Some initial measurements (referenced to ground with E88CCs removed);
+5V Supply = 4.97VDC
B+ supply = -298.6VDC
Junction of R140 & D16 = -137.1VDC
Juncton of R139 & D16 = -131.4VDC
They all look OK to me and were stable over the 5mins or so it was powered up
More interesting is the Ref voltage at the junction of R131 & C118 which initially measured 215.2V but over the 5min period decayed to 213.2V. BTW, the 85A2 lights up very quickly.
+5V Supply = 4.97VDC
B+ supply = -298.6VDC
Junction of R140 & D16 = -137.1VDC
Juncton of R139 & D16 = -131.4VDC
They all look OK to me and were stable over the 5mins or so it was powered up
More interesting is the Ref voltage at the junction of R131 & C118 which initially measured 215.2V but over the 5min period decayed to 213.2V. BTW, the 85A2 lights up very quickly.
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Next test...
I inserted the valves for just one half of the DAC and measured and listened - there was music, a bit longer this time, and then the noise gradually appeared again. Measurements were the same as I reported in my previous post except the 'REF' decayed to -213VDC over the period before the noise started, though it was at that voltage for a minute or two before the noise so I'm not sure if there is a correlation there, but it did play for longer with only half the valves inserted?
Is the fact that it played longer with only half the valves a clue?
I'll do the exact same test, with the same valve trio, on the other channel after a coffee.
I inserted the valves for just one half of the DAC and measured and listened - there was music, a bit longer this time, and then the noise gradually appeared again. Measurements were the same as I reported in my previous post except the 'REF' decayed to -213VDC over the period before the noise started, though it was at that voltage for a minute or two before the noise so I'm not sure if there is a correlation there, but it did play for longer with only half the valves inserted?
Is the fact that it played longer with only half the valves a clue?
I'll do the exact same test, with the same valve trio, on the other channel after a coffee.
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Hi Marcel.
I just repeated the three valve test on the other channel and the result is the same - not really that surprising but for completeness I'll repeat the tests with the other trio.
I'm currently using the bit clock as per the functionality testing notes.
I'm thinking about winding down to DSD64?
I just repeated the three valve test on the other channel and the result is the same - not really that surprising but for completeness I'll repeat the tests with the other trio.
I'm currently using the bit clock as per the functionality testing notes.
I'm thinking about winding down to DSD64?
It Works!
We're in business!
Setting HQ Player to DSD64 (jumpers and pots untouched), I've just listened for the best part of an hour with no problems. I got confident enough to plug my best 32ohm headphones in and made some adjustments to the HQPlayer filter settings (because I had it set up for DSD256/512).
The only anomaly I have is that REF continues to slowly decay, after an hour it was down to -212VDC - a thermal issue - should I be concerned?
Coffee time and some fresh air in the garden before I hook up my best HPA (a DIY Audio Noir) and my 600ohm BeyerDynamic DT880 headphones - the most revealing headphone set up I have.
So Marcel, it looks like you were right about it being a timing issue. Should I experiment later by adjusting RV3/4 and trying DSD128 again?
Oh, and it sounds very good! Kudos to you Marcel.
We're in business!
Setting HQ Player to DSD64 (jumpers and pots untouched), I've just listened for the best part of an hour with no problems. I got confident enough to plug my best 32ohm headphones in and made some adjustments to the HQPlayer filter settings (because I had it set up for DSD256/512).
The only anomaly I have is that REF continues to slowly decay, after an hour it was down to -212VDC - a thermal issue - should I be concerned?
Coffee time and some fresh air in the garden before I hook up my best HPA (a DIY Audio Noir) and my 600ohm BeyerDynamic DT880 headphones - the most revealing headphone set up I have.
So Marcel, it looks like you were right about it being a timing issue. Should I experiment later by adjusting RV3/4 and trying DSD128 again?
Oh, and it sounds very good! Kudos to you Marcel.
Great to hear that it is functional and sounds good!
Does the -300 V also drift to -297 V?
RV3 and RV4 are meant for fine-tuning the timing between the flip-flops U4, U27 and the valves U1, U2, U28, U30, but they also affect the timing between U9, U10 and U4, U27, so it would certainly be interesting to see how high you can go with RV3 and RV4 set to minimum resistance.
Does the -300 V also drift to -297 V?
RV3 and RV4 are meant for fine-tuning the timing between the flip-flops U4, U27 and the valves U1, U2, U28, U30, but they also affect the timing between U9, U10 and U4, U27, so it would certainly be interesting to see how high you can go with RV3 and RV4 set to minimum resistance.
I don't think the B+ drifted much but i didn't monitor it as consistently as the REF voltage - I'll do so carefully next time.
Chores just got in the way of more testing and I need to head out on my bike for some exercise shortly but I'll do a quick test at DSD128 with RV3/4 adjusted to minimum.
Chores just got in the way of more testing and I need to head out on my bike for some exercise shortly but I'll do a quick test at DSD128 with RV3/4 adjusted to minimum.
RV3/4 set to minimum - half an hour of playback at DSD128 without any issues. It sounds even better too!
DSD256 next but first some exercise and a change of scenery.
Oh, and you were right Marcel, the B+ drifted down - I readusted it back to -300VDC once everything was nicely warmed up and REF increased with it.
DSD256 next but first some exercise and a change of scenery.
Oh, and you were right Marcel, the B+ drifted down - I readusted it back to -300VDC once everything was nicely warmed up and REF increased with it.
You wrote that you are using the bit clock, but looking again at the picture, you have R58 populated and R59 not populated. With the Amanero-style input interface, that would normally mean you use the master clock rather than the bit clock. Do you use some jumper wires to connect the bit clock to the pin normally used for the master clock?
Hi Marcel. No, what you see is how it is so I must be inadvertently using the Master Clock. Implications? The oscillators on my reclocker board are an NKD 45 & 49MHz pair (BTW, I did try playback of both 44.1 and 48KHz data family files yesterday).
I've not tried DSD256 yet but will do so after breakfast.
I've not heard from Dan about his build - I wonder how he's getting on - I hope he's well!?
I've not tried DSD256 yet but will do so after breakfast.
I've not heard from Dan about his build - I wonder how he's getting on - I hope he's well!?
The implications are that I can't guarantee proper timing of the input flip-flops because I have no data on the timing of the master clock versus the other signals (it is probably OK, I just can't be entirely sure), and that you need the divide by two function, otherwise everything runs at twice the clock frequency it was designed for.
That is, could you please remove the jumper from P8 and move the jumpers on P9 and P11 such that pin 2 gets connected to pin 3 rather than to pin 1?
That is, could you please remove the jumper from P8 and move the jumpers on P9 and P11 such that pin 2 gets connected to pin 3 rather than to pin 1?
Jumpers set as per Marcel's previous post.
I've been playing music at DSD256 for an extended period with no issues, in fact it just keeps getting better and better.
Without touching RV1/2 (they're both centred) the DAC is silent as far as my ears can tell. The music out of it has a fantastic richness but without any stodginess, every voice/instrument is clearly discernible and, to use an old cliche, I'm hearing things I hadn't picked up on before. I still have the fun of exploring the HQPlayer settings further to see if I can optimise the playback to my tastes even more.
I tried DSD512 too and it works except that the computer I'm using for the testing isn't powerful enough to do the HQplayer processing so there are lots of dropouts. I do have a more powerful, audio-dedicated, workstation available so I'll give DSD512 another try at some point.
Now I know that this project is a keeper I'll finalise the build and I've started to design a chassis top plate to close it up.
IMO this DAC deserves to be built by more people. OK, it needs to be fed a high quality SDM (DSD) datastream and it's ridiculously inefficient to power all those valves to just produce a line-level analogue signal but it is ridiculously good and so easy to listen to.
I've been playing music at DSD256 for an extended period with no issues, in fact it just keeps getting better and better.
Without touching RV1/2 (they're both centred) the DAC is silent as far as my ears can tell. The music out of it has a fantastic richness but without any stodginess, every voice/instrument is clearly discernible and, to use an old cliche, I'm hearing things I hadn't picked up on before. I still have the fun of exploring the HQPlayer settings further to see if I can optimise the playback to my tastes even more.
I tried DSD512 too and it works except that the computer I'm using for the testing isn't powerful enough to do the HQplayer processing so there are lots of dropouts. I do have a more powerful, audio-dedicated, workstation available so I'll give DSD512 another try at some point.
Now I know that this project is a keeper I'll finalise the build and I've started to design a chassis top plate to close it up.
IMO this DAC deserves to be built by more people. OK, it needs to be fed a high quality SDM (DSD) datastream and it's ridiculously inefficient to power all those valves to just produce a line-level analogue signal but it is ridiculously good and so easy to listen to.
Great that it works at all intended DSD rates! If you can provide me with the schematics of the reclocker board, or maybe a datasheet if any, I can try to calculate whether the timing of the data transfer to the first flip-flops is reliable. Otherwise you run a small risk of getting the loud noise back in some specific temperature range.
Thanks Marcel.
I have used Pavel's reclocker, developed in the Signalyst DSC1 thread context by DIY Audio member ppy. You can find information about it on his website;
https://puredsd.ru/
Look for 'PPY's ReClocker' about halfway down.
Cheers
Ray
I have used Pavel's reclocker, developed in the Signalyst DSC1 thread context by DIY Audio member ppy. You can find information about it on his website;
https://puredsd.ru/
Look for 'PPY's ReClocker' about halfway down.
Cheers
Ray