Any actual difference between '59 Bassman and JTM45?

[wasteofo2]

I've heard alot that Marshall just copied the '59 Bassman to make their JTM45. So, does that mean that Marshall literally copied the wiring exactly, and that a 4x12 Bassman and a 4x12 JTM45 with the same tubes and speakers would be the exact same amp with a different label, or does it mean that the JTM45 was closely (or loosely) based on the '59 Bassman, and even with the same tubes and speakers, they'd sound noticably differnet from each other?

Thanks,
Jacob

 

[kmcguitars]

Re: Any actual difference between '59 Bassman and JTM45?

I'd say it's closer to loosly based on the fender design. Some of the parts
where not avilable in the U.K. So Jim Marshall had to cut corners and maybe
even change some values. Most notablaly the English Equilvalant of the
6L6... The good Ole' EL34. But they where look'in under the hood of the
bassman without a doubt to see what made it tick. :13:

 

[jpage]

Re: Any actual difference between '59 Bassman and JTM45?

I'd say it's closer to loosly based on the fender design. Some of the parts
where not avilable in the U.K. So Jim Marshall had to cut corners and maybe
even change some values. Most notablaly the English Equilvalant of the
6L6... The good Ole' EL34. But they where look'in under the hood of the
bassman without a doubt to see what made it tick. :13:

+1 & nice sig!

 

[wasteofo2]

Re: Any actual difference between '59 Bassman and JTM45?

Was it only things like tubes and speakers that were different though, or was it also things in the wiring that wouldn't be as easy to change?

 

[kmcguitars]

Re: Any actual difference between '59 Bassman and JTM45?

Was it only things like tubes and speakers that were different though, or was it also things in the wiring that wouldn't be as easy to change?

You would have to get the schematic's of both and compair!!

 

[mrid]

Re: Any actual difference between '59 Bassman and JTM45?

paging Lewguitar... :laugh2:

 

[Scott_F]

Re: Any actual difference between '59 Bassman and JTM45?

most critical factor with respect to parts that Marshall could or couldn't find.... Transformers.

Trannies make such a HUGE difference in tone in amps. They don't often get their due respect.

 

[STRATDELUXER97]

Re: Any actual difference between '59 Bassman and JTM45?

Marshalls early or original chassis were made from aluminum...Marshall used 16 ohm impedences and the overall phasing of the Marshall was opposite the fender 59 Bassman...Just enough subtle things in the Marshall's design to make it sound different from the Bassman...But yes the JTM 45 was pretty much an exact copy circuit wise of the 59 Bassman 5F6-A circuit you can compare in Tube Amp Book, Dave Funk's Book,and the Doyle Marshall Book...Marshalls were built around the 4x12 cab and was the reason for the 16 ohm impedences for the transformers...6L6 and KT66 were the early tubes used,but later Marshalls opted for the EL34 Euro tubes because of cost..

John

 

[Big Mike Blues]

Re: Any actual difference between '59 Bassman and JTM45?

Jack sockets ( Nylon Cliff Jacks being the standard, unlike the Metal Switchcraft here) Trannys, Tubes, pretty much it IIRC

Plus the 12's instead of 10's and a head, cab setup

 

[wasteofo2]

Re: Any actual difference between '59 Bassman and JTM45?

Hmm, looks like I'll have to figure out what transformers actually do before I can appreciate the 2 amps differences.

 

[Lewguitar]

Re: Any actual difference between '59 Bassman and JTM45?

They are extremely similar! Differant output tubes and differant transformer supplier but that's about it. Also, from what I understand, the JTM-45 plays 180 degrees out of phase compared to the 5F6-A Bassman it is copied from. That means the speakers would go "out" on the Bassman when the speakers would be going "in" on the JTM-45...and vice versa. There's an excellant chapter comparing the two amps in detail in Gerald Weber's book. You should get it. Lew

 

[STRATDELUXER97]

Re: Any actual difference between '59 Bassman and JTM45?

They are extremely similar! Differant output tubes and differant transformer supplier but that's about it. Also, from what I understand, the JTM-45 plays 180 degrees out of phase compared to the 5F6-A Bassman it is copied from. That means the speakers would go "out" on the Bassman when the speakers would be going "in" on the JTM-45...and vice versa. There's an excellant chapter comparing the two amps in detail in Gerald Weber's book. You should get it. Lew

Lew....You didn't read my post on this above I guess buddy...Almost verbatim.... Sorry beat ya to the punch.... :wink: I Love old Marshalls! :dance:

John

 

[Lewguitar]

Re: Any actual difference between '59 Bassman and JTM45?

I did read it but missed the part about phasing...sorry 'bout that! Lew

 

[STRATDELUXER97]

Re: Any actual difference between '59 Bassman and JTM45?

I did read it but missed the part about phasing...sorry 'bout that! Lew

I just beat ya to the post is all buddy...At least we got it covered "together"..Saw Eddie Money yesterday in St Pete Florida...Great concert! It was a free outdoor concert actually...Eddie's guitarist rips! :dance:

John

 

[Lewguitar]

Re: Any actual difference between '59 Bassman and JTM45?

Eddie Money? Wow...haven't heard that name in a while.

I'm out of here...heading up to the divide to do a little (are you ready for this?) SNOWSHOEING!

But first I'll stop at the post office and pickup my new Tube Screamers... :dance: Lew

 

[sonnyblu]

Re: Any actual difference between '59 Bassman and JTM45?

I use a JTM45 RI and a Craig Collins Bassman Clone, both running through
2 X 12 Marshall 1965B cabinets. Both with JJ 6L6 GC's... my JTM45 I would guess is closer to 33 watts or so, the Bassman copy is 45 watts. They both have the beautiful big open sound and airy high end and chime. But the Marshall does (To my ears) have fatter mids... they work great together... I have loved this setup for quite some time. The Bassman stays cleaner and the Marshall dirties up more because I can drive the output section a little. So it's very cool... more recently I have added a 50 Watt Plexi to fatten up the mids even more.

 

[JOLLY]

Re: Any actual difference between '59 Bassman and JTM45?

Far out. A three and a half year old thread has risen from the dead.

 

[sonnyblu]

Re: Any actual difference between '59 Bassman and JTM45?

That is only because I am ISO information... excuse me.