8 Channels ADAT Lightpipe for our preamps ?

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Neeno

Well-known member
Joined
Sep 4, 2004
Messages
446
Location
Switzerland
Does anyone know how to build ad ADAT Lightpipe for a 8 channels preamp ? I think that this would be great to fit our RME, MOTU and PROTOOLS SYSTEMS !

Anyone can help me ?

Thanks a lot !

Greets, Neeno !
 
Take a look at the "Wavefront" (formerly Alesis) range of interfacing chips:

http://www.profusionplc.com/franchises/wavefront.htm

This falls beyond DIY in my opinion..

Jakob E.
 
I have just looked at the web site...
Sorry did I read that right....

An ADAT Optical encoder takes four pair of stereo outputs and converts them into a 24bit stream at a cost of £4 a chip
To physically get the lightpipe out you need another piece of equipment which is a TOSLINK Lighpipe adapter TORX173(at a cost of roughly £6 each)
You will also need a word clock input to the encoder anbody know how this is done...
fascinating...
I for one would want someone to explain...
 
maybe yes... but i'm not sure...
i know that you need 4 ADC converters, something like Crystal or AMK... i'll prefer AKM (RME and Digidesign use this ADC on some interfaces and on the HD 192...)

Every ADC converter, will convert 2 mono signals...

I don't think that it's so simple... but maybe it would be...

Greets
Neeeeeeeeeeeeeeeeeeeeeeeeeeno
 
It looks relatively simple, maybe not trivial. I think the biggest challenge would be generating a bit clock for the ADC and syncing this to a word clock input, as the AL1401 bit clock is an internal signal. If you want to do a ADC-DAC pair, you could use the ADAT input as the clock source, configure the AL1403 in master mode, and hook up the signals like inferred in the bottom of the application schematic. I think for 96 kHz, you still run the word clock at 48 kHz and the left and right signals lose their meaning - the left one is the earlier conversion, the right is the later one - you get only four channels per lightpipe connection instead of eight.
 
let me give you guys some hints here :)

Try using 2 PCM4204's (4chan each of 118dB) - that will interface straight to the ADAT chips.

The only complex thing (I think) is generating the word-clock etc. I know that TI doesn't exaclty have a solution...

Could you take a Bit-Clock for the device and use a counter? (so it clocks once every 256 bit-clock pulses)???

I'm not soooooo hot on the deep down and dirty type analogue stuff, so any opinions or ideas you have will be gratefully accepted :D

Cheers m'dears...

R
 
This topic is back and it would be SO cool if there was someone out there that has made this work! What about modifying one of those cheap ADAT interfaces from that "B" company with better chips? Easier to make our own? Joel
 
maybe it would be possible to bypass the internal clock of one of those cheapo brand convertors, and just have a project that is a jitter free (as much as possible) superstable clock source. basically just taking a cheapo unit and upgrading it with an external source. and also upgrade the line paths with DOA's or something fancy.
transformers would be too expensive IMO.
i would love for this to happen as well, ive been needing an affordable converter set, but the affordable stuff is complete shit.
-bryan
 
Even the cheap converters often have an input for an external clock if you want to use one. It would just be a matter of building and packaging one up and then hooking it in. I don't know what would be involved in that.
 
anyone have expierience designing digital clock sources? hehheh thats gotta be one hell of a design process.
maybe we can just reverse an apogee or something?
is that even possible?
 
The new Behringer 8 channel A/D - D/A box is cheap, full of Alesis convertors, has lightpipe both ways and actually seems to sound fine. For a few hundred bucks you could buy it and modify it directly into your system and it would give you all the components you need already on a board with WC.
 
Does it really sounds OK?

I think it wpuld be nice to get one of those and canging the line amp. Oh, don´t forget to trash the mic preamps!

Maybe an opamp upgrade at the line inputs... Anyone have one of those to check the opamps at the line inputs?? It´s pretty cheap for 8 channels of ADDA...
 
[quote author="dramadisease"]anyone have expierience designing digital clock sources? hehheh thats gotta be one hell of a design process.
maybe we can just reverse an apogee or something?
is that even possible?[/quote]
It's pretty easy really. Stable clocks for local signals don't take gobs of effort to stay clean I've done quite a few for embedded data collection modules. It's when they have to go out into the world that it turns into a Gordian knot.

-dave
 
Well, it's very easy (trivial, even) if the converter is the master. What gets difficult is when someone else wants to be the clock master, then you need to lock the DAC to it, and typically generate a new bit clock for the DAC.
 
[quote author="rafafredd"]Does it really sounds OK?

I think it wpuld be nice to get one of those and canging the line amp. Oh, don´t forget to trash the mic preamps!

Maybe an opamp upgrade at the line inputs... Anyone have one of those to check the opamps at the line inputs?? It´s pretty cheap for 8 channels of ADDA...[/quote]

My thoughts exactly - you get all the convertors and clock and lightpipe, and cheap too, and just go ahead and hot up all the analog components and maybe the PSU.
 

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