Wierd sound from my Express, need help PLS !

[DaveWell]

After the volume is half ( at 12 oclock) ther's ther's a " Wooommmm" sound

Need help to fix that.

is this can be the NFB ???

Thanks !

[Littlewyan]

Have you tried taking the amp off of the cabinet and putting it on the floor away from it? Not in front of it though.

[Richie]

Sounds like a microphonic tube. Try changing the first preamp tube.
And as was mentioned, try moving the amp off the cab.

[apache]

If the above advice doesn't fix it, you could consider reversing the OT primaries. I had a similar problem with a loud deep sound when the volume was raised and that solved it.

The sound I got was a bit different, so maybe you have a different problem.

[johnnyreece]

Was the amp working fine, then it started doing this? Or is this a new build that's been doing it from the start?

[DaveWell]

The amp was working really fine and start doing this sound.

And when i move the amp from the cabinet, sound disappear and come back.

Look like a bad tube.

[Richie]

The video was showing no guitar plugged in the the input. does it change if a guitar is plugged in,with guitar volume down.

If the jack is a switching type, and is not making contact on the close part, or with no guitar plugged in, it could be causing a noise problem.

Sometimes the switch contact gets a little dust or film on it. Just something that also might cause this happening.

[DaveWell]

every thing is brand new..

I take off the amp out of the head shell and put it in the side of the cab and no more problem...

[geetarpicker]

Ken Fischer would often suggest to not stack an Express or Liverpool on top of the cab. A foam pad can often work to isolate the head if you really want to stack it. It is a high gain amp, and as such quite picky about preamp tubes. If a tube is only slightly microphonic it can still be problematic in these amps.

[Gibsonman63]

every thing is brand new..

I take off the amp out of the head shell and put it in the side of the cab and no more problem...

There's a clue. Check the screw clearance for the cover plate to the potentiometer lugs. I had one that was too close and when I put it in the cabinet and screwed everything down it was just enough pressure to short out.

[DaveWell]

Thanks ,

I will order 3 new pre-amp tube low microphonic... JJ's i think.

Will see if it help

Thanks to all

[Littlewyan]

Might want to look at what Gibsonman said before ordering new valves. Could be as simple as that.

[Rick]

The video was showing no guitar plugged in the the input. does it change if a guitar is plugged in,with guitar volume down.

If the jack is a switching type, and is not making contact on the close part, or with no guitar plugged in, it could be causing a noise problem.

Sometimes the switch contact gets a little dust or film on it. Just something that also might cause this happening.

I've had this problem on numerous occasions. It seems a little oil or grime often gets in between the grounding contacts, brand new jacks will do this, and the filament ends up not being grounded causing hum and noise.

[Reeltarded]

Loose leg on a component that rubs when vibration gets to a certain amplitude.

Or just keep throwing money at it.

[Jana]

People tell me that I am a problem--can you throw money at me?

As for weird sounds, my amps all make weird sounds. These sounds tend to cease when I stop playing or turn the volume all the way to zero. Go figure.