Chiming, singing, bell-like sound problem

[ampdoc1]

You may have a different problem that I did, but my amp was in a combo cab. In that instance the speaker vibrations were apparently setting up a resonance in the tube glass. The rubber "dampers" stopped that completely. Not that you couldn't get a noise by thumping on the tubes, but that is pretty much par for the course on any high gain stage.

adoc

[JD0x0]

1. Yes this happens independently of what guitar I use. strat, tele, LP

2. I have plugged straight into IN and also into FX loop. Both had it.

have i been able to answer correctly? ( coz English is not my native language )

regards

If both had it, it sounds like it's in the power amp. Im not sure what you mean by this "ping" bell like sound but it sounds like maybe the presence is cranked way up. When i crank the presence on my amp it has a more very bell like attack which is very bright. Maybe you wired the presence wrong or used a different value pot (or resistor)

[jelle]

Have you tried hitting parts in the amp with a chopstick when the amp is on and the controls are halfway?

[megemen]

ok, i have been tapping here and there in the amp and i have been able to find just one place ( see the pic )where i heard tapping sound as i tapped with the chpstick, now what?
regards

[ayan]

ok, i have been tapping here and there in the amp and i have been able to find just one place ( see the pic )where i heard tapping sound as i tapped with the chpstick, now what?
regards

If you plugged into the FX return and you heard the noise you're trying to get rid of, it means that the noise is happening after the input to the phase inverter. I would focus my energy in that area, although you seem to be able to generate the noise when you tap on the grid (I believe, based on the picture) of the 1st preamp.

There are not very many connections between the input to the PI and the end of the amp (that is, the output transformer). I would look for all of the wiring there, keeping an eye out for cold solder joints, etc. If nothing seems worng with them, I wonder if it could be something about the transformer.

Let me ask you another question: have you heard the amp through a differnet speaker cabinet?

Gil

[talbany]

I have had those cheap ceramic capacitors (the 220k bypass) exhibit microphonics,..Also see if it helps with the head lifted from the cab..vibration related.. thought I would mention..

Tony

[67plexi]

megemen, I can't tell looking at your photo. Polyester film capacitors can be microphonic. Is the .047uf touching the back of the chassis try a 1/4" of silicone to buffer that capacitor from the chassis.

good luck.

[Structo]

Steve is right, take some clear silicone caulk and put a bead between all the orange drops that are close or touching.
In fact I would separate them by about 1/8" then add the silicone.
This will help with microphonics of the caps.

[mastercihan]

megemen, I can't tell looking at your photo. Polyester film capacitors can be microphonic. Is the .047uf touching the back of the chassis try a 1/4" of silicone to buffer that capacitor from the chassis.

good luck.

It can't be from caps.They are best quality caps in the market. Check the 6v6 and the 6l6 bias selector swich.Bias elector swich have to positioned opposite direction of output transformer... Tubes have to connected the blue and brown cables not the brown- blue white trace.

if its opposite side correct and re-bias tubes with your multimeter and bias pot

[Structo]

I respectively disagree.
Film and ceramic caps can be very microphonic.

Just tap around inside a live amp near the input to see what I mean.

He has a dual primary output transformer.
This allows the use of 6V6 and 6L6 tubes.
THat is why that switch is there.
I can't make out the colors but I assume he has that right.

[mastercihan]

I respectively disagree.
Film and ceramic caps can be very microphonic.

Just tap around inside a live amp near the input to see what I mean.

He has a dual primary output transformer.
This allows the use of 6V6 and 6L6 tubes.
THat is why that switch is there.
I can't make out the colors but I assume he has that right.

İ didn't mean the connecton.I tried to mean the position of that swich.Are ou shure it is the rigth position .İt has not seen in the photo...

Believe me i built hundred of this amps and orange drop caps are best in the tone and very low micraphonics then other same stile caps...They are not film or ceramics you mentioned -- they are polypropylene caps

[Bob-I]

ok, i have been tapping here and there in the amp and i have been able to find just one place ( see the pic )where i heard tapping sound as i tapped with the chpstick, now what?
regards

Have you replaced V1? If no that's the first thing I'd do. If you don't have another tube swap V1 with V2 and see if there's a change. If it still rings when you tap at the same location, disconnect the LNFB cap and resistors.

Sherlock Holmes said, if you take in all the possibilities and eliminate all but one, that must be the answer no matter how unlikely it may seem. Yes, quality components can be bad.

[Steven_nl]

I'm ignorant, but if this also happens when you plug your guitar into the fx return wouldn't that mean it's a problem after the pre-amp?

[JD0x0]

I'm ignorant, but if this also happens when you plug your guitar into the fx return wouldn't that mean it's a problem after the pre-amp?

Yes and this has been mentioned a few times, yet ignored. V1 might be slightly microphonic but the problem was at the power amp since it could be heard when the preamp was BYPASSED.

My gut is leaning towards negative feedback from the presence still. If it's feeding back too much signal it will be very bright with a sharp bell, or chiming sound. The excessive high end can also create microphonics, if youve ever noticed more treble=more prone to microphonic feedback.

[megemen]

I bypassed the preamp section and the problem still there.