Hi everybody,
I am still working on my 5.1 DIY CLass-D amplifier, but abandoned the TPA3255 modules for an all-Hypex-setup.
I just finished everything, all bench testing went fine (all channels work, dead quiet speakers, clear sound when connected to battery powered mp3 player on all six channels).
But connected to a Denon X4000, I have terrible ground loop noises on all 4 UcD400OEM channels, but NO ground loop noises on the UcD700HG channel...???
The setup is:
2 * UcD400 OEM V6 on one (non Hypex) SMPS, connected to RCA, RCA GND and UcD GND tied together
3 * UcD400 OEM V6 on one (non Hypex) SMPS, connected to RCA, RCA GND and UcD GND tied together
1 * UcD700HG on Hypex SMPS1200U700, connected to RCA, RCA GND and UcD GND tied together
The 400OEMs are using the buffered inputs (shortened ping 30-31, 26-27)
I just installed the big hypex SMPS, since the former solution of using a generic 80V SMPS never worked so well.
The UcD700 runs dead quiet, even if connected to the Denon X4000. It is only the OEM modules which expose the noise.
I already tried connecting just one UcD400 module to one SMPS, same story (ground loop noise when connected to consumer audio device).
I also tried an old stereo UcD180 amp (which is wired the same way) I had lying around - no noise at all.
I know of both hypex docs "AN amplifier signal wiring", and the longer document where the AES48 / RCA / banlanced connections are explained in detail.
I tried connecting RCA signal GND to the chassis, and leaving cold input floating, no change.
What I did not try so far is put in the 100nf/100 ohms filter to GND in place at the RCA input.
So, with all the six RCA input GNDs just tied to each GND (pin 1 XLR), and connected to a battery powered device = no noise
All the six RCA input GNDs just tied to each GND (pin 1 XLR) , UcD700 connected to a mains powered device = no noise
All the six RCA input GNDs just tied to each GND (pin 1 XLR) , UcD400OEM connected to a mains powered device = terrible noise
What is mystefies me is that the UcD700 behaves differently than the UcD400OEM... One could guess that it has something to do with all UcD400OEM modules being connected together through their backplates, but I already measured the connection to each modules GND plane, their is none.
I hope you can help me, I want to finish this project...
To be clear, I also reached out to Hypex support, but maybe somebody else here has an idea.
Now I could also buy a Hypex SMPS3kA400, but I do not think that the "generic" SMPS are to blame (because of having no issues if a signal source with no mains connection is being used).
Regards,
Arndt
I am still working on my 5.1 DIY CLass-D amplifier, but abandoned the TPA3255 modules for an all-Hypex-setup.
I just finished everything, all bench testing went fine (all channels work, dead quiet speakers, clear sound when connected to battery powered mp3 player on all six channels).
But connected to a Denon X4000, I have terrible ground loop noises on all 4 UcD400OEM channels, but NO ground loop noises on the UcD700HG channel...???
The setup is:
2 * UcD400 OEM V6 on one (non Hypex) SMPS, connected to RCA, RCA GND and UcD GND tied together
3 * UcD400 OEM V6 on one (non Hypex) SMPS, connected to RCA, RCA GND and UcD GND tied together
1 * UcD700HG on Hypex SMPS1200U700, connected to RCA, RCA GND and UcD GND tied together
The 400OEMs are using the buffered inputs (shortened ping 30-31, 26-27)
I just installed the big hypex SMPS, since the former solution of using a generic 80V SMPS never worked so well.
The UcD700 runs dead quiet, even if connected to the Denon X4000. It is only the OEM modules which expose the noise.
I already tried connecting just one UcD400 module to one SMPS, same story (ground loop noise when connected to consumer audio device).
I also tried an old stereo UcD180 amp (which is wired the same way) I had lying around - no noise at all.
I know of both hypex docs "AN amplifier signal wiring", and the longer document where the AES48 / RCA / banlanced connections are explained in detail.
I tried connecting RCA signal GND to the chassis, and leaving cold input floating, no change.
What I did not try so far is put in the 100nf/100 ohms filter to GND in place at the RCA input.
So, with all the six RCA input GNDs just tied to each GND (pin 1 XLR), and connected to a battery powered device = no noise
All the six RCA input GNDs just tied to each GND (pin 1 XLR) , UcD700 connected to a mains powered device = no noise
All the six RCA input GNDs just tied to each GND (pin 1 XLR) , UcD400OEM connected to a mains powered device = terrible noise
What is mystefies me is that the UcD700 behaves differently than the UcD400OEM... One could guess that it has something to do with all UcD400OEM modules being connected together through their backplates, but I already measured the connection to each modules GND plane, their is none.
I hope you can help me, I want to finish this project...
To be clear, I also reached out to Hypex support, but maybe somebody else here has an idea.
Now I could also buy a Hypex SMPS3kA400, but I do not think that the "generic" SMPS are to blame (because of having no issues if a signal source with no mains connection is being used).
Regards,
Arndt
