Tremolux Amp repair FINISHED

[JazzGuitarGimp]

Have you tried a different speaker?

Oops, just found that on page 2. Never mind!

[Firestorm]

Might be getting down to trying an OT swap.

Well, try that if you can. I still think it's parasitic. I still think it's in the preamps. Now I'll shut up.

[martin manning]

I still recalling Mike Safreed's problem that was eventually solved by flipping the PI plate loads and bias feeds. Shortening the grid leads to the power tubes did it, he thought. May be parasitic, but ruling out the OT would be nice.

[xtian]

OK, gentlemen, I am satisfied the the preamp stages are sound. First I removed the PI and power tubes, and disconnected the preamps from the PI at the mixer resistors. I ran the preamps into the FX return on my Tweaker 15 head. They sounded great.

Next, I installed the PI and power tubes, and plugged in a dummy load (still running preamps out into the Tweaker). Still sounded great.

Finally I rewired the Tremolux as it should be, and just jumpered out to the Tweaker at the mixer resitors. Sill, perfect sound.

And here's an important observation I have failed to mention, because it didn't really slap me in the face until using the Tweaker as a power amp == the Tremolux's output is WAY too low when dimed. It should have a hell of a lot more power. It's way quieter than my 15 watt Tweaker.

So. Preamps are good.

OTs are only $50. Think I'll order one.

[xtian]

I just trimmed all the leads on the OT and resoldered. No change.

Anyone think of some OT tests I can do before I order a replacement?

[Firestorm]

I just trimmed all the leads on the OT and resoldered. No change.

Anyone think of some OT tests I can do before I order a replacement?

Go ahead. If that ain't it, you can use it later.

It's parasitic. A bitch to solve.

[Baddog01]

I didnt read the whole thread but im guessing you tried diffrent power tubes at some point. You checked all ground and the speaker jacks to make sure there tight.
Sounds like with the volume loss you have an output transformer issue.

Keith

[xtian]

I didnt read the whole thread but im guessing you tried diffrent per tubes at some point. You checked all ground and the speaker jacks to make sure there tight.
Sounds like with the output volume loss you have an output transformer issue.

Keith

Right, right. Swapped, mixed, matched. Thx.

There will be a lull in the action while parts ship from AZ. Y'all may move about the cabin and use the rest rooms but please for the love of Dug do not congregate near the pilot's door.

[Milkmansound]

I'm getting a very similar distortion in an amp I'm working on. Spent a few hours today hunting to no avail. Feeling your pain here - just shooting into the dark with no satisfaction. Shooting blanks like Hef.

I am certain that my problem is parasitic and in the preamp because it's a point to point layout. Might try some snubber caps a la '70s Fender just to locate it. You should try that too - there's a reason fender did it and no one says you have to leave them there. At least you'll know which triode to futz with

[xtian]

God bless Canadian iron!!!

I installed a replacement OT (Hammond1750J), and it SOLVED THE PROBLEM!

Sound is loud and glorious. Breaks up beautifully. Nice nice nice. So relieved.

Thanks again, everyone, for your input.

[xtian]

Question: Often, when first starting up, the tremolo does not function. I twiddle some knobs, and in a few seconds or a minute, it starts working normally. Is this a common problem with the neon bulb roach?

[Firestorm]

Question: Often, when first starting up, the tremolo does not function. I twiddle some knobs, and in a few seconds or a minute, it starts working normally. Is this a common problem with the neon bulb roach?

Make sure the 12AT7 is good and strong. This circuit turns of the LFO with raw bias voltage so grounding it out usually kick starts the tube.

Cool that the OT solved it. Have to add to the list of things to try early on.

[Baddog01]

Glad it worked....

[Mant]

Great thread with a happy ending.

[beasleybodyshop]

This made me do a double take! I had the exact same amp on my bench saturday: