511335 Bees 8824 54756 TI AR 8 a asadar M aad IE pe 3t ee 11111 LILE 4 tt Ut eg S www altoproaudio com Version 1 4 September 2005 a LTO English SAFETY RELATED SYMBOLS CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN This symbol wherever used alerts you to the pre sence of un insulated and dangerous voltages with in the product enclosure These are voltages that may be sufficient to constitute the risk of electric shock or death This symbol wherever used alerts you to impo rtant operating and maintenance instructions Please read Protective Ground Terminal AC mains Alternating Current Hazardous Live Terminal Pep Denotes the product is turned on OFF Denotes the product is turned off WARNING Describes precautions that should be observed to prevent the possibility of death or injury to the user CAUTION Describes precautions that should be observed to prevent damage to the product Disposing of this product should not be placed in municipal waste and should be Separate collection WARNING e Power Supply Ensure that the mains sour
5. IEC receptacle Physical Dimension WXDXH 626mm x 400mm x 38 115mm 24 64 x 15 75 x 1 49 4 53 Net weight 9 3Kg 20 526 9 WARRANTY 1 WARRANTY REGISTRATION CARD To obtain Warranty Service the buyer should first fill out and return the enclosed Warranty Registration Card within 10 days of the Purchase Date All the information presented in this Warranty Registration Card gives the manufacturer a better understanding of the sales status so as to purport a more effective and efficient after sales warranty service Please fill out all the information carefully and genuinely miswriting or absence of this card will void your warranty service 2 RETURN NOTICE 2 1 In case of return for any warranty service please make sure that the product is well packed in its original shipping carton and it can protect your unit from any other extra damage 2 2 Please provide a copy of your sales receipt or other proof of purchase with the returned machine and give detail information about your return address and contact telephone number 2 3 A brief description of the defect will be appreciated 2 4 Please prepay all the costs involved in the return shipping handling and insurance 3 TERMS AND CONDITIONS 3 1 ALTO warrants that this product will be free from any defects in materials and or workmanship for a period of 1 year from the purchase date if you have completed the Warranty Registration Card in tim
6. LED indicates when the Phantom Power is switched on EQ switch Engage this button to add the stereo graphic EQ into the MAIN MIX output circuit It can be used to modify the frequency contour of a sound If you release the button free the stereo graphic EQ will be bypassed STEREO GRAPHIC EQ Each one of these faders will boost or attenuate 15dB the selected frequency at a preset bandwidth When all the sliders are in the centre position the output of the equalizer is flat response 2 TRACK IN OUT 2 TRACK IN OUT TAPE IN L oe 2 NN 2 N Use the Tape input if you wish to listen to your Mix from a Taper e e Q Recorder or DAT You can assign the signal coming from the 0 LAMP R 12V 0 5 Taper Recorder either to a pair of studio monitor using the I I Control Room assignment on the front panel or you can also TAPE IN TAPE OUT send the signal directly to the Main Mix TAPE OUT These RCA jacks will route the main mix into a tape recorder LAMP This lovable LAMP is very convenient for your operation it is located in the top right corner of the front panel and provides the 12V socket that can drive any standard BNC type lamp Please use the customized gooseneck lamps the GL SQ and GL RO are both options PHONES PHONES e These sockets will send out the monitor signal to a pair of headphones 4 12 REAR PANEL Description POWER ON OFF switch This switch is used to turn th
7. SECON 5 11 4 14 REAR pvo eye as A aia ei 15 5 INSTALLATION AND 8 19 6 PRESET EISE 21 DIAGRAMS i E 22 8 5 23 9 WARRANT 25 1 INTRODUCTION Thank you very much for expressing your confidence in ALTO products by purchasing ALTO L 20 20 Channel Compact Integrated Mixer with Digital Effects The L 20 is professional compact mixer You will get the smooth accurate more natural and open sound from this apparatus it is really ideal for large gigs recording and fixed PA installations The L 20 20 Channel Compact Integrated Mixer with Digital Effects is packed with features that can not be found in other consoles of its size 14 mono these are provided with Ultra Low Noise microphone pre amplifiers and Phantom Power at 48 Volt and 4 stereo input channels and each of them is provided with warm natural EQ channel1 12 are mono channels and equipped with 3 band MID sweep EQ channel 13 20 are stereo channels and equipped with 4 band fixed frequency EQ 24 bits digital stereo effect processor with 256 presets 16 presets x 16 variations 4 AUX sends se parate level control on each channel highly accurate 12 segme
8. by channel s MUTE switch 24 BIT DIGITAL EFFECTS PRESETS Adjust this knob to select the right effect you wish to perform There are total 16 options for you several kinds of reverb mono and stereo delay effects with modulation and versatile two effect combination eo 15 0 EFFECTS OUT ett VARIATIONS Since you have selected the preferable effect the next step please go with the fine consideration there are also total 16 variations for each preset and each variation may be managed by several different factors MUTE switch L stereo GRAPHIC eq l This switch is used to activate deactivate the effect facility Sometimes you can also use the DFX FOOT SWITCH on rear panel for convenient operation PEAK LED This LED lights up when the input signal is too strong In case of the digital effect module being muted this LED also lights up EFFECTS OUT Rotate this knob to adjust the level of effect signal that intercepted from internal DSP processor and directly sent to DFX OUT which can be varied from co to 15dB DFX2 INT RETURN EFFECTS TO MONITOR These AUX1 and AUX2 controls are used to set the signal level from AUX RETURNA which signal will be sent to AUX SEND1 and AUX SEND2 The adjustable range can be varied from co to 4154 POWER LED The LED indicates when the Power is on in your L 20 PHANTOM LED This
9. matrix e 2 TRACK IN assignable to main mix control room headphone outputs e Highly accurate 12 segment output level meters 3 READY TO START 3 1 Please check the AC Voltage available in your Country before connecting your L 20 to the AC socket 3 2 Be sure that the main power switch is turned off before connecting the Mixer to the AC socket Also you should make sure that all Input and Output Controls are turned down This will avoid damages to your speakers and avoid excessive noise 3 3 Before turning on the L 20 you shall connect it to a power amplifier and turn on the mixer BEFORE the power amplifier Once you have finished your working session you shall turn the mixer off AFTER the power amplifier 3 4 Before disconnecting the L 20 always turn off the Power switch 3 5 Do not use solvents to clean your L 20 A and clean cloth will be OK 4 CONTROL ELEMENTS 000000000 o9715283 5 8 8 8484 8484 111 20 CHANNEL COMPACT INTEGRATED LIVE SOUND MIXER DIGITAL EFFECTS 248115 DIGITAL STEREO EFFECTS PROCESSOR stereo Graphic 1 SUBGROUPS LAMP 12V0 5A PHONES LINE IN 19 2 TRACK IN OUT TAPE IN TAPE OUT 6 LEFT LEFT LINE IN 20 LINE IN 17 LINE IN 18 LINE IN 15 LEFT BAUUNBAL LINE IN 16 LEFT BAUUNBAL LINE IN 14 LINE IN 9 LINE IN 10 LINE IN 11 LINE IN 12 LINE IN 13
10. more than a profession it is a passion and an obsession We have in fact been designing professional audio products for a number of years in cooperation with many of the world s major brands The ALTO line represents unparalleled analogue and digital products made by musicians for musicians With our design centres in Italy the Netherlands and the United Kingdom we provide you with world class designs while our software development teams continue to develop an impressive range of audio specific algorithms By purchasing our ALTO products you become the most important member of our ALTO AUDIO TEAM We would like to share with you our passion for what we design and invite you to make suggestions which will aid us in develop ing future products for you We guarantee you our commitment for quality continual research and development and of course the best prices The ALTO L 20 is an extremely flexible ultra low noise 20 channel compact integrated live sound mixer with Digital Effects configured with 12 mono and 4 stereo input channels each channel is equipped with a variety of key features including a warm natural sounding EQ Peak LEDs and PAN BAL control etc Besides the L 20 is equipped with the miraculous 24 bit digital stereo effect processor with 256 presets Seeing is believing let s meet the ALTO L 20 We would like to thank all the people who made the ALTO L 20 20 Channel Compact Integrated Live Sound Mixer with Digital Effects p
11. 86 4 22313737 email alto altoproaudio com Fax 886 4 22346757 All rights reserved to ALTO All features and content might be changed without prior notice Any photocopy translation or reproduction of part of this manual without written permission is forbidden Copyright 2005 SEIKAKU GROUP NF01494 1 4
12. LINE INT 6 LINE IN 8 LINE IN 3 LINE IN 4 LINE IN 5 LINE IN 6 LINE IN 2 LINEIN 1 4 CONTROL ELEMENTS 4 1 The MONO MIC LINE Channels These are Channel 1 through Channel 12 You can connect balanced low im pedance microphones to the XLR socket On the 1 4 phone jack you can connect either a microphone or a line level instrument You shall never connect an unbalanced microphone to the XLR socket if you do not want to damage both the Microphone and the Mixer 48 Volt phantom power It is available only to the XLR Mic sockets Never plug in a microphone when phantom power is already on Before turning phantom power on make sure that all faders are all the way down In this way you will protect your Stage Monitors and Main Loudspeakers 4 2 INPUT LEVEL Setting This Control is provided with 2 different indication rings One is for the Microphone and the other for the Line levels When you use a microphone you shall read the OUTSIDE ring 0 60 dB When you use a Line level instrument you shall read the INSIDE ring 15 45 dB For optimum operation you shall set this control in a way that the peak LED will blink occasionally in order to avoid distortion on the input channel 4 3 MONO Channel INSERT Insert points are provided for the Mono Mic Channels When you insert a TRS jack in the insert socket the signal will be taken out after the Input Gain Contro
13. OLO mode button and the LED next the button will illuminate SUBGROUPS ASSIGN TO MAIN MIX Through these switches you can operate the subgroup faders as a master control for assigning the subgroups to MAIN MIX Engage the LEFT switch to send the corresponding subgroup signal to MAIN MIX L and the RIGHT switch for MAIN MIX R When engaging the both switches the signal will be sent to L R of MAIN MIX SUBGROUPS These faders are used to control the levels of signals sent to the SUBGROUPS OUT the adjustable range is from to 10dB Any channel that is assigned to the subgroups not muted and not turned down will assi gned to the SUB OUTS MAIN MIX LEVEL This fader sets the amount of signal sent either to the Main Mix Output sockets or to the Tape Output LED METER The stereo 12 segments LED Meter will indicate the signal level sent to CTRL ROOM and PHONE outputs 2TK TO MIX Engaging this switch allows you to combine the 2 TRACK Output with the MAIN MIX In other words feeds the 2TRACK IN signals into MAIN L R output SOLO MODE This button provides two modes up for PFL Pre Fader Listen mode and down for AFL After Fader Listen mode Engage the button the soloed signal will output following the LEVEL control otherwise release the button will output the soloed signal before the level control Please note that the SOLO function can never affect the mix at main recording output and also can t be affected
14. OLO switch never affects any mix other than the CONTROL ROOM The other three buttons can be considered as signal assignment switches Pressing the SUB 1 2 will assign the channel signal to Subgroup1 2 you can depend on the PAN BAL switch to adjust the amount of channel signal sent to the SUB1 versus SUB2 when turns the PAN BAL to completely left then the signal can be only controlled by Subgroup1 and vice versa In the same way pressing the SUB 3 4 or MAIN L R will assign the channel signal to Subgroup3 4 or MAIN MIX L R and will also be affected by PAN BAL control 4 12 MASTER Section CONTROL ROOM SOURCE You can choose to monitor any combination of MAIN MIX SUB1 2 SUB 3 4 and 2TK IN via these MATRIX switches Engaging these switches these stereo signals will be delivered to the PHONES CONTROL AUX SENDS ROOM and METERS display Q Note When any SOLO switch was engaged the SOLO signal will replace other signals and also be sent to the CONTROL ROOM PHONES and METERS MAIN L R STEREO AUX RETURNS Q 0115 0 O y 415 co 415 CTRL ROOM SOURCE MAIN MIX e PHONES SUB 1 2 SUB 3 4 AUX SEND1 CTRL ROOM 2TKIN AUX SEND2 So WEL MAIN MIX 2TK TO MIX 25 2 05 07 0 o SUB 1 2 AUX RETURNS SOLO 2
15. URN2 to AUX SEND2 bus The adjustable range goes from co to 15 MAIN CTRL R MAIN MI MIX MAIN MIX SUB 1 2 SUB 3 4 2TKIN CTRL ROOM SOURCE 9 5 CTRL ROOM O o gt SUB 1 2 AUX RETURNS 5010 SUB 34 MAIN MIX LEVEL SET 25 4 7 2 er SOLOMODE mL PFI am AFL OUTPUT LEVEL 8 5 e 060000 A ON A 70000000001 aes 888 5 30 30 30 30 30 40 40 40 40 40 60 60 60 0 60 oo SUB1 SUB2 SUB3 SUB4 MAIN MIX LEVEL 28 29 AUX RETURNG is equipped with the MAIN MIX CTRL R button Release the button to send the stereo signal from AUX RETURNS to MAIN MIX buses Engage the button then the stereo signal will be sent to CTRL R output SUB1 2 SUB3 4 MAIN MIX These three buttons are configured for AUX RETURNA they can be regarded as the signal assignment switches Engage the SUB1 2 button to assign the stereo signal from AUX RETURN4 to Submix1 2 the same SUB3 4 for Submix3 4 MAIN MIX for MAIN MIX buses AUX RETURN SOLO The function of AUX RETURN SOLO is like the channel SOLO button Engaging it sends the signal from AUX RETURN 1 4 to the CTRL OUT PHONES outputs and METERS display It can also be affected by S
16. air of powered studio monitor speakers Position EQ controls on middle position Position panoramic PAN control on center position e With a headphone or studio monitor speakers connected apply a Line Level input signal so that the PEAK LED does not light up At this point increase the input gain so that the PEAK LED will blink occasionally In this way you will maintain good headroom and ideal dynamic range Now connect a microphone and ask the singer to sing loud into the microphone Turn slowly the Gain Control clockwise and have the PEAK LED blink only occasionally Now repeat the same sequence for all input channels The Main LED Meter could move up into the red section In this case you can adjust the overall output level through the MAIN MIX control 5 1 SOME FINAL TIPS ON WIRING CONFIGURATION You can connect unbalanced equipment to balanced inputs and outputs Simply follow these schematics Tip Sleeve Ring Strain Clamp Sleeve G Ring Right Signal Tip Left Signal round Screen Use for Headphone 1 4 Stereo TRS Jack Plug Sleeve Strain Clamp Tip Signal Sleeve Ground Screen Use for Mono Line In Mono 1 4 Jack Plugs 1 4 Mono TS Jack Plug Tip SI eeve Ring Strain Clamp Ring Return Signal Tip Send Signal Sleeve Ground Screen Use for Insert Points 1 4 Stereo TRS Jack Plug 2 Hot 1 Ground Screen 3 Cold Use for Ba
17. ce voltage AC outlet matches the voltage rating of the product Failure to do so could result in damage to the product and possibly the user Unplug the product before electrical storms occur and when unused for long periods of time to reduce the risk of electric shock or fire External Connection Always use proper ready made insulated mains cabling power cord Failure to do so could result in shock death or fire If in doubt seek advice from a registered electrician Do Not Remove Any Covers Within the product are areas where high voltages may present To reduce the risk of electric shock do not remove any covers unless the AC mains power cord is removed Covers should be removed by qualified service personnel only No user serviceable parts inside Fuse To prevent fire and damage to the product use only the recommended fuse type as indicated in this manual Do not short circuit the fuse holder Before replacing the fuse make sure that the product is OFF and disconnected from the AC outlet Protective Ground Before turning the product ON make sure that it is connected to Ground This is to prevent the risk of electric shock Never cut internal or external Ground wires Likewise never remove Ground wiring from the Protective Ground Terminal Operating Conditions Always install in accordance with the manufacturer s instructions To avoid the risk of electric shock and damage do not subject this product
18. dB Distortion THD amp N 0 005 at 4dBu 1kHz Equalization Impedances Microphone input 1 4kOhm Channel Insert return 2 5kOhm All other inputs 10kOhm or greater Tape out 1kOhm All other output 1200hm Hi shelving Mid bell mono 15dB 12kHz 15dB 100Hz to 8kHz Hi Mid stereo 15dB 3kHz Mid low stereo Low shelving 1588 500Hz 15dB 80Hz Low Cut filter 75Hz 18dB oct DSP Section A D and D A converters 24 bit DSP resolution 24 bit Type of effects Hall Room Vocal amp Plate REVERBS Mono amp Stereo DELAY max DELAY TIME 650ms Chorus Flanger amp Reverb MODULATIONS REVERB DELAY REVERB CHORUS REVERB FLANGER combinations Presets 256 Controls 16 position PRESET Selector 16 position VARIATION selector PEAK LED MUTE SWITCH with LED indicator Main Mix Section Noise Bus noise Fader 0 dB channels muted 100dBr ref 4dBu Fader all input channels assigned and set to Max output UNITY gain 90dBr ref 4dBu 22dBu balanced XLR 22dBu unbalanced 1 4 jacks AUX Returns gain range AUX Sends max out to 15dB 22dBu Power supply Main voltage USA Canada 100 120V 60Hz Europe 210 240V 50Hz U K Australia 240V 50Hz Power Consumption 70 watts Fuse 100 120V T800mAL 210 240V T500mAL Main connection Standard
19. e 3 2 The warranty service is only available to the original consumer who purchased this product directly from the retail dealer and it can not be transferred 3 3 During the warranty service ALTO may repair or replace this product at its own option at no charge to you for parts or for labor in accordance with the right side of this limited warranty 3 4 This warranty does not apply to the damages to this product that occurred as the following conditions Instead of operating in accordance with the user s manual thoroughly any abuse or misuse of this product Normal tear and wear The product has been altered or modified any way Damage which may have been caused either directly or indirectly by another product force etc e Abnormal service or repairing by anyone other than the qualified personnel or technician And in such cases all the expenses will be charged to the buyer 3 5 In no event shall ALTO be liable for any incidental or consequential damages Some states do not allow the exclu sion or limitation of incidental or consequential damages so the above exclusion or limitation may not apply to you 3 6 This warranty gives you the specific rights and these rights are compatible with the state laws you may also have other statutory rights that may vary from state to state SEIKAKU TECHNICAL GROUP LIMITED No 1 Lane 17 Sec 2 Han Shi West Road Taichung 40151 Taiwan http www altoproaudio com Tel 8
20. e LED shows green it indicates that there present signal on corresponding channel When the LED turns into red it warns you that you are reaching signal saturation and possible distortion then you should reduce the input level for avoiding distortion 4 9 MUTE Switch Each channel is equipped with the MUTE switch Pressing this switch is equal to turning the fader down which can mute the cor responding channel output except for channel INSERT send and SOLO in PFL mode And the MUTE LED will illuminate EFT RIGHT LEFT RIGHT 0 EQ EQ HI HI 12kHz 12kHz 5 MID HI MID 3kHz FREQ MID LOW 10 e 500Hz 1 0 100H25 SkHz LOW LOW 80Hz 80Hz 15 00 15 2 POST 2 05 PRE 12 P 12 DFX1 EXT 0 15 4 DFX2 INT 2 6 gt a e ii LI 4 10 FADER This Fader will adjust the overall level of this channel and set the amount of signal sent to the Main output or the corresponding subgroup output 4 11 ASSIGNMENT Control Each channel provides four push buttons SUB1 2 SUB3 4 MAIN L R and SOLO Pressing the SOLO button the corresponding SOLO LED will ill uminate and the SOLO signal will replace other signals sent to the headphone CONTROL ROOM and meters Usually use the SOLO function in live work to preview channels before they are let into the mix It is useful to set an instrument s input level and EQ and you can also solo any channel that you want to The S
21. e Main Power ON and 46 4 OFF PHANTOM ON OFF switch This switch will apply 48 Volt Phantom Power only ON e to the 14 XLR microphone inputs Never connect OFF microphones when the Phantom Power is on already Apparaten skall anslutas till jordat uttag nar den ansluts till ett natverk AC inlet with fuse holder Use it to connect your L 20 to the Main AC with the supplied AC cord Please check the Voltage available in your Country and how the Voltage for your L 20 EUROPE is configured before attempting to connect your L 20 NEM S to the Main AC a aS AC INPUT 5 N USA Canada Aust 100 120V 60Hz 240V 50Hz Fuse T800mAL Fuse T500mAL MAIN MIX OUTPUT BAL UNBAL MAIN INSERT AUX SENDS MONO CTRL OUT DFX OUT eee BAL UNBAL FOOT SWITCH 48 49 50 6261 53 MAIN MIX OUTPUT This stereo output is supplied with both the XLR and 1 4 phone sockets and it is controlled by the Main Mix Level MAIN OUTPUT LEVEL This button sets the main mix output level to match the input of the device that you are ready to connect Engage this button to reduce the output level from MAIN MIX OUTPUT by 30dBu it used to match the semipro 30dBu device on the contrary to match the professional 4dBu device MAIN INSERT These two 1 4 phone sockets are stereo insert points and u
22. e it to get rid of high frequency noises or to boost the sound of cymbals or the high harmonics of the human voice The gain range goes from 15dB to 15dB with a center frequency of 12 kHz 4 6 2 MID This is the Midrange control It provides 15dB of boost or cut flat at the center detent and the FREQ knob sets the center frequency the adjustable range is from 100Hz to 8kHz It can affect most fundamental frequencies of all musical instruments and human voice An attentive use of this control will give you a very wide panorama of sound effects 4 6 3 HI MID This control gives you up to 15dB boost or cut at 3kHz It is useful for controlling voice It can accurately polish your performance via adjusting this knob 14 LINE 15 MONO BAL UNBAL LINE IN 16 RIGHT MIC GAIN 6048 MIC EQ HI 12kHz 4 MID 0 e FREQ 1001 7 kHz LOW 80Hz 15 LINE IN 17 LEFT MONO LINE IN 18 RIGHT LINE GAIN 17 18 18757 415 a a 15 1579 1 a a Q EQ HI 12kHz HI MID 3kHz MID LOW 500Hz LOW 80Hz 2 2 Ox LEFT RIGHT e LEFT RIGHT 415 Qe 415 e 0 0 3 3 DFX1 DFX1 EXT EXT 15 oy 15 4 4 DFX2 DFX2 INT INT 15 45 gt lt gt a PAN BAL 4 6 4 MID LOW This control gives you up to 15dB boost or cut at 500Hz 4 6 5 LOW Thi
23. l Trim sent to an external processor such as a compressor limiter and returned into the channel strip immediately before the EQ section Of course the jacks used must be stereo Tip Send Ring Return 4 4 LOW CUT FILTER MIC 1 LINE 1 BAL UNBAL INSERT 048 60dB 15dB 45dB LINE LOW CUT 75Hz 18dB Oct POWER PHANTOM By pressing this button you will activate a 75 Hz low frequency filter with a slope of 18 dB per octave You can use this function to reduce hum and stage rumble when using microphones 4 5 STEREO INPUTS 6 These Channel 13 through 20 They are organised in stereo pair 13 14 and 15 16 pairs also feature XLR Mic inputs 13 and 14 and they are provided with 1 4 TRS phone sockets If you connect only the left jack the input will operate in mono mode Your L 20 also provides the practical input level setting MIC GAIN the adjustable range is from OdB to 60dB for MIC 13 MIC 14 and LINE GAIN the adjustable range is from 20dB to 20dB for LINE IN 17 18 and LINE IN 19 20 4 6 EQUALISER The mono input channels channel 1 channel 12 are equipped with 3 band MID sweep EQ HI band MID band and LOW band And the stereo channels channel 13 channel 20 are equipped with 4 band fixed frequency equalization HI band HI MID band MID LOW band and LOW band All bands provide up to 15dB of boost or cut 4 6 1 HI This is the Treble control You can us
24. lanced Mic Inputs For unbalanced use connect pin 1 to 3 3 pin XLR Male Plug seen from soldering side 2 Hot 1 Ground Screen 3 Cold Use for Main output For unbalanced use leave pin 3 unconnected 3 pin XLR Line Socket seen from soldering side Ring Return Signal Connected together To Channel Insert Sleeve Ground Screen Tip Signal To Tape or FX Input Sleeve Ground Screen Tapped Connection Direct Output Lead Enables the Insert to be used as a Direct Output while maintaining the channel signal flow gt To Processor Input Sleeve Ground Screen zs Tip Send Signal 7 Channel Insert Sleeve Ring Ring Return Signal Processor Output Y Stereo lead for insert Connection To be used when the processor does not employ a single jack connection for the In Out Connections 6 PRESET LIST Controllable parameter No Preset Description 1 VOCAL 1 Simulate a room with small delay time Decay time 0 8 1 1s Pre delay 0 79ms 2 VOCAL 2 Simulate a small space with slight decay time Decay time 0 8 2 5s Pre delay 0 79ms 3 LARGE HALL Simulate a large acoustic space of the sound Decay time 3 6 5 45 Pre delay 23 55ms 4 SMALL HALL Simulate a small acoustic space of the sound Decay time 1 0 2 9s Pre delay 20 45ms 5 LARGE ROOM Simulate a studio room with many early reflections Decay time 2 9 4 5s Pre delay 23 55ms SMALL ROOM Simulate a bright
25. nt bar graph meters 2 Track inputs assignable to main mix control room headphone outputs and subgroups output Your L 20 is very easy to operate but we advise you to go through each Section of this Manual carefully In this way you will get the best out of your L 20 2 FEATURES The L 20 20 Channel Compact Integrated Mixer with Digital Effects is designed for professional appliance It will provide the following features 14 MIC input channels with gold plated XLRs and balanced LINE inputs 4 Stereo input channels with balanced TRS jacks e Ultra low noise discrete Mic Preamps with 48V Phantom Power e Extremely high headroom offering more dynamic range 60mm high precision faders Each input channel with Mute SOLO function Overload amp signal present LEDs and low cut filters except for stereo channel SUB 1 2 SUB 3 4 MAIN L R signal assignment switch e 4 AUX sends per channel 2 PRE POST faders switch able for monitoring application and effects amp sound processor input 2 POST faders for internal digital DFX or as external send e 4 band fixed EQ on stereo line channels 3 band EQ with swept mid on microphone channels Channel inserts and direct outputs on each mono channel plus main mix insert for flexible connection of outboard equipment 24 bit DSP effect 256 effects 16 presets x 16 variations Stereo 9 band graphic EQ BNC socket for connecting lamp Control room phones
26. ossible especially to our designers and ALTO staff It is their passion for music and professional audio that has made it possible for us to offer you our most important team member our continued support Thank you very much ALTO AUDIO TEAM TABLE OF CONTENTS 1 INTRODUCTION 4 2 IEATURES a ADM AA T 5 3 FREAD Y 1 OS TAR a r ox m ap 6 S a a a E O 22228 T 4 1 The MONO MIC LINE 4 1 naana kakaa kudai 8 4 2 INPUT Ie 8 4 3 MONO Channel 1 esee serine annees 8 4 4 LOW CUT FILTER soinera eiia 8 4 5 STEREO INPUTS Cre vae ieanneddensveiadeastapsstaaeandesonetianccorteabivaaisdadansebaandiasebataas 9 46 CEQUABISER MINIME MILII 9 4 7 AUX SENDS Level 2 2 0 0000000000000 010000000000 10 4 8 57211111 57 rai e oom 10 4 9 SG PEAK disse 10 4 10 MUTE SW iia T 10 11 FADER Mmm 11 4 12 ASSIGNMENT O o gelben dl es uer ere 11 2135 MASTER
27. recording function etc SUBGROUPS OUT These 1 4 phone sockets are used to connect the inputs of deck or available for a complicated PA live sound system You will find it is the best tool when you operate the SUBGROUPS OUT SUBGROUPS INSERT These 1 4 phone sockets are insert points They are used to connect processors such as compressor limiter EQ etc When insert external processor into these jacks the subgroup stereo signal will be taken out then returned to before subgroups fader Of course these jacks used must be stereo Tip Send Ring Return 5 INSTALLATION AND CONNECTION Ok you have got to this point and you are now in the position to successfully operate your L 20 However we advise you to read carefully the following section to be the real Master of your own Mix Not paying attention enough to the input signal level to the routing of the signal and the assignment of the signal will result in unwanted distortion a corrupted signal or no sound at all So you should follow this procedure for every single channel Turn down all Input and Output Gain Controls Connect phantom powered microphones before switching on the 48Volt Phantom Power switch If you have a power amplifier connected to your L 20 set the Level of the amplifier at no more than 75 Now set the CONTROL ROOM PHONES level at no more than 50 In this way you will be able to hear later what you are doing connecting a pair of headphones or a p
28. s is the Bass control Boost male voice or kickdrum and bass guitar Your system will sound much bigger than what itis The gain range goes from 15dB to 15dB and the center frequency is 80 Hz 4 7 AUX SENDS Level Control These four controls are used to adjust the level of the signal sent to AUX buses and their adjustable range goes from co to 15dB AUX1 and AUX2 can be switched to PRE POST FADER via the PRE POST button so generally they can be used for monitor application and effects amp sound processors input AUX3 and AUX4 are configured as POST Faders In this typical compact unit excluding sending out directly to the external effect or processor equipment AUX SEND 4 can also be assigned to the internal onboard effect module 4 8 PAN BAL Control The PANORAMA control for MONO channels and the BALANCE control for STEREO channels Rotate the control to determine the amount of channel signal sent to left right of MAIN MIX when Main L R push button is pressed Keep the control in center position and your signal will be positioned in the middle of stage Turn the control fully counterclockwise the signal will be present only on the left of MAIN MIX and vice versa Besides the PAN or BAL control has the same affection to SUB 1 2 and SUB 3 4 if the SUB 1 2 or SUB 3 4 push button is pressed 4 9 SG PEAK LED Inside your L 20 the audio signal is monitored in several different stages and then sent to the SG PEAK LED When th
29. sed to connect processors such as compressors equalisers etc When insert a external processor into the jack the Main stereo signal will be taken out after the EQ and returned into the MAIN MIX output before the MAIN MIX fader MONO output This 1 4 phone socket is balanced unbalanced mono mix output connector it can be regarded as a sum output of the left and right of MAIN MIX MONO level control This knob sets the level of mono mix output signal which be varied from to 15dB CTRL OUT These 1 4 phone sockets will be used to send the control room signal to the Studio Monitor speakers or a se cond set of PA DFX OUT This 1 4 phone socket is used to output the effect signal that comes from internal DSP module and the signal can be controlled in level by EFFECTS OUT control FOOTSWITCH This 1 4 phone socket can be used to connect an external footswitch to turn on off the onboard effect module AUX SENDS These 1 4 phone sockets are used to send out the signal from the AUX Bus to external devices such as effects AUX RETURNS Use these stereo 1 4 phone sockets to return the sound of an effect unit to the Main Mix You can also use them as an extra auxiliary input CH11 SUBGROUPS OUT DIRECT OUTS Each MONO MIC LINE channel CH1 CH12 is equipped the 1 4 phone socket for direct output These jacks are used to send the signal from the channel path to external device for
30. studio room Decay time 0 7 2 1s Pre delay 20 45ms 7 PLATE Simulate the transducers sound like classic bright Decay time vocal plate Pre delay TAPE REVERB Simulate a record head and multiple playback heads Decay time 1 3 5 4s at intervals along the tape Pre delay 0 84ms SPRING REVERB Simulate the analog transducers springs lightly Decay time 1 3 5 4s stretched sound Pre delay 0 35 0 MONO DELAY Reproduce the sound input on the outputafter a Period 60 650ms lapse of time STEREO DELAY Recreate the input sound on the stereo output with Period 210 400ms different time Feedback 37 73 2 FLANGER Simulate to play with another person carryingout Rate 0 16 2 79Hz sam e the notes on the same instrument 13 CHORUS Recreate the illusion of more than one instrument Rate 0 5 5Hz from a single instrument sound 14 REV DELAY Delay with room effect Delay period 211 375ms Rev decay time 1 0 2 9s 15 REV FLANGER Stereo chorus and large room reverb Flanger Rate 0 16 2 52Hz Rev decay time 1 5 2 95 16 REV tCHORUS Simulate the sound effect achieved by rotating horn Chorus rate 0 5 4 74Hz speakers and a bass cylinder Rev decay time 1 5 2 9s 11 7 BLOCK DIAGRAMS aon 22 31 Andino WOO 1419 1ndLno lt 1 X
31. to any liquid rain or moisture Do not use this product when in close proximity to water Do not install this product near any direct heat source Do not block areas of ventilation Failure to do so could result in fire Keep product away from naked flames IMPORTANT SAFETY INSTRUCTIONS Read these instructions Follow all instructions Keep these instructions Do not discard Heed all warnings Only use attachments accessories specified by the manufacturer Power Cord and Plug Do not tamper with the power cord or plug These are designed for your safety Do not remove Ground connections If the plug does not fit your AC outlet seek advice from a qualified electrician Protect the power cord and plug from any physical stress to avoid risk of electric shock Do not place heavy objects on the power cord This could cause electric shock or fire Cleaning When required either blow off dust from the product or use a dry cloth Do not use any solvents such as Benzol or Alcohol For safety keep product clean and free from dust Servicing Refer all servicing to qualified service personnel only Do not perform any servicing other than those instruc tions contained within the User s Manual PREFACE Dear Customer Thank you for choosing the ALTO L 20 20 Channel Compact Integrated Live Sound Mixer with Digital Effects which is the result of our ALTO AUDIO TEAM s endeavours For the ALTO AUDIO TEAM music and audio are
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