Marshall tone question-JTM45 vs. 1986 bass plexi circuit

sweetpea

Silver Supporting Member
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932
I was just wondering what the tonal differences are between these two circuits. Thanks for any information in advance.
 

908SSP

Member
Messages
5,796
They are close. The JTM has a tube rectifier and KT66 tubes the Plexi has SS rectifier and EL34 tubes. Of course they use different transformers. I have both I like both. The JTM is a bit smoother softer sweeter, the JMP has more bunch and more crunch more mids.
 

Fireball XL5

Gold Supporting Member
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3,098
I own a Marshall 1986 Bass (EL34's, ss rect.) and have owned a Germino Classic 45 JTM 45 (KT66, tube rect.) that I can compare.

At low volumes the JTM 45 has a glassy clean tone with chimey highs, a slightly scooped midrange, and big bass. Very 3D and open sounding with good headroom for it's moderate wattage. When pushed into overdrive the amp delivers a fat blues rock crunch that is a bit less focused and not as tight as the solid state rectified Bass head. It can sound mean, but I'd classify it's overdrive to be more on the bluesy side of the fence.

In contrast the 1986 Bass is much louder and a more aggressive amp. At low volume the clean - while not as 3D and as open as the JTM 45 - has a cool bell-like quality with more midrange energy. When pushed the amp gets all the crunch, balls and overdrive of the Lead model, but has a somewhat rounder tone and a softer top end. More aggresive, tighter and not as bluesy sounding as the JTM 45, my 1986 Bass head will do that AC/DC "clean but mean" "kerraaangg" tone in spades.

Both are GREAT amps IMO. :AOK
 

sweetpea

Silver Supporting Member
Messages
932
Thanks so much for the great comparison. Does the 1986 circuit have some chime also when playing clean and how is the headroom?
 

Fireball XL5

Gold Supporting Member
Messages
3,098
Thanks so much for the great comparison. Does the 1986 circuit have some chime also when playing clean and how is the headroom?

The 1986 does not have the same glassy sparkle in the highs like the JTM 45, but it is still a great clean tone IMO - just different - with good headroom. It's a more aggressive sounding clean with more mids rather than a chimey clean.
 

908SSP

Member
Messages
5,796
68 responds great to a treble booster too. And a lot depends on the speakers as to what you actually hear.

But if you're referring to some cheap Ceriatone then all bets are off. I am talking about the real thing.
 




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