audio-talk

Hello, I am a new member here.

I am considering building my mono block Avondale voyager amps with separate encloures for psu and the rest. My main concern is impedance from having the cap bank so far away from the amp boards. Maybe a final smoothing capacitor could be put in the amp board enclosure to deal with noise picked up by the cabling ?

Getting the psu away from the amplifier seems to be a good move but at what cost ?

Many thanks, Stu

This is a solid state amp which already has several thousand mfds in the PSU. Does it hum already as is?

I'm not sure that impedance comes into this issue really.

It might make an interesting exercise by experimenting with different 'umbilical chords' (e.g. length, weave) and see how much 'hum' you can pick up.

There are several reasons why an amp can hum without it being a smoothing of the psu. As for sonic benefits of an 'umbilical chord', well I'd be surprised - they are already monoblocked and I'd have thought that is pretty much 'improvements' (from a shared psu or anything else to do with the psu)

I'd have never thought of this solution if a solution is necessary in the first place.

Now, am I being negative? Am I talking nonsense? Apologies if I am.

Thanks for your reply Andrew.

Yes it is solid state with separate psu for front end and output stage. The front end has a regulator and 6,600uf of smoothing (3x 2,200uf with inductors between). The output stage has 3x 10,00uf smoothing.

Things i have read on the net include having the cap banks as close to the amp boards as possible. But several companies have two box amps near the top of their range (Naim 300 & 500, NVA statement range).

having a two box Avondale voyager monoblock will entail numerous connections having to be provided between psu and amp enclosure.

I don't think you are talking rubbish but i have demonstrated to myself through experiment that moving transformers away from amps and regs etc does bring sonic benefits even when there was no audible hum to begin with.

Stu

There may be merit in moving the transformer away from the rest of the amp, but I would leave as much as possible as close to the power stage. I would also look into transformer snubbing to reduce harmonics from it.

If you find moving the transformer away makes it better, my instinct would be to find why it improves things as the extra compromises that high current coupling between the two boxes will bring could make a lot of other things worst.

I would agree with Nick, focus on finding decently made transformers, shield them and keep everything in a single case.

Thanks both of you.

I hear what you are saying. My transformers are already high quality custom wound by Canterbury windings.

Snubbing is a bit of a shot in the dark unless you do the measurements and maths which is a bit beyond me and my knowledge level at the moment.

Shielding i can do. 5mm steel would do a good job i think and not get saturated.

Stu

Do you have a scope?

http://www.audio-talk.co.uk/phpBB3/view ... it=snubber

No scope here unfortunately, just dmm and variac.

I keep saying i will get one but having never used one it would probably take me an age to learn how to use it properly.

Stu

Forgot to say thanks for the link Nick.

karatestu wrote: ↑Sun Mar 05, 2017 4:46 pm No scope here unfortunately, just dmm and variac.

I keep saying i will get one but having never used one it would probably take me an age to learn how to use it properly.

Stu

If you want to send me the TX I am happy to measure it and find the snubber values for you.

Hi Nick,

That is a very generous offer, thank you. I have four identical power amp transformers , all with two secondaries (front end winding and output stage winding.

I see you are in West Yorkshire. I am at Tadcaster so possibly not that far away ?

Thanks, Stu

Yep, between Halifax and Bradford.

It will only take 20min or so to find the resistor value. Drop me a PM and we can arrange something.

Brilliant, thanks Nick.

Not sure when I can come over yet. I will let you know.

Many thanks, Stu