Some questions on an Adcom 5400

[Chamberman]

You could just move C922 over to C923, you're still on a 120VAC main so you wouldn't need to replace that MOV with a 240V part. I ran my later model 5400 for a few days with the transformer primaries in series and a much higher Iq, (IIRC about 25WPC Class A). I was worried about overheating of the transformer while operating this way so I made it a point to monitor it to see if it appeared to be overheating and no issues arose.

 

[wct]

Hi Chamberman

Thank you for that good piece of advice. And so I followed your advice and the amp is now up and running.
Brought it up slowly on a variac.

So far no problems, certainly no smoke

Playing music on the work bench with a small set of test speakers.

So I guess for the moment my one remaining question is about the fact that the front end of the amp
is necessarily running on reduced rails along with the output stage.

Does the fact that the front end is running on reduced rails compromise the effort?
Does it effect the linearity, distortion characteristics or the ability of the front end to drive the capacitance of the output stage?

Thanks for the input.

Curt

 

[Zen Mod]

Papa is Da Man for that question

 

[Nelson Pass]

The answer is yes. The Fets love some voltage, so when you reduce the
rails, you will get more distortion of various sorts.

However, the amp does have a fiar amount of feedback, so as long as the
output stage is biased up, I think it'll be OK. Keep in mind that with halving
the rails, your power will go to significantly less than 1/4 of the previous.

 

[Chamberman]

Here's where my Adcom 5400 ended up, post 13.
I'm still using it, but have plans to make some changes to it probably this winter.