So I've been searching and searching and searching, but I cannot seem to find on instance of a DAC project that will convert more than two channels. Does such a thing exist. I was thinking of using a DSP (probably from a computer sound card) to actively crossover a bi or tri amp system in the digital domain, but t his would require a 4 or 6 channel DAC. I know that SPDIF is capable of outputting that many channels but cannot find anything on decoding that many channels. Can someone point me in the right direction?
That's my site actually. If you need to do multichannel the Alesis chips are by far the easiest way to do it. I'm not aware of anything other than ADAT that has out-of-box encode and decode hardware.
There are many multichannel DACs available, targeted towards AC3/DTS. Some of them are quite good, although single channel or stereo DACs probably sound better.
There are many multichannel DACs available, targeted towards AC3/DTS. Some of them are quite good, although single channel or stereo DACs probably sound better.
I've found several multichannel DAC's. Unfortunately my circuit design skills aren't up to designing something on my own (give me a year or two, I'll get there). The ADAC looks killer, but does wayyyy more than I need. I'm just looking for a stand alone DAC. Does anybody know of a project, even one that I could buy a PCB for. Thanks.
Hey dunderchief
I've been thinking about designing a high quality multichannel DAC for a while now... Thing is I don't really need one at this point and I have quite a lot on my fork, but if you want, I guess I can go ahead and just design the thing.
The idea was that it should have exceptional sound quality, so I want to use single or dual DAC IC's but nothing more. This means quite a few IC's in total. Also I wanted to give mine balanced outputs, so DAC IC's which require external I/V converters is a must. This is a good idea anyway, since you can get better quality by building discrete I/V converters.
Like I said, if you're interested I can make a plan to design one.
DJ
I've been thinking about designing a high quality multichannel DAC for a while now... Thing is I don't really need one at this point and I have quite a lot on my fork, but if you want, I guess I can go ahead and just design the thing.
The idea was that it should have exceptional sound quality, so I want to use single or dual DAC IC's but nothing more. This means quite a few IC's in total. Also I wanted to give mine balanced outputs, so DAC IC's which require external I/V converters is a must. This is a good idea anyway, since you can get better quality by building discrete I/V converters.
Like I said, if you're interested I can make a plan to design one.
DJ
THAT'S PERFECT!!!! Sounds like exactly what I would be looking for. My only worry is what the person in the last post said. Would it need to be a specific type of SPDIF or other digital input? If you are willing to design something like this I would be eternally greatful. Please don't rush through anything else on my behalf, wouldn't want to affect anything, but if you get something done up, feel free to use me as a guinea pig or anything else you need.
Cheers
-Steve
Cheers
-Steve
Don't worry too much about what the other guy said.
As long as you understand that I have some other things to do as well and that this project would therefore take a while, I'll be willing to design it.
Do you have access to PCB manufacturing facilities, or can you have some made?
I'm thinking that I can do a preliminary design (rather quickly), but it would save time if you can build and test the prototype. Then you can report back to me and I'll do the necessary adjustment/s to the design.
How does that sound?
DJ
As long as you understand that I have some other things to do as well and that this project would therefore take a while, I'll be willing to design it.
Do you have access to PCB manufacturing facilities, or can you have some made?
I'm thinking that I can do a preliminary design (rather quickly), but it would save time if you can build and test the prototype. Then you can report back to me and I'll do the necessary adjustment/s to the design.
How does that sound?
DJ
I'm assuming I do. I'm an electrical engineering student at a major University, so I have to imagine that they have the capability to do so. I will do some checking and get back to you. I won't even be back full time until the end of September so like I said, please do not rush anything else. Again thanks for doing this and let me know what you would like me to do. The easiest way to get ahold of me will probably be to use email, and if you have ideas on what chips you would like to use and general parts it would be great if you could let me know a few of the basics I will need as I would like to start getting some parts. Thanks again.
Cheers
-Steve
Cheers
-Steve
I'm also at a university over here, and our PCB manufacturing isn't very good. It's fine for prototyping, but nothing fancy. No solder mask, no silkscreen etc. Let me know how yours is if you have any. Perhaps when the design is final you can have a board made for me too(?).
I'll get back to you on the parts after the coming weekend, I'll only have time for this project then. Sorry.
DJ
I'll get back to you on the parts after the coming weekend, I'll only have time for this project then. Sorry.
DJ
Hey dunderchief
I've just started looking over the info I have on various ICs etc for the DAC project. Since Texas Instruments make some of the best ICs for our purposes, and they have a very nice sample programme, I'm going to try to use mostly their products. So far, this is the basic ideas I've come up with:
8 separate DAC channels
1x balanced & 1x unbalanced output per channel
super low jitter clock circuit
totally separated digital and analogue power supplies (perhaps more than one of each)
high quality low pass filter to ensure maximum amount of noise from digital circuitry is removed
Most of this would seem obvious, but I'm just stating it so you know I was busy with the project over here. I will start drawing up the schematic next weekend, if not tomorrow.
Cheers
DJ
I've just started looking over the info I have on various ICs etc for the DAC project. Since Texas Instruments make some of the best ICs for our purposes, and they have a very nice sample programme, I'm going to try to use mostly their products. So far, this is the basic ideas I've come up with:
8 separate DAC channels
1x balanced & 1x unbalanced output per channel
super low jitter clock circuit
totally separated digital and analogue power supplies (perhaps more than one of each)
high quality low pass filter to ensure maximum amount of noise from digital circuitry is removed
Most of this would seem obvious, but I'm just stating it so you know I was busy with the project over here. I will start drawing up the schematic next weekend, if not tomorrow.
Cheers
DJ
Sounds like an plan to me. Any idea specifically which TI chip you like? Power supply is where I'm most interested in design. While I'll certainly be making one of these for home use I'm also considering using in a mobile situation, doing active crossovers through a computer in my car. I'm gonna start designing a PS that will run off of 12v DC, but that's another story, it will certainly be going in the home first. Am I correct in saying that you're in South Africa? If not where are you? I think my program has a pretty good deal with both TI and Nation as far as getting parts so if you were interested I could be getting twice the parts needed and be able to send them to you. Keep me posted
Cheers
-Steve
Cheers
-Steve
Hey again...
Well the chip I would most like to use is TI's PCM1792, because it's their best performance DAC. Sadly it's not on sample, so I think I'll go with PCM1738 which is almost as good. That is unless you can get us some 1792s.
Also from TI, I would like to use the PLL1708 as part of the clock circuitry. I intend to spend a lot of time finetuning the clock, since this can obviously have great effects on the final audio quality.
I'm still not sure exactly what opamps I will use, but it will probably be OPA627 or 637 (singles) and OPA2132 or 2134 (duals).
Like I said I'll hopefully get to drawing up a basic schematic this weekend. Oh, and yes I'm in South Africa.
Cheers for now.
DJ
Well the chip I would most like to use is TI's PCM1792, because it's their best performance DAC. Sadly it's not on sample, so I think I'll go with PCM1738 which is almost as good. That is unless you can get us some 1792s.
Also from TI, I would like to use the PLL1708 as part of the clock circuitry. I intend to spend a lot of time finetuning the clock, since this can obviously have great effects on the final audio quality.
I'm still not sure exactly what opamps I will use, but it will probably be OPA627 or 637 (singles) and OPA2132 or 2134 (duals).
Like I said I'll hopefully get to drawing up a basic schematic this weekend. Oh, and yes I'm in South Africa.
Cheers for now.
DJ
OK, so I've been looking over a bunch of stuff and I'm wondering what the input section of the DAC is going to look like. Will it simply take a 2ch input and break it up into 4 left and 4 right analog channels, or will it accept 8 different channels. I'm still reading up on the limitations of the SPDIF system.
Sure, split the SPDIF into I2S, then feed it to your 4 DAC ICs.
Itll only be stereo tho... you cant do anymore than 2 channels using plain SPDIF.
To go over 2 channels you need to do Dolby AC3, DTS, etc. which cant(*) be done DIY.
* - ok, it can, and has been, but if your asking about this stuff you wont be able to do it... i know i cant.
Hey again Steve.
Sorry but I didn't get very far with the schematic over the weekend since I was ill. My head is still spinning a little.
Like I said previously, I would like to make 8 totally separate DAC channels. Implying that you can configure them in many ways, ie one stereo input out to all 8 outputs or 8 inputs out to 8 outputs.
True you don't get home cinema processors that puts out all the separate channels digitally, but that is one of my (very ambitious) projects for later on. I need to build such a processor since I am planning to build my active TDAA powered speakers next. No DAC and digital all the way to the driver. Ask if you wanna know more.
What have you found out about your PCB facilities?
I'll keep you updated and I'll probably have hte schematic done at the end of the week.
DJ
Sorry but I didn't get very far with the schematic over the weekend since I was ill. My head is still spinning a little.
Like I said previously, I would like to make 8 totally separate DAC channels. Implying that you can configure them in many ways, ie one stereo input out to all 8 outputs or 8 inputs out to 8 outputs.
True you don't get home cinema processors that puts out all the separate channels digitally, but that is one of my (very ambitious) projects for later on. I need to build such a processor since I am planning to build my active TDAA powered speakers next. No DAC and digital all the way to the driver. Ask if you wanna know more.
What have you found out about your PCB facilities?
I'll keep you updated and I'll probably have hte schematic done at the end of the week.
DJ
I'd be really interested in the TDAA design, but I have to say I know little to nothing about the concept.
How do you plan to receive 8 digital channels to the DAC? Since standard SPDIF can only send 2ch will you have 4 inputs? Just trying to get a full grasp of what's going on.
Being as it's summer term the person I wrote to at University is a little slow in getting back to me. I'll let you know as soon as I hear from them on the what we can do about PCB's.
Thanks again.
Cheers
-Steve
How do you plan to receive 8 digital channels to the DAC? Since standard SPDIF can only send 2ch will you have 4 inputs? Just trying to get a full grasp of what's going on.
Being as it's summer term the person I wrote to at University is a little slow in getting back to me. I'll let you know as soon as I hear from them on the what we can do about PCB's.
Thanks again.
Cheers
-Steve
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