Something Stirs in the Spare Room.

[Nick]

We all know that choke input supplies are good for SE valve amps at any rate

Some of us prefer well regulated supplies (active ones, SS or Valve). Just saying.

[Cressy Snr]

We all know that choke input supplies are good for SE valve amps at any rate

Some of us prefer well regulated supplies (active ones, SS or Valve). Just saying.

Aye, I prefer them too.

[simon]

A couple of thoughts Steve.

Have you looked at the PS in PSUD? I'd be a bit surprised if you could hear the ripple on the output valves with your relatively low efficiency speakers but it would be interesting to model it.

Where do you have your earth connected to? Is it at the second filter cap as shown?

[Cressy Snr]

A couple of thoughts Steve.

Have you looked at the PS in PSUD? I'd be a bit surprised if you could hear the ripple on the output valves with your relatively low efficiency speakers but it would be interesting to model it.

Where do you have your earth connected to? Is it at the second filter cap as shown?

They all go to a busbar connected to the chassis earth.

Sadly, I have never, ever succeeded in making a LC supply that is quiet, no matter how much capacitance I throw at it. I can use exactly the same earthing arrangements with cap input and get a totally silent power supply, not a whisper of noise, even through headphones. But choke input? not a chance; never managed it. Wish I knew why.

It’s not quite as bad as it appears, it’s only ear to the driver stuff, but I would like silence without active regulation. Maybe its asking too much of simplicity.

[simon]

They all go to a busbar connected to the chassis earth.

Can you just have one connection to ground, at the second filter cap? It's possible, if I understand correctly how it's wired, that connections to the busbar before the second filter cap could inject noise/ripple into the busbar. By the second filter cap the ripple should be at the minimum so less noise.

So wire the earth from component to component from the rectifier to the second filter cap, then connect to the busbar there. Apologies if I've misunderstood.

[Cressy Snr]

They all go to a busbar connected to the chassis earth.

Can you just have one connection to ground, at the second filter cap? It's possible, if I understand correctly how it's wired, that connections to the busbar before the second filter cap could inject noise/ripple into the busbar. By the second filter cap the ripple should be at the minimum so less noise.

So wire the earth from component to component from the rectifier to the second filter cap, then connect to the busbar there. Apologies if I've misunderstood.

Cheers Simon, just done that and success! It is not absolute silence, but it’s near as dammit. Effectively, the mods you suggested meant that I had only moved the second cap earth by about 10cm. Ridiculous, but there it is. Much, much better. Thanks

[simon]

Result!

[Nick]

They all go to a busbar connected to the chassis earth.

Can you just have one connection to ground, at the second filter cap? It's possible, if I understand correctly how it's wired, that connections to the busbar before the second filter cap could inject noise/ripple into the busbar. By the second filter cap the ripple should be at the minimum so less noise.

So wire the earth from component to component from the rectifier to the second filter cap, then connect to the busbar there. Apologies if I've misunderstood.

Cheers Simon, just done that and success! It is not absolute silence, but it’s near as dammit. Effectively, the mods you suggested meant that I had only moved the second cap earth by about 10cm. Ridiculous, but there it is. Much, much better. Thanks

Yep, you have to consider the cap charging current at the front of any power supply and make sure that you are not inducing voltages into places they should not be. 10cm of wire may not seem like much of a resistance, but remember if its inducing noise into the earth you may be injecting that noise directly into the front of the amplifier.

I know it may sound a bit tedious, but neat is rarely (if ever) the best layout.