Presonus Audio electronic Stereo Amplifier DigiMAX LT User Manual

DigiMAX LT  
Eight-Channel Mic-Preamplifier with  
adat™ Lightpipe Output  
USER’S MANUAL 1.0  
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PAD  
PAD  
PAD  
PAD  
PAD  
PAD  
PAD  
PAD  
SAMPLE  
RATE  
EXT  
CLOCK  
POWER  
30  
30  
30  
30  
30  
30  
30  
30  
+48V  
+48V  
+48V  
+48V  
+48V  
+48V  
+48V  
+48V  
32k 44.1k 48k  
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60  
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60  
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dB  
GAIN  
dB  
GAIN  
dB  
GAIN  
dB  
GAIN  
dB  
GAIN  
dB  
GAIN  
dB  
GAIN  
dB  
GAIN  
1
1
2
3
4
5
6
7
8
115/230 VAC  
(by internal  
jumpers)  
~
WORD CLOCK  
POWER  
CHANNEL  
8
CHANNEL  
7
CHANNEL  
6
CHANNEL  
5
CHANNEL  
4
CHANNEL  
3
CHANNEL  
2
CHANNEL  
1
20WATTS  
CREATED,  
DESIGNED  
AND  
MANUFACTURED  
IN THE USA  
7
5
3
1
2
IN  
OUT  
CHANNEL INSERT POINTS  
adat™  
optical  
interface  
8
6
4
DIGITAL  
AUDIO  
OUTPUT  
MICROPHONE  
-
XLR  
MICROPHONE  
LINE INPUT  
-
XLR  
MICROPHONE  
LINE INPUT  
-
XLR  
MICROPHONE  
-
XLR  
MICROPHONE  
LINE INPUT  
-
XLR  
MICROPHONE  
LINE INPUT  
-
XLR  
MICROPHONE  
-
XLR  
MICROPHONE  
- XLR  
TRS  
LINE INPUT  
-
TRS  
-
TRS  
-
TRS  
LINE INPUT  
-
TRS  
-
TRS  
-
TRS  
LINE INPUT  
-
TRS  
LINE INPUT  
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Copyright © 2002, PreSonus Audio Electronics, Inc.  
ALL RIGHTS RESERVED  
 
OVERVIEW 1  
1.1 INTRODUCTION  
Thank you for purchasing the PreSonus DigiMAX LT Eight-Channel Mic-Preampli-  
fier with adat™ Lightpipe Output. This preamp was designed using state of the  
art components to deliver crystal clear audio for an indefinite period of time. We  
believe the DigiMAX LT to be an exceptional sounding unit and an exceptional  
value.  
Please contact us at 1-800-750-0323 with your questions or comments regard-  
ing this product. PreSonus Audio Electronics, Inc. is committed to constant  
product improvement and believes the best way to accomplish this task is by  
listening to the experts on our gear, our valued customers. We appreciate the  
support you have shown us through the purchase of this product.  
Please pay close attention to how you connect your DigiMAX LT to your system.  
Improper grounding is the most common cause of noise problems found in  
studio or live sound systems. We urge you to scan this manual before hooking  
up your DigiMAX LT to familiarize yourself with its features and applications.  
Good luck and enjoy your DigiMAX LT!  
1
 
1 OVERVIEW  
1.2 FEATURES  
Dual Servo Mic Preamps  
Each channel of your DigiMAX LT provides ultra low noise and wide gain control  
allowing the user to boost a desirable signal without increasing unwanted  
background noise.  
48V Phantom Power  
Each channel of the DigiMAX LT has 48V of phantom power available. When the  
phantom power switch is engaged, power is supplied at a constant rate. This  
assures optimum performance of your condenser microphone(s) and that it will  
be free of distortion associated with insufficient power. This switch is located on  
the front panel next to each gain knob.  
-20dB Pad  
A -20dB pad is available on each channel of the DigiMAX LT for reducing  
incoming signal levels. Using this pad can provide a more manageable signal  
from high output devices giving the operator greater control over the incoming  
signal and a much reduced chance of over-driving the input, thereby avoiding  
distortion.  
Neutrik™ Combo Connectors  
Each channel of the DigiMAX LT has a mic/line connector using the Neutrik™  
combo connector. This revolutionary style connector lets you use either ꢀ” or  
XLR connectors in the same input.  
Sample Rate Selector  
The DigiMAX LT has a switch on the front panel that lets the operator choose  
the sample rate. It provides selectable rates of 32k, 44.1k and 48k.  
Ext Clock  
When the External clock switch is engaged the DigiMAX LT goes into ‘chase’  
mode and automatically recognizes which of the three sampling rates is  
required for optimum synchronization.  
Digital Optical Output  
The DigiMAX LT has an adat™ (lightpipe) output that can be used with any com-  
mercially available digital optical cable. This cable can supply eight simultaneous  
outputs.  
2
 
CONTROLS AND CONNECTIONS 2  
2.1 FRONT PANEL  
-20 -10 CLIP  
-20 -10 CLIP  
-20 -10 CLIP  
-20 -10 CLIP  
-20 -10 CLIP  
-20 -10 CLIP  
-20 -10 CLIP  
-20 -10 CLIP  
PAD  
PAD  
PAD  
PAD  
PAD  
PAD  
PAD  
PAD  
SAMPLE  
RATE  
EXT  
CLOCK  
POWER  
30  
30  
30  
30  
30  
30  
30  
30  
+48V  
+48V  
+48V  
+48V  
+48V  
+48V  
+48V  
+48V  
32k 44.1k 48k  
0
60  
0
60  
0
60  
0
60  
0
60  
0
60  
0
60  
0
60  
dB  
GAIN  
dB  
GAIN  
dB  
GAIN  
dB  
GAIN  
dB  
GAIN  
dB  
GAIN  
dB  
GAIN  
dB  
GAIN  
1
1
2
3
4
5
6
7
8
Notice that the front panel is divided into eight preamplifier sections, sample  
rate selector with indicators and external clock switch.  
+48V  
A switch labeled +48V is located next to each gain knob.  
This switch may be engaged to provide phantom power for  
condensor mics and any other device which may require  
phantom power by way of the XLR input. This power is  
1
2
supplied at a constant rate to allow use of all eight inputs  
simultaneously, without any degradation of audio quality.  
Pin 1 = GND, Pin 2 = +48V, Pin 3 = +48V  
3
Gain Control  
This knob provides 44dB of gain to the processed signal. The amplifier has  
inherent gain of 10dB thus delivering a total gain possibility of 54dB.  
-20dB Pad  
A -20dB pad is available on each channel of the DigiMAX LT for reducing  
incoming signal levels. Using this pad can provide a more manageable signal  
from high output devices giving the operator greater control over the incoming  
signal and a much reduced chance of over-driving the input, thereby avoiding  
distortion.  
The pad is available only for the XLR input on each channel. The pad does not  
work for the line level inputs.  
Channel LEDs  
The three LEDs found on each channel are provided to serve different functions:  
-20dBu - The LED farthest to the left is labeled -20 and serves to monitor  
whether or not signal is present at the channel output.  
-10dBu - The LED in the middle is labeled -10 and indicates a signal level  
of -10dBU  
3
 
CONTROLS & CONNECTIONS 2  
Clip - The LED labeled CLIP indicates at a signal level of +22dB. Care should be  
taken to avoid using signal levels that cause this LED to become active. Signal  
levels that reach or exceed this amount of output will cause undesirable artifacts  
(distortion) in the channel output signal that is being indicated by this LED. The  
signal level is reduced by rotating the channel’s control counter-clockwise.  
Sample Rate Selector  
The section at the extreme right of the front panel contains the sample rate  
selector switch with LED indicators provided for 32k, 44.1k and 48k. This  
section also contains a switch labeled EXT. CLOCK. When this switch is engaged  
the operating clock rate of 32k, 44.1, or 48k will be determined by the incom-  
ing signal from an external device through the word clock in input on the back  
panel of the DigiMAX LT.  
4
 
CONTROLS & CONNECTIONS 2  
2.2 BACK PANEL BASIC LAYOUT  
115/230 VAC  
(by internal  
jumpers)  
~
WORD CLOCK  
POWER  
CHANNEL  
8
CHANNEL  
7
CHANNEL  
6
CHANNEL  
5
CHANNEL  
4
CHANNEL  
3
CHANNEL  
2
CHANNEL  
1
20WATTS  
CREATED,  
DESIGNED  
AND  
MANUFACTURED  
IN THE USA  
7
5
3
1
2
IN  
OUT  
CHANNEL INSERT POINTS  
adat™  
optical  
interface  
8
6
4
DIGITAL  
AUDIO  
OUTPUT  
MICROPHONE  
-
XLR  
MICROPHONE  
-
XLR  
MICROPHONE  
-
XLR  
MICROPHONE  
-
XLR  
MICROPHONE  
-
XLR  
MICROPHONE  
-
XLR  
MICROPHONE  
-
XLR  
MICROPHONE  
- XLR  
TRS  
LINE INPUT  
-
TRS  
LINE INPUT  
-
TRS  
LINE INPUT  
-
TRS  
LINE INPUT  
-
TRS  
LINE INPUT  
-
TRS  
LINE INPUT  
-
TRS  
LINE INPUT  
-
TRS  
LINE INPUT  
-
Digital Optical Output  
An adat™ optical output (lightpipe) is provided on the rear panel of the DigiMAX  
LT. Eight simultaneous 24bit outputs are possible when using the optical out.  
Word Clock Out/In  
The word clock output and input are accessed through separate BNC con-  
nectors. The internal sample rate can be set to send 32k, 44.1k, or 48k. The  
word clock in scans the incoming information and automatically synchs to the  
necessary sample rate.  
Insert  
Each channel of the DigiMAX LT has an insert that sends and returns the signal  
from the associated channel. This insert can be very useful for dynamics  
processing (such as compressing, limiting, etc.) or for monitoring purposes by  
helping in overcoming the time discrepancy that may be encountered in some  
digital recording situations. For more detailed instructions on uses and wiring  
of the inserts please see the application guide at the end of the manual. This  
insert is wired as follows:  
Tip  
Sleeve  
Sleeve  
Ring  
Tip  
TIP = Send  
RING = Return  
SLEEVE = GND  
Ring  
5
 
3 OPERATIONS  
3.1 DYNAMIC MICROPHONES  
Dynamic microphones are characterized by lower output levels. Hence, more  
gain is needed to amplify a dynamic microphone to operating level. Occasionally  
it is necessary to add the -20dB pad to the microphone to avoid distortion (e.g.  
when recording percussion).  
Do not use phantom power when using dynamic microphones.  
3.2 PHANTOM POWERED MICROPHONES  
Phantom powered microphones such as condenser and some ribbon micro-  
phones require external power to preamplify the microphone acoustic pickup.  
These microphones typically have much higher output than dynamic micro-  
phones. Hence the -20dB pad is almost always necessary when close micing to  
avoid clipping the amplifier.  
3.3 LINE LEVEL INPUTS  
The ꢀ” inputs on the DigiMAX LT are designed for use with line level or low  
impedance inputs not instrument level inputs. These inputs will work for line  
level devices such as keyboards, samplers, drum machines, CD players, etc.  
3.4 APPLICATION GUIDE  
Outboard Dynamics Processing Example  
The DigiMAX LT has an insert on every channel that allows you to insert your  
own dynamics processor, such as a compressor, EQ, limiter, or etc. To do this,  
all you need is your dynamics processor and a TRS insert cable. This cable is Y-  
shaped, has a single TRS ꢀ” jack on one end and two ꢀ” TS jacks on the other  
end. The single end will look like a stereo ꢀ” connector jack. This end of the  
cable plugs into the insert jack on the back of the DigiMAX LT. The other ends  
of the cable plug into the input and output of the outboard unit. If the outboard  
unit does not work immediately, you may want to try swapping the jacks that  
are plugged into the input and output of the outboard unit.  
Insert Jacks As Analog Outputs Example 1  
You may have noticed by now that the DigiMAX LT does  
not have a standard analog output. In the event that you  
want to have analog outputs as well as the lightpipe output,  
you can use the inserts as analog outputs. To do this, all  
you need is a ꢀ” TS cable. Plug the cable in until you feel  
6
 
OPERATIONS 3  
it ‘click’ once. The cable will appear to be ‘half plugged in. Using the insert in  
this fashion will not break the signal chain and will allow the lightpipe output to  
function correctly.  
Insert Jack As Analog Outputs Example 2  
In the event that you do not need the lightpipe output, you can use the inserts  
as analog outputs. To do this, all you need is a TRS insert cable. This cable is  
Y-shaped, has a single TRS ꢀ” jack on one end and two ꢀ” TS jacks on the  
other end. The single end will look like a stereo ꢀ” connector. This end of the  
cable plugs into the insert jack above the input on the back of the DigiMAX LT.  
You would use the SEND end of the cable as the output cable.  
By using the insert as an analog output with an insert cable, you will not be  
able to pass a signal through to the adat™ (lightpipe) output. The reason for  
this is that a signal is sent to a piece of outboard gear from the insert jack and  
then returned to the insert after being processed. So, in other words you are  
breaking the signal chain by using the send and not the return.  
Using The DigiMAX LT As A Front End For Digital Recording Systems  
The DigiMAX LT is the perfect front end for a digital recording system. The pre-  
amps on the unit allow you to boost the signal going to your recorder without  
adding extra, unwanted, noise. All digital recorders require that word clock be  
transmitted with a digital audio signal to ensure sample accuracy and syn-  
chronization. Word clock scans incoming information and automatically synchs  
to the necessary sample rate. In other words, word clock ensures that the  
recorder and the sending device (in this case the DigiMAX LT) send and receive  
digital audio at the same rate. If there is no word clock synch then you will hear  
pops, clicks, or weird digital dropout noise. Word clock can either be transmit-  
ted through the lightpipe cable (fiber-optic) or by BNC cable. If the DigiMAX  
LT is the master (sending word clock out to the recorder), then there are two  
possible connection scenarios. Both cases require that the EXT CLOCK button  
on the front of the unit be depressed (not pushed in) and that the appropriate  
sample rate be selected by using the SAMPLE RATE button on the front of the  
unit. The first case in which the DigiMAX LT is the master would require that the  
word clock output of the DigiMAX LT be connected to the word clock input of the  
recorder by BNC cable. The second case in which the DigiMAX LT is the master  
would require that the recorder receive word clock from the adat™ lightpipe  
fiber-optic cable. This second scenario requires that the digital recorder be set  
to receive word clock via lightpipe. This is often done by either hitting a button  
7
 
3 OPERATIONS  
on the recorder that says external clock or by setting a drop down menu option  
to receive sync from an external source or lightpipe.  
In the event that you want to slave the DigiMAX LT to another device you would  
need to do two things. First, press the EXT CLOCK button on the front of the  
unit. Second, you would hook a BNC cable from the word clock output of the  
sending device to the word clock input on the back of the DigiMAX LT.  
Bypassing The DigiMAX LT Preamps  
The DigiMAX LT can be used as an analog to digital converter. The setup for this  
application requires a TRS insert cable. This cable is Y-shaped, has a single TRS  
ꢀ” jack on one end and two ꢀ” TS jacks on the other end. The single end will  
look like a stereo ꢀ” connector. This end of the cable plugs into the insert jack  
on the back of the DigiMAX LT. You would use the return end of the cable as the  
input cable. By plugging a device into the return cable, you would be entering  
the signal chain after the preamp. This would allow you to digitize a signal (such  
as a keyboard or CD player) without passing through the DigiMAX LT preamp.  
The DigiMAX LT is not designed for direct use with record players - An RIAA  
(Recording Industry of America Association) phono preamplifier would have to  
be inserted in between the record player and the DigiMAX LT. If this RIAA phono  
preamplifier is not used then you would not hear an accurate representation of  
the recording.  
The DigiMAX LT is designed for use with line level or low impedance inputs NOT  
instrument level inputs - The 1/4” inputs on the DigiMAX LT are lower imped-  
ance than our typical instrument inputs. In other words, if you were to plug a  
guitar into the DigiMAX LT directly, you probably wouldnít hear anything. Use of  
an impedance matching direct box will provide the correct impedance for instru-  
ments (ex: guitar, bass, etc.). However, you can plug microphones (dynamic or  
condenser), keyboards, samplers, drum machines, CD Players and etc. into the  
DIGIMAX LT.  
8
 
OPERATIONS 3  
9
 
4 TECHNICAL SPECIFICATIONS  
Number of Channels ................................................................................ 8  
Input  
Input Impedance, XLR Input............................................................. 1.3k Ω  
Input Impedance, Line Level Input...................................................... 10k Ω  
Connectors ...................................................................... Neutrik™ Combo  
Panel Controls  
Gain .................................................................................... 0dB to +40dB  
Pad................................................................................................. -20dB  
Phantom Power................................................................................. +48V  
Meters  
Signal Present LED ..........................................................................-20dBu  
Signal Level LED..............................................................................-10dBu  
Clip LED .......................................................................................+22dBu  
Output  
adat™ Lightpipe Digital Optical.............................................................24bit  
Insert (TRS)  
Send (Unbalanced)....................................................................... 51 Ohms  
Return (Unbalanced)..................................................................... 10 Ohms  
Digital  
Sampling Rates........................................................ 32kHz, 44.1kHz, 48kHz  
Performance  
Headroom .....................................................................................+22dBu  
Freq. Response ...................................................... 20Hz - 50kHz (+/- .5dB)  
THD + Noise (Unweighted) ............................................................<0.009%  
Noise Floor .....................................................................................-94dBu  
Signal to Noise................................................................................ >98dB  
Analog Dynamic Range....................................................................>120dB  
Power Supply Rejection.................................................................... >98dB  
Amplifier Type............................................................................Dual Servo  
Power Supply  
Type ...................................................................................Linear, Internal  
10  
 
TECHNICAL SPECIFICATIONS 4  
Input...........................................100/120/220/240VAC (Factory Configured)  
Power ..........................................................................................80 Watts  
Physical  
Size..............................................................................................1U Rack  
Dimensions........................................................................19” X 1.75” X 9”  
Weight........................................................................................... 15 lbs.  
Chassis .............................................................................................Steel  
Panel .........................................................................................Aluminum  
As a commitment to constant improvement, PreSonus reserves the right to change any  
specification stated herein at any time in the future without prior notification.  
11  
 
5 PRESONUS LIMITED WARRANTY  
IN THE UNITED STATES  
PreSonus Audio Electronics Inc. warrants this product to be free of defects in material  
and workmanship for a period of one year from the date of original retail purchase.  
This warranty is enforceable only by the original retail purchaser. To be protected by this  
warranty, the purchaser must complete and return the enclosed warranty card within 14  
days of purchase. During the warranty period PreSonus shall, at its sole and absolute  
option, to either repair or replace, free of charge, any product that proves to be defective  
on inspection by PreSonus or its authorized service representative. To obtain warranty  
service, the purchaser must first call or write PreSonus at the address and telephone  
number printed below to obtain a Return Authorization Number and instructions of where  
to return the unit for service. All inquiries must be accompanied by a description of  
the problem. All authorized returns must be sent to the PreSonus repair facility postage  
prepaid, insured and properly packaged. PreSonus reserves the right to update any unit  
returned for repair. PreSonus reserves the right to change or improve the design of the  
product at any time without prior notice. This warranty does not cover claims for damage  
due to abuse, neglect, alteration or attempted repair by unauthorized personnel, and is  
limited to failures arising during normal use that are due to defects in material or workman-  
ship in the product. Any implied warranties, including implied warranties of merchantability  
and fitness for a particular purpose, are limited in duration to the length of this limited  
warranty. Some states do not allow limitations on how long an implied warranty lasts,  
so the above limitation may not apply to you. In no event will PreSonus be liable for  
incidental, consequential or other damages resulting from the breach of any express or  
implied warranty, including, among other things, damage to property, damage based on  
inconvenience or on loss of use of the product, and, to the extent permitted by law,  
damages for personal injury. Some states do not allow the exclusion of limitation of  
incidental or consequential damages, so the above limitation or exclusion may not apply  
to you. This warranty gives you specific legal rights, and you may also have other rights,  
which vary form state to state. This warranty only applies to products sold and used in  
the United States of America. For warranty information in all other countries please refer  
to your local distributor.  
PreSonus Audio Electronics, Inc.  
7257 Florida Blvd.  
Baton Rouge, LA 70806  
(225) 216-7887  
Copyright © 2002, PreSonus Audio Electronics, Incorporated. All rights reserved.  
12  
 
PRESONUS LIMITED WARRANTY 5  
OUTSIDE OF THE UNITED STATES  
PreSonus Audio Electronics products are warranted only in the country where originally  
purchased, through the authorized PreSonus distributor in the country of original purchase,  
against defects in material and workmanship. The specific period of this limited warranty  
shall be that which is described to the original retail purchaser by the authorized PreSonus  
dealer or distributor at the time of purchase. PreSonus does not, however, warrant its  
products against any and all defects: 1) arising Out of materials or workmanship not  
provided or furnished by PreSonus, or 2) resulting from abnormal use of the product or use  
in violation of instructions, or 3) in products repaired or serviced by other than authorized  
PreSonus repair facilities, or 4) in products with removed or defaced serial numbers, or 5)  
in components or parts or products expressly warranted by another manufacturer. PreSo-  
nus agrees, through the applicable authorized distributor in the country of original retail  
purchase, to repair or replace defects covered by this limited warranty with parts or prod-  
ucts of original or improved design, at its option in each respect, if the defective product  
is shipped prior to the end of the warranty period to the designated authorized PreSonus  
warranty repair facility in the country where purchased, or to the PreSonus factory in the  
U.S., in the original packaging or a replacement supplied by PreSonus, with all transporta-  
tion cost and full insurance paid each way by the purchaser or owner. All remedies and the  
measure of damages are limited to the above services. It is possible that economic loss or  
injury to person or property may result from the failure of the product; However, even if  
PreSonus has been advised of this possibility, this limited warranty does not cover any such  
consequential or incidental damages. Some states or countries do not allow the limitations  
or exclusion of incidental or consequential damages, so the above limitation may not apply  
to you. Any and all warranties, express or implied, arising by law, course of dealing, course  
of performance, usage of trade, or otherwise, including but not limited to implied warran-  
ties of merchantability and fitness for a particular purpose, are limited to a period of one  
year from either the date of original retail purchase or, in the event no proof of purchase  
date is available, the date of manufacture. Some states or countries do not allow limitations  
on how long an implied warranty last, so the above limitations may not apply to you. This  
limited warranty gives you specific legal rights, and you may also have other rights which  
vary from state to state, country to country.  
PreSonus Audio Electronics, Inc.  
7257 Florida St.  
Baton Rouge, LA 70806  
(225) 216-7887  
Copyright © 2002, PreSonus Audio Electronics, Incorporated. All rights reserved.  
13  
 

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