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A while back I commented about my experiments with 'no-dac decoding of DSD. At the time I was using a very simple low-pass filter to derive an analogue output from DSD. The sound quality was really good but there were some issued with pops and clicks. There's a whole thread on the No-DAC approach at DIY Audio.
Wind the clock forward a couple of years an things have improved and DSD is becoming established as an alternative to PCM in some quarters so I thought I would revisit DSD playback motivated by the sound quality I experienced previously. Amanero have now produced DSD specific firmware for their USB board that addresses the pops/clicks and it can now process upto DSD512 data rates as well. Signalyst has always been one of the main proponents of DSD and developed an open-hardware delta-sigma D/A convertor, the DSC1; https://www.signalyst.com/hardware.html This has been developed by others. I recently purchased a derivative of the DSC1 from a DIY-Audio member who lives in Russia. The DSC2 operates in differential mode and the output filtering is handled by transformers instead of op-amps. This morning I put the components together on a 'breadboard'; Feeding the Amanero DSD256, upsampled from CD quality FLAC rips with HQ Player, and I've spent several hours listening. The sound quality is outstanding, rich but very detailed and really engaging, it imediately caught my partner's ear and she came and listened too, always a good sign as she has minimal interest in my 'gadgets' or tinkering. We experienced none of the noise/pops/clicks of the previous experiments either. The DSC2 beats my current Twisted Pear Sabre 9018 equipped DAC and costs significantly less too. I'm hoping to be able to compare it with the latest Twisted Pear Sabre 9028 DAC in the next couple of weeks. I have some further tweaks planned, primarily to install an isolator/reclocker between the Amanero and the decoder board and maybe try a shunt power supply. Then I can think about boxing it up.
Reply with quote #2
Hi Ray, Very cool project. Are you going to incorporate femto Clocks? I hear prices have come way down on them and they blow picos away.
Reply with quote #3
Hmm, Femto clocks; the first thing is to try a Twisted Pear Cronus reclocker that I have available (equipped with Crystek oscillators) to see if it makes a difference over the Amanero board's oscillators - my understanding of DSD, which isn't great, is that this approach is less sensitive to jitter than more conventional PCM decoders. We'll see.
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Did you flash the Amanero module with firmware 1099c ? And if so does it then handle both PCM and DSD over the USB input ? The reason I ask is that I would like a solution where I could perhaps offer PCM or DSD to the USB interface and then convert everything to DSD using a converter solution (like the AK4137) between the USB module and the DSD2 board (as some people seem have done). If the Amanero is able to automatically recognise the source then it would make for a flexible solution. Not sure what the AK4137 would make of a signal that was already converted to DSD ? This is all new territory for me so please excuse any silly questions.
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I'm only using my Amanero board with the DSD decoder I started this thread about so have had no reason to feed it PCM data. I'm using firmware version 2003, which is a Linux specific version currently (I guess it will be ported to Windows at some point). DSD playback is optimised in V2003.
Feedback I've seen is that AK4137 compromises sound quality so if you want the best performance I recommend upsampling PCM to DSD with HQ Player. I don't think AK4137 cares whether it receives PCM or DSD, it just processes to produce the required output as appropriate.
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Ray, Thanks for the reply and the information. I will attempt to trial it in both configurations and assess sound quality vs convenience. The only other advantage an intermediate board would offer would be the ability to connect other sources (convenience factor again). I am looking forward to see what my OTLs make of it all and take the opportunity to thank you for sharing your experience. Shaun