Dick Seacup Posted December 14, 2009 Posted December 14, 2009 Recently came across this allegation elsewhere. Not sure if it's true and don't feel like going to track down schematics to compare. Anyone ever hear this? Thoughts?
tulk1 Posted December 14, 2009 Posted December 14, 2009 It uses British "valves" instead of American "tubes". ....... From Wikipedia (Changing History with the flick of a send button) : Many famous amplifier manufacturers, including Marshall and Traynor, based their first batch of amplifiers upon the 5F6A Bassman, in examples such as Marshall's JTM45 (a clone of Bassman, using British-equivalent parts), and Traynor's YBA-1 (Head form of Bassman).
GuitArtMan Posted December 14, 2009 Posted December 14, 2009 I thought that was a pretty common fact. Marshall pretty much made a British version of the bassman using British tubes and 2x12s rather than 4x10s and the JTM-45 was born.
tulk1 Posted December 14, 2009 Posted December 14, 2009 I thought that was a pretty common fact. Marshall pretty much made a British version of the bassman using British tubes and 2x12s rather than 4x10s and the JTM-45 was born. Well, you know Dixie lives a sheltered life.
Dick Seacup Posted December 14, 2009 Author Posted December 14, 2009 I learn something new every day. I knew Marshall had copied a Fender circuit but had no idea which.
slider313 Posted December 14, 2009 Posted December 14, 2009 Actually I believe the first JTM45 was a head with a 4x10 closed back cabinet. As with all circuits, the sum of all parts makes it what it is. Marshall may have copied the circuit but the Drake transformers they used, the Mullard EL34 power tubes and ecc83 preamp tubes and Celestion speakers are a BIG part of the "recipe".
GuitArtMan Posted December 14, 2009 Posted December 14, 2009 Actually I believe the first JTM45 was a head with a 4x10 closed back cabinet. As with all circuits, the sum of all parts makes it what it is. Marshall may have copied the circuit but the Drake transformers they used, the Mullard EL34 power tubes and ecc83 preamp tubes and Celestion speakers are a BIG part of the "recipe". The JTM-45 didn't use el34s, they used KT-66s. The el34s came later with the JMP-50, and then the GZ-34 recifier was phased out in favor of the solid state rectifier.
rjsanders Posted December 14, 2009 Posted December 14, 2009 Ken Fischer discussed this in "the Trainwreck Pages" section that appears in a Gerald Weber book, Tube Amp Talk for the Guitarist and Tech. sum-up: the earliest JTM45 copied the late Tweed Bassman (5F6A) circuit. Ken had seen & serviced many examples of the JTMs and noted different values & makes of electronics used (caps & resistors) 4 significant diffs that make a JTM sound different than a Bassman, even though they have the same circuit: -different transformers -different speakers & cab designs -aluminum chassis -speaker wiring and being in or out of phase with output transformer
gopeteygo Posted December 14, 2009 Posted December 14, 2009 Sell ya my Ceriatone clone if you're interested...........
pegleg32 Posted December 15, 2009 Posted December 15, 2009 Ken Fischer discussed this in "the Trainwreck Pages" section that appears in a Gerald Weber book, Tube Amp Talk for the Guitarist and Tech. Thanks for that tip Jeff, I just ordered the book from Amazon.
slider313 Posted December 15, 2009 Posted December 15, 2009 The JTM-45 didn't use el34s, they used KT-66s. The el34s came later with the JMP-50, and then the GZ-34 recifier was phased out in favor of the solid state rectifier. My mistake. Yes, it used Genelex KT66's. The point I was trying to make is the different parts used make the sum of those parts a completly different sounding amp. IMHO the transformers are a big part of that difference. Look at the new Fender "reissue" Super Reverb, Deluxe Reverb and Princeton Reverb. They don't sound like the originals. Many of the handwired boutique clones don't even sound like the originals.
rjsanders Posted December 15, 2009 Posted December 15, 2009 Thanks for that tip Jeff, I just ordered the book from Amazon. a little pricey, but worth it (IMHO) just for those TW Pages. note: Ken & Gerald had a falling out later on over biz deal. for my part it doesn't invalidate the contents of the book, published when they were good buds. there's also a great interview w/Ken in Dave Hunter's amp book, my current recommended book for non-tech (i.e., me) and techs alike on how amps work and stuff
rjsanders Posted December 15, 2009 Posted December 15, 2009 The JTM-45 didn't use el34s, they used KT-66s. The el34s came later with the JMP-50, and then the GZ-34 recifier was phased out in favor of the solid state rectifier. i b'lieve they started with 5881s. and a friend, who knew the production & engineering guys on the Beano album, thinks those were the tubes in EC's amp...
JeffB Posted December 15, 2009 Posted December 15, 2009 I had the JTM45 RI head. Sold it early this year. Finally understand what sellers remorse is.
iim7v7im7 Posted December 15, 2009 Posted December 15, 2009 As others have said well here... Fender 5F6A circuit design, built by UK hobbiest builders, using UK transformers, UK valves and UK speakers with its chassis turned on its side = JTM-45 This is where Jim Marshall started in 1962. I'm sure that US amps cost a fortune in the UK back then which is what spured him on. :-) Bob
hubberjub Posted December 15, 2009 Posted December 15, 2009 Sell ya my Ceriatone clone if you're interested........... Wait, you have a Ceriatone clone or a Ceriatone? If you had a Ceriatone clone then that means your amp is a clone of a clone of a clone. If it's just a Ceriatone that means it's just a clone of a clone. That's not very interesting. Sorry, it's a slow day at work.
tulk1 Posted December 15, 2009 Posted December 15, 2009 Wait, you have a Ceriatone clone or a Ceriatone? If you had a Ceriatone clone then that means your amp is a clone of a clone of a clone. If it's just a Ceriatone that means it's just a clone of a clone. That's not very interesting. Sorry, it's a slow day at work. I love that song "Bring in the Clones". Great old standard.
Dick Seacup Posted December 15, 2009 Author Posted December 15, 2009 I love that song "Bring in the Clones". Great old standard. I think I know this one: Aren't you rich? Does it have a pair? Don't lift the ground unless you want to lose your hair. Where are the clones? Is it tonal bliss? Would Leo approve? One who keeps chasing the sound One with a tin ear Where are the clones? Send in the clones. Just when I stopped buying amps Finally knowing the one I wanted was yours Playing my leads with the usual flair Sure of my lines Notes that aren't there Does your speaker fart? Builder's fault, I fear. I thought I'd want what you want Sorry, I can't hear. And where are the clones? Send in the clones. Oh, don't bother, they're here. Aren't you rich? I don't think you're queer. Losing my timing, due to my tin ear And where are the clones? There ought to be clones. Well, maybe next year.
tulk1 Posted December 15, 2009 Posted December 15, 2009 I think I know this one: Aren't you rich? Does it have a pair? Don't lift the ground unless you want to lose your hair. Where are the clones? Is it tonal bliss? Would Leo approve? One who keeps chasing the sound One with a tin ear Where are the clones? Send in the clones. Just when I stopped buying amps Finally knowing the one I wanted was yours Playing my leads with the usual flair Sure of my lines Notes that aren't there Does your speaker fart? Builder's fault, I fear. I thought I'd want what you want Sorry, I can't hear. And where are the clones? Send in the clones. Oh, don't bother, they're here. Aren't you rich? I don't think you're queer. Losing my timing, due to my tin ear And where are the clones? There ought to be clones. Well, maybe next year. Thats it!!! I'm impressed. (and just a bit scared that you came up with it that fast!)
GuitArtMan Posted December 15, 2009 Posted December 15, 2009 i b'lieve they started with 5881s. and a friend, who knew the production & engineering guys on the Beano album, thinks those were the tubes in EC's amp... When the JTM-45 RI first came out they had 5881s becuase no one had reissued the KT66 yet. The Marshall heads all cried "foul". Still it's possible Marshall did make some vintage JTM-45s with 5881s, it was the '60s for cryin' out loud! Use what ever parts you have on hand!
big bob Posted December 15, 2009 Posted December 15, 2009 Sell ya my Ceriatone clone if you're interested........... How much... could be fun.
Rude Dog Posted December 19, 2009 Posted December 19, 2009 As far as I know, the bassman is a Western electric circuit; the JTM45 is exactly the same, but different... transformers and speakers speakers and other components make it different...
rjsanders Posted January 21, 2010 Posted January 21, 2010 When the JTM-45 RI first came out they had 5881s becuase no one had reissued the KT66 yet. The Marshall heads all cried "foul". Still it's possible Marshall did make some vintage JTM-45s with 5881s, it was the '60s for cryin' out loud! Use what ever parts you have on hand! way i heard it, the first model 1962s used 5881s until <varies> about mid-1965, then the switch to KT66s, then later on the EL34s (i love 5881s)
212Mavguy Posted January 21, 2010 Posted January 21, 2010 way i heard it, the first model 1962s used 5881s until <varies> about mid-1965, then the switch to KT66s, then later on the EL34s (i love 5881s) +1, I have a Siegmund Midnight Blues Breaker head, Genalex kt66's, just got through playing my Millie through it, gorgeous!
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