If HQPlayer is doing all the heavy lifting then I would think for DSD we can do away with the AK4137 and go direct into a DSD DAC. Best if you could test this with the AK4490 in direct mode, once you get your external volume sorted.
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After I sorted out the relay problem on my simple LP filter DSD 'DAC' project I have been really enjoying it plugged into my main system over the weekend. I've been feeding it DSD256, upsampled CD rips on HQPlayer, and the sound is very musical.
My thinking has turned to how it will perform with a couple of your new modules, which should slip in very easily. With the future in mind for upgrading this project but also building a tube filter/buffer, some questions if I may;
1. Have you finalised the power supply requirements for the new direct drive DSD boards?
2. Is the DC servo before or after your on-board LP filter?
3. Is the server defeatable?
This info would help me to plan the projects and get ahead with some assembly in preparation.
Cheers
Ray
My thinking has turned to how it will perform with a couple of your new modules, which should slip in very easily. With the future in mind for upgrading this project but also building a tube filter/buffer, some questions if I may;
1. Have you finalised the power supply requirements for the new direct drive DSD boards?
2. Is the DC servo before or after your on-board LP filter?
3. Is the server defeatable?
This info would help me to plan the projects and get ahead with some assembly in preparation.
Cheers
Ray
Things are slowly shaping up. I am not doing another prototype so pretty much aiming for a release version with everything integrated. You will need dual independent 12V dc supplies (or bipolar types) as shown. Supplies can be raw dc also (12Vmin-18Vmax).
Servo sense is at the output terminal itself after the on-board LPF but being direct coupled it does not matter whether it is before or after. Servo is an integral part and cannot be disabled by user. It is not in the signal path and functioning well as expected. If servo is removed then you will need dc block caps or transformers that I am trying to avoid.
I will need some time to fine tune the layout and vol control firmware - no ETA yet. So until then you can go ahead with your setup and experiment with filters/tubes (and PCM vs DSD). Maybe you can get someone to loan their top-gun PCM DAC for a shootout 😉
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Oh cool. So you convert it to multibit DSD within the chip, and implement the volume control?
I am really noticing lately how processor intensive it is applying volume control to DSD via HQplayer.
The AK4490 can also do volume control to DSD like the 9018. But the way Sonny has it setup on his DAC, the DSD bypasses that section and goes straight to direct mode. It's supposed to sound better this way, but I don't have the firmware to flash it to the other way to compare myself.
Did you try with, and without with your DAC? If so could you hear a difference?
Coming together nicely Acko.
Thanks. Just specifying some parts for future projects so can order without risk now.
In my 'cheap and cheerful' prototype I have a couple of 15V regulated supplies that power the output buffer I'm using so it looks like I could slot in your new board quite easily as I won't need the buffer then.
Just thinking about the potential tube-based filter/buffer project. DC not such an issue then as it can be used for biasing tubes. To use the tube filter I would need to remove the onboard filter and tap the signal at the input to your filter, which would have the affect of taking the servo out of circuit?
I will need some time to fine tune the layout and vol control firmware - no ETA yet. So until then you can go ahead with your setup and experiment with filters/tubes (and PCM vs DSD). Maybe you can get someone to loan their top-gun PCM DAC for a shootout 😉[/QUOTE]
I have a top-gun PCM DAC;
http://www.diyaudio.com/forums/group-buys/227502-amanero-isolator-reclocker-gb-172.html#post4206993
and, of course, it can do DSD too. I have done some comparisons and thus far my rating is;
PCM on ESS9018 >> DSD on ESS9018 >> DSD 'no-DAC'
However there is an element of apples and pears in that the ESS9018 is a network renderer on UPnP/DLNA whereas the 'no-DAC' is a HQPlayer network renderer. If I could get the ESS9018 working with HQPlayer I would be happier with any comparison but I seem to have come to a halt on that as I haven't been able to get HQPlayer NAA and Botic to co-exist.
I have also yet to explore the full panoply of HQPlayer DSD options.
Ray
Thanks. Just specifying some parts for future projects so can order without risk now.
In my 'cheap and cheerful' prototype I have a couple of 15V regulated supplies that power the output buffer I'm using so it looks like I could slot in your new board quite easily as I won't need the buffer then.
Just thinking about the potential tube-based filter/buffer project. DC not such an issue then as it can be used for biasing tubes. To use the tube filter I would need to remove the onboard filter and tap the signal at the input to your filter, which would have the affect of taking the servo out of circuit?
I will need some time to fine tune the layout and vol control firmware - no ETA yet. So until then you can go ahead with your setup and experiment with filters/tubes (and PCM vs DSD). Maybe you can get someone to loan their top-gun PCM DAC for a shootout 😉[/QUOTE]
I have a top-gun PCM DAC;
http://www.diyaudio.com/forums/group-buys/227502-amanero-isolator-reclocker-gb-172.html#post4206993
and, of course, it can do DSD too. I have done some comparisons and thus far my rating is;
PCM on ESS9018 >> DSD on ESS9018 >> DSD 'no-DAC'
However there is an element of apples and pears in that the ESS9018 is a network renderer on UPnP/DLNA whereas the 'no-DAC' is a HQPlayer network renderer. If I could get the ESS9018 working with HQPlayer I would be happier with any comparison but I seem to have come to a halt on that as I haven't been able to get HQPlayer NAA and Botic to co-exist.
I have also yet to explore the full panoply of HQPlayer DSD options.
Ray
That's starting to look/sound very promising albeit a bit more elaborate then the original concept which is simplicity itself. Looking forward to see what you've come up with.
Nice & straight forward PSU requirement.
Yes, something like that with its own processing unit. Can be bypassed also so comparisons will be made once completed.
1. Do not use this dc to bias tube or other stages. It is like a variable offset and you wouldn't want to use this as a bias voltage.
2. The servo and filters are separate circuits and do not interact. The filter is a simple LPF and is part of the internal output stage. I am currently using 50k cut-off but may decide on a 100k for the final cut. There is no need to tap into the circuit, just connect additional filter stages to the output as required.
Oh, yes, thanks for the reminder and really appreciate you sharing the shootout results! There are quite a number of factors involved and let's see if this DSD DAC improves the standings. Also, hopefully as we go along we can get more results about PCM vs DSD and R2R vs SDM vs NoDAC
Thanks for the update/info Acko.
I get the message and will go with your stock modules for my next upgrade - I planned to do that anyway.
What's your thinking about raising the LP cut-off to 100KHz - won't that restrict it's use to some people or are you saying it shouldn't be used below a certain DSD rate?
One of the reasons I've been contemplating a tube stage is that my power amps seem to thrive on a high-current capable source - any thoughts on that with respect to your output stage?
Christmas is coming and a nice present would be most welcome!😀
Ray
I get the message and will go with your stock modules for my next upgrade - I planned to do that anyway.
What's your thinking about raising the LP cut-off to 100KHz - won't that restrict it's use to some people or are you saying it shouldn't be used below a certain DSD rate?
One of the reasons I've been contemplating a tube stage is that my power amps seem to thrive on a high-current capable source - any thoughts on that with respect to your output stage?
Christmas is coming and a nice present would be most welcome!😀
Ray
This is the intention, based on understanding of DSD so far. So, yes, moving away from Scarlet Book DSD64 that is not exactly great and requires heaps of filtering. At DS256, filtering becomes more relaxed and we can take advantage of the wider bandwidth
You can bring down the cut-off frequency by adding caps on the output side and there are pads on the board for this. Of course, if you are adding external tube buffers/filters that are set to 50KHz fc then these will dominate.
Output is voltage-mode (Zo~600 ohm), easy for HiZ stages but can also be driven in current mode with 20mA p-p max if this is more suitable for your amplifier. Alternatively buffer is required. What is the Zin of your amplifier?
😱cutting close here, most likely results from tests only at this rate ...
Thanks Acko.
I imagined you were targeting DSD256 and higher as optimal, which I can't disagree with.
My amps have an input Impedance of 100K and sensitivity of 0.8 volt; looks nice and benign on paper but they definitely sound better when driven actively compared with a passive source. On my current DSD project I use a JG buffer on the output. It also has a 22uF DC blocking caps and I'm sure you're modules will make a significant improvement just by removing them, let alone the other improvements you're bringing.
I had my tongue firmly in my cheek with the Christmas comment, just showing my enthusiasm for what you're developing.😉
Ray
I imagined you were targeting DSD256 and higher as optimal, which I can't disagree with.
My amps have an input Impedance of 100K and sensitivity of 0.8 volt; looks nice and benign on paper but they definitely sound better when driven actively compared with a passive source. On my current DSD project I use a JG buffer on the output. It also has a 22uF DC blocking caps and I'm sure you're modules will make a significant improvement just by removing them, let alone the other improvements you're bringing.
I had my tongue firmly in my cheek with the Christmas comment, just showing my enthusiasm for what you're developing.😉
Ray
Thanks Ray, no problems, happy to help as much I can 🙂
I am curious about the effect of buffer added. Good you brought this up and requires further investigation
Technically speaking 100K Zin of your amplifier is very easy to drive with just 0.6% drop of signal and 30uA load pk if connected to this DAC. It has a pure resistive Zout of 600 ohm for the entire audio band. The output drivers can supply 20mA peak. Anyway, something to think about and I will also see if adding buffer makes a difference. You can also use the JG Buffers here with blocking caps
Hi Acko,
What's your approx ETA you have something to sell? Are you also offering supplies to power them?
What's your take on using SMPS on the latest digital gear? I'm getting great results with SMPS's using with Sonny's DAC. However I have some low noise linear supplies here I haven't even tried yet with it.
What's your approx ETA you have something to sell? Are you also offering supplies to power them?
What's your take on using SMPS on the latest digital gear? I'm getting great results with SMPS's using with Sonny's DAC. However I have some low noise linear supplies here I haven't even tried yet with it.
Looks like well into 2016 at this stage... a bit of uncharted territory and number of options for tweaking further.
PSUs, similar to the ones on my webpages will do.
SMPS vs linear is something to compare with further tests. You may want to hook up your linear supplies and let us know. I guess Sonny's output stage have great PSSR already
BTW, Have you tried with passive volume using DSD direct?
I've listened to DSD quite a bit with his output stage connected right into the Hypex NC500's unbuffered inputs. It plays quite loud, but not too loud for listening, however, I feel the output stage is being stressed at these levels driving the low impedance inputs of those amps unbuffered. As a result there's a bit of hardening in the sound.
I'm working out details on an analog volume control right now. The HQPLAYER DSD volume control has been a disappointment with DSD for me, so I'm wondering if passing the DSD through the SDM part of the chip to provide DSD volume control would be superior.
I
I'm working out details on an analog volume control right now. The HQPLAYER DSD volume control has been a disappointment with DSD for me, so I'm wondering if passing the DSD through the SDM part of the chip to provide DSD volume control would be superior.
I
Thanks Mike,
The Hypex NC500 are low impedance types Zin 1.8k only! so this could be the reason why Sonny's discrete output stage struggles with it. I am just estimating here, if you connect to my DSD DAC expect ~30% drop in signal and 12mA pk load current drawn - still under the max 20mA capacity of the output drivers. There are options to increase the drive capability further - something that I will look into later to match the NC500
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Yeah his output stage is beefy for a DAC, just a bit weak for this application. I do have high current buffers though, but much too loud with them in the chain without volume control 🙂
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