20/20 AD User Guide

Using the 20/20 AD

In 2-channel mode, when the LINK switch is off, each of the two channels is

LINK

compressed independently. When the LINK switch is on, the louder of the two

 

channels sets the amount of compression. This serves the same function as

 

“stereo link” in analog compressors. When you are recording a stereo signal and

 

want to maintain the stereo image, LINK should be on. However, if you have the

 

compressor set up to protect against short overloads, or if you have the release

 

time set to 0, keeping LINK off will probably sound better. When recording two

 

mono signals, LINK should be off.

 

In 4-channel mode, when the LINK switch is off, channels 1 and 2 and channels

 

3 and 4 are linked in stereo pairs. When the link switch is on, all four channels

 

are linked. (There is no way to compress four mono signals.)

 

When the DISPLAY switch is on, the level meters indicate the amount of DISPLAY compressor gain reduction in each channel. This shows the amount that gain (in

dB) which is being reduced as the input level exceeds the threshold.

The 20/20 AD provides two sets of digital audio output connectors with three Digital Audio Outputs connectors in each set. In four-channel mode, the first set contains digitized CH1

and CH2, the second set contains CH3 and CH4. In two-channel mode, both sets contain identical copies of digitized CH1 and CH2. The unused set may be used to drive a backup recorder or to synchronize another 20/20 AD.

Each set of digital outputs contains three connectors: an XLR connector which transmits AES3 digital audio, an RCA connector which transmits an S/PDIF- compatible digital audio signal, and a TOSLINK-compatible optical transmitter. All outputs are always active. The front panel FORMAT switch selects between AES and S/PDIF-compatible Channel Status bits, but it doesn’t enable or disable the actual transmitters. Make sure that the FORMAT setting is set for AES when using the XLR connector and S/PDIF when using the RCA or optical connectors.

Pin 1 of the AES outputs is connected to system ground through jumpers W26 and W27. If the shield is connected to ground at the receiver end, these jumpers should be opened. Note that, because of the transformer or optical isolation, it is not necessary to connect the ground between the 20/20 AD and the equipment receiving the digital audio data, regardless of which output type you choose.

As mentioned above, only appropriate high-frequency cables should be used for digital audio. Refer to Page 7 for recommended cables.

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Lexicon 20/20 AD manual Link