Marshall JCM800

[kevster]

Hey all,

I just brought home a JCM800 head that my worship leader was given as a permanent loan. The amp is supposed to be functional, but with some "issues"... I don't know as I haven't even powered it up yet, and it'll likely be the weekend before I do, but I'm told it has the following issues:

Noisy pots
Picks up interference or other signals regularly
Channel switching is "noisy"
The 4 x 10 Peavey 5150 cab it's paired with is supposed to be a thin sounding piece of crap. (Not my words)

I get the frame of reference for this crowd here, so I wanted to ask your opinions about this amp and cab. Both the technical and the subjective tonal opinion of the gear.

Is this amp anything good when it's right? Marshall is kind of "out of vogue" with a lot of contemporary players. If it is too 70's or 80's Marshall cliche, we might not be able to use it too much. I'd still get it working right, but we'd probably use it as a back up.

Anything listed that sounds familiar with this amp/cab?

Anything jump out as being obvious problems to head for first?

The amp spent its time in an air conditioning equipment room which was also held the isolation cabinets for the amps. Having taken off the back of this amp, I see some surface corrosion on the chassis and surface rust on the outer edges of the transformers... I already know it will take a thorough going through to make sure the jacks and pots are clean and protected.

TIA everyone.

[jestaudio]

Got to say i lovethe old Marshall stuff, i,ve used the jcm for recording on a number of occasions for rock blues and jazz, for the slightly overdiven lead sound i personally don't belive it can be beaten, cant comment abot the speakers as every marshall rig i,ve used has celestions, usually v30,s which is my prefered speaker but on the other hand i have ised peavey speakers in a live context and found them to be pretty good, normally 2x12s or single 12s

[martin manning]

JCM800 refers to a number of amp models of 1980's vintage. Which one is this?

[kevster]

JCM800 refers to a number of amp models of 1980's vintage. Which one is this?

2205.

[Reeltarded]

Just clean it and roll some tubes through there first. Out of vogue? No way. It's the second best Marshall sound.

G-12-75s

It's a metal amp.

At gain settings less than 7 and master less than 5 it's brutally unmagical.

The tone controls do almost nothing.

[kevster]

Just clean it and roll some tubes through there first. Out of vogue? No way. It's the second best Marshall sound.

G-12-75s

It's a metal amp.

At gain settings less than 7 and master less than 5 it's brutally unmagical.

The tone controls do almost nothing.

I'm not saying there's no market for it, it's just that the current P & W guitar tones are distinctly non-Marshall tones.

The amps supposedly worked, so I'll check and see what the tubes are really like. If they aren't too bad, I'll go ahead and leave them for now. I'll just tell the church to pick them up at a later date.

You mention something REALLY SIGNIFICANT, the VOLUME. If it has to be 7+ and 5+, it probably will not isolate well... That could be a deal breaker for using it in church. I thought about finding a good 1 x 12 to pair it up with. I know that the stack or half stack is the norm for this type of amp, but we don't need to move that much air.

Thanks!!!

[labb]

Sounds like a prime candidate for a VVR mod. Hall amplification sells one for a 50 watt amp for $30. Or you can build one for about $10.

[Colossal]

The JCM800 is a fantastic platform for modding and some of the most insane hot-rodded Marshall tones can be had using the 2203/2204 foundation. I personally love the Marshall sound. I dialed a buddy's in and it is an amazing amp, truly glorious tone when they are set up right.

As for volume, there is no doubt that any Marshall sounds best cranked, that is what they do and are for, and I'm sure God Himself would smile and say It Is Good. Your amp will probably sound great with a 1x12 with an EV but I sure don't typically equate JCM800 and Church in the same sentence

[jaysg]

It's a good platform. I wouldn't say that P&W is a JCM800 free-zone.

[Cliff Schecht]

The JCM800 is a fantastic platform for modding and some of the most insane hot-rodded Marshall tones can be had using the 2203/2204 foundation. I personally love the Marshall sound. I dialed a buddy's in and it is an amazing amp, truly glorious tone when they are set up right.

As for volume, there is no doubt that any Marshall sounds best cranked, that is what they do and are for, and I'm sure God Himself would smile and say It Is Good. Your amp will probably sound great with a 1x12 with an EV but I sure don't typically equate JCM800 and Church in the same sentence

What did you do to your buddy's amp? I'm building a 100W Marshall (2203) in about a month or so..

[Gibsonman63]

I traded mine and now regret it. I still have my JCM800 4210, which is a 1x12 combo of the same amp, minus presence control. The clean channel sounds really good cranked. It's actually only semi-clean, but seems to have the right balance of clean and dirt for some tasty blues. The other channel is pure rock and roll.

Great sounding rock amp IMO. There were two versions of this amp. The early 80's amps had a different channel switching scheme and suffered from channel bleed. The IC chip version is the later one. There are quite a few threads on the Music Electronics Forum about these amps and they have some discussion of fixing the channel bleed.

Get it working correctly before you mod. Try to resist the urge to drill holes in it.

The noisy pots could be leaking capacitors. It was on mine. Check for DC voltage and trace the schematic upstream from there.

[gldtp99]

What did you do to your buddy's amp? I'm building a 100W Marshall (2203) in about a month or so..

I recently built up a 50 watt Splawn Quickrod-based lead channel head---It's pretty impressive sounding---- i've been working with many versions of modded Marshall JCM 800 circuits for the past two yrs and this one is far superior to all the others---everybody who plays it loves it from the first note.
I'll be using this as a Lead circuit in some future channel switcher 150 watt heads.
Stop over to my shop and try it out and see if you like it--- i have the schematic and i'll show you the changes i made in this particular head---there are some other modded JCM 800 circuit amps there, too................gldtp99

[Colossal]

What did you do to your buddy's amp? I'm building a 100W Marshall (2203) in about a month or so..

Installed some new pots, replaced the grid leaks for the output section to spec (some genius had the wrong values in there), replaced some drifted parts and leaky caps, etc.

[M Fowler]

I built a JCM800 2204 and have gigged with that amp doing early rock-N-roll, soft rock and country variety music.

The Marshall can be used for more than just long hair music folks.

Mark

[Reeltarded]

Mark, you need to get a long blonde wig, and we can put together a Nelsons Brothers thing..

Sincerely,

Matthew

PS I think I am the one on the left.

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