JM Trainwreck Express - Control Settings

[Littlewyan]

Whilst looking at the Trainwreck Facebook page I went through photos of the new Express builds and noticed the controls were set in a certain way for the photos. I wondered if these were the settings that JM preferred with these Express builds and thought I'd try them on my own Express. So I set my Express with the same settings (there is no bright switch on these builds so I left mine off) and found the tone was very similar to the tone I get with all knobs at noon with the bright switch on the 500pF setting.

Try it yourself

[Colossal]

I wonder if the 500p bright cap is just wired full time. Without it, the amp loses something special. It's still cool without, but the added presence/3D thing the 500p is a must (for me anyway). Lot less headache than wiring the switch too.

[Littlewyan]

If you look at the settings though the Treble is turned up full or just below full. So no need for a bright cap . It works pretty well I have to say so I'm going to try it at next practice. Sounded alright at home. I know what you mean about the bright cap though. I'm surprised Glen's Stancor OT Amp doesn't need it turned on!

[M Fowler]

I personally never use a bright cap with an Express I've built and I've used lots of different PT/OT brands.

I prefer no bright switch and no presence pot, instead a high cut pot. But that's modding not trying to tune an Express to taste I guess.

Mark

[RJ Guitars]

I've had a few conversations with JM and he actually has bought some of my NOS parts... kinda funny in it's own way. Anyway, he is a great guy to talk to and he is a lot like the rest of us in looking to build really cool amps using the info provided by Ken Fischer (admittedly he has way better access than we do to Ken's notes and history). I'm not sure what JM does but for myself I do tend to "pose" the knobs for my photo shoots... I have this weird thing about setting things to have symmetry, or in some cases I overcome that with an attempt to make the settings look "realistic" which is probably not ideal sonically. Not sure if JM has this weirdness but it's a thought.

I had a client that cloned his own original Liverpool using my parts package and he said something that was interesting as he gave me the final report on his clone. He said that he had photographed the exact locations of all his knobs on the original Wreck at a point where he felt tone Nirvana lived. When he finished the new amp he said those same knob settings proved to be ideal in the new amp as well. I didn't have access to the original pots to measure them individually but it did help me believe that the PEC pots I furnished must have been pretty close in taper and value to the originals.

Al that to say, maybe there is a somewhat repeatable sweet spot that is common to any given Wreck circuit.

[Littlewyan]

Thanks for the info RJ thats quite interesting. I just assumed JM might have shown the settings he thought was best as they vary slightly between amps. Then again I could be reading into it a bit much!

I found the pot taper on my Express to be ok in that everything at 12 with the bright switch on 500pf is best for me and the taper is pretty good for what I want. They're alpha pots. Its not a slow taper but it works ok.

[2tone]

Interesting to hear the use of the 500 pf bright cap in Expresses or Liverpools. With strats and teles, I never ever could employ the bright switch in any of my Expresses or Liverpools. Only with a darker humbucker, but otherwise I wouldn't ever use them..But I never ran the volume pots much over 2 oclock..

[redshark]

2tone, I totally agree with you. I don't see any use for the bright switch unless you have a guitar with high gain buckers. Pickups like Duncan JB's or Di Marzio super distortion is the reason for that bright switch to exist. those pickups were popular in the 80's when most of the trainwrecks were built.
Any vintage stype pickup strat, tele, P-90's or even old stype PAF buckers don't need the bright switch on.
Those express amps in the pics built by JM are 80 watt express amps, I think with 4 EL-34's and no bright switch IIRC.

[redshark]

RJ, I think you're correct about the PEC pots. Not long ago I had a chance to compare my rocket amp to a real one and with controls set identical the amps behaved same way considering gain levels.
Only diference was that the real one sounded bigger. Hard to explain with words. Maybe the diference was in the output transformer. Or, I didn't try but maybe the bass control turned up a bit in my amp could compensate, who knows!!!