This is the first attempt to get Thorstens Delta-Sigma circuit working and see what it does. So I mostly built it out of components I had laying around (especially notice the ugly blue ceramic suppression caps, since I didn't have 100n film caps...
).
I used a piece of aluminium with two holes for the tubes and hardwired the circuit. I wired the passive filter on a piece of veroboard and connected it to the outputs of the DAC.
I have a HV tube PSU that I use for the supply to the circuit and used a small PCB tranny for the heater voltage. In the end I want to mount the tubes horizontally and fit everything in the player.
Ray.
).I used a piece of aluminium with two holes for the tubes and hardwired the circuit. I wired the passive filter on a piece of veroboard and connected it to the outputs of the DAC.
I have a HV tube PSU that I use for the supply to the circuit and used a small PCB tranny for the heater voltage. In the end I want to mount the tubes horizontally and fit everything in the player.
Ray.
Attachments
This is looking very interesting indeed.
I have never worked with tubes and have never seen a circuit diagram (except old tvs lol) with them either so its all new to me
I bet the tubes sticking out of the cabinet would be very nice indeed.
Please can you sent che for circuit when you are done.
Also what sound are you getting, better bass more treble etc?
I have never worked with tubes and have never seen a circuit diagram (except old tvs lol) with them either so its all new to me
I bet the tubes sticking out of the cabinet would be very nice indeed.
Please can you sent che for circuit when you are done.
Also what sound are you getting, better bass more treble etc?
Yeah, the PSU is a bit nasty, but very handy for testing purposes
It is an exact copy of Thorsten's circuit, and i'm very pleased with the first results, but I think there's a bit HF noise remaining in the signal (you can hear a slight hiss in the tweeter) and the output signal is not that strong. So i'm going to see if it can be tweaked, but I want to try a transformer also. See, this circuit uses only one of the DAC's voltage outputs, and a tranny can do a symmetrical to single ended conversion AND analog filtering.
It is not "that warm tubey sound" (thank goodness). It sounds like the same player with a good analog stage and opamps, but there's a lot MORE of all the good things present.
The soundstage has LOTS more space, the highs and mids are WAY cleaner and have opened-up, especially the -S and -T sound very precise. And overall the sound can be soooo relaxed, more peace and quiet in the background with Diana Krall, but if you play something like Bjork it is very dynamic and fast.
It is an exact copy of Thorsten's circuit, and i'm very pleased with the first results, but I think there's a bit HF noise remaining in the signal (you can hear a slight hiss in the tweeter) and the output signal is not that strong. So i'm going to see if it can be tweaked, but I want to try a transformer also. See, this circuit uses only one of the DAC's voltage outputs, and a tranny can do a symmetrical to single ended conversion AND analog filtering.
It is not "that warm tubey sound" (thank goodness). It sounds like the same player with a good analog stage and opamps, but there's a lot MORE of all the good things present.
The soundstage has LOTS more space, the highs and mids are WAY cleaner and have opened-up, especially the -S and -T sound very precise. And overall the sound can be soooo relaxed, more peace and quiet in the background with Diana Krall, but if you play something like Bjork it is very dynamic and fast.
poynton said:
Yep, that's it. Thanks Andy.
Very interesting article by the way.
This is all compared against a modded CD63 and a newly modded CD67-OSE. The tube-player is a CD57 chassis which uses my "old" modded CD67-OSE PCB. So both the PCB's are about equally modded.
The CD57 holds a Tent XO-clock, the others a Kwak-clock. There is some difference in the parts I used (Elnas in the CD57, Rubycons in the CD67 etc. etc.) but not much. All players use the on-board supply, no extra tranny's and regulators (yet...).
Ray.
Hi rowemeister
Sorry, forgot to mention, I have fitted schottky diodes at the rectification stages.
I did, in my general upgrade of caps, place (I think it was 0.01uF) ceramic caps as decoupling on the servo drivers (is it TCA3072, don't have my service manual to hand), but made no other progress in that area.
I'm sure there is scope to improve that area, and especially the HF amp, but haven't put any thought into it yet.
"I have browndog pcbs with OPA132 and OPA627 and previously had OPA2134 fitted. The 2134 was brilliant especially for the cost but the new browndog combo is utterly amazing.Save up and go for this combo much more air and openness."
I'm still unsure why you don't use two 627s per adaptor (except cost, of course). The 2107 is, on paper at least, a compromise somewhere between the 2134 and 2 627s (in fact it was the closest to a dual 627 I could find at the time), although I admit the 627 is superior, I do recommend it over others I've tried.
I agree I should disable the HDAM. At the time, I was trying to compare HDAM vs no HDAM, and not disabling it made that easier. I will be doing it for sure soon, I'm just lazy.
My bypassed HDAM feeds straight to some gold plated chassis phono sockets via cat 5 twisted pair at the moment. I do wonder if the connectors are making a difference. They need mounting properly, and I see the need to rebuild the back panel for easy servicing soon.
It really is astounding what can be achieved with this little player. I have a stock CD41 that I use as an inaccurate stock reference, and these days, in comparison it reminds me an old knackered discman I used to have. Nice.
65hc,
Wow, those valves looking cracking! I bet they do sound great. I've never worked with valves, and have never really studied them. I like to know how something works before I work on it.
Simon, valves can kill, but the large voltages have very little current, so perhaps not quite as deadly as you might initially suspect. I'd be just as worried about a very high powered SS amp. (but be careful!)
Cheers,
Phil
Sorry, forgot to mention, I have fitted schottky diodes at the rectification stages.
I did, in my general upgrade of caps, place (I think it was 0.01uF) ceramic caps as decoupling on the servo drivers (is it TCA3072, don't have my service manual to hand), but made no other progress in that area.
I'm sure there is scope to improve that area, and especially the HF amp, but haven't put any thought into it yet.
"I have browndog pcbs with OPA132 and OPA627 and previously had OPA2134 fitted. The 2134 was brilliant especially for the cost but the new browndog combo is utterly amazing.Save up and go for this combo much more air and openness."
I'm still unsure why you don't use two 627s per adaptor (except cost, of course). The 2107 is, on paper at least, a compromise somewhere between the 2134 and 2 627s (in fact it was the closest to a dual 627 I could find at the time), although I admit the 627 is superior, I do recommend it over others I've tried.
I agree I should disable the HDAM. At the time, I was trying to compare HDAM vs no HDAM, and not disabling it made that easier. I will be doing it for sure soon, I'm just lazy.
My bypassed HDAM feeds straight to some gold plated chassis phono sockets via cat 5 twisted pair at the moment. I do wonder if the connectors are making a difference. They need mounting properly, and I see the need to rebuild the back panel for easy servicing soon.
It really is astounding what can be achieved with this little player. I have a stock CD41 that I use as an inaccurate stock reference, and these days, in comparison it reminds me an old knackered discman I used to have. Nice.
65hc,
Wow, those valves looking cracking! I bet they do sound great. I've never worked with valves, and have never really studied them. I like to know how something works before I work on it.
Simon, valves can kill, but the large voltages have very little current, so perhaps not quite as deadly as you might initially suspect. I'd be just as worried about a very high powered SS amp. (but be careful!)
Cheers,
Phil