Difference between marshall plexi and JCM800? Please dont laugh :(

[Young Angus]

I cant remember if ive already asked this question, but what are the main differences (valve types, available tones etc.) between a JCM800 and a plexi.

Although i know a bit about the plexi's (not much though), i know next to nothing about a JCM800 only that a lot of 80s dudes that i love used them.

How did the two amps clean sounds compare? and more more more

 

[Gearjoneser]

Reissue's aside, the internal differences are that Plexi's were
wired point to point on a heat resistant board with big components, not the tiny one's you see on printed circuit boards.
Also, the circuit is a bit different, which is too much to go into here.
The Plexi also employed a very large output transformer that was called a laydown transformer ( sideways).

The JCM 800 introduced the grillcloth on the head. The printed circuit board had smaller components, but was pretty close to point to point, since the PC board had big tracers (signal routing)
It is also a master volume head, so it had 2 inputs and a volume
and gain control.

The sound difference, to my ears, is that the plexi is very woody
and glassy sounding, with a huge girth to the sound, but the gain
is the sound of a clean amp being driven into natural tube gain.
The best examples of tone are Hendrix for strat. Early ZZ Top,
Free, and old AC/DC for humbuckers.

The JCM 800 sound is more mid-spikey and metallic with a buzzier sounding gain. The best examples of JCM 800 are Judas Priest,
Kiss, Ozzy, and most 80's metal. Keep in mind, most of the gainiest JCM 800 tones were either modded 800's or had an OD in front, especially for all the solos.

 

[Deadbolt]

There are quite a few 800 models so if you have an idea of what kind of sound your going for might help, or what kind of sound your curous about. The 800's have a different voice then the plexi's i feel still both awesome amps, just a matter of preference.

 

[Maximusgordon 2.0]

The plexis have the most wide open sound you could ever want, if you love the sound of your guitar and just want to hear a loud and awesome, woody sounding version of it plexi is the way to go. The gain is as natural and pure as it comes and can clean up 100%. JCM 800 has more gain and a tighter more modern sound that is ment to be played for high gain stuff and sound focused and clear. Its brighter and is generally better behaved than a plexi. On the high sensitivity input it will never clean up fully and there is a diode generated distortion that is always on, it doesnt sound to great untill the tubes are working a bit, then it really help define the tube's distortion and sounds great.

 

[Young Angus]

Thanks guys.

But what type of tubes are in the 800's? I know the plexis use el34's (at least i think they do), do the 800's use them too? And im just talking about the old 800's which wouldhave been used for peoples sounds like warrant and the darkness's lead tone (which i think is a combo).

 

[Gearjoneser]

The Plexi sound is EL-34 and so is the JCM 800's, but some early 800's had 6550's which were fatter and cleaner sounding.
Those heads can always be rebiased for the EL-34's.

 

[Young Angus]

Cool thanks gearjoneser

I wonder could an ENGL head with 5881 or 6L6 power tubes be re-biased for EL34's?

 

[Deadbolt]

I think the reason why your not completely satisfied with your ENGL is becasue of the fact it has 6l6's. I think your looking for the EL-34 sound. as for rebiasing it and switching it to El's i am unsure.good luck.

 

[Steve_R]

The 6550 and EL34 tubes have the same base configuration. I did the Torres conversion mod on my 2204 and it only involves 1 bias resistor.
It is more involved to convert from 6l6s to EL34s.

 

[JammerMatt]

The sound difference, to my ears, is that the plexi is very woody
and glassy sounding, with a huge girth to the sound, but the gain
is the sound of a clean amp being driven into natural tube gain.
The best examples of tone are Hendrix for strat. Early ZZ Top,
Free, and old AC/DC for humbuckers.

The JCM 800 sound is more mid-spikey and metallic with a buzzier sounding gain. The best examples of JCM 800 are Judas Priest,
Kiss, Ozzy, and most 80's metal. Keep in mind, most of the gainiest JCM 800 tones were either modded 800's or had an OD in front, especially for all the solos. [/B]

A-ha!! My Line6 seems to do a pretty good version (to my ears) of the JCM800. However, it never quite seems "gainy", or fluid enough without hitting the onboard distortion, or using the TS-9 in front of it. Now I know.

Thanks for the info Joneser.

 

[Young Angus]

I think the reason why your not completely satisfied with your ENGL is becasue of the fact it has 6l6's. I think your looking for the EL-34 sound. as for rebiasing it and switching it to El's i am unsure.good luck.

Just to clear this up my amp has KT88's, not 6L6's.

Do KT88's have the same base whatever as 6550's, and hence EL34's? Or are they bigger or different or something?