Just gave myself a few minutes of panic and despondency! 
I've just moved the DAC from the workbench to next to my work desk so it's easier to explore the HQP settings and to use it with my Noir HPA and Bayer DT880 headphones - no sound! After a bit of head scratching I remembered to plug the 5V LDO reglator back in.
Now listening to DSD256 through the Noir and DT880s - simply delightful - I've never heard Eva Cassidy sounding so good!
This morning I finished the assembly and added the bling! I just need to organise a top for the chassis to, literally, top-of the project.
I've just moved the DAC from the workbench to next to my work desk so it's easier to explore the HQP settings and to use it with my Noir HPA and Bayer DT880 headphones - no sound! After a bit of head scratching I remembered to plug the 5V LDO reglator back in.
Now listening to DSD256 through the Noir and DT880s - simply delightful - I've never heard Eva Cassidy sounding so good!
This morning I finished the assembly and added the bling! I just need to organise a top for the chassis to, literally, top-of the project.
Thanks for the kind words mterbekke.
When I've banked more time listening to it, including introducing it into the main sytem, I'll expand on my experience with it. As for shortcomings, as of now I would summarise them as, it's not cheap, it It needs to be fed a high quality SDM (DSD) datastream (no PCM) which some will find rather inconvenient and it's ridiculously inefficient to power all those valves to just produce a line-level analogue signal but it is also, IMO, ridiculously good and so easy to listen to.
Ray
When I've banked more time listening to it, including introducing it into the main sytem, I'll expand on my experience with it. As for shortcomings, as of now I would summarise them as, it's not cheap, it It needs to be fed a high quality SDM (DSD) datastream (no PCM) which some will find rather inconvenient and it's ridiculously inefficient to power all those valves to just produce a line-level analogue signal but it is also, IMO, ridiculously good and so easy to listen to.
Ray
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Ray's second shortcoming can be solved by building the original valve DAC rather than the DSD only version, but then it's even more expensive and DSD support is worse. The original valve DAC can only handle DSD up to and including DSD128 and internally decimates it to 201.6 kHz noise shaped PCM, before interpolating it again and converting it into a 27 Mbit/s sigma-delta modulate.
Anything with tubes is rather power hungry and inefficient, but luckily it has other qualities as well ;-)
HQPlayer will be a valuable part of explorable tweak tools, as well as tube rolling and the likes, if you're planning on doing those.
Have fun Ray, I look forward to seeing the progress, I'm sure there are a lot more lurkers than just me looking at this.
Marco
Hi Marcel.
The beauty of dsd is that the dac can be made extremely simple and all the power hungry calculations can be kept away from the analog circuitry (pc based or else).
I'm all for that, don't mind pcm won't work at all.
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Indeed Marco, indeed.
With six E88CC tubes required I'm not expecting to do a lot of rolling. The set in the DAC at the moment are gold-pin Brimar equivalentss and the 85A2 is a Mullard. All being well there is a possibility of getting a set of current production E88CCs to try but we'll see how that works out.
I always liked the Philips (jan 6922) a lot, never dull yet precise and transparent, but many (all of them?), had the problem of deteriorating differently within many months or at least a few years (A1 and A2 would differ in parameters). I don't know of any other tube that has this.
I'm not familiar with the Brimars, but the Mullard's can be excellent. I wouldn't prioritise rolling them neither.
You use HQPlayer, right? Are you on version 4 or 3? I'm still at 3, I mostly use xtr and polysinc ext2. XTR seems to add a bit more "bite", sometimes that's necessary. I'm curious what you'll end up with.
One of my specific interests with "no dac dac's" is if you have any birdy noises or other artefacts when setting hqplayer's volume to around -20 to -40 dB? Some "no dac dac's" have problems in that range, the amsdm7 filter can fix this if you do.
Iirc Pavel even recommends this filter for his earlier designs, I also need them sometimes. I'm suspicious of the nrtz nature sometimes displaying that behaviour, but haven't tested that hypothesis so curious to know also.
Knowing Marcel, he propably fixed it in hardware and you very well might know this already, but it seemed important to point out and make sure.
G'night!
I'm not familiar with the Brimars, but the Mullard's can be excellent. I wouldn't prioritise rolling them neither.
You use HQPlayer, right? Are you on version 4 or 3? I'm still at 3, I mostly use xtr and polysinc ext2. XTR seems to add a bit more "bite", sometimes that's necessary. I'm curious what you'll end up with.
One of my specific interests with "no dac dac's" is if you have any birdy noises or other artefacts when setting hqplayer's volume to around -20 to -40 dB? Some "no dac dac's" have problems in that range, the amsdm7 filter can fix this if you do.
Iirc Pavel even recommends this filter for his earlier designs, I also need them sometimes. I'm suspicious of the nrtz nature sometimes displaying that behaviour, but haven't tested that hypothesis so curious to know also.
Knowing Marcel, he propably fixed it in hardware and you very well might know this already, but it seemed important to point out and make sure.
G'night!
Hi again Marco. the only extraneous noises my 62yr old ears have picked up have been background stuff on recordings that I haven't heard before - people moving and that sort of thing! As far as I can hear the DAC has an essentially silent background.
I have HQP3 and an eval copy of HQP4 - I like 4 and will have to purchase a licence soon. At the moment I've settled on the settings below but will explore more. I don't use the HQP volume control at the moment as my HPA takes care of that.
I have HQP3 and an eval copy of HQP4 - I like 4 and will have to purchase a licence soon. At the moment I've settled on the settings below but will explore more. I don't use the HQP volume control at the moment as my HPA takes care of that.
Attachments
That reminds me of the first time I listened to music with the original valve DAC. It was the Nisi Dominus of Vivaldi played by Le Banquet Celeste. I had heard the same music from the same artists live in Utrecht about a month earlier. The music sounded very beautiful, but whenever it was silent, I heard this weird sound in the background. I started thinking about ways to debug this issue until I realized it was the pump of the organ, which sounded exactly the same during the concert in Utrecht.
As reported in the valve DAC article, the DAC has some noise modulation, rather similar to an instantaneous compander system. You can hear it when playing back a full-scale 1 Hz sine wave with a high-pass filter between the DAC and the amplifier and with the volume turned up a lot. I never heard it on any type of music.
As reported in the valve DAC article, the DAC has some noise modulation, rather similar to an instantaneous compander system. You can hear it when playing back a full-scale 1 Hz sine wave with a high-pass filter between the DAC and the amplifier and with the volume turned up a lot. I never heard it on any type of music.
I've been re-exploring my music collection again this evening, thoroughly enjoying the experience and hearing pieces in a new light. Now, I know that in the scale of things I haven't listened to that many DACs, but what I can say is that of those I've listened to this is the best, bettering my previous baseline, a DSC2 (V2.5), by a significant margin. My Buffalo 3SE sounds quite 'flat' in comparison.
This Valve DAC is just delightful to listen to; excuse my exuberance, but it is true. Oh for the Covid situation to abate so that I could share my experience with some Audio chums.
Next week I will complete the build of my new amplifier and then we'll see what the combination can do with my Lowther horns. BTW, I've already listened to the amplifier and know it to be excellent and have only pulled it out of the system to complete the chassis aspects of the project. There's an irony in this in that my two best DACs, this one and the DSC2, have output transformers and none of my tube amplifiers does, all being OTL designs.
This Valve DAC is just delightful to listen to; excuse my exuberance, but it is true. Oh for the Covid situation to abate so that I could share my experience with some Audio chums.
Next week I will complete the build of my new amplifier and then we'll see what the combination can do with my Lowther horns. BTW, I've already listened to the amplifier and know it to be excellent and have only pulled it out of the system to complete the chassis aspects of the project. There's an irony in this in that my two best DACs, this one and the DSC2, have output transformers and none of my tube amplifiers does, all being OTL designs.
This feedback is enticing. I had put my name down for the original proposed group buy, which fell through due to a lack of interest from other DIYers. Given this project is even more niche, I suspect a group buy is even more unlikely. If either of you have a list of all the things required to put the differential DSD version together, I’d appreciate it.
Hi Raj1. I did try to promote a group buy for the PCBs when I decided to progress this project but only one other member, snax, committed and we shared the costs between us - more participation would have been good as it would have reduced our personal outlay but the water has run under the bridge now.
Marcel has made all the documentation, PCB fabrication files and, IIRC, the code for the ASRC component of his original design, required to build this DAC freely available.
There were spare PCBs from our purchase but mine are spoken for already. I don't know the status of snax's project or his spare board as he hasn't posted for a while.
I'm not personally inclined to promote another group buy for PCBs for no better reason than not needing one.
If you decide to take the plunge I'm happy to try and help though Marcel is obviously the one with the expertise and knowledge and he has alays been very patient and supportive.
Marcel has made all the documentation, PCB fabrication files and, IIRC, the code for the ASRC component of his original design, required to build this DAC freely available.
There were spare PCBs from our purchase but mine are spoken for already. I don't know the status of snax's project or his spare board as he hasn't posted for a while.
I'm not personally inclined to promote another group buy for PCBs for no better reason than not needing one.
If you decide to take the plunge I'm happy to try and help though Marcel is obviously the one with the expertise and knowledge and he has alays been very patient and supportive.
The PCBs snax and I procurred were puchased from PCBway. MOQ from PCBway was 5 PCBs. I just checked and the five PCBs that we purchased back along cost $405. That was the best price I could find at the time.
The design of the PCB is clearly an intrinsic part of Marcel's design, including the custom layer stack, and it would be unwise to ignore that.
The design of the PCB is clearly an intrinsic part of Marcel's design, including the custom layer stack, and it would be unwise to ignore that.
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