Something I was thinking about...
Since everyone wants different features, why not designing a multi pcb dac?
In example, one for the PS, one for the dac itself, one for the output stage.
A modular system that works with plugins: if you want to add ASR, just remove the wires between the reciever board and the dac board, and put the ASR board between them
Would this work, or would the interconnections/wires/various bords degrade the signal quality?
Since everyone wants different features, why not designing a multi pcb dac?
In example, one for the PS, one for the dac itself, one for the output stage.
A modular system that works with plugins: if you want to add ASR, just remove the wires between the reciever board and the dac board, and put the ASR board between them
Would this work, or would the interconnections/wires/various bords degrade the signal quality?
multiboard DAC
A multiboard DAC is the way to go for a modular approach.
I have noticed with DIY & tweaking hifi that certain tweaks and settings work better for certain music & recordings, and worse for others. I'm thinking that if a DAC is built with lots of features that can be switched in and out, then you are able to adjust the sound to best suit the source material without having to resort to a soldering iron.
With the features documented above, there would be quite a number of possible combinations allowing you to experiment to your hearts content. The digital tweaks would be easy to switch in and out, the analogue tweaks (eg. select different filter or output buffer) would need to be well implemented to ensure the switch does not affect the quality. It wont be as simple as just switching in/out these features due to interaction & compatibility reasons (eg. sinc filter & decima upsampling) but with some care it should work.
Regards,
Dean
A multiboard DAC is the way to go for a modular approach.
I have noticed with DIY & tweaking hifi that certain tweaks and settings work better for certain music & recordings, and worse for others. I'm thinking that if a DAC is built with lots of features that can be switched in and out, then you are able to adjust the sound to best suit the source material without having to resort to a soldering iron.
With the features documented above, there would be quite a number of possible combinations allowing you to experiment to your hearts content. The digital tweaks would be easy to switch in and out, the analogue tweaks (eg. select different filter or output buffer) would need to be well implemented to ensure the switch does not affect the quality. It wont be as simple as just switching in/out these features due to interaction & compatibility reasons (eg. sinc filter & decima upsampling) but with some care it should work.
Regards,
Dean
Covering part of the requirements:
http://www.diyvideo.com/forums/showthread.php?postid=102172#post102172
Anyway, i'm looking at transformers at the moment. 1:15 could do the job with two tda's balanced. Then i can put the transformer over the the normal and inverted output and i don't have DC over it (the one i'm looking at can't handle DC)
Now testing with some crappy transformers, but not enough gain and bandwith. PCB is installed into a cd650 (it's alive again) but, just for now, using the player powersupply. That will be the next thing after the output (and i finally get some sound..)
Greetings,
Guido
http://www.diyvideo.com/forums/showthread.php?postid=102172#post102172
Anyway, i'm looking at transformers at the moment. 1:15 could do the job with two tda's balanced. Then i can put the transformer over the the normal and inverted output and i don't have DC over it (the one i'm looking at can't handle DC)
Now testing with some crappy transformers, but not enough gain and bandwith. PCB is installed into a cd650 (it's alive again) but, just for now, using the player powersupply. That will be the next thing after the output (and i finally get some sound..)
Greetings,
Guido
Guido,
Interesting idea splitting the i2s signal into L and R for separate D/A conversion.
Have you compared your implementation with 2 x TDA1541 DACs in parallel? Common concensus here seems to be that putting the TDA in parallel gives more body to the sound (I have not checked this yet).
Using a transformer for output is definately a good option for output.
Regards,
Dean
Interesting idea splitting the i2s signal into L and R for separate D/A conversion.
Have you compared your implementation with 2 x TDA1541 DACs in parallel? Common concensus here seems to be that putting the TDA in parallel gives more body to the sound (I have not checked this yet).
Using a transformer for output is definately a good option for output.
Regards,
Dean
balanced outputs
4 x TDA1541 for balanced outputs?
Maybe, but not for the price of 4 x TDA1541A S2!! There are several ways of approaching a balanced output with only 1 DAC chip, use of a transformer, balanced discrete output, balanced buffer output (eg. DRV134) or logically inverting the i2s input on a separate DAC chip (I would need to research this one further).
Personally I'd parallel the DACs and use an output stage that supports both balanced and unbalanced.
Regards,
Dean
4 x TDA1541 for balanced outputs?
Maybe, but not for the price of 4 x TDA1541A S2!! There are several ways of approaching a balanced output with only 1 DAC chip, use of a transformer, balanced discrete output, balanced buffer output (eg. DRV134) or logically inverting the i2s input on a separate DAC chip (I would need to research this one further).
Personally I'd parallel the DACs and use an output stage that supports both balanced and unbalanced.
Regards,
Dean
IMHO a modular approach would be best. This is the route I have taken with my DAC. The receiver, reclock, dac, output and power supplies are all on separate boards. This way I don't have to redo everything when tweaking one of the modules. This approach has been especially useful for the output stage, as I have a few different ones on the go that I am evaluating / tweaking. I imagine there is probably a (very) slight loss of quality due to interconnecting wires, but then I think this is balanced by better isolation between noisy parts (receiver) and sensitive parts (output stage)
deandob said:
Dean,
Did not try this yet, there is a jumper on the pcb to choose equal or balanced output. However, balanced should be better, since it blockes common mode signals. E.g. PS noise.
Also going to look into DEM reclocking someday, maybe this is also an option for your project. But remember, the more stuff people want in it, the less chance that something will be realised...
GuidoB
modular approach
Zodiac,
What DAC chip did you use? Are you willing to share the schematics and even PCB gerber files for the modules? This would save some time re-inventing the wheel.
I've been looking into the design options today. I have a number of questions around the receiver design that others may answer:
- Has anyone compared the CS8414 with the CS8412CP? Although these chips operate in the digital domain, there are mixed reports about what sounds better for 16/44 CD. The CS8412 would be a preference due to its DIP pinout, and although the chip is out of production there still seems to be plenty of places to purchase them. The CS8412 apparently does not handle jitter as well as the CS8414 but the async reclocking circuit can look after that.
- Use a transformer for the receiver input instead of an isolation cap, has anyone compared the two implementations?
Regards,
Dean
Zodiac,
What DAC chip did you use? Are you willing to share the schematics and even PCB gerber files for the modules? This would save some time re-inventing the wheel.
I've been looking into the design options today. I have a number of questions around the receiver design that others may answer:
- Has anyone compared the CS8414 with the CS8412CP? Although these chips operate in the digital domain, there are mixed reports about what sounds better for 16/44 CD. The CS8412 would be a preference due to its DIP pinout, and although the chip is out of production there still seems to be plenty of places to purchase them. The CS8412 apparently does not handle jitter as well as the CS8414 but the async reclocking circuit can look after that.
- Use a transformer for the receiver input instead of an isolation cap, has anyone compared the two implementations?
Regards,
Dean
Does any other dutchman want to order from Elib as well ? When I wanted to order Elib was so considerate to mention the high transport costs to the Netherlands. He suggested to order with other dutchmen as well to limit transport costs to a moderate level.
[dutch mode on]Dus als je ook een Dual Crown of S2 wilt mail me dan via de Admins hier en dan bestellen we ze samen. Scheelt weer in de portokosten.[dutch mode off]
Groeten/Regards,
Jean-Paul
[dutch mode on]Dus als je ook een Dual Crown of S2 wilt mail me dan via de Admins hier en dan bestellen we ze samen. Scheelt weer in de portokosten.[dutch mode off]
Groeten/Regards,
Jean-Paul
TDA1541A design
As there have been a few requests for this, I have started to put together a design (mostly based on the design info on this board so I wont claim to be original). I have just downloaded Eagle and still coming to grips with it, I will post the schematic over the next few days for comment.
In discussions with Elib, it is possible to get PCBs made in China for a decent price however dont expect it to be $2 for a board as these are for 300+ runs. Should still be cheap if a group buy is organised.
Regards,
Dean
As there have been a few requests for this, I have started to put together a design (mostly based on the design info on this board so I wont claim to be original). I have just downloaded Eagle and still coming to grips with it, I will post the schematic over the next few days for comment.
In discussions with Elib, it is possible to get PCBs made in China for a decent price however dont expect it to be $2 for a board as these are for 300+ runs. Should still be cheap if a group buy is organised.
Regards,
Dean
Just wondering if you have decided whether to build a modular circuit board design? This may help with the group buy because those that only need a portion of the circuit can still join the purchase. What I mean is that some may want to get the board for just the digital receiver and the clock and uses its own DAC, or some may be interested using the board as the basis of some multi-DAC design.
i2s input
Yep, the board will take i2s input on the DAC board, and yes you need to be as close to the transport as possible. I'm putting together the specification & design for the receiver board now. I'm debating if a pulse transformer is necessary - research shows that a transformer is needed for isolation but that it should be connected at the source end not the receiver. The PCB will cater for one but it can be bypassed.
Yep, the board will take i2s input on the DAC board, and yes you need to be as close to the transport as possible. I'm putting together the specification & design for the receiver board now. I'm debating if a pulse transformer is necessary - research shows that a transformer is needed for isolation but that it should be connected at the source end not the receiver. The PCB will cater for one but it can be bypassed.
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