This tube output stage is sounding quite good, so I thought Id share it.
The cascaded DN2540 have stellar performance. Impedance in the gigohms.(attached)
Having the two stages DC coupled really helped preserve purity.
Other than the 13RIV im also using a NOS boost filter from a circuit attached only difference are my RIV is 13R and the other is 6R5.
Ill measure the THD soon, so I can post if anyone is interested.
The cascaded DN2540 have stellar performance. Impedance in the gigohms.(attached)
Having the two stages DC coupled really helped preserve purity.
Other than the 13RIV im also using a NOS boost filter from a circuit attached only difference are my RIV is 13R and the other is 6R5.
Ill measure the THD soon, so I can post if anyone is interested.
Attachments
@ryanj
I played around with the tda1541a a decade ago. At that time it seemed that John recommended small pps film caps to be placed under the tda as decoupling caps. Has that view been revised since then (since you didn’t implement it and you’ve also read the full ECdesigns thread presumably)?
I played around with the tda1541a a decade ago. At that time it seemed that John recommended small pps film caps to be placed under the tda as decoupling caps. Has that view been revised since then (since you didn’t implement it and you’ve also read the full ECdesigns thread presumably)?
I do remember when he soldered the 14 decoupling caps directly underneath the chip and soldered directly to the legs (I never tried this), but this was when he was still running the DEM at much higher frequencies. Now with the DEM running at 50Hz - much more capacitance is needed to filter out the 50Hz ripple, The D3 design was made because the D2 couldn't accommodate the 100u caps to allow a 50Hz DEM. To me the benefit of running a 50Hz DEM outweighed keeping the current loops tight like in the D2.
Hi guys,
I'm really liking this tube stage, so clean with great control in the bass.
I attached the THD results of the 6n23p circuit in post #1301 driving a 100k load.
The 8k harmonic is a problem with my test setup as it is there all the time, so it can be disregarded.
The rising response and peaks at 16k onward are reduced when driving a 10k load and the harmonics increase by a few dB.
Overall im quite pleased that H3 is below -100dBc. I'll try and have a play around to reduce H2, but I think it sounds just great the way it is.
The power supply still needs some work to reduce noise but even with my 95dB/W speakers I dont notice much of an issue once the solar inverters quiet down after dark.
Ok, im going to reconnect my F5 and enjoy the music!
Peace everyone!
I'm really liking this tube stage, so clean with great control in the bass.
I attached the THD results of the 6n23p circuit in post #1301 driving a 100k load.
The 8k harmonic is a problem with my test setup as it is there all the time, so it can be disregarded.
The rising response and peaks at 16k onward are reduced when driving a 10k load and the harmonics increase by a few dB.
Overall im quite pleased that H3 is below -100dBc. I'll try and have a play around to reduce H2, but I think it sounds just great the way it is.
The power supply still needs some work to reduce noise but even with my 95dB/W speakers I dont notice much of an issue once the solar inverters quiet down after dark.
Ok, im going to reconnect my F5 and enjoy the music!
Peace everyone!
Attachments
Last edited:
Ryan,
Have you seen this guys site? He has done a whole set of articles on TDA1541 implementation…..for example, IV stages.
https://www.mvaudiolabs.com/digital/tda1541-iv-stage-options/
I’ll probably try the G-G D3A sometime with DC B+ and regulated heaters.
Thanks for posting your results.
I still listen to my D3 every day after all these years with my hybrid 5687 I/V. Of course I have more d3 boards and one more S1 chip….need to try balanced sometime.
https://iancanada.ca/products/6b-opa861-zero-feedback-balanced-i-v-board
Have you seen this guys site? He has done a whole set of articles on TDA1541 implementation…..for example, IV stages.
https://www.mvaudiolabs.com/digital/tda1541-iv-stage-options/
I’ll probably try the G-G D3A sometime with DC B+ and regulated heaters.
Thanks for posting your results.
I still listen to my D3 every day after all these years with my hybrid 5687 I/V. Of course I have more d3 boards and one more S1 chip….need to try balanced sometime.
https://iancanada.ca/products/6b-opa861-zero-feedback-balanced-i-v-board
Hi Greg,
Yeah I've come across that site, very helpful indeed, although I haven't tried any of the IV stages listed there. At the moment im really pleased with the tube stage im using for now.
Let us know what you think of the grounded grid D3A IV stage when you get to it, from what ive heard its a good performer.
Can you share any details of your hybrid 5687 IV stage?
Just recently I've added a Clone note LDR attenuator between DAC and Amp - highly recommended, you can literally dial in the dynamics with the LDR, and its very transparent.
Good to hear from you Greg. 
Yeah I've come across that site, very helpful indeed, although I haven't tried any of the IV stages listed there. At the moment im really pleased with the tube stage im using for now.
Let us know what you think of the grounded grid D3A IV stage when you get to it, from what ive heard its a good performer.
Can you share any details of your hybrid 5687 IV stage?
Just recently I've added a Clone note LDR attenuator between DAC and Amp - highly recommended, you can literally dial in the dynamics with the LDR, and its very transparent.
Good to hear from you Greg.
Ryan,
It's great to be back here after a hiatus and talking to you guys and seeing what everyone is doing with their I/V ideas! I've been busy building tube amps and SIT amps, so many projects in the pipeline! Anyway, those are other stories.
The I/V that I'm using is the Abbas 5687 hybrid. It loads the TDA1541 at nearly zero R with a Germanium P-P front end followed by a 5687. HV rectification is accomplished with a 6AX3. It swings about 3.5v P-P. It's a little embarrassing that I can't tell you anything more than that because I didn't draw a schematic for it, nor does Abbas provide one (and of course we would never display someones commercial work here). I simply orded it, it arrived and I installed it in my chassis and never looked back. It's a wonderful sounding I/V and the 5687 is just an incredible tube (and affordable). It's very clean and smooth sounding in my setup: It manages to be both very analog and inciteful sounding. The way your board performs with this I/V is just wonderful and it's the standard that I judge all digital audio against. The TDA1541 when done right just sounds natural: instruments have dimension to them that I've never heard from any other DAC scheme.
All of these manufacturers are doing FPGA running R2R or FPGA and I just think they simply cannot compete with this chip. Yes, they are achieving higher effective bit rates, but it hardly matters.
He's now doing this particular I/V with 5v rectifiers. Valve rectification in the HV section is one of those things that generates a lot of opinions, so, I'll just leave it at that. When I build this d3a, I'll choose one of the super quiet HV maida like Nerochromes (https://neurochrome.com/products/21st-century-maida-regulator) or Salas HV reg. which I used for the ES9018 I/V. I alose have a Jan Didden HV boards that I need to use.
Here's Abbas' current sheet of his completed PCB offerings, and I would add that he is always open to doing other things.
https://docs.google.com/spreadsheets/d/16L4eOQPwkG-4FDVqbTBwc_FrxpRGshPEFqceI259mo0/edit?pli=1#gid=0
https://www.abbasaudio.com/en/
I just recently implemented the Audial USB to simultaneous board. I was using the JL-sounds board for a number of years and it's fine, but I do think the Audial board is slightly better and I'm getting zero pops when bit depth changes from album to album!
https://www.audialonline.com/blog/usb-interface-board-mark-3/
Unfortunately, I don't think Pedja is going to offer this board again, or at least, not any time soon. But, if theres enough interest, maybe.... The board can either be run in i2s or Simultanous mode. Of course, I'm running mine in Simultaneous.
Anyway, lot's of fun things to think about and the D3 board has created a fabulous experience!
Cheers,
Greg
It's great to be back here after a hiatus and talking to you guys and seeing what everyone is doing with their I/V ideas! I've been busy building tube amps and SIT amps, so many projects in the pipeline! Anyway, those are other stories.
The I/V that I'm using is the Abbas 5687 hybrid. It loads the TDA1541 at nearly zero R with a Germanium P-P front end followed by a 5687. HV rectification is accomplished with a 6AX3. It swings about 3.5v P-P. It's a little embarrassing that I can't tell you anything more than that because I didn't draw a schematic for it, nor does Abbas provide one (and of course we would never display someones commercial work here). I simply orded it, it arrived and I installed it in my chassis and never looked back. It's a wonderful sounding I/V and the 5687 is just an incredible tube (and affordable). It's very clean and smooth sounding in my setup: It manages to be both very analog and inciteful sounding. The way your board performs with this I/V is just wonderful and it's the standard that I judge all digital audio against. The TDA1541 when done right just sounds natural: instruments have dimension to them that I've never heard from any other DAC scheme.
All of these manufacturers are doing FPGA running R2R or FPGA and I just think they simply cannot compete with this chip. Yes, they are achieving higher effective bit rates, but it hardly matters.
He's now doing this particular I/V with 5v rectifiers. Valve rectification in the HV section is one of those things that generates a lot of opinions, so, I'll just leave it at that. When I build this d3a, I'll choose one of the super quiet HV maida like Nerochromes (https://neurochrome.com/products/21st-century-maida-regulator) or Salas HV reg. which I used for the ES9018 I/V. I alose have a Jan Didden HV boards that I need to use.
Here's Abbas' current sheet of his completed PCB offerings, and I would add that he is always open to doing other things.
https://docs.google.com/spreadsheets/d/16L4eOQPwkG-4FDVqbTBwc_FrxpRGshPEFqceI259mo0/edit?pli=1#gid=0
https://www.abbasaudio.com/en/
I just recently implemented the Audial USB to simultaneous board. I was using the JL-sounds board for a number of years and it's fine, but I do think the Audial board is slightly better and I'm getting zero pops when bit depth changes from album to album!
https://www.audialonline.com/blog/usb-interface-board-mark-3/
Unfortunately, I don't think Pedja is going to offer this board again, or at least, not any time soon. But, if theres enough interest, maybe.... The board can either be run in i2s or Simultanous mode. Of course, I'm running mine in Simultaneous.
Anyway, lot's of fun things to think about and the D3 board has created a fabulous experience!
Cheers,
Greg
Thanks for taking the time to give a detailed post of your diy adventures Greg, appreciated.
I'm really glad you and many others are getting such enjoyment out of the D3 recipe. I poured my heart into the way it sounds because I love the way music can move me energetically, music is medicine.
Anyway, just thought I'd give my thoughts on why its sounds the way it does, good to see your having fun building audio gear, its extremely fun, rewarding and there's plenty to learn along the way.
Those SIT amps have got my attention, such simple designs would surely help preserve signal purity. I think I'll look into them further, also very interested in Nelson Pass's M2 amp,
For my tube stage I plan on trying the Salas SSHV2, very curious how it will impact the sound.
The nature of the TDA1541A using ECL being somewhat immune to noise is one of the reasons why the 1541 sounds the way it does, jitter is greatly minimized so the music flows the way music should. Although I dont think it is totally immune, which is why when further effort is made to lessen jitter (50Hz DEM, lower digital input swing with lower bandwidth, and a low jitter clock signal) it seems to get even better sounding. I believe jitter in music reproduction is totally detrimental to the flow of music - the more jitter, the more unnatural it will sound because it is disrupting the flow of the music.
I'm really glad you and many others are getting such enjoyment out of the D3 recipe. I poured my heart into the way it sounds because I love the way music can move me energetically, music is medicine.
Anyway, just thought I'd give my thoughts on why its sounds the way it does, good to see your having fun building audio gear, its extremely fun, rewarding and there's plenty to learn along the way.
Those SIT amps have got my attention, such simple designs would surely help preserve signal purity. I think I'll look into them further, also very interested in Nelson Pass's M2 amp,
For my tube stage I plan on trying the Salas SSHV2, very curious how it will impact the sound.