UcD modules' limits on delivered current.

[beppe61]

Is the schematic of the UcD 400 available somewhere?
I understand that most of the components used to built it are very standard off-the-shelf parts.
Input coupling caps are cheap elkos.
I understand there is just a pair of standard mosfets in the output stage (do not know the model though).
I wonder what this technology could reach with the best parts available on the market (like Sanken output devices for instance. I understand they are by far the best output deivces).
I am quite astonished after my first listening session.
In the next future I will test it on my recalcitrant Dynaudios.
By now I am extremely impressed by what I have listened.

Thank you very much to anyone.
Kind regards,

beppe

[classd4sure]

I wonder what this technology could reach with the best parts available on the market (like Sanken output devices for instance. I understand they are by far the best output deivces).

Greetings Sir Beppe,

Do they make decent mosfets for power switching? Requirements are probably a little different than what's best for linear amplification.

The modules have some decent mosfets for switching already. I wouldn't bother swapping them around at all.

You can play around with things like caps though.

There is no schematic available.

Good stuff though, huh? It only gets better.

Best,
Chris

[beppe61]

Originally posted by classd4sure

Greetings Sir Beppe,
Do they make decent mosfets for power switching?
Requirements are probably a little different than what's best for linear amplification.
The modules have some decent mosfets for switching already.
I wouldn't bother swapping them around at all.
You can play around with things like caps though.
There is no schematic available.
Good stuff though, huh? It only gets better.
Best,
Chris

The modules have some decent mosfets for switching already.
Thank you Mr Chris for the kind advice.
As usual I am quite superficial.
You can play around with things like caps though.
I have seen the pcbs. Actually the tiny input caps look poor enough to swap them for something better performing.
I would try to place some PP caps there.
As I understand the input impedance is 100 Kohm, a 0,47-1uF film caps should be fine. Am I wrong?
I feel a little uncomfortable about direct coupling, even if this is the best solution by far.
I think this technology is a tremendous achievement.
Very very remarkable.
I read some listening impressions and power amps based on UcD embarassed well known high-end amps.

High-end for the masses ?

thank you very much again.
Kind regards,

beppe

[classd4sure]

Hello,

Didn't you say your preamp has coupling caps on the output? That would do fine alone.

2.2uF before the op amp would be fine. Currently they're after it, valued at 22uF.

A film cap or straight wire would be a good improvement.

Regards,
Chris

[beppe61]

Originally posted by classd4sure
Hello,
1) Didn't you say your preamp has coupling caps on the output? That would do fine alone. 2.2uF before the op amp would be fine. Currently they're after it, valued at 22uF.
A film cap or straight wire would be a good improvement.
Regards,
Chris

Yes Mr Chris. My Bryston has a 4,7uF output cap.
So the caps are after the input op-amp.
I think I would not touch anything, at first.
The amp I listened had modules 400 in stock form and performed just wonderfully.
Expecially considering where I come from (Adcom GFA 545).

Thanks a lot and regards,

beppe

[deafandumb]

Forgive me for posting here....but I need some advice on my UcD 400. The amp was built for me (since I know nothing about electronics) but it kept on blowing fuses (4 A) after a few starts when the power was turned on. There must be hundreds of reasons but what would be the most likely one? Is it normal because of power surge and what can I do to solve it?

Most grateful for any answer, and once again sorry to interrupt.

[classd4sure]

Who built your amp, Ric Shultz?

Where's the fuse, power rails or mains? I guess mains? Try a 10 amp. Usually a soft start circuit is used to limit inrush current, without it you'll need a beefier fuse.

[deafandumb]

Thanks for replying classd4ever. The unit was built locally with some upgrade parts and included a soft start! That is why I am concerned why this is still occurring? Would a 10 A fuse be too much for some parts to take? Thanks again.

[deafandumb]

Sorry, it should be classd4sure! BTW, mine is a dual-mono but there is only 1 soft start, maybe that is not enough?

[classd4sure]

OK, bad advice then. Since it includes a soft start and is blowing the fuse I'd be a hell of alot more paranoid.

If you don't know electronics at all, is there a possibility you can bring it back to whoever built it and have them look it over?

Otherwise it might be time to invest in a multimeter and get familiar with it, check for shorts to the case.