I'm not an expert, but it seems that the best success is a 1:1 of trafos to PSU boards.
it seems ok to have multiple amp modules draw off the same PSU board but having multiple PSUs on one set of diodes or 1 trafo could cause ground loops.
like PB said, double up on the bulk storage caps on the central PSU.
it seems ok to have multiple amp modules draw off the same PSU board but having multiple PSUs on one set of diodes or 1 trafo could cause ground loops.
like PB said, double up on the bulk storage caps on the central PSU.
I can't speak for chipamps, but I had been running a dual PCB Class A HA from one PSU and a single JLH PSU addon , then I changed to dual PSUs and dual JLH PCBs running off a single outboard 18-0-18 30VA transformer. There was an improvement in soundstage etc.
Later, a friend (DIYAudio member) told me that he had even better results when using dual transformers as well. Eventually, I did what he suggested and changed to dual mono type construction. There appeared to be a further improvement in channel separation, and as my friend suggested, ït just sounded more "right"
Sandyk
Later, a friend (DIYAudio member) told me that he had even better results when using dual transformers as well. Eventually, I did what he suggested and changed to dual mono type construction. There appeared to be a further improvement in channel separation, and as my friend suggested, ït just sounded more "right"
Sandyk
Hi,
if you use a centre tapped transformer for your single Bridge Rectifier then you must have ONE Main Audio Ground.
This Main Audio Ground must be shared between all channels.
This seems to have fewer problems if you have one PSU.
If you have a dual secondary transformer you can either have a single PSU & single Bridge Rectifier as above
or
using twin Bridge Rectifiers you have the option to have an Audio Ground dedicated to each channel. This requires. dual secondary, two sets of dual Bridge Rectifiers, two sets of Smoothing Capacitors and two sets of Disconnecting Network to tie in the Safety Earth.
Each channel must strictly follow star grounding and must use low loop area for all flow and return pairs.
if you use a centre tapped transformer for your single Bridge Rectifier then you must have ONE Main Audio Ground.
This Main Audio Ground must be shared between all channels.
This seems to have fewer problems if you have one PSU.
If you have a dual secondary transformer you can either have a single PSU & single Bridge Rectifier as above
or
using twin Bridge Rectifiers you have the option to have an Audio Ground dedicated to each channel. This requires. dual secondary, two sets of dual Bridge Rectifiers, two sets of Smoothing Capacitors and two sets of Disconnecting Network to tie in the Safety Earth.
Each channel must strictly follow star grounding and must use low loop area for all flow and return pairs.
AndrewT,
Hummm . It seems that there were a misundersting due to my bad English...
In fact I should have shortly a dual secondary transformer (2 x 25V 300VA). (bought it for 30 Euros delivered)
I have in my hands the dual secondary transformer, 2 amp board http://www.chipamp.com/images/lm3886amp-parts.jpg and 2 power supply board http://www.chipamp.com/diyaudio/snubber.jpg also here http://www.chipamp.com/images/ps-rev3-sch.gif
Normally, with one dual secondary transformer, we use 2 amp boards + 1 power supply board. like this http://www.chipamp.com/images/lm3886amp-assembly.jpg
But I have 2 Power supply boards (and don't plan to use 2 transformers). So my question was, instead of using only one power supply board, won't it ne better to use both power supply boards (connected to the same dual secondary transformer).
Sorry again for my bad English
Hummm . It seems that there were a misundersting due to my bad English...
In fact I should have shortly a dual secondary transformer (2 x 25V 300VA). (bought it for 30 Euros delivered)
I have in my hands the dual secondary transformer, 2 amp board http://www.chipamp.com/images/lm3886amp-parts.jpg and 2 power supply board http://www.chipamp.com/diyaudio/snubber.jpg also here http://www.chipamp.com/images/ps-rev3-sch.gif
Normally, with one dual secondary transformer, we use 2 amp boards + 1 power supply board. like this http://www.chipamp.com/images/lm3886amp-assembly.jpg
But I have 2 Power supply boards (and don't plan to use 2 transformers). So my question was, instead of using only one power supply board, won't it ne better to use both power supply boards (connected to the same dual secondary transformer).
Sorry again for my bad English
one winding going to TWO bridge rectifiers is, I believe, a source of trouble.
so to keep things clean and simple, one trafo winding (from any trafo) goes to one full wave diode bridge (4 diodes). that goes to a few bulk caps and so on.
no cross conneting of 1 winding to 2 bridges or 2 windings to 1 bridge (at least I would not do that).
so to keep things clean and simple, one trafo winding (from any trafo) goes to one full wave diode bridge (4 diodes). that goes to a few bulk caps and so on.
no cross conneting of 1 winding to 2 bridges or 2 windings to 1 bridge (at least I would not do that).
my last paragraph describes how I would wire up two dual polarity supplies to one dual secondary transformer. This will not be as immune to various grounding problems as a pair of monoblocks.
Paragraph 2 (before the "or") describes the single PSU you have shown the link for. This can be made to work, but again it is not as immune to grounding problems as a pair of monoblocks.
I am in a similar situation with 3886 boards having their own bridge + caps attached.
Using one trafo (20VAC X 2), I tried to connect two PSU boards from one trafo, and there was big hum.
Currently I am using only one PSU powering both 3886, but I wonder if I can split each 20VAC into each PSU + AMP in voltage doubler configuration.
I mean:
Instead of (20VAC + 20VAC connected as 40VAC CT)
One 20VAC powering one PSU as voltage doubler
What would be the problem here?
Using one trafo (20VAC X 2), I tried to connect two PSU boards from one trafo, and there was big hum.
Currently I am using only one PSU powering both 3886, but I wonder if I can split each 20VAC into each PSU + AMP in voltage doubler configuration.
I mean:
Instead of (20VAC + 20VAC connected as 40VAC CT)
One 20VAC powering one PSU as voltage doubler
What would be the problem here?
Hi,
I am building the PeeCeeBee V4h power amp and I have to decide what is the best PSU configuration to use, the transforme that I have is the Amplimo 8026 dual secondaries 40VAC - 10A each and I already have a pair of these PSU pcbs 35A Low Noise Bridge Rectifier Filter CLC/ CRC Audio Power Supply Board Bare PCB | eBay
also 8pcs of Nippon Chemi-Con 22.000uF/80V caps EKMH800VRT223MB80T and finally 4pcs 26MB140A full wave bridge rectifiers, I know I cannot use both PSU boards with a single transformer so my question is should I go for a dual bridge PSU (schematic above) common for both channells using just one of the boards or is it better to go for a dual mono PSU like the one below after I tap the transformer secondaries ? What are the advantages and disadvantages of each configuration?
I am building the PeeCeeBee V4h power amp and I have to decide what is the best PSU configuration to use, the transforme that I have is the Amplimo 8026 dual secondaries 40VAC - 10A each and I already have a pair of these PSU pcbs 35A Low Noise Bridge Rectifier Filter CLC/ CRC Audio Power Supply Board Bare PCB | eBay
also 8pcs of Nippon Chemi-Con 22.000uF/80V caps EKMH800VRT223MB80T and finally 4pcs 26MB140A full wave bridge rectifiers, I know I cannot use both PSU boards with a single transformer so my question is should I go for a dual bridge PSU (schematic above) common for both channells using just one of the boards or is it better to go for a dual mono PSU like the one below after I tap the transformer secondaries ? What are the advantages and disadvantages of each configuration?
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I would go for the second design. The reason is that if a supply rail, the positive or negative, is pulled downward due to a sudden high current consumption in one amplifier channel, this rail is also pulled downward for the other amplifier channel. You want the two amplifier channels to work as independent of one another as reasonably possible.
I have seen amplifiers constructed like that in the past. If this configuration is particularly prone to introduce hum issues I cannot say as I haven't used that configuration myself recently.
Wait for someone with "hands-on" experience. Or, try one and if problems then the other.
Good luck with your project.
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