Welcome! Need support, you got it. Or share you ideas and experiences.
67.104.10.163
In Reply to: RE: How do I tell if I have a 200C or 200CX posted by SQLGuy on March 08, 2009 at 20:24:54
What we noticed years ago is that sometimes the laminations came loose and all you had to do was tighten the bolts that hold the lams together. Try that. We never had much luck with varnish. Cyno acrylate in a vacuum chamber worked well to quiet the lams, but I think possibly tightening the four bolts might do it. Most had noticeable hum only if you put your ear up to the unit. It can also be that your AC has a bit of DC on it. Try measuring the DC voltage on the power line and see.
Hi Paul,Well, I've checked already for DC on my lines... none there. This transformer does run pretty hot, though. After a couple hours idling the laminations are too hot to touch for more than 1/2 a second or so.
I tried tightening the through-bolts further, but that didn't make any noticeable difference in hum. I just did a test, and, with the amp pretty well warmed up, I can hear it pretty clearly from 15 feet away. It sounds, though, like the transformer is resonating at some harmonic of 60Hz... at least, there are definitely overtones to be heard.
Can you recommend a place that can do the CA treatment you mentioned? I had contacted Paraline since they are the original manufacturer for this transformer.
Thanks,
Paul
Edits: 03/09/09 03/10/09
The cyno treatment would have to be done at the time it is manufactured. I don't think it would work now. I think the heat is right, or at least it seems so. Maybe have Paraline make a new one for you?
Hi Paul,
I finally got my re-dipped transformer back from Paraline. It still hums a bit, but it's manageable for now. I also replaced the contactor (which was humming quite a bit itself) with a Teledyne solid state relay. Dead quiet and a drop-in replacement for the contactor... I'm pretty happy with that.
Anyway, the one last thing I'd like to do is add some balanced inputs. The amp suffers from a decent amount of ground loop noise in my system, even when everything's plugged into the same outlet; I'm hoping/expecting that running it balanced will cut this down quite a bit.
Do you have any recommendations on what kind of an input circuit to use to add a balanced input to this amp? I had heard of some other owners that had had balanced inputs added to their 200c's or cx's, but I don't know whether that was a factory service you guys offered or something third party.
Thanks,
Paul
Adding balanced inputs probably wouldn't be that hard as the input has a diff pair if I remember correctly. You might want to contact Dr. Bob Odell out in Pasadena California who designed the amp. I am pretty sure I have Bob's email address somewhere so if you email me I can give it to you. The other option would be to send it to Rick Cullen www.cullencircuits.com and ask Rick what he'd charge to modify the amp for you.
Post a Followup:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2009, Audio Asylum, all rights reserved ]
[ Go Green ]
[ Take5 ]