Alesis ADAT blackface, can it be modified?

This is really wandering into "stop screwing around and just buy a new converter" territory, but there are so many of these machines laying around that I just have to ask.

I own one, and I love the metering, the ease of use, etc. But I only use it for converters. I have a small studio, one bedroom. Only used for tracking one instrument at a time and mixing. While, I generally never never need more than two inputs at a time, I DO need outboard gear IO for mixing. The problem with the Alesis is that it will only do a/d or d/a at one time, with the push of a button. I have an E-MU 1212m card that has two input, so I can use one of them for tracking and one for an effect return, but that only lets me use one compressor, eq, etc. at a time.

Can the digital signal be jumpered somehow, bypassing the switch that enables the d/a? I took the thing apart to see what's going on in there. The converters are all together on their own board in the back, then are sent off to the digital processing board. Looks like the optical receiver/transmitter is on a small, connector-mounted board and has a wired connection going to the main digital board. I don't know much of anything about digital side signal processing. Does anyone have a schematic for these? Any helping this broke, crazy a*hole?

Or should this be in the truth table section?

Man, this is really the cliff of diminishing returns.  I'd at least spend $50 to convert to the 20 bit machines for better sound.  Buy two for $100 and have in and out?  I dunno. 

There's likely someone who will give you a machine that has a dead head stack or transport, then you'll have two.  I'd at least consider whether you can get bidirectional with another machine. 

Yeah, I won't dig into it if there will be real money involved. Only if there's just a jumper I could place to route the optical input straight to the D/A converters, but I don't know enough about it to know if it's that simple at all.

Maybe somebody point me to some medium to light reading about the digital side?

The last factory ADAT mod? Turns it back into a VCR! ;D
(sorry, I couldn't help myself...)
If you can score an AI-3, it does what you want in 1 rack space as idiot proof as can be

I'll probably end up getting an ada8000. Although it won't be for some time.

I also hate the cheesy preamps they put on the front end, as well as the front panel inputs.

Those blackface meters are superior for sure, esp with a BRC to set the hold status.

See this is what got me thinking, the ada8000 has the wave semi al1402/1401 decoder/encoders. The digital signals go directly to the converter ics from there, I'm gonna take another look and see if the adat used the same encoders, or a similar one, and maybe the digital signal can be hotwired from the optical decoder to the converter ics.

Ok, so I'm an idiot. Alesis invented the lightpipe protocol, so this unit pre-dates the wave semi ics. I'd have to trace out where the encoding/decoding is happening, if it's not all microcontroller (which I'm guessing it is) or, grab some wavesemi al1401/1402 chips and build all surrounding circuitry, including word clock input. Which, isn't impossible, but maybe more work than it's worth. Although, if I were to make a small board that could go into the unit, redirect the opto inputs/outputs, converter digital i/o and some power, I could have 8 i/o channels. Maybe even send the digital inputs to the original digital processing board as well, so I can keep my meters.

Something to tinker with I guess.

I don't really understand what you're doing or talking about... just skimmed your posts... but I have to say I am a fan of these blackface units.  They are much maligned, but the converters were a breakthrough at the time and I still like them.  The converters IMO sound very good, considering they are 16 bit only.  I liked them because they have no dithering, and I still do. They sounded cleaner to me than the later generation 20-bit units.  I still have sessions recorded with these that sound great today.  I flew the tracks into a DAW using the BRC and light pipe...  One secret, use the unbalanced -10 dB i/o with these converters.  The analog amp circuit of the +4 balanced doesn't stand up well, and this is one major reason these old units didn't sound as good as later gear.  The graininess came from the analog circuit, not the converters.  If you use the unbalanced 1/4" inputs, they sound very, very good.  Only 16-bit of course, and most any modern 24-bit converter will likely sound at least a tad better, but few 16-bit converters will, IMO... unless going for very top end.... But the average converter... like a MOTU... these old ADATs are still as good or possibly better at 16-bit IMO...    Anyway, they are totally usable even today.  If I were you I would just use the recorders as intended, with tape and all.  Then fly the tracks into your DAW. 

I'm trying to use one unit as a converter only, but it's not capable of in and out simultaneously. I agree, though. Great sounding converters.

There was a Horizon aftermarket upgrade that gave you balanced, gain adjustable 1/4" ins and outs.  It sounded noticeably better than the stock 1/4" in/out. 

And still, without having two of these (taking up half my limited rack space) I'm still unable to use the converters the way I want to.

I'll be looking into building a custom ada8000 sometime in the future. For now, my studio is in prototyping mode anyway, so no tracking or mixing will be done anytime soon.