Dropping resistor values on Allens

[62Tele]

Having the dropping resistors on my Allen Accomplice changed to blackface values today (ie from 10k to 1/4.7K) and adding a 10pf cap on the reverb. Also have an Allen Brown Sugar and considering doing the same - has the same 10K dropping resistors after the filter caps. Any reason why this would not work to increase the headroom and "Fenderize" the reverb on the Brown Sugar circuit the same as it does on the Accomplice?

The schematics look like the amps are pretty similar with some pre-amp and cathode bias differences, just wanted to see if there was any reason not to do this one the Brown one. Of course I'll get my tech's opinion as well, just wanted to see what folks here know.

Thanks

[ecm1117]

Sorry that I don't have an answer for you, but once you complete these mods, I'm very interested in your thoughts about how they affect your amp. I also have an Accomplice and was considering doing the same thing.

[62Tele]

No problem. My tech is looking through schematics now to be sure the mod is safe (ie downstream resistors are appropriate for the voltages etc). I'll try to drop you a note when this is done.

[topbrent]

Those mods will work great on the brown sugar as well.

The only other mod that you may consider, down the road, is to simulate the 50k load loss of the opto-roach trem that blackface amps have.

[62Tele]

Thanks topbrent, I thought I might hear from you.

Both amps are ending up in 1x12 combo cabs and one of 'em will get my Fane alnico (both amps sound great through it). only decision left is what speaker goes in the other. Got any fav's with these amps? FWIW, I didn't bond with the RWB, but I could see a loud and clean speaker of some type working well in the Accomplice. I was thinking EV, but they're just too heavy. Anything you like?

[ecm1117]

Looking forward to your report!

Re: speakers, I got my Accomplice with a Celestion G12H-80, which was a decent all-around speaker. I then briefly tried a Weber Michigan (w/ paper dome) and felt it was too dark. I now have an Emminence Tonker in it and I love it. I needed the amp to be very loud and with a big clean sound; I got what I wanted. The only downside to the Tonker is that it can be fizzy with distortion, especially at lower volumes.

[62Tele]

ecm1117/topbrent,

My amp tech got tied up until after Christmas, but I have the following from David which sounds very sensible;

You might try changing the first resistor to a 1K 3W. The second needs to remain at 10K as it feeds the preamp tubes. It is sort of like the Fender 4.7K but doesn't have as many tubes drawing current from it (no normal channel preamp tube or vibrato tube) so the 10K is what you want in there.

I had a preamp voltage switch on my Old Flames for a while that switched that first resistor from 10K to 1K. It was a subtle change at best and most wondered what the switch did. I dropped it from the latest model.

You might try a lower gain preamp tube for V1 and even a 12AT7 for V4, the phase inverter. That might get you a more noticeable improvement than changing a resistor.

You might also try a plug-in solid-state rectifier with 6L6s. It will tighten up the bottom end and make you think you have a more powerful amp with more clean headroom.

You could try the preamp tube changes or the 1K resistor on either the Accomplice or the Brown Sugar. Keep the bass set fairly low for maximum headroom.

David

I'll probably change out the first dropping resistor on both amps, add the cap on the reverbs and try a solid state rectifier on the Accomplice (David added that the Brown Sugar should NOT have a SS rectifier). Of course tube swaps on both are easy. I might alos change out the OT on the Brown Sugar to the 40 watt version - I typically prefer bigger OT's.

I'm still on the fence about speakers. I didn't dig the RWB for the same distortion issues you're mentioning. Both of my Allens love the Fane. Just curious what else might give me a different flavor and add to the mix.

[topbrent]

Good advice on the part of D.A.

I like using a 12at7 in V4 (PI), as it sounds more fendery...

I also like using a 12at7 in V2, as it helps the reverb sound more...fendery...

A 12AY7 in V1 will clean up the front end nicely too..

Easy swaps to test.

[ecm1117]

Any updates on the mods?

[jaydub69]

Good advice on the part of D.A.

I like using a 12at7 in V4 (PI), as it sounds more fendery...

I also like using a 12at7 in V2, as it helps the reverb sound more...fendery...

A 12AY7 in V1 will clean up the front end nicely too..

Easy swaps to test.

Did you try any or all of this?

I would love to affect my ever trailing reverb somehow.

-john

[TweeDLX]

Did you try any or all of this?

I would love to affect my ever trailing reverb somehow.

-john
A lot of people get a different reverb tank to tame that. Standard Fender-type Accutronics 2 spring. In my Accomplice, I tried a number of different speakers: Eminence Texas Heat (pretty good); 1961 Jensen P12N (great tone, but broke up too soon for me); Celestion G12M (too flabby); G12H30 (nice); Vintage 30 (too bright); G12H80 (very nice, but too much top end); and settled on the R,W & B as the best sounding overall. I reduced cathode bypass cap values to 4.7uf and re-did the "Raw" control as a standard mid pot. I also used 12AT7's in the reverb and PI slots. Do I care that it doesn't sound like a BF Fender? No way! It's a sweet amp.

Mike

[Lanesplitter]

I don't have an Allen amp, but my latest build uses his chassis, transformers, and reverb tank. I agree that the 3-spring reverb is a little too much. Almost delay-like. Can it be tamed with a little low-pass filtering, or should I just buy a 2-spring tank?