ADAT A/D Questions

Fishmed

Well-known member
If you have digital lightpipes connected from a PC card to an ADAT, can the ADAT be used as an A/D converter... basically recording straight to the PC and not to the ADAT?

If so, can you still monitor the signal through the ADAT's analog outputs?

:confused: ...just curious!
 
Basically, the analog outputs on the ADAT use the analog inputs to monitor. There is a way to monitor the A/D converters at the analog outputs, but Alesis does not recommend this way of monitoring because of the DC offsett recalibrations that that happen create some nasty sounds... :)

Now, to your question.

Basically, I think you want to know if for instance if you can use ADAT tracks 1&2 for A/D conversion, then use ADAT tracks 7&8 for the D/A conversion, with tracks 1&2 running to a soundcard which will output to ADAT tracks 7&8. Am I correct?

Here is the problem. ADAT's can only use either the digital or analog inputs at one time. It will output through the digital out's at all times. So, if you where wanting to use the digital in's to monitor stuff from the lightpipe out of a soundcard that was actually getting it's signal from the ADAT's A/D converter, you could not because the ADAT cannot be in digial and analog input mode at the same time. Do you understand what I am saying?

So, you could not use one ADAT for A/D conversion going to a soundcard as well as using the same machine for D/A conversion of the same source, or any source coming from the soundcard at the same time as using the same ADAT for A/D conversions since the ADAT can only input digital or analog, but not both, at the same time.

If you had two different machines, you could put one machine in analog input mode for A/D conversions, and the other in digital input mode for D/A conversions. I have not tried this, but it seems like it would work.

Does this help?

Ed
 
Oops, got a little ahead of myself there.

Yes, the ADAT can be used as A/D converters, and you can still hear the input source at the analog outputs since the outputs use the analog inputs for monitoring purposes. ADAT's output through their digital and analog outs at the same time.

The issue is whether your sound card is getting it's sync from the lightpipe in or a sync cable from the ADAT's.
 
This does help, but I am still trying to figure out the part of the DC offset recalibrations. Say if I put the ADAT's in's and out's to the insert of say eight channels of a mixing board. Would I not be monitoring the out's of the ADAT on the mixer from the insert's return? One last thing, do you have to have a tape in the machine to monitor the signal, or to just use the ADAT as a A/D converter?

Thanx for your help man.

[This message has been edited by Fishmed (edited 04-12-2000).]
 
You missed one little thing "the analog outputs use the analog inputs to monitor". When you enable a track for recording, even with no tape in the machine, and tape not rolling, the analog input is routed to the analog output directly. So, it is not doing a A/D/A conversion. But, the analog input is also hitting the A/D converter because the signal IS present at the digital outputs too. Thus, if you are using a digital console, you can monitor the record enabled track before actually recording anything.

Ed
 
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