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Thanks to everyone ... esp Bruce

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5/22/2005 7:02 PM

Thanks to everyone ... esp Bruce

I was taking my 5E3 apart to send it to Bruce. It had a frizzy sound in it and I could not find it. A friend was over and we were talking about it. He wanted to hear the noise. I fire it up. The fizzt starts and he reaches over and touches the chassis and almost all the noise pretty much disappeared.

So ... we take it apart and start touching things with a dowel rod. As we located the buzz places we tried killing them. I used some double faced tape a few small boards and felt. I think I have them all fixed up now!

Apparently the chassis resonated with various notes. This was vibrate the tubes or various elements and this was causing the noise in the amp.

I did not realize such a thing could happen. I would not have thought to check it had Bruch not suggested it (I should send you some money just for the advice!).

Dale

5/22/2005 9:03 PM

I built a small guitar amp from the guts of an old 50's phonograph. I used all salvage parts, even the resistors and caps. It sounded great except for a really loud BRRZZZZ!!! that would pop up under heavy overdrive. It sounded like, and I thought it was, a parasitic oscillation. The layout was a little suspect since I was working with salvaged parts in a very small space. But just to be sure I plugged it into an extention cabinet and the noise dissapeared. It took awile to find it but boy does it sound good now.

Just wanted so share a sympathetic story

FWIW I'd like to share a tip for anyone plagued with that awful rattle from microphonic EL84 tubes. I use heavy heat resistant rubber gasket material. Not the black stuff, it can become conductive (don't ask me how I know

). Use the orange stuff. I cut a circle out about the size of the tube base and poke holes for the pins. Slip this onto the tube pins and snug it against the base before you install the tubes and clip the retainers on. It has helped me to get more life out of a pair of tubes before they start to go microphinic.

Chuck

5/23/2005 12:21 AM

Bruce /Mission Amps

Glad to hear you figured that one out.
I had a stinker buzz one time that after a few hours of moving parts, poking parts, stretching leads, moving leads, tensioning lugs and sockets.... etc, etc, etc., ... I discovered I could alter the pitch and buzz intensity by loosening the darn eyelet board mounting screws.
The actual fix took about 15mins and required me to remove the two eyelet board screws, slip a rubber grommet under the insulation board at each screw mounting hole, then reinserting the screws through the board and grommets and snugging them down. Thus floating the insulation board over the actual metal chassis.
That TOTALLY fixed the problem in that one.

Bruce

5/24/2005 7:57 PM
Dale	Well, I would not have found things had it not been for you and others. Again, thanks! Dale

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