Express squeeling!

[Ukko75]

Now my express squeels, even at all controlls zero but precense! I have been moving vires etc but it is still there. I dont know what to do next. I changed my OT while ago and first it was normal, exept now.

[geetarpicker]

You might try pushing the OT primary wires down against the chassis. My oriignal Express used to be finicky in this way and required a small piece of foam rubber to hold the primary wires down tight right as they went under the power supply board. They were also twisted with a couple loops. For some reason nowdays the foam rubber is gone but the amp no longer oscillates even with all the knobs fully up.

I'd suggest posting a pic of your amp so we can take a look.

[xtian]

Now my express squeels, even at all controlls zero but precense! I have been moving vires etc but it is still there. I dont know what to do next. I changed my OT while ago and first it was normal, exept now.

Not sure why the squeal didn't appear when you first replaced the OT, but this sounds like classic NFB feedback, doesn't it? Try swapping the OT primary wires (usually red and blue).

[Ukko75]

I will try swap the primary wires. I recall that they first was wrong way and then i changed them. I will post some pictures tomorrow. I tried diffrent phase inverter tube and it not squeeled until other pots where up. Could really michrophonic tube squeels in that place? That is really sad that all the good sounding tubes are really michrophonic.

[Blackburn]

Maybe, instead of 'good sounding' tubes, you should find some 'excellent sounding' tubes?

[cbass]

If its squealing with all controls at zero.Its definately more of problem than a tube swap.

[Ukko75]

i tried swap those wires put they where right. There is no effect if i push the primary wires down. Here is couple pictures of it.

[Ukko75]

Finally i found the source that oscillation! OT:s secondary ground wire was too close OT primary wires. Now i can turn all knobs at noon and amp is quiet.