Back when snax and I ordered our PCBs, DIY Audio member 'JPS64' became quite interested in reworking the design into modularised PCBs and did quite a bit of work on it - the result would I think have been more compact (obviously nothing like a chip) and it would have reduced the cost of the PCBs. He seemed to lose interest so I don't think it ever got finished. If you search this thread for JPS64 posts you'll find some of his work.
In a similar vein, I have wondered if a version of the Valve DAC could be built using Russian sub-miniature 'pencil' valves as they seem to be well regarded and affordable; I've got some for an amp project but I've not come across an equivalent to the E88CCs used in the Valve DAC. Sub-miniatures generally run at lower plate voltages.
In a similar vein, I have wondered if a version of the Valve DAC could be built using Russian sub-miniature 'pencil' valves as they seem to be well regarded and affordable; I've got some for an amp project but I've not come across an equivalent to the E88CCs used in the Valve DAC. Sub-miniatures generally run at lower plate voltages.
Probably of academic interest under current circumstances but where in the UK are you?
That's a shame that you're the other side of the country; closer by and we might have been able to sort something where I leave my Valve DAC with you for an evening - it would be great to get the opinion of a second pair of ears.
Oh, and that's a generous guesture regarding the transformers - I'll keep my fingers crossed.
Oh, and that's a generous guesture regarding the transformers - I'll keep my fingers crossed.
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There's usually a correlation between quality and cost I find.
Anyway, I have more tweaking to do.
This afternoon I introduced my Valve DAC to my new 13E1 SE-OTL amp that I'm just finishing putting together. Speakers are my Lowther EX4 (15ohm) AllFun horns. The upside is that the music sounds fantastic, the downside is that I have some more noise to try and eliminate - it's not audible in the listening position but with my ear to the Lowther driver I can hear it so it'll bug me if I don't try to tweak it away. I'm assuming it's because I'm using more gain in the system to drive the Lowthers. To confirm the scenario wasn't a problem with the new amp I put my 300B SE-OTL back in and the noise was still there. With the Valve DAC on but not playing anything both amps are essentially silent when listening close to the speaker cones. I have some more solo flute music to listen to.
Oh, and on the short listen so far I prefer the 13E1 to the 300B amp; it isn't quite as sweet at the top but overall has more weight and authority. Maybe that's what going from four tubes in parallel to a single tube gives you?
I also have a 6C33C SE-OTL project but it's on the bench at the moment so that'll be a story for another day.
Finally, I now have my DSC2 DAC plugged into my HPA at my desk - It's still a fantastic DAC that I would have no problem living with.
Anyway, I have more tweaking to do.
This afternoon I introduced my Valve DAC to my new 13E1 SE-OTL amp that I'm just finishing putting together. Speakers are my Lowther EX4 (15ohm) AllFun horns. The upside is that the music sounds fantastic, the downside is that I have some more noise to try and eliminate - it's not audible in the listening position but with my ear to the Lowther driver I can hear it so it'll bug me if I don't try to tweak it away. I'm assuming it's because I'm using more gain in the system to drive the Lowthers. To confirm the scenario wasn't a problem with the new amp I put my 300B SE-OTL back in and the noise was still there. With the Valve DAC on but not playing anything both amps are essentially silent when listening close to the speaker cones. I have some more solo flute music to listen to.
Oh, and on the short listen so far I prefer the 13E1 to the 300B amp; it isn't quite as sweet at the top but overall has more weight and authority. Maybe that's what going from four tubes in parallel to a single tube gives you?
I also have a 6C33C SE-OTL project but it's on the bench at the moment so that'll be a story for another day.
Finally, I now have my DSC2 DAC plugged into my HPA at my desk - It's still a fantastic DAC that I would have no problem living with.
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I've just downloaded the sound of silence - not the Simon and Garfunkel song but this;
Silent CD
maybe of use to you too?
Please note: I've just 'played' a track through my DSC2 and there is a loud click when the track starts - I guess all those zeros may confuse the muting - so make sure you take precautions to protect your ears and your kit. You should also take note of the warning on the website to turn your volume back down after listening to silence, otherwise you might get a bit of a surprise when you play some music.
Silent CD
maybe of use to you too?
Please note: I've just 'played' a track through my DSC2 and there is a loud click when the track starts - I guess all those zeros may confuse the muting - so make sure you take precautions to protect your ears and your kit. You should also take note of the warning on the website to turn your volume back down after listening to silence, otherwise you might get a bit of a surprise when you play some music.
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Here's where we are with the GB - it's still open.
diyAchim - 1 PCB
Raj!1 - 1 PCB (UK)
dubulup - 2 PCB (USA)
ericoto -1 PCB
HenSch - 2 PCB (Germany)
mterbekke - 2 PCB (Netherlands, confirmed)
rfbrw - 1 PCB
Pistollero - 1 PCB (Portugal)
luchoh - 1 PCB (USA)
pgour - 1 PCB
agent.5 - 1 PCB (USA)
spm - 1 PCB (UK)
Total = 15
BTW, the price differential between 15 and 20 PCBs is trivial, IIRC around $30.
diyAchim - 1 PCB
Raj!1 - 1 PCB (UK)
dubulup - 2 PCB (USA)
ericoto -1 PCB
HenSch - 2 PCB (Germany)
mterbekke - 2 PCB (Netherlands, confirmed)
rfbrw - 1 PCB
Pistollero - 1 PCB (Portugal)
luchoh - 1 PCB (USA)
pgour - 1 PCB
agent.5 - 1 PCB (USA)
spm - 1 PCB (UK)
Total = 15
BTW, the price differential between 15 and 20 PCBs is trivial, IIRC around $30.
That recording of silence s really handy, it makes adjusting the noise floor so much easier than waiting for silence in music passages.
I've been playing 'silence' and adjusting the Valve DAC to minimise the noise floor and have made some good progress. Adjusting RV1 and RV2, I've not been able to eliminate the 'static-like' noise completely but it is now so low (at DSD256) that I cannot hear it unless my head is right up against the Lowther driver - that is with the volume set to a level I would use to play music. There is a little more noise at DSD512 and DSD128 seems to be about the same level as DSD256. I've achieved about the same level of noise for both left and right.
Marcel, For RV1 minimum noise is at about the 3 o'clock position but for RV2 lowest noise is with it rotated fully-clockwise? I was also thinking that multiturn potentiometers would have been nice for fine adjustments.
I think I've now settled on DSD256 as my baseline rate as DSD512 doesn't seem to bring anything extra except for a slightly higher noise floor. That's with my preferred HQP settings and it's entirely possible that other settings might give different results/preferences.
I did start to explore RV3 and RV4. They were set to fully clockwise when we first got the Valve DAC up and running when I experienced the noise issue. I backed them off a little but couldn't discern any difference in the noise floor. I was conscious that I had the HQP volume level very high for the tweaking and that made me nervous of making more adjustments in case I triggered the clocking noise again. I'll have a coffee and see if I can pluck up the courage to explore further.
I have to say that so far the Valve DAC documentation Marcel produced has been spot-on and the DAC has responded to adjustment exactly as per his design rationale. I hope that all of this is building the confidence of the GB subscribers that with care and attention this fairly complex project is realisable.
I've been playing 'silence' and adjusting the Valve DAC to minimise the noise floor and have made some good progress. Adjusting RV1 and RV2, I've not been able to eliminate the 'static-like' noise completely but it is now so low (at DSD256) that I cannot hear it unless my head is right up against the Lowther driver - that is with the volume set to a level I would use to play music. There is a little more noise at DSD512 and DSD128 seems to be about the same level as DSD256. I've achieved about the same level of noise for both left and right.
Marcel, For RV1 minimum noise is at about the 3 o'clock position but for RV2 lowest noise is with it rotated fully-clockwise? I was also thinking that multiturn potentiometers would have been nice for fine adjustments.
I think I've now settled on DSD256 as my baseline rate as DSD512 doesn't seem to bring anything extra except for a slightly higher noise floor. That's with my preferred HQP settings and it's entirely possible that other settings might give different results/preferences.
I did start to explore RV3 and RV4. They were set to fully clockwise when we first got the Valve DAC up and running when I experienced the noise issue. I backed them off a little but couldn't discern any difference in the noise floor. I was conscious that I had the HQP volume level very high for the tweaking and that made me nervous of making more adjustments in case I triggered the clocking noise again. I'll have a coffee and see if I can pluck up the courage to explore further.
I have to say that so far the Valve DAC documentation Marcel produced has been spot-on and the DAC has responded to adjustment exactly as per his design rationale. I hope that all of this is building the confidence of the GB subscribers that with care and attention this fairly complex project is realisable.
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This is useful info for anyone setting things up first time.
Off topic: have you played with the Sinc-L filters of HQP4? That’s what I currently use with one of the ADSM variants. Depending on processing power and graphics card memory, the max DSD rate that you can run might be lower, but some recordings sound a lot better with this combo.
Off topic: have you played with the Sinc-L filters of HQP4? That’s what I currently use with one of the ADSM variants. Depending on processing power and graphics card memory, the max DSD rate that you can run might be lower, but some recordings sound a lot better with this combo.
No, not tried Sinc-L - will do later. I have to say that I've not been overly adventurous playing with the HQP settings - life is too short to spend listening to the same pieces over and over with different settings so I have tended to take recommnedations and just explore a little around them.
diyAchim - 1 PCB
Raj!1 - 1 PCB (UK)
dubulup - 2 PCB (USA)
ericoto -1 PCB
HenSch - 2 PCB (Germany)
mterbekke - 2 PCB (Netherlands, confirmed)
rfbrw - 1 PCB
Pistollero - 1 PCB (Portugal)
luchoh - 1 PCB (USA)
pgour - 1 PCB
agent.5 - 1 PCB (USA)
spm - 1 PCB (UK)
torb - 1 PCB (Finland)
Total = 16
Raj!1 - 1 PCB (UK)
dubulup - 2 PCB (USA)
ericoto -1 PCB
HenSch - 2 PCB (Germany)
mterbekke - 2 PCB (Netherlands, confirmed)
rfbrw - 1 PCB
Pistollero - 1 PCB (Portugal)
luchoh - 1 PCB (USA)
pgour - 1 PCB
agent.5 - 1 PCB (USA)
spm - 1 PCB (UK)
torb - 1 PCB (Finland)
Total = 16
Ok, I’ll bite. Would love to have a balanced tube output stage
diyAchim - 1 PCB
Raj!1 - 1 PCB (UK)
dubulup - 2 PCB (USA)
ericoto -1 PCB
HenSch - 2 PCB (Germany)
mterbekke - 2 PCB (Netherlands, confirmed)
rfbrw - 1 PCB
Pistollero - 1 PCB (Portugal)
luchoh - 1 PCB (USA)
pgour - 1 PCB
agent.5 - 1 PCB (USA)
spm - 1 PCB (UK)
torb - 1 PCB (Finland)
thuanth43 - 1 PCB (Singapore)
Total = 17
Would love to have a balanced tube output stage diyAchim - 1 PCB
Raj!1 - 1 PCB (UK)
dubulup - 2 PCB (USA)
ericoto -1 PCB
HenSch - 2 PCB (Germany)
mterbekke - 2 PCB (Netherlands, confirmed)
rfbrw - 1 PCB
Pistollero - 1 PCB (Portugal)
luchoh - 1 PCB (USA)
pgour - 1 PCB
agent.5 - 1 PCB (USA)
spm - 1 PCB (UK)
torb - 1 PCB (Finland)
thuanth43 - 1 PCB (Singapore)
Total = 17