@batteryman , Balanced for sure. The D3 boards allow you to parallel another 1541A for each balanced channel so just trying to plan ahead.
was the 75r IV on the outputs of the 1541? Or on the outputs of the transformers?
Transformers are the next step for me for sure. I just didn't want to spend $375 just yet for the Sowter's. I wanted to get something playing first before I took that step. I figured since I already have the SEN boards I'll try them plus I'm a sucker for the jfet sound.
was the 75r IV on the outputs of the 1541? Or on the outputs of the transformers?
Transformers are the next step for me for sure. I just didn't want to spend $375 just yet for the Sowter's. I wanted to get something playing first before I took that step. I figured since I already have the SEN boards I'll try them plus I'm a sucker for the jfet sound.
I was thinking about whether a common mode choke of around 30-50mh could be used to filter out digital noise.
I use them to clean up SMPS so no reason why they shouldn't work. They have a very low resistance (<1r) so the 2ma offset shouldn't have any effect.
You can see the results on DC here:
https://www.diyaudio.com/community/threads/audio-grade-smps.411284/#post-7655390
I use them to clean up SMPS so no reason why they shouldn't work. They have a very low resistance (<1r) so the 2ma offset shouldn't have any effect.
You can see the results on DC here:
https://www.diyaudio.com/community/threads/audio-grade-smps.411284/#post-7655390
@dddac thanks for your input! I was learning from your designs when studying dac's. You have a lot of experience in paralleling dac's, have you paralelled 1541 or only 1543? My first idea was to use only one biasing circuit but Zoran and fabrice63 sort of convinced me to close the output current loops at each dac individually. Very good idea of pre-loading LM7815, thanks! RC (say CRC) filetring at the output of LM7815 would be partially in the output signal loop. Is it better to have an CRC there than just bare LM7815?
An updated PCB board project. The main change is a different routing of DGND on Layer 2. It is now such that the input signals first encounter the DGND pin 14 of each DAC and only then DGND connects to pin 5 AGND. This is achieved by a cut between the DGND pour below the input attenuators and the patch that connects pins 14 and 5:
Red tracks are Top layer, brown is DGND on Layer 2.
Layer 3 (cyan tracks) with power connections and GND of -15V (the pour on the bottom):
Bottom (Layer4) with AGND pour (blue), arranged in a sort of a star connection, so that DEM caps first see the pin 5. The GND of +5V, -5V regulators is connected here in the upper part:
The outputs and the connections between pins 16 will be made by P2P wiring directly at the bottom of the PCB.
Red tracks are Top layer, brown is DGND on Layer 2.
Layer 3 (cyan tracks) with power connections and GND of -15V (the pour on the bottom):
Bottom (Layer4) with AGND pour (blue), arranged in a sort of a star connection, so that DEM caps first see the pin 5. The GND of +5V, -5V regulators is connected here in the upper part:
The outputs and the connections between pins 16 will be made by P2P wiring directly at the bottom of the PCB.
Attachments
Hi,
I have two PS strategies in mind:
1) Start with plain vanilla LM78/79 + Oscon and Elna Cerafine soldered directly to the 1541A pins underneath the PCB. Coming from the tube audio, I don't trust much the sonics of SMD caps (perhaps wrongly...)
2) If the design works as I hope, I want to try superregs instead of LM78/79, in particular TentLbas shunts are on my radar. Then, according to Guido, there is no need for any additional decoupling caps.
On the related note, anybody knows why there are so few designs with superregs powering TDA1541A floating around? Wasn't the 1995 research
https://refsnregs.waltjung.org/Regs_for_High_Perf_Audio_4.pdf a sort of an example to follow? People don't pick this thread? Why not?
I have two PS strategies in mind:
1) Start with plain vanilla LM78/79 + Oscon and Elna Cerafine soldered directly to the 1541A pins underneath the PCB. Coming from the tube audio, I don't trust much the sonics of SMD caps (perhaps wrongly...)
2) If the design works as I hope, I want to try superregs instead of LM78/79, in particular TentLbas shunts are on my radar. Then, according to Guido, there is no need for any additional decoupling caps.
On the related note, anybody knows why there are so few designs with superregs powering TDA1541A floating around? Wasn't the 1995 research
https://refsnregs.waltjung.org/Regs_for_High_Perf_Audio_4.pdf a sort of an example to follow? People don't pick this thread? Why not?
I'll be very interested to see by deep measurements these bounces , and If so what is their real effect on the TDA digital side , in any ways obviously
@ phixphi , smd cap have NO sonic signature whatsoever in power supply decoupling in there , and if you run the 50 Hz DEM the only pps film cap is the 1uf
caps ( every of them ) should be right where we need them , which means at the TDA's pins , nowhere else , draw your stackup as so
the less traces the better , always , and each trace has its current return , always too
read back the thread carefully , everything has been already said , more than twice
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FWIW, I have enjoyed playing with power supplies to the +-5V and -15V loads. IMHO, these supplies are pivotal to subjective sound. I suspect you will be happy when you land on the Tentlabs shunts. I used Salas shunts and found joy with Blackgate caps on the pins. Even then, adding 1.5F supercaps after the shunts on the +-5V loads took it to the next level.
@Brijac I just parallel the supercaps. My Shunts seem happy feeding a dead short for a few minutes... Then I just leave the DAC powered 7/24.
My guess is the sound might be marginally better with bigger caps. I used the 1.5F Nesscaps I happen to have. I'm a fan of the 90%/10% rule. If I get 90% of the benefit for 10% of the cost I am job done.
My guess is the sound might be marginally better with bigger caps. I used the 1.5F Nesscaps I happen to have. I'm a fan of the 90%/10% rule. If I get 90% of the benefit for 10% of the cost I am job done.
Thanks wlowes for the input! Yes, reading about TDA1541A it is clear the PSU is critical with all the complicated current loops. MVLabs, who influeced me a lot, mentions he spend about 30% of the design time designing his shunts. I'm surprised there has not been much discussion about superregs. Or at least what my extensive googling showed was not much. In particular, no info on anybody using Tentlabs shunts.
No, not a bit. I think the trick to better digital sound might be to have very low ESR with lots of amps on the digital PS. Most of the regs have some sort of over current protection that allows them to feed the caps until they are charged.
I also use BlackGate HiQ caps as close to the pins of the 1541a as possible. Could be my imagination, but I feel BG and TDA1541a is a match made in heaven.
I also use BlackGate HiQ caps as close to the pins of the 1541a as possible. Could be my imagination, but I feel BG and TDA1541a is a match made in heaven.