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Posted: Tue Nov 03, 2020 11:11 am
by BearBoy
Marshall themselves seem to think the Bassman inspired them...
Marshall wrote:HISTORY OF THE JTM45
We made it over 50 years ago and it's so good that we're still making it today.
Posted: 21 November 2019
It’s the amp that started it all, the Jim Terry Marshall 45, more commonly known as the JTM 45. But rewind to 1962 and the amps available in the UK just weren’t cutting it for the grit driven rockers of the time. The most popular amps of the time were imported from overseas and often took a long time to get to the players, which left a gap in the market. Marshall decided to try and fill the gap and along came the first ever JTM 45.
SO WHAT HAPPENED?
The original amp was based on the Fender Bassman, the favourite amp of Terry Marshall at the time. Like the Bassman early versions of the JTM used 6L6 or US 5881 valves in the output stage, later models were upgraded to the KT66, EL34, or KT88 valves. The Marshall team didn’t just change the valves though, there were some more significant differences including the all-aluminium chassis, a 12AX7 valve as the first in the chain, and a modified negative feedback circuit which affected the harmonics produced by the amplifier.
Marshall wesbite LANK
Posted: Tue Nov 03, 2020 11:20 am
by Doog
BUT IT NEEDS TO BE THAT EXACT SPECIFIC MODEL NUMBER, OR NONE OF THIS IS RELEVANT AT ALL
Posted: Tue Nov 03, 2020 11:47 am
by Mike
NickD wrote:Mike's too modest to say it, but you are kinda teaching your grandmother to suck eggs there.
or I sort of don't really care, like.
I may have been wrong about the circuit, but believe it or not I'm not really actually fussed I made that mistake. It was the Bassman I meant, and I'm sort of inclined to believe that Thom's amp isn't wildly dissimilar in an Apples/Oranges kind of way, but again - really not actually fussed.
Whatever floats your boat, Fakir.
Posted: Tue Nov 03, 2020 1:01 pm
by benecol
I'm still reeling from someone pushing Thom, possibly the nicest person on shortscale, to the point of telling them to fuck off.
Posted: Tue Nov 03, 2020 1:11 pm
by Thom
benecol wrote:I'm still reeling from someone pushing Thom, possibly the nicest person on shortscale, to the point of telling them to fuck off.
<3
Posted: Tue Nov 03, 2020 1:30 pm
by Fakir Mustache
Mike wrote:NickD wrote:Mike's too modest to say it, but you are kinda teaching your grandmother to suck eggs there.
or I sort of don't really care, like.
I may have been wrong about the circuit, but believe it or not I'm not really actually fussed I made that mistake. It was the Bassman I meant, and I'm sort of inclined to believe that Thom's amp isn't wildly dissimilar in an Apples/Oranges kind of way, but again - really not actually fussed.
Whatever floats your boat, Fakir.
I wasn't really trying to piss you off or anything, or care if I'm wrong myself.
But in any case, I do believe moving the cathode follower tone stack from the last triode of the preamp to the very first triode and connected to the plate moves it into a completely different typology, and there's also that common stage before the cathode follower on the 50s amps that is different.
The 1.5K cathode resistors and cathode bypass caps are also pretty different, that wouldn't make them another typology though.
Also, I never used vulgar language against anyone in this thread, other people have done so against me.
I also assumed basic technical knowledge was common knowledge on here, I'm sorry. I should have gotten a clue from the 50,000 threads about people with "conversion" necks that have the same number of frets up to the heel and complain that they won't properly intonate.
Posted: Tue Nov 03, 2020 1:44 pm
by NickD
I don't know, maybe don't be contrary and snarky for the sake of it.
Posted: Tue Nov 03, 2020 1:48 pm
by plopswagon
Didn’t Leo just copy his first circuits from the RCA handbook?
Posted: Tue Nov 03, 2020 2:18 pm
by sunshiner
Tweed amps to my knowledge were cathode biased. Better response to picking dynamics, had "more natural" and early breakup, but overall got mushy when fully cranked. Such type of running power tubes produces relatively low output. Blackface/silverface amps are fixed bias. Overall much cleaner and tighter sound, but has "less of a mojo". Also more powerful. Deluxe Reverb's plate voltage is somewhere around 400V which allows to squeeze 22W out of a pair 6V6s. Leo picked this solution to make amps have high clean stage volume
First Marshals were tweed bassman clones with British tubes afaik. Fixed bias amps are your "classic Fender cleans" . Tweed amps are beloved by Neil Young, Clapton, Bonamassa, etc. Bonamassa probably has one of the biggest collections of tweed amps
Posted: Tue Nov 03, 2020 2:28 pm
by Doog
Fakir Mustache wrote:Also, I never used vulgar language against anyone in this thread, other people have done so against me.
I also assumed basic technical knowledge was common knowledge on here, I'm sorry. I should have gotten a clue from the 50,000 threads about people with "conversion" necks that have the same number of frets up to the heel and complain that they won't properly intonate.
Good thing you didn't use any curse words, just opting for being sneery and unpleasant. Everyone knows
those are the two best vehicles for spreading knowledge and personal growth!
Posted: Tue Nov 03, 2020 2:57 pm
by NickD
sunshiner wrote:
First Marshals were tweed bassman clones with British tubes afaik. Fixed bias amps are your "classic Fender cleans" . Tweed amps are beloved by Neil Young, Clapton, Bonamassa, etc. Bonamassa probably has one of the biggest collections of tweed amps
Aye, Bonamassa switched from Marshalls, Silver Jubilees IIRC. Bonamassa gets some stick but he's just a gearhead like us. The only 'rock star' I've seen post on forums too.
Posted: Tue Nov 03, 2020 3:01 pm
by Bacchus
NickD wrote:Bonamassa gets some stick but he's just a gearhead like us.
Except he's shite at guitar.
NickD wrote:The only 'rock star' I've seen post on forums too.
What about Freddy?
Posted: Tue Nov 03, 2020 3:19 pm
by sunshiner
NickD wrote:
Aye, Bonamassa switched from Marshalls, Silver Jubilees IIRC. Bonamassa gets some stick but he's just a gearhead like us. The only 'rock star' I've seen post on forums too.
Bonamassa has almost encyclopedic knowledge on everything from early electric blues and 50s rocknroll to the 60s rock including the gear and is deeply reverend to all of that. He's very humble, hardworking (gigs more than anyone else) and besides from his band that he tours with he always tries to bring other often not well known to the general public names to the spotlight. He grew up in a family of a guitar store owner and spent all his childhood going on guitar safaries all over the North East USA. Even that early he probably saw and played all the golden era guitars and amps
Posted: Tue Nov 03, 2020 3:21 pm
by NickD
Bacchus wrote:NickD wrote:Bonamassa gets some stick but he's just a gearhead like us.
Except he's shite at guitar.
NickD wrote:The only 'rock star' I've seen post on forums too.
What about Freddy?
I’m shite at guitar too!
If Freddy is a rock star then we might have to include Plops - although he was just the bass player...
Posted: Tue Nov 03, 2020 3:28 pm
by plopswagon
^ and my bass playing never made the Wall Street Journal.
Posted: Tue Nov 03, 2020 4:04 pm
by NickS
plopswagon wrote:Didn’t Leo just copy his first circuits from the RCA handbook?
OT, back in the day I did get the application note on how to make a 400W power amp using KT88s but couldn't afford the transformers. WEM's 100W transistor amps power stages were straight out of the handbook , though later models included some over-current protection that wasn't in the app note.