Thank you everyone: I have learned so much since joining this forum less than 48 hours ago....!
Thanks for both the advice and the links to further reading which has proven wonderfully educational so far.
So: here I go, an attempt to sumarise what I have gleaned so far - please can people correct me where I am wrong before I end up going too far down the 'wrong roads'...
Audio Digital to Analogue Converters (rather than DAC chips) are very much a sum of all parts: most important being the correct choice of combining power supply / good quality descrete components (capacitors, resistors, tranformers, opamps etc) with the appropriate DAC chip and then choosing the best "output/analogue" stage (opamp/transformer) to produce a "good/great" sound.
Broadly speaking Audio DAC chips can come in three 'flavours'(I have put asterisks around the 'preferred' option):
1) Voltage out e.g: WM 8740/8742 *WM8741* ('Wolfson') / AK4xxx ('AKM') / Texas Instruments PCM 1xxx ('Burr Brown')
2) Current out e.g: ES9018 ('Sabre'/'ESS')
3) R-2R - a chain of voltage dividing resistors to produce a sine wave/analogue out eg: dam1021 ('Soekris/DAM'): Output stage The Legato Discrete Balanced I/V Stage [not sure at all about this yet...]
When the digital signal has been processed by the DAC chip it is presented to the 'output/analogue' stage: if the DAC chip is a 'voltage out' DAC; directly connecting the DAC to a transformer would be recommended for this stage, and, inherently acts as a low pass/high pass filter.
If the DAC is a 'current out' an opamp output/analogue stage is recommended. (Anyone please elaborate...!)
How am I doing so far please everyone?
Now I think I will investigate quantran 's suggestion of an AK board - please could anyone give me links to suggestions please.
I believe that I will then have to purchase a TOSLINK (optical) to S/PDIF converter to allow optical in to the DAC board; a set of transformers (one for each channel) and build a suitable power supply for the board / TOSLINK to S/PDIF coverter.
Will the transformer output stage need to be amplified at all before reaching my (for now) integrated amplifier line-in (i.e. is it a good idea to protect the signal/boost it slightly (valves?) between the Audio DAC transformer output stage and the line in of my integrated amp?)
Thanks for both the advice and the links to further reading which has proven wonderfully educational so far.
So: here I go, an attempt to sumarise what I have gleaned so far - please can people correct me where I am wrong before I end up going too far down the 'wrong roads'...
Audio Digital to Analogue Converters (rather than DAC chips) are very much a sum of all parts: most important being the correct choice of combining power supply / good quality descrete components (capacitors, resistors, tranformers, opamps etc) with the appropriate DAC chip and then choosing the best "output/analogue" stage (opamp/transformer) to produce a "good/great" sound.
Broadly speaking Audio DAC chips can come in three 'flavours'(I have put asterisks around the 'preferred' option):
1) Voltage out e.g: WM 8740/8742 *WM8741* ('Wolfson') / AK4xxx ('AKM') / Texas Instruments PCM 1xxx ('Burr Brown')
2) Current out e.g: ES9018 ('Sabre'/'ESS')
3) R-2R - a chain of voltage dividing resistors to produce a sine wave/analogue out eg: dam1021 ('Soekris/DAM'): Output stage The Legato Discrete Balanced I/V Stage [not sure at all about this yet...]
When the digital signal has been processed by the DAC chip it is presented to the 'output/analogue' stage: if the DAC chip is a 'voltage out' DAC; directly connecting the DAC to a transformer would be recommended for this stage, and, inherently acts as a low pass/high pass filter.
If the DAC is a 'current out' an opamp output/analogue stage is recommended. (Anyone please elaborate...!)
How am I doing so far please everyone?
Now I think I will investigate quantran 's suggestion of an AK board - please could anyone give me links to suggestions please.
I believe that I will then have to purchase a TOSLINK (optical) to S/PDIF converter to allow optical in to the DAC board; a set of transformers (one for each channel) and build a suitable power supply for the board / TOSLINK to S/PDIF coverter.
Will the transformer output stage need to be amplified at all before reaching my (for now) integrated amplifier line-in (i.e. is it a good idea to protect the signal/boost it slightly (valves?) between the Audio DAC transformer output stage and the line in of my integrated amp?)
So now it seems that my decision between DAC chips is either:
1) the AK4xxx (please can anyone advise which one is currently advised?) with a transformer output/analogue stage
2) the SABRE ES90xx (again, please can anyone advise?) with an ['opamp?] output/analogue stage
Any advice here / links to boards please?
Will there be a huge benefit with the AK4xxx chip (and perhaps the ES90xx) of having a dual/parallel DAC board (one for each channel) from people's experience, or, is the benefit not easily heard?
Thank you everyone once again for your time and advice 🙂
1) the AK4xxx (please can anyone advise which one is currently advised?) with a transformer output/analogue stage
2) the SABRE ES90xx (again, please can anyone advise?) with an ['opamp?] output/analogue stage
Any advice here / links to boards please?
Will there be a huge benefit with the AK4xxx chip (and perhaps the ES90xx) of having a dual/parallel DAC board (one for each channel) from people's experience, or, is the benefit not easily heard?
Thank you everyone once again for your time and advice 🙂
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Aha! Thank you RajkoM, that is very interesting to analyse and see the transformers in the output stage.
Did you make the output board with the Lundahl transformers yourself or buy it please (it looks a bit complex as opposed to connecting the transformers directly to the DAC output for me, at this stage...)
You have brought the Wolfson WM8741 back into debate....
May I ask what DAC board you used and where you sourced it from please?
🙂
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All on a universal PCBs is my own DIY.
DAC board is old Weiliang DAC-5 from China. Bought as a full kit and pretty tweaked (capacitors, resistors, regulators...)
2SK170 buffer has its own PSU with many CRCRCRC filters.
I suggest cermet volume pot. NOS german "Ruwido" pot is best to me, but current "Vishay" pot in a plastic housing is quite good.
DAC board is old Weiliang DAC-5 from China. Bought as a full kit and pretty tweaked (capacitors, resistors, regulators...)
2SK170 buffer has its own PSU with many CRCRCRC filters.
I suggest cermet volume pot. NOS german "Ruwido" pot is best to me, but current "Vishay" pot in a plastic housing is quite good.
If you deside to go with Twisted Pear, perhaps OPUS, you will get excellent workmanship, excellent support and documentation and a verified good design. There might be a slight premium on the price compared to China imports, but I think the prices are very fair. BUT, if you want exotics or that special mystique of certain flourishments of design, I feel TP fails to deliver. It's more engineering than cuisine. Still, engineering often works.
Dual mono will lower the noise floor and so increase the dynamic range. It is easily measurable in most cases, but audible? Perhaps. Audible enough for the price? Consensus seems that often yes, but then again, money is not very scarce in these things nor is subjective validation. Bonus is that you get a balanced source and can forget about common noise in your cables (if the whole signal chain is built balanced). Again, may be significant improvement. Helps with ground-loops at least or in a very noisy (radiowise) environment or with long long cables.
About your list, r-2r is voltage out, so no I-V or indeed output stage is needed as such. If the dac is current out, the signal is pretty much useless for a normal audio amplifier without some sort of I-V. But, for example, Sabres, being current out, if forced will run voltage out signals but with significant reduction of measured performance. This might or might not be special for the Sabre architecture, I'm not sure.
I also wanted to point out that for voltage-out dacs, you don't necessarily need transformers and it is not the most linear solution to do the filtering. But if you like the sound and the idea of iron on the output, then you do and there is no frequency response or distortion curve that's going to change that.
Remember to not mix things like I-V, filter and buffer stage. These have different tasks and all can be called or be included in output or analog stage. All of these can be done passively (with transformers or not), discretely (with tubes or transistors) or with op-amps. Or any combination of these. (A buffer, being an amplifier, cannot be done passively of course...) The dac chips themselves also already have varying amounts of these analog stages inside.
Amplifying/buffering the (voltage) signal before the power amp (or indeed the pre-amp) is not necessarily needed. Here you have to study impedance matching/bridging. Simplified, your DAC output impedance should be low and amp input high. I think 20 times higher is the rule of thumb (10x is fine). This is to keep the dac output from overloading and maximize the voltage transfer (largest possible signal). I think the output trafos help with this part.
But as I mentioned earlier, low level signals are more subject to noise and/or can't drive capacitive loads (long cables) and a simple buffer, or a pre-amp if you want volume control, will make both the impedance and noise problems significantly smaller and you can even use longer than 20 cm interconnects without a worry.
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What a terrific answer T129 thank you 🙂
I really appreciate you clarifying / adding detail to the stages involved; that has helped me a lot.
I really appreciate you clarifying / adding detail to the stages involved; that has helped me a lot.
The current AK4xxx variants are similar. They share the same technology. The newer chips have better specs but I think the specs of the chips are not really that important. They are beyond the resolution available from CD. even for high definition audio format the ak4396 is sufficient. What's important is to choose a good design. You can find several topics on the forum discussing different DACs. Everyone has an opinion, I think.
I went with the AK4396 which can convert 24/192 sources.
Another excellent candidate is CS4398. Very nice tone for a delta sigma DAC.
Hi quantran
I am now looking at AK4xxx boards - do you have any recommendations of suppliers / boards, or, is it best to go for a Chinese / eBay board to experiment / modify?
Please could you give a bit more detail of how you made the power supplies shown in your photo?
Thanks again for all your help 🙂
You may consider this one for experiment
https://www.ebay.com/itm/162015880520
There is a threat about this dac here:
http://www.diyaudio.com/forums/digi...2496-ak4393-dac-kit-cs8416-ak4393-5532-a.html
The earlier version has ak4393 chip. The current version uses ak4396.
I bought the pcb with the smd chips only and started from there. I use one power transformer with 4 separate secondary windings to make 4 independent power supplies. Two of them are based on LT3042 regulators bought from diyinhk. The other two uses LT1963 for pre-regulator and LT1763 on the second level.
FYI, I also add an upsampling chip cs8421 between the receiver chip and the dac chip. It upsample any input signal to 24/192.
https://www.ebay.com/itm/162015880520
There is a threat about this dac here:
http://www.diyaudio.com/forums/digi...2496-ak4393-dac-kit-cs8416-ak4393-5532-a.html
The earlier version has ak4393 chip. The current version uses ak4396.
I bought the pcb with the smd chips only and started from there. I use one power transformer with 4 separate secondary windings to make 4 independent power supplies. Two of them are based on LT3042 regulators bought from diyinhk. The other two uses LT1963 for pre-regulator and LT1763 on the second level.
FYI, I also add an upsampling chip cs8421 between the receiver chip and the dac chip. It upsample any input signal to 24/192.
Hi @RajkoM - I wondered why you decided to put a volume control in your DAC and not use the amplifier volume control you feed this into - is it because you only use a power amplifier?
Thanks!
Thanks!
Hi quantran,
Very interesting threads - I have learnt some new opinions....
It just makes me want to have all the 'kit' to hand to try all the different options (hee hee!) - maybe when I'm rich and retire... 😉
I'm leaning very heavily to this board:
New Assembled Dual WM8741 AK4118 Chip 192K DAC Audio Decoder w LCD Display | eBay
Putting a set of transformers on the output instead of the opamps perhaps - once having tried replacing the opamps first (to learn...)
Very interested in your/anyone's thoughts....
Very interesting threads - I have learnt some new opinions....
It just makes me want to have all the 'kit' to hand to try all the different options (hee hee!) - maybe when I'm rich and retire... 😉
I'm leaning very heavily to this board:
New Assembled Dual WM8741 AK4118 Chip 192K DAC Audio Decoder w LCD Display | eBay
Putting a set of transformers on the output instead of the opamps perhaps - once having tried replacing the opamps first (to learn...)
Very interested in your/anyone's thoughts....
Yes. I only use power amplifier.
I have no volume control on my tube SET amplifier. None of them is no good enough for my taste 😀
Hi quantran,
Great idea!
I found this from your link for the UK: NEW LJM CS8416 + AK4396 + NE5532 2496 DAC Kit 24BIT 192K J163 | eBay
I think that I would like to take your advice and go ahead with this board 🙂
Please could you elaborate on your power supply choice (maybe some links?) and whether this board would be appropriate to feed the output into two transformers (which ones / specs maybe?).
As for an optical in - do i need to buy something like this kit to feed into the DAC board?: 74HCT14D Optical input to Coaxial output module OPT to COAX board for DAC | eBay
As for the cs8421 chip.... any links how on earth I could also embark upon that...?!?
Many thanks for all your help quantran! I feel like I am getting close to a dseign / almost ready to order parts... how exciting!
Great idea!
I found this from your link for the UK: NEW LJM CS8416 + AK4396 + NE5532 2496 DAC Kit 24BIT 192K J163 | eBay
I think that I would like to take your advice and go ahead with this board 🙂
Please could you elaborate on your power supply choice (maybe some links?) and whether this board would be appropriate to feed the output into two transformers (which ones / specs maybe?).
As for an optical in - do i need to buy something like this kit to feed into the DAC board?: 74HCT14D Optical input to Coaxial output module OPT to COAX board for DAC | eBay
As for the cs8421 chip.... any links how on earth I could also embark upon that...?!?
Many thanks for all your help quantran! I feel like I am getting close to a dseign / almost ready to order parts... how exciting!
Thank quantran:
the question I have is: if I get a 'higher spec' DAC board, will this obviate the need for a CS8421 upsampling board?
the question I have is: if I get a 'higher spec' DAC board, will this obviate the need for a CS8421 upsampling board?
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