Latest DSD Decoder Project

What people are working on at the moment
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Ray P
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#31 Re: Latest DSD Decoder Project

Post by Ray P »

I'm back in business. The new Cronus checked out and I've now got the BBB playing music (at DSD512) as an HQ Player NAA (network audio appliance). So now I need to proceed to hooking up the DSD board to the Cronus.
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#32 Re: Latest DSD Decoder Project

Post by Ray P »

Wolfgang wrote: Sat Jun 22, 2019 4:43 pm I hope I don’t upset anybody or go too much “off-topic” with this comment but in my limited understanding the strength of the Soekris R-2R DAC lies in the possibility to adjust the balance between low pass filter linear phase and (unavoidable) passband ripples which can be described as pre- and post echoes determined by the impulse response of the filter. I think that’s what the “filter brewing thread” in diyaudio is trying to achieve. A simple low pass filter of a DSD DAC doesn’t have this option.And the practical listening experience is much more affected by these" filter issues " than by some limitations of DSD to reproduce silent passages accurately.
Have a look at the features of HQPlayer;

https://www.signalyst.com/consumer.html
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Wolfgang
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#33 Re: Latest DSD Decoder Project

Post by Wolfgang »

I tested HQ Player in my system some time ago. So I am not completely unfamiliar with it but at the same time I cannot say that have enough information to be sure how to interpret the real effect of what is called the “Resampling Filters”. I guess that’s what we are talking about in this context.
Are they mainly dealing with the upsampling process in general and simply try to readjust somehow everything (whatever that would be) or are they really dealing with phase and impulse response of the low pass filter? And how would they do this without knowing what DAC is being used? Just be trial and error and listening to what sounds best? This would be also an appropriate approach because that’s what we are doing when using different JPLAY settings, AudioOptimizer filters etc.? But here is also the difference compared to uploading filters for the Soekris DAC. These filters do so much more and really can completely re-shape the sound because this approach focusses more precisely on the actual problem in a more conceptual way so to say and before listening.
The shape of the impulse response can be found above the cut off frequency but the pass band ripples which are responsible for the pre- and post echoes are within the listening frequency band (20-20KHz). And that makes it so complicated if one tries to find the best filter response for the best sound.
So IMO this is kind of hard to solve with a piece of software for general use for all kind of DACs and situations and with a limited set of predefined filters. I cannot offer any solution and also only try and listen myself but in the case of the DSD DAC I simply wouldn’t know whether it is the upsampling process or the filter which sounds a certain way and why I would go through the upsampling process if I can simply change filter settings. Where is the benefit if in the end it’s always the output filter that defines the sound and which I have to shape? But maybe this is anyway a more academic problem?
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Ray P
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#34 Re: Latest DSD Decoder Project

Post by Ray P »

Hi Wolfgang. I'm not suggesting any equivalency, just that there are options for experimenting with DSD.

At the end of the day it always comes down to what sounds best for the individual and for me personally that's DSD via HQPlayer, which is why I'm working on a DSD decoder for my main system and my Soekris DAC is destined to go into my Masterpiece headphone amp.
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#35 Re: Latest DSD Decoder Project

Post by Wolfgang »

At the end of the day it always comes down to what sounds best for the individual...
Couldn't agree more, Ray.
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#36 Re: Latest DSD Decoder Project

Post by Ray P »

As i couldn't finish the 13E1 amp build I applied myself to progressing this project. Just two small tasks outstanding, connecting the muting connections and testing it, then installing the output transformers. Maybe we'll get some music out of it tomorrow.
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#37 Re: Latest DSD Decoder Project

Post by Ray P »

I have music from my DSD decoder build - rather belatedly and it didn't help to be completely thrown off track by receiving a Twisted Pear Cronus reclocker with the wrong regulator chip.

Anyway, with a replacement Cronus installed everything is working well and music is playing without any issues/problems - correct speed, no obvious noise and no loud bumps/pops. I can't comment on absolute sound quality yet as I'm listening through a cheap pair of computer speakers while I check everything out. All that remains to do is to properly connect the outputs to the chassis phono sockets and to screw the lid on. Here are a couple of pictures;

Image

Image

I'll try it in the main system during the week.
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#38 Re: Latest DSD Decoder Project

Post by Cressy Snr »

Shoddy, :)
Sgt. Baker started talkin’ with a Bullhorn in his hand.
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#39 Re: Latest DSD Decoder Project

Post by Ray P »

Cressy Snr wrote: Mon Aug 26, 2019 10:17 pm Shoddy, :)
I know, I know!

I've just found the PCB I've been looking for - look at the transformer in the top right.... :oops:
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#40 Re: Latest DSD Decoder Project

Post by IslandPink »

It was on the tip of my tongue, Steve, couldn't quite find the word.
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#41 Re: Latest DSD Decoder Project

Post by Wolfgang »

Ray, I can see that you use 3 psus for your DAC. How did you resolve the problem with different potentials of the ground planes? Any minor hum or not fully "open" sound? And how will you resolve this when you use the tube output stage?
I had to struggle with my DAC for a while to clean everything up and had to use unorthodox solutions.
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#42 Re: Latest DSD Decoder Project

Post by Ray P »

Wolfgang, there are actually four separate power supplies and most of what you see in the chassis isn't actually the decoder, that's just the stacked boards in the top left corner of the chassis. All the stuff you see in front of the decoder boards is the network appliance (Beaglebone) and a digital isolator/reclocker (Twisted Pear Hermes/Cronus)- that has two power supplies precisely because of the galvanic isolation delivered by the isolator that keeps any noise from the network-side ground out of the decoder. The decoder board has two low noise power supplies for left and right channels as they're separate but after the isolator the three power supplies are all referenced to the same ground; the other thing to remember is that this is all essentially digital, it is only the act of putting the digital SDM (DSD) data through the FIR filters that an analogue signal is derived and that itself is galvanically isolated from the analogue system that follows the decoder by the output transformers.

There is no tube stage in this decoder project.

As I said in my post, to date I've only listened to the output on some active computer speakers so far to prove that it basically works but they're pretty poor so I can't yet draw any conclusions about the sound quality with respect to openess etc. -it plays music without any obvious noise is all I can say so far.
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#43 Re: Latest DSD Decoder Project

Post by Ray P »

I've been at home today so I left the DSC2 decoder playing music all day into a headphone amp to start the 'burn-in' process. The HPA is nothing very special but an awful lot better than listening to the computer speakers and I did actually listen through my headphones for an hour or two; I like what I'm hearing so far. I'm looking forward to hearing it in the main system at the weekend.
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#44 Re: Latest DSD Decoder Project

Post by Ray P »

I returned to this project last evening; last time I played it when I introduced it to the main system I found it had acquired a disconcerting hum and last evening I finally found the cause - a poor ground connection under one of the boards. Now properly connected and wow, playing through my new Noir HPA the sound is amazingly good so I'll try it again in the main system this weekend.
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