Marshall JCM800

[M Fowler]

What the one on the right isn't wearing a USMC patch the dirt-ball!

[Zippy]

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

http://www.robbenfordguitardojo.com/dojoFaves.html

"I've been using an amp on some of the songs for the McDonald sessions belonging to our engineer/drummer Shannon that I hope to find for myself: it's a Marshall limited addition JCM45. Great tone, breaks up in a sweet way but can give you a beautiful clean sound as well if you don't hit it too hard. Apparently only three hundred were made. I'm playing it thru a 4x10 Marshall cab that's working well. Not sure what speakers are in there but they may not be stock. If you find one, congratulations! Great recording amp..."

Don't tell the Dumble forum.

[azatplayer]

I had an 83' 2204, its the ONLY amp i regret selling, was killer.
They actually have some great big bold cleans before they get down and dirty.

AND why should the devil get all the good amps anyways!!!

[Structo]

I believe that Stevie Ray Vaughn used Marshall amps for his clean tone early on and used the famed Vibrolux for his distortion.

I think most people just associate that hard rock sizzle tone to Marshalls.

Another point is that I have read that AC DC's tone is mostly clean, just louder than crap.

[kevster]

If this thing fires up and really sounds good (after any maintenance), it will get used. We won't use a "stereotypical" Marshall, but if this is as versatile as has been discussed here, it'll be fine.

As long as we can isolate the beast.

I'm planning on starting this on Saturday. I don't know how involved a project it'll be with this amp....

[Gaz]

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

http://www.robbenfordguitardojo.com/dojoFaves.html

"I've been using an amp on some of the songs for the McDonald sessions belonging to our engineer/drummer Shannon that I hope to find for myself: it's a Marshall limited addition JCM45. Great tone, breaks up in a sweet way but can give you a beautiful clean sound as well if you don't hit it too hard. Apparently only three hundred were made. I'm playing it thru a 4x10 Marshall cab that's working well. Not sure what speakers are in there but they may not be stock. If you find one, congratulations! Great recording amp..."

Don't tell the Dumble forum.

Did he mean JTM 45? can't find a lick of info on any limited edition JCM45.

[Gaz]

Okay, I think he's talking about a a special offset JTM45 reissue...guitarists

[kevster]

Well back to the JCM800. I got together 10 minutes in row so I plugged up and ran it through a few paces with my LP and a cord.

It was exactly what I suspected in some ways and not in others. Here are some issues I found:

1. The reverb knob is only for decoration, it does NOTHING. (???)

2. It is a Marshall through and through. It gives you THAT sound in spades. In less than 30 seconds I was playing Pearl Jam's Alive and it was EXACTLY their tone. I backed off and tried some other things, but it has a sweet spot of 8+ gain.

3. It's a very articulate amp. Pick attack is not very forgiving on this. That is good when you are used to it... I'm not so used to a sensitive amp right now, so I PAID ATTENTION.

4. This thing has a very common (I've heard it before in Marshalls) hiss... The static is constant, and proportional to changes in either or both volume/gain. I'm thinking we've got some cap issues to address.

5. I tried every pot, and none of them that are working are crackling or popping.... One less thing to have to troubleshoot.

It says it has a 50W output... (Duh, 2205 vs. 2210... Hey, I never worried about Marshall models...) I was thinking it'd be a 100w head, as I was told. I'll have it all open and exposed soon enough...

Anything sound like a good place to start?... Obviously, I'm going to walk through to clean everything and do a visual, but this can't be all that uncommon with these beasts. I had it with my old Valvestate too, but I never serviced that myself.

Anyone?

[kevster]

Well back to the JCM800. I got together 10 minutes in row so I plugged up and ran it through a few paces with my LP and a cord.

It was exactly what I suspected in some ways and not in others. Here are some issues I found:

1. The reverb knob is only for decoration, it does NOTHING. (???)

2. It is a Marshall through and through. It gives you THAT sound in spades. In less than 30 seconds I was playing Pearl Jam's Alive and it was EXACTLY their tone. I backed off and tried some other things, but it has a sweet spot of 8+ gain.

3. It's a very articulate amp. Pick attack is not very forgiving on this. That is good when you are used to it... I'm not so used to a sensitive amp right now, so I PAID ATTENTION.

4. This thing has a very common (I've heard it before in Marshalls) hiss... The static is constant, and proportional to changes in either or both volume/gain. I'm thinking we've got some cap issues to address.

5. I tried every pot, and none of them that are working are crackling or popping.... One less thing to have to troubleshoot.

It says it has a 50W output... (Duh, 2205 vs. 2210... Hey, I never worried about Marshall models...) I was thinking it'd be a 100w head, as I was told. I'll have it all open and exposed soon enough...

Anything sound like a good place to start?... Obviously, I'm going to walk through to clean everything and do a visual, but this can't be all that uncommon with these beasts. I had it with my old Valvestate too, but I never serviced that myself.

Anyone?

OK, the whole list of issues is is down to one. Two things I found.

1. The guy who had it last had it impedence mismatched... The Peavey 5150 4 x 10 it's paired with is a 16 ohm cab, they had it set on 4 ohm...

2. The reverb works great with a good footswitch. The footswitch is the same as another one I had around here, so I tried the other and it worked fine.

I stuck my pedal board in front of it and it'll do fine. This is not going to be the "lead player's" amp. This is going to be 2nd electric whihc does layers, intros, rhythm, etc.

I really like the amp with my EQ in front. A good tone, a great "light fuzz OD" when you can dial it in, and very good volume control. I can have this at living room volume and it still does ok. The gain pot is really sensitive right in that sweet spot between clean and truly overdriven.. It's still a great amp. It's not a D-style, but that's a subjective thing.

So, I'm going to start cleaning this thing up... Anybody want to float what they think is causing the hiss? It is more volume sensitive than gain sensitive. It does not change with tone shaping. It does not change with reverb adjustment.... It is constant until I put it on standby.... Chopstick test of the tube covers revealed no microphonic tubes...

Anyone?

[Reeltarded]

Hiss? Hisstorectomy.

Don't tell any chicks I said that.

[bcmatt]

The gain pot is really sensitive right in that sweet spot between clean and truly overdriven..

I hear you on that! Very touchy right in there!

I find that my JCM800 has quite a nice clean tone. When jamming with them, I don't tell the old-timers that are using it that it's known as a famous metal amp. As long as the Master Volume is above 1 o'clock, it's starting into good tone area and it doesn't sound choked even if the preamp volume is only at 8 o'clock (clean). Of course, I'd never get distortion out if it in church without VVR unless I'm willing to choke out the tone using the MV. I recently cooked the VVR2 I have installed, so these supposed 50- watt Marshalls might be putting out too much for the Mosfet... I'll try another and maybe try installing a fan near the heat-sink.

Anyways, I digress... I think it could be a great rhythm amp for church if you are willing to get your crunch from pedals (I know... sacrilegious for a JCM).

As for the hiss:
I guess some of the first things I would do that don't involve any electronics work, is to make sure there are tube shields over all the preamp tubes. I'd probably try swapping around the 12ax7s to see if they make it quieter or sounding better in a different order. As far as standard modern cheap 12ax7s people often try Tung-Sol 12ax7s in the first preamp slot for less noise...

Also, not sure whether Marshall does this already, but I would try glueing some aluminum foil to the inside bottom of the head cab with some spray adhesive in order to close up the chassis on all sides when it is put back in. I did that with my DC30 clone and it seemed to resolve a lot of the radio signal interference issues... but my 2204 clone is actually open and quite silent...

I've actually been finding lately that it's been a fantastic Rhodes amp too... even used it quite distorted for a song on our recent album and I quite liked the effect.
It's a very churchy song called "I Will Praise You" and you can hear the Rhodes->JCM during the singing of the verses:
http://www.facebook.com/TheBurnIns?sk=app_2405167945
(Click on "View More Songs" in order to see that one)

[kevster]

The gain pot is really sensitive right in that sweet spot between clean and truly overdriven..

I hear you on that! Very touchy right in there!

I find that my JCM800 has quite a nice clean tone. When jamming with them, I don't tell the old-timers that are using it that it's known as a famous metal amp. As long as the Master Volume is above 1 o'clock, it's starting into good tone area and it doesn't sound choked even if the preamp volume is only at 8 o'clock (clean). Of course, I'd never get distortion out if it in church without VVR unless I'm willing to choke out the tone using the MV. I recently cooked the VVR2 I have installed, so these supposed 50- watt Marshalls might be putting out too much for the Mosfet... I'll try another and maybe try installing a fan near the heat-sink.

Anyways, I digress... I think it could be a great rhythm amp for church if you are willing to get your crunch from pedals (I know... sacrilegious for a JCM).

As for the hiss:
I guess some of the first things I would do that don't involve any electronics work, is to make sure there are tube shields over all the preamp tubes. I'd probably try swapping around the 12ax7s to see if they make it quieter or sounding better in a different order. As far as standard modern cheap 12ax7s people often try Tung-Sol 12ax7s in the first preamp slot for less noise...

Also, not sure whether Marshall does this already, but I would try glueing some aluminum foil to the inside bottom of the head cab with some spray adhesive in order to close up the chassis on all sides when it is put back in. I did that with my DC30 clone and it seemed to resolve a lot of the radio signal interference issues... but my 2204 clone is actually open and quite silent...

I've actually been finding lately that it's been a fantastic Rhodes amp too... even used it quite distorted for a song on our recent album and I quite liked the effect.
It's a very churchy song called "I Will Praise You" and you can hear the Rhodes->JCM during the singing of the verses:
http://www.facebook.com/TheBurnIns?sk=app_2405167945
(Click on "View More Songs" in order to see that one)

Good stuff Matt!

Yeah, it'll be a touchy booger. We'll have to pull some knobs off to keep a lid on the beast.

I'm going to walk through it some more on the weekend and test it just after a couple services to see if it picks up outside noise. I think it's just internal right now. I'll trade the pre-amp tubes, etc, and we'll see if she'll take it down to a whisper...

Pedals may be a necessary evil if we are going to keep a lid on things... Hate it, but that's the nature of it....

Thanks guy!!

[ampdoc1]

I just repaired a 80's JCM800 (2205),..one of the tube had shorted and melted the tube base. Replaced them with ceramic sockets, wired it up and now it's good to go.

But i don't deal with EL34s very often. I usually buy from Ruby, but I don't know what the best manufacturers are.

Any recommendations?

[selloutrr]

IMHO best current production EL34's are winged =C=
followed by JJ/Tesla

Ruby doesn't manufacture tubes. Like Groove Tubes they buy in bulk test and rebrand. The only nice part about over paying fo Ruby tubes (mostly Sovtek) they come with a 90 day warranty.

[cruisemates]

Can you tell us what controls it has - it is single channel, with or without reverb, effects loop? and are the input jacks horizontal or verticle?