Bright caps on EXP volume pot

[rooster]

Well, I'm not Allyn but I can tell you that you have done it the way I prefer - and the way this post suggests to do it.

You made a lot of very neat and intricate bends to the caps. FWIW, on my EXP the caps are attached more closer to the pot, with the longer leads trailing out to the switch. Others on this post have addressed this as well - shortening the end leads - but its hard to say whether it makes a sonic difference. I definitely think placing the caps on the non-wiper lug of the pot is the main thing.

[fzfwyv]

Just tried this in my new Liverpool and the noise is reduced. Nice find!

-Rich

[rooster]

Yeah, on this note, I noticed that Ron Worley upgraded the Express Build PDF to cover the Kelly bright switch layout - which is what this is - over the original PDF which was Francesca. .......Not a lot of fanfare when he did it, but he at least did it. Hopefully all who ran with the Francesca Build PDF will notice this and make the change.

[Ron Worley]

OK, I'm confused here.....

Rooster, I did not see your post after I returned from Europe... sorry bro....

I looked at the old shitty Ceriatone layout, my new layout, the pictures of Francesca- and they're all the same:
the tied leads of the caps go to the wiper (middle) lug, and the center lug of the brite switch goes to the right most lug closest to the treble pot.

See the Franny pic attached- this is how I have built 2 Express amps and it matches all the documentation I have...

I do see the "undocumented Express" has it the other way round... WTFO???

Somebody clue me in here.... Ken did do some things wrong- on Franny, he does not keep the heater wire polarity constant for some reason....

Ron

[geetarpicker]

The filament wiring isn't all the same polarity in my '89 original either, V1 is wired out of phase with the others. Also, the bright switch in my Express is wired like that "undocumented" Express in the pic section, and NOT like Francesca. Mine has the center terminal of the switch running to the center terminal of the volume pot, and the caps tied together and run to the last pot lug, and the 1st lug grounded. Mine also has a 50pf/500pf cap selection (not 100/500) though I always runs the 500pf position.

I don't know if the polarity inversion helps the S/N or if it was a mistake. I think I recall other originals being different than mine but still not all in phase filament wise.

Ken did make mistakes though, he wasn't well a good part of his building years. On my original he had run the screen voltage lead to the wrong end of the 1ks on the output tubes (pins 4 instead of 6), rendering the resistors not in the circuit. It did sound good. However I pointed that out to Ken years later and he said that was a mistake and that I should move the wires as it would be easier on tubes.

Folks have commented they liked the results of the later bright switch wiring, both tonally and for better S/N. I always said I liked the 500pf position (albiet if the volume is 1/2 or more) and folks didn't really "get it" until they tried it that way. Sorry Ron if you hadn't heard of this later model TW "revision"!

[Ron Worley]

No, I hadn't heard of this difference, must have missed it due to work, etc. thanks Glen for clearing that up.

Regarding the heater wiring, perhaps Ken had some sort of reason for the crossed polarity, but I know from my Fender repair work and all that I've read that the conventional theory is to have consistent polarity across all the heaters to keep the hum down. But we all know that Ken was not conventional in many respects, therein lies the genius....

Is it also fair to say that this mod would also apply to the Liverpool as well as they have an identical preamp section???

I just did the wiring on the brite switch on my Liverpool build last night.... before I read this That's a lot of tedious rework I now have to do...

Bugger....

Ron

[fzfwyv]

This does apply to the Liverpool. I've talked a bit about my new build in a thread I started, and among other things, the 500pf bright position is totally usable in my Liverpool. My previous 2 builds it was out of the question.

So....something went right with this build, and with the "new" wiring of the bright switch, I di notice a difference witht he noise level reduced.

-Rich

[rawnster]

Tonight, I swapped out the leads on the bright switch, running the cap leads to the far tab, and running the middle connection of the bright switch to the middle tab on the pot. This change did not increase nor decrease the amp's hiss. No change at all. Bummer. I thought something cool was discovered in lowering the express's inherent hiss characteristic.

Oh well, back to ordering metal film resistors.

[rawnster]

One thing I forgot to mention was that while the wire swapping didn't lower any noise, it did make the bright switch more musical sounding. In particular was the 500pf cap. Before it was way too strident and harsh. Now it's still bright, of course, but lots of the edge has been removed. Very cool.


Anyway........