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Evans amp help!

3/18/2006 10:03 PM
Patrick Smith	Evans amp help! I have an Evans amp (200 watts FET thing) that developed a buzzzzzzzzzzzzzzzzzzzzzz, pretty loud actually. Here's a funny note about the buzz. When the amp is on and nothing is plugged into it, it's just fine, no buzz. put something in the effects loop and there it is. When you just plug into the amp with no effects loop it was still there but not as bad. I replaced all 4 FETs to rule those out and it did the same thing. THEN i flipped the power switch (goes 2 ways for grounding) back and forth and it would pop. I was thinking hmmmmmmmmmm maybe a problem with the switch or the cap on the switch when ALL OF A SUDDEN the noise went away! Unfortunantly so did most of the volume of the amp. It's wierd! It sounds just like it always did, except maybe 1/5 of the volume. No cutting out. The tone controls work, reverb etc. The thing works just fine except it has lost most of it's volume. One more lil' quirk to this problem. If you use the effects loop it's really quiet, the loss of volume i'm talking about. BUT if you you don't use the effects loop and just run into the amp the volume is dropped even further. I'm at a loss with this thing. The amps i know are the old Marshalls and Fenders. I've never had an amp do this, sound like it always does just with a massive volume cut. Output capacitor/s maybe? I'm lost on this one. Guys ANY help or suggestion would be most appreciated, so thanks bunches in advance. PMS

3/18/2006 10:03 PM

Patrick Smith

Evans amp help!

I have an Evans amp (200 watts FET thing) that developed a buzzzzzzzzzzzzzzzzzzzzzz, pretty loud actually.

Here's a funny note about the buzz. When the amp is on and nothing is plugged into it, it's just fine, no buzz. put something in the effects loop and there it is. When you just plug into the amp with no effects loop it was still there but not as bad.

I replaced all 4 FETs to rule those out and it did the same thing. THEN i flipped the power switch (goes 2 ways for grounding) back and forth and it would pop. I was thinking hmmmmmmmmmm maybe a problem with the switch or the cap on the switch when ALL OF A SUDDEN the noise went away! Unfortunantly so did most of the volume of the amp.

It's wierd! It sounds just like it always did, except maybe 1/5 of the volume. No cutting out. The tone controls work, reverb etc.

The thing works just fine except it has lost most of it's volume.

One more lil' quirk to this problem. If you use the effects loop it's really quiet, the loss of volume i'm talking about. BUT if you you don't use the effects loop and just run into the amp the volume is dropped even further.

I'm at a loss with this thing. The amps i know are the old Marshalls and Fenders. I've never had an amp do this, sound like it always does just with a massive volume cut. Output capacitor/s maybe? I'm lost on this one.

Guys ANY help or suggestion would be most appreciated, so thanks bunches in advance.

PMS

Replies:

Don Symes The timing of that symptom does sug... -- 3/18/2006 11:30 PM
R.G. It could well be parasitic oscillat... -- 3/19/2006 7:48 AM