reverb howl and oscillation

[bruno]

How do you guys generally deal with reverb howl and oscillation... I have an amp here that starts howling like the sound of a boat horn, and it starts quite early on with the reverb set on 2 or 3, from there on it just start oscillating more and more.

I'm thinking, leadress, using shielded cable on the reverb wiring, and maybe some foam under the reverb tank.

any more ideas?

[Tiny_Daddy]

If you remove the tank from the cabinet and away from the speaker does it behave? If so there may just be too much gain in the reverb recovery circuit. Also it helps to close the tank with a thin board on the bottom, and place the tank in a Tolex bag, and add a piece of 1/4 inch thick self-adhesive foam to the top of the tank.

[Fresh_Start]

1 - place "return" end of reverb tank as far away from PT as possible

2 - shield leads running to and from the Reverb pot

3 - follow TD's suggestion and tape a thick piece of cardboard over the open side of the reverb tank, then put that into a vinyl bag.  Staple velcro strips to bottom of cab & use those to hold tank in place.

4 - try different 12AT7 tubes.  I had one circuit that liked the 4th or 5th 12AT7... ARGH!

5 - mess around with cables to and from tank.  Keep them on opposite sides of the tank inside the bag, and keep them slightly separated going up the wall of the cab.

Good luck!

Chip

P.S.  Can you tell that I've built three Blackface Reverbs?

[Leevi]

I could add that use good cables.
Sometimes it helps if you solder the cables directly to the pins inside the tank.
This helps in case of heads since you don't need to reserve place for the plugs.
/Leevi