Hi Vitali
First of all: Nice amps you are building
. You are a very good Diy'er , I surely like your workmanship. Keep it up !
Hi Johnny,
One question
You said you Toroidy a transformer of 3000VA.
You tried to put him in charge?
I have used in the new project 2500 VA transformers from Toroidy.
At a bias of 3.6 A had a very strong mechanical noise.
I tried DC filter, snuber, CRCCC, CLCC, NTC60 - no good result.
I tried last resort - I opened external winding and we put both in resin. To my 90% of noise disappeared.
It became quiet after I added in series with the primary winding 2xNTC60 (10R+10R).
Every time I listen ... I'm amazed how this amplifier may sound good
Much better than the first version (with transformer 1500 VA)
Thank you
I think you have misunderstood. The 3000VA transformer is not for the Pass, is it for the Borbely Millennium poweramp, which I am also building.
What I am going to use in the Pass clones, I have not decided yet.
I have not tested the 3000VA under heavy load yet, but I am going to put it in a metal can and fill it with resin, like you did. (Just to be on the safe side, and it with will also look better with a polished metal can like the ones in my preamp.)
Like I said in a e-mail to you, the ones you have built have not the right amount of output-fets. You have the "light" Chinese version with 12 pairs pr. side. The right number is 18 pairs pr. side ! You also have a passive CCS (resistors), witch was only used in XA160.5 Mk.1
From Mk.2 and later models like XA160.8 there is an active CCS. We are building a Mk.2 version with active CCS and 18 pairs output-fets pr. side.
We have now all the information that we need. It is now up to my partner to get his finger out, and redesign some pcb's
. Hint, hint
Anyway, I'm so happy that you are pleased with the sound of your new amplifiers
. Fantastic good DIY !
All the best,
your friend Johnny