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Old 16th July 2016, 12:14 AM   #1
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Default Serious talk: No DAC chip, but a FPGA?

No DAC chip, but a FPGA, is it possible to achieve groundbreakable level?
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Old 16th July 2016, 10:49 PM   #2
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Chord's DAVE seems to be using this approach, gets very highly rated. But then it is extremely expensive for a DAC...
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Old 19th July 2016, 01:28 AM   #3
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Quote:
Originally Posted by mtoc View Post
No DAC chip, but a FPGA, is it possible to achieve groundbreakable level?
An FPGA? Doing what, exactly?

Switching an R2R network? Isn't that what the Soekris DAC is?
Delta-sigma modulation?
Extracting excess money from the pockets of audiophiles?
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Old 22nd October 2016, 08:49 PM   #4
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Fulfilling the duties of a DAC without the necessity for an additional DAC chip. Seems to be what the Chord Dave does. Anyone have any idea how to implement such a thing in an FPGA like the Spartan 6? Please share or pm me.
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Old 22nd October 2016, 11:10 PM   #5
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There are a number of dedicated chips which implement the functions of a DAC without needing an additional DAC chip. For example TI has its range of PWM processors, as does ST.

http://www.ti.com/lit/ds/symlink/tas5508.pdf
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Old 22nd October 2016, 11:17 PM   #6
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Originally Posted by mtoc View Post
No DAC chip, but a FPGA, is it possible to achieve groundbreakable level?
There's little preventing someone more enterprising from baking a lot of the distributed logic of an r-2r DAC (e.g. Soekris's offering) into a single FPGA.

IMO, not worth it. Either put your money and sweat into an existing solution or deep-dive into one of the highest-end audio DAC ASICs and implement it to an inch of its life. (Which would still provide a LOT of intellectual challenge)
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Old 27th October 2016, 09:51 AM   #7
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Here's an interesting video of the designer of what many consider to be the best DAC in the world - the Dave - describing his work: https://www.youtube.com/watch?v=80iu7ifXsOo. The specs are significantly more impressive than any other DAC that I know of.

I don't think the design has anything to do with an R2R dac and to me the technology implemented in the dave - from what I can tell 100+ dsp operations happening simultaneously, is way beyond the capabilities of the top Delta Sigma and R2R chips/discrete available today. I just purchased a Gustard A20H on a whim. In my research and experience with AKM chips, I'm looking forward to hearing it very much. The newly released AKM AK4497 and ESS9038 will render all previous DACs obsolete in my opinion (my opinion). However if funds permitted, I'd skip the likes of MSB, TotalDAC (have extensive experience with Zfoil resistors though and they're amazing), Esoteric (which features the AK4497 in their flagship $20,000 SACD player), and so on, and purchase a Chord Dave. Unfortunately the Hugo is just too barebones and feature limited to justify the cost. Until traction around a DIY project of the sort mentioned in the OP gains some traction, I can only dream.
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Old 27th October 2016, 10:27 AM   #8
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Default FPGA Vs ASIC Vs OEM Sokeris

Quote:
Originally Posted by DPH View Post
There's little preventing someone more enterprising from baking a lot of the distributed logic of an r-2r DAC (e.g. Soekris's offering) into a single FPGA.

IMO, not worth it. Either put your money and sweat into an existing solution or deep-dive into one of the highest-end audio DAC ASICs and implement it to an inch of its life. (Which would still provide a LOT of intellectual challenge)
Hi DPH,
I am interested in designing (TBO, paying for someone else to design it!) an FPGA solution, but your suggestion of a ASIC solution also sounds like an option...?
I am way out of depth when it comes to the tech talk.....Could you please explain in simple terms the general principals /pro's / cons of FPGA Vs ASIC Vs an OEM vesion of the Sokeris or similar?

Thanks for your time and all the best
Derek.
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Old 27th October 2016, 06:34 PM   #9
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An ASIC DAC and the FPGA as implemented in the Chord seem very different in my understanding. An ASIC dac would = all dacs not including the DAVE and discrete dacs like the TotalDAC. If going this route, I expect the aforementioned AKM and ESS chips to be the best option. http://www.ti.com/lit/an/snaa129/snaa129.pdf

From what I can tell, the Dave implements decimation filtering/sample rate reduction to eliminate aliasing --> waveform 'rebuilt' using a 'waveshaper' which is akin to 'infinite oversampling.'

The pros I see of an FPGA implementation is a significantly more advanced and complex process, compared with a standard DAC chip, all occurring in a single IC, resulting in a much simpler overall design.

Last edited by milezone; 27th October 2016 at 06:59 PM.
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Old 27th October 2016, 06:41 PM   #10
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Using an FPGA does not have to be expensive. The Edirol FA66 is a good example of a very good cheap DAC based on such.

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