Feedback problem

[toneseeker74]

My amp often has feedback as low as 2 on the volume even without a guitar plugged in. Sometimes the problem goes away, or it won't go into feedback until much higher on the volume knob. Usually happens with bright channel only. Thoughts on how to fix this? Thanks

 

[Boogie Bill]

Re: Feedback problem

You probably have a microphonic preamp tube. You don't mention what kind of amp; it's difficult to diagnose with incomplete information. But, it could also be a power tube. Mesa has some good info on their site on diagnosing tube issues.

Bill

 

[toneseeker74]

Re: Feedback problem

The amp is a Traynor YBA-1 tube head that I run into a 4x12. I have tapped all the tubes, and I get a glassy "tink" sound on every tube. I swapped tubes and got the same result.

 

[Boogie Bill]

Re: Feedback problem

Does it feedback going straight into the amp, no pedals?

Bill

 

[toneseeker74]

Re: Feedback problem

Yes, it even feeds back if no guitar cable is plugged in.

 

[Boogie Bill]

Re: Feedback problem

After reading your other posts, I realized you entered the "You messed with it and broke it!" area of the Bermuda Triangle. There's usually a reason why amps are designed a certain way, and sometimes attempting a mod only screws it up. You got something backwards somewhere that's causing the feedback. Admit defeat....it's tech time, and move on.

Very, very doubtful that ANYONE on ANY internet forum is going to be able to help you.

Sorry...

Bill

 

[ehdwuld]

Re: Feedback problem

.

 

[GoldenVulture]

Re: Feedback problem

Feedback loop of the output section [ usually negative feedback ] might be faulty. There's a resistor in it that might be flaky.
It produces an electronic squeal/feedback, not an acoustic feedback.

 

[toneseeker74]

Re: Feedback problem

After reading your other posts, I realized you entered the "You messed with it and broke it!" area of the Bermuda Triangle. There's usually a reason why amps are designed a certain way, and sometimes attempting a mod only screws it up. You got something backwards somewhere that's causing the feedback. Admit defeat....it's tech time, and move on.

Very, very doubtful that ANYONE on ANY internet forum is going to be able to help you.

Sorry...

Bill

I have been thinking about putting all the stock parts back in. But I am not giving up yet ��
All the mods were basic changes to Marshall JMP values, swapping until I got the response I want. Maybe I have tackled a bigger beast than I had imagined, but I'm going to keep on trying to sort this out ��

 

[Edgecrusher]

Re: Feedback problem

Swapping the stock parts back in probably wont help it... in my experience might even make it worse. From what you've posted my money is on you have soldered something wrong or you burned something on the board... something...but now there is a bad connection.

When i first started modding I always tried to do only 1 or 2 changes at a time so I could stop and check my work to make sure I wasnt fubaring something. I see guys make a dozen changes and something is wrong and they dont know how to ferret it out. If you check every change or 2 its much easier to back track. When you get more sure of your skills you start making more changes at once. But its cheap insurance at the beginning.

If it was me I would go over all my connections twice maybe 3 times even those i didnt change just in cast i bumped something while working. Then I would get out my meter and start testing every connection I had made if i still couldnt find it I would start working backwards undoing one change at a time.


Thing is you can take something like this to a tech but being you monkeyed with it hes digging in the dark just like you are. The downside is it might take him a bit to find it and you wind up paying more cause he was hunting the needle in the hay stack. Upside is maybe with his experienced eyes he can see something you dont.