Mounting an External Amplifier power supply??

[MurphyUHF10]

Hi There,

For my next amplifier project, I plan to mount the power supply in its own external case seperate to the power amp module.. But am a little confused as to the best method,, so some feedback will be appreciated..

My research about this has found 3 common methods:

1) Only mount Transformer seperately, leaving the Bridge rectifier and Capacitor banks in the same case as the power amp module.

2) Mount Transformer, bridge, Cap banks in the seperate case.

3) Mount Transformer, bridge, Cap banks in the seperate case, but have a second bank of capacitors next to the power amp module as well...

So, has anyone got experience with external power supply for a power amp??

Cheers.
Murphy

[Gopher]

Murpho

Without doubt number 3. You could add some resistance or inductance between the two cap banks or, cheaper still, just use thin gauge wire to connect the PSU and amp.

[AndrewT]

I agree, method 3 is the only one that can come upto performance expectations.
Do go and read the quandaries of deciding how to earth your two chassis arrangement. That may put you off the idea.

[mymindinside]

Hi Andrew,
i have been trying to wrap my head around this (2 case grounding and safety) as well,
could you point us in the right direction with a link please?

cheers,
mymindinside

[MurphyUHF10]

Originally Posted by AndrewT

I agree, method 3 is the only one that can come upto performance expectations.
Do go and read the quandaries of deciding how to earth your two chassis arrangement. That may put you off the idea.

Hmmm,, interesting.. Couldn't be that hard?? I imagine just to use 3 core wire between the 2 cases, and the third 'earth' wire be attached to chasis.. Just like a normal IEC connector has Earth attached to chasis, you could run 3 core between cases, 2 for AC from Transformer, and 1 for linking chasis..

Am I in the right direction??

Murphy

[qusp]

yeah wouldnt you just use a well shielded 3+ wire umbilical and use the shield as chassis ground and 3rd earth wire for power supply/star ground? but yes it does throw a bit of a spanner in the works, as the main star ground for the build would normally be centered at the main supply caps

[MurphyUHF10]

Originally Posted by qusp

yeah wouldnt you just use a well shielded 3+ wire umbilical and use the shield as chassis ground and 3rd earth wire for power supply/star ground? but yes it does throw a bit of a spanner in the works, as the main star ground for the build would normally be centered at the main supply caps

Hmmm, definately a spanner in the works.. i did not think of that.. But, the chasis is earthed via the earth wire anyway.. so if you run a shield, aren't you having "multpile connection to earth" which is a recipe for ground loops??

Cheers..

[jitter]

Originally Posted by mymindinside

could you point us in the right direction with a link please?

Here you go: Audio Component Grounding and Interconnection.

After reading this you'll know why the author writes: "Loops aren't bad, it depends on what's in them." This should make your dilemma much less problematic.

[AndrewT]

Originally Posted by qusp

the main star ground for the build would normally be centered at the main supply caps

the main Audio Ground Star is never centred at the main supply caps !

[qusp]

I knew someone was going to be picky about that and somehow knew it would most likely be you of course in the end it should be at IEC and is, but first signal ground and PS ground converge at the main suply cap junction do they not? and does the above 2 box build cause a bit of an issue there? by main I guess I was meaning more points converging, not the last port of call. also to be more specific, an extension of the point between the main supply caps, not the actual physical center, center of potential

sorry I must remember when posting in such subjects to not leave anything up to assumption