PreSonus DigiMax LT Manual
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This article is based on a PreSonus manual and are used with the kind permission from the people at PreSonus.
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The original manuals can be found at PreSonus's Technical Support Website.
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DigiMAX LT USERS MANUAL
OVERVIEW
Contents |
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 commercially available digital optical cable. This cable can supply eight simultaneous outputs.
CONTROLS AND CONNECTIONS
FRONT PANEL
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 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
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.
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
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 channels control counter-clockwise.
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 incoming signal from an external device through the word clock in input on the back panel of the DigiMAX LT.
BACK PANEL BASIC LAYOUT
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 connectors. 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:
OPERATIONS
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.
PHANTOM POWERED MICROPHONES
Phantom powered microphones such as condenser and some ribbon microphones require external power to preamplify the microphone acoustic pickup. These microphones typically have much higher output than dynamic microphones. Hence the -20dB pad is almost always necessary when close micing to avoid clipping the amplifier.
LINE LEVEL INPUTS
The 1/4 inch 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.
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 1/4 jack on one end and two 1/4 TS jacks on the other end. The single end will look like a stereo 1/4 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 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.
The end that plugs into the LT should have the Tip and Ring connected (signal carrier) and the Sleeve is ground. However, the ring contact should not be connected to the ring conductor. The other end of the cable should have the Ring and Sleeve bound (ground) and the Tip alone is the signal carrier. Remember, the Ring contact should not be attached to the Ring conductor. Please refer to the diagram above for visual clarification.
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 preamps 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 synchronization. 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 transmitted 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 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 impedance than our typical instrument inputs. In other words, if you were to plug a guitar into the DigiMAX LT directly, you probably wouldnt hear anything. Use of an impedance matching direct box will provide the correct impedance for instruments (ex: guitar, bass, etc.). However, you can plug microphones (dynamic or condenser), keyboards, samplers, drum machines, CD Players and etc. into the DIGIMAX LT.
TECHNICAL SPECIFICATIONS
Number of Channels 8
Input
Input Impedance, XLR Input1.3k
Input Impedance, Line Level Input10k
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 Optical24bit
Insert (TRS)
Send (Unbalanced)51 Ohms
Return (Unbalanced)10 Ohms
Digital
Sampling Rates32kHz, 44.1kHz, 48kHz
Performance
Headroom+22dBu
Freq. Response20Hz - 50kHz (+/- .5dB)
THD + Noise (Unweighted)<0.009%
Noise Floor-94dBu
Signal to Noise>98dB
Analog Dynamic Range>120dB
Power Supply Rejection>98dB
Amplifier TypeDual Servo
Power Supply
TypeLinear, Internal
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
