1 post / 0 new
admin2

Choppy Distortion when on High Gain

AuthorMessage
 

lee schinagl
Posted on Sunday, September 22, 2002 - 06:38 pm:   

I just had my 112RP sixty-five serviced last summer. They cleaned the pots and resoldered the wiring but I still am getting VERY dirty distortion when I push up the Master Gain. It is not smooth and has a broken up tone to it. I don't
know what kind of power tubes I have(Black Logo Faceplate), but they claim they also rebiased the tubes. As a side note, I bought it used in 80 and it had a JBL 12 installed when I bought it. It is in great condition and I play it 6-10 hours a week.
The clean channel is REAL clean and sounds fine. It is just the overdrive tone that sounds muddy.
Any thoughts?
Steve Kennedy
Posted on Wednesday, September 25, 2002 - 12:32 pm:   

Did it always sound this way or did it change somewhere along the line? Did it change AFTER they worked on it? Does the amp get hot or do the plates on the output tubes glow red? Has it always sounded like it does now?

If you know it is a real problem (which it sounds like it is), it could be almost anything... a bad cap, transistor, a bad opamp or CMOS switch I.C. (on newer models) or it could be dirty relay contacts (on earlier models).

In any case, a tech would have to probably troubleshoot with a scope to find the culprit.

Just a guess or two...

Steve

Lee F. Schinagl
Posted on Saturday, September 28, 2002 - 08:58 am:   

Thanks Steve,

I didn't play through it for many years so I can't remember if it always was that way but it was definately doing doing it prior to my having it cleaned. I remember that that was one of the things that prompted me to get it checked.
I will check the tubes though and see if it looks hot. BTW , I had to play outside in 100+ degree weather last summer and it held out ok , but I hope it didn't fry anything.

Lee
Lee Schinagl
Posted on Sunday, October 06, 2002 - 01:26 am:   

Another thing....

It seems to clean up a bit when I turn up the volume(@5). When it's on @2.5 with the gain up to 5-7 it is when the distortion breaks up the most. Maybe because I have an RP and not an RD I don't have a very good distortion to my amp.