a couple of questions about ADAT/ S/PDIF and digital connections in general

[minofifa]

Hey all
Well i have been checking out the E-MU 1220 M and it says that there are 18 imputs. I only see 2 XLR pramps and 6 TRS imputs giving a total of 8. Where do the other 10 come from? I have also seen it has ADAT ins and outs. So my question is how exactly does a digital connection work (i'm assuming that ADAT is similar to S/PDIF and they are digital)?

Say for example, that i hooked an m-audio octane 8-pre preamp up to the E-MU 1220M via the ADAT connection. Would all 8 channels run though this, and would they come in properly in the recording software? if this is how it works, why don't more people just get a card that has like 4 adat ins and thus would have lots of inputs to work with insted of having a zillion trs ins? I know that many pres offer TRS outs which need a TRS imput to go into but many of the newer pres have ADAT outs as well.

It is obvious that i am very confused so any light on the subject would help me out greatly. Thanks for the knowhow.

 

[minofifa]

well i was checking out the m-audio octane specs page and it says that it only samples up to 48 khz... bummer. So does this mean that if i want to use the ADAT out, i have to let the octane do the A/D conversion at 48 khz? it wouldn't make much pont to run it to th e-mu's converters at 96 khz then would it....

Well are there any other 8 channel pre's that sample at 96 khz?

 

[crankz1]

The specifications for ADAT lightpipe is 8 channels at 48kHz max. You can however, run at 96kHz.
Take my MOTU 828mkII for instance .... If I want to run at 88.2 or 96 via ADAT inputs, the channels are halved (4 channels). Though I'm quiet pleased running at 48.

As far as the number of inputs ....
The MOTU is somewhat similar to the 1220
2 XLR pre-amped analog front inputs + 8 line level analog rear inputs + 8 channels via ADAT at 48kHz or 4 at 88.2/96 + 2 channels via SPDIF. Giving a max of 20 inputs.

The thing with ADAT and SPDIF is that .... those units contain their own converters, thus the analog signal is converted to digital prior to entering the 1220 or MOTU or whatever card's digital IN's. Some do offer the ability to route the analog inputs directly to the analog outputs. Giving you the choice of using the unit as analog In and Out ... Or convert the analog to digital and output it digitally via ADAT/SPDIF.
How they get recognized as additional inputs is all done by the drivers for the card and it's control panel.
For me to utilize all 20 IN's on my MOTU, I have to use the supplied ASIO drivers and enable the digital inputs via the MOTU's control panel. Then it's just a matter of configuring all the inputs within the DAW programs I use.

HTH

-Ken

 

[minofifa]

cool, thanks crankz, that cleared up a lot.

So do you have a preamp that runs an ADAT out to an ADAT in on your motu? May i ask why do you limit yourself to 48khz if you paid for a sound card that can do 96 khz? What bit depth does ADAT encode at? And finally is there a difference between ADAT and S/PDIF in terms of quality or are they just two different formats for the same thing bascially?