Any thoughts on a UL Twin?

[dave////irongater]

It's a beat to crap 1980 model.
From the little bits of info out here (KO'C) & a few others I'm thinking of:

-Tweeding CH 1,
-PPI MV,
-Triode 2 tubes,
-AC level pot replacing the ground SW to control the other pair
-Preset internal resonance/precense feedback arrangement

Thanks for any thoughts!

[dave////irongater]

i guess this should have gone in the mods section..

[Dutch]

Originally Posted by dave////irongater

It's a beat to crap 1980 model.
From the little bits of info out here (KO'C) & a few others I'm thinking of:

-Tweeding CH 1,
-PPI MV,
-Triode 2 tubes,
-AC level pot replacing the ground SW to control the other pair
-Preset internal resonance/precense feedback arrangement

Thanks for any thoughts!

Dave--
Just removing the negative feedback should get you a noticeable improvement in sound.

The post-PI MV would be a pretty good idea, too.

Another idea--if you remove the -FB, try putting the normal channel into the unused other grid of the PI instead of capacitively coupling it to ground, and change both PI plate resistors to 100k. Basically, run it like a Vox AC30 PI. This will put both channels in-phase, and will also eliminate the signal loading problems that usually crop up when mixing a tweedified channel with tonestack last in the circuit with a BF/SF channel with the considerably lower impedance 12AX7 gain stage output.

[dave////irongater]

Dutch, Thanks for replying! I was hoping one of you sharp guys would kick in. What happemed to your old "See Ya"?

[dave////irongater]

Anybody else have any thoughts?

[Dutch]

Originally Posted by dave////irongater

Dutch, Thanks for replying! I was hoping one of you sharp guys would kick in. What happemed to your old "See Ya"?

Dave--
Well, you got *me* instead....

Forgot this last time, so here goes:

C ya,
Dutch

[kg]

i second the suggestion of tossing the NFB loop and run a straight UL final.

[Smitty]

I agree with the suggestions to get rid of the negative feedback. UL provides all you'll ever want.

Although it's a little tricky to do pentode triode switching in a PPP configuration without a big switch, you may want to try removing the jumper and 470 ohm screen resistor from each side of the UL tap going to pin four (V7 to V8 and V9 to V10) and try running one tube on each side in triode mode. Just strap pin four to pin three with a 100 ohm 1/4 watt resistor.

Sort of a cheapo simulclass.