A guy at work approached me after work and said he had some guitar amps I might be interested in. He popped the trunk and there sat a Peavey Firebass 700, but behind it, faced away from me, was a long, large tube head. It spanned the width of his trunk and being into tubes and building a small 5 watt head myself, I wondered what I could "make" from it. When he dragged it out and I saw the front I almost fell down.


Apparently his Dad, who is a long time musician, was cleaning out his garage when the son said he knew a guy that was into "amps" and brought them to work. Electrical condition is unknown and seeing the fuse caps all missing from the Marshall isn't inspiring but worth trying to get it running.





I pulled the chassis and glass to find all Marshall brand pre-amp tubes with four Sovtec's in the output.

The chassis cleaned up pretty well aside from a bit of staining and the underside is spotless.




He was just going to give them to me, but after I looked at how much the Marshall cost new, I offered to give him some $$$ for it once I figure out all that's wrong with it.

Best thing to happen at work...ever.

ETA Pic of chassis topside.

UPDATE-
Got the parts I needed to get it powered up.
I turned it on without any tubes in it and nothing smoked or got hot. It had plate and heater voltage so I put the pre amp tubes in and fired it back up. The pre amp tubes all light up and again, nothing funky going on. I also measured the plate voltage and grid bias voltage and they are in spec.
Three of the power tubes "look" ok, but one has some chalky white inside as well as some of the "mirror" finish flaking off. I'm just going to order a matched quad set of power tubes instead of risking putting the questionable originals back in.
I'll borrow my buddy's tube tester and test the three that don't look smoked. If they are ok, it will give me some fodder for another amp project.

UPDATE-2
It's ALIVE!!
Received the new tubes from A.E.S. and installed them today. Hooked up my Behringer 2x10 cab and the Strat to it and flipped the power switch. A few minutes later I flipped the standby switch and fiddled with the gain and volume controls and sweet tones flowed  from the cab.



Some of the pots are a bit dirty so they will get a spritz of cleaner before going back into it's cabinet. Now to clean up said cabinet.

That is a great coworker and a wonderful amp. Good on you for offering him some cash even though they were free.

Thanks! I just plugged in the Firebass and no joy. The fans come on, but no power indicator L.E.D. nor is there ant output. Maybe I'll troubleshoot it later. The Marshall has priority.

Nice, congrats!

Looks like all the innards are there. You can get all the missing fuse holder parts at amplifiedparts.com, they're an outlet store for CE Distribution, so they have all sorts of odds & ends for amps.

And are those 6L6s? They look a little fat for EL34s. And which model number? 4100?

Yes, 6L6's  No, 5881's and it is a model 4100.

Edit - correct tube type.

Cool.

Here's all the schematics in case you want them, just scroll down to 4100 under JCM900. http://www.drtube.com/library/schematics/69-marshall-schemas#JCM900

And of course you know this means that you've completely fallen into the rabbit hole? That 900 is going to spawn a 1960 cab, several overdrive pedals, more guitars, more amps, and on, and on, and on......

It's worse than BRD.

Sweet!

Thanks! I already have two strains of BRD, the standard BRD and Black Radio Disease. I guess one more won't hurt.
Heck, over the last two years I have accumulated enough musical equipment to start a small band...and I'm not a musician, just a hacker.

It's ALIVE! (bump)

Congrats!

Nice!

<Napoleon Dynamite>  L U C K Y </ND>

Here it is all cleaned up and back in it's cabinet.





It has a bit of staining on the tolex and a small "crunch" on the lower right in the rear, but it sounds real good. It absolutely dwarfs the 2x10 cabinet it's hooked to.
Halfstack Fullstack here I come!

Back in the late 70's I hung out and jammed with a bunch of friends. One of the guys "I didn't know very well" had a Marshall 50 watt head and a full stack. He played a Gibson Les Paul Custom and he sounded fantastic. I never will forget that sound. I am not into that kind of music today but I would still like to have a vintage Marshall amp. Nice score OP I wish I worked with people like that.

I work with a good bunch of guys for sure. I told said co-worker today I got it running and offered him $200 for it. He took it. Everybody is happy!

Too bad you can't shove KT88s in there.

That'd be amazing.

Awesome deal!

True, but he does have another option. Other than the 6L6/5881 family, he can also use KT66s if he wants a little more sag in the poweramp.

But since the Marshall 100 watt power section has basically gone unchanged since the Model 1959, all a guy has to do is swap out the trannies, a few resistors, to run the power tubes you want. In this case, all he needs are a stock set of Dagnalls like you would find in a JVM 410H (EL34) or a JCM800KK (KT88). Marshall used the same trannies for both amps, but some guys like to swap them out for something else, so the Dagnalls pop up on EBay once in awhile.

Trannie thread? J/K. So far I like the Marshall the way it is but being a relative "newb" to guitars and amps, I don't have much experience to base my opinion on.  I have five amps now, The Fender Deluxe 90, Fender Super Champ X2, Peavey Vyper 15, my home-built 5W tube head and now this Marshall. The Marshall is definitely the loudest and makes the little Peavey Vyper sound "cheap", but the Vyper has all the effects built in. Hmmm, Peavey line out to Marshall line in?

It'll probably sound better than the Vypyr does on it's own, but probably not as good as the Marshall on it's own. The best solution for that is to just keep an eye on Craigslist for used stompboxes or a decent used processor.

So... what's happened with the Firebass?  There's a cult following for those things - they are truly powerful heads, and they'll sit right in there with the loudest guitar rigs with an appropriate cabinet.

The Firebass went back to the father of my co-worker. He has a musician buddy that needs some parts from it. It may end up back with me at some point though.

this story is false.  You gave it away when you said great tones came out of a JCM900  Dual Reverb.

Man... that's harsh.

It's no Plexi... but it's worlds better than several other of the Marshall line.

I was going to keep quiet on the subject but since you went down that road I'll suggest that if the tone of the JCM900 is found to be lacking one option is to remove/disconect/add a switch to the clipping diodes in the preamp and rely on tbe tubes for distortion rather than the silicon diodes.

Nice score!

I'm with OiRogers on this one.

Some people can't just take 900s for what they are. Marshall took the 800, did their version of the Jose Mod, and tweaked a few more things in the preamp. That's basically what a 900 is.

But some people don't like it when Marshall comes up with something out of the norm.

Wow. I didn't know there was so much hate for the JCM900's. Considering what I have in it ($325) I think I'll keep it regardless of the hate.

I'll give you like treefiddy plus shipping.

If it dials in and produces a tone you love... Screw everyone else.

I'd jump on a 900 for under 350$ without hesitation.  You did great.

There is definitely a lot of hate for 900s (hence the purple).  It's just a matter of what you prefer.  I know people that hate the Jcm2000 DSLs.  They always sounded good when Gary Moore used them *shrugs* .  

Still a good find.  I'd pick one up if I got a good deal on it.  It's a fricken valve Marshall

I'll pipe up when an amp model or company has a bad reputation for quality of parts or workmanship, but I won't heckle a guy over tone because it's a very subjective matter. So, screw the haters. If it gets your rocks off, that's all that matters.

While the JCM900 isn't my first choice I certainly wouldn't turn one down for what you paid.  The 900 is an excellent basis for modifications.  You seem to have the know-how so I think that 900 can sound any way you want.  Even if that tone is the stock 900 tone.

Ok, thanks guys. Whew, I thought maybe I bought the turd of all Marshalls. I may mod it someday, but it's fine for now. Now off to find a 1960 cab..

Ignore the haters!  


As a Marshall fan, I'm jealous.

There ya go.

I hope you get as lucky with the cab pricing as you did with the amp.

I got back into playing guitar a bit about 2 years ago.  As such, I'd find myself starting to frequent (though not posting on) a few of the guitar/amp discussion boards.  And one thing I learned is that each of these forums seems to have a favorite amp brand or model that they just love to slag.  Not because they're actually bad, but it tends to be some uppity cork-sniffing tonefag decides that they don't like them, and makes fun of that, and that tends to be the official "consensus" of that board, and everyone just kinda follows along with it.  

I still can't find a whole lot wrong, sound-wise, with the JTM, JCM800, JCM900, or JCM2000.  They all offer something a bit different, and if it sounds like crap, it's certainly because of how it's set up.  And even that's just my own opinion of it.  So yeah, your 900 is an awesome find, and you'll find tons of great sounds in it!  

I'm not sure which is more infuriating to read - guitar gear forums, or audiophile forums.

Opinions on these?
JCM 900 cab
another
another?lol

Are these prices in line with your AO?
Thanks!

Wow, $200 for a 1960 is crazy cheap.  Grill fabric looks a bit torn, but if it works and you can deal with that, I don't see a real down-side.  Just the drivers are worth more than $200!  For what it's worth, I bought an Avatar 4x12 in basically new condition for $200.  I didn't like the G12T-75s that were in it, so I sold them and in effect got the cab for free, and loaded it with speakers of my choosing.  

$300 is also a great buy.  Around here, 1960s are closer to $400 in well-used shape, with most running in the $500 range.  You've gotta like G12T-75s to really dig on the base 1960; there's also the V model with Vintage 30s, and the C model with Greenbacks.  

Don't be afraid of non-Marshall 4x12s, either.  Avatar, Bogner, Peavey, Mesa, and Orange stuff might be available.  Otherwise, if the G12T-75 is what you want, $200-$300 for a 1960 cab simply can't be beat!

My first real amp was a JCM900 MkIII 50 watt 2x12 combo

still have it

I've been seeing 1960 cabs go for around $350-$500 around here, and I recently saw a trashed one for $250.

The first one is an angled/top cab and the second is a straight/bottom cab. Personally I would try to figure out how to get both so I could have a full stack, but if I had to choose one it would be the bottom cab. They have a little better bass response and grille cloth is cheap enough. You can buy it from places like amplifiedparts.com, avatarspeakers.com, and others.

And like was mentioned above, G12T-75 speakers can be harsh, but if you dial in your amp correctly, they aren't bad at all. They do best when you dial back the treble and presence and turn up the mids. They also do well when you mix them with V30s or Greenbacks (I'm currently running G12T-75s & V30s in my 1960 and Avatar Vintage, it's a good combo).

And if you end up not liking the 75s at all, you can probably get around $50 each if you decide to go with something else.

Thanks guys! Here's another I just found. It looks to be in better shape.
Angled cab

That one won't last long. I'd snap it up like yesterday.

No joke.  The bastards down there are just awash in damn cheap Marshall 1960s!

Apparently. Makes me wonder how many used cabs Dave Mustaine dumped on the used market over the years when he still lived in Arizona.

Shit that would be in the $500 range in Minnesota.

It's a pretty sweet looking deal...

Must be a bunch. My BIL in L.A. has one of his old tour cabs that was loaded with Sheffields. BIL used it for some session work, but now it is at a semipermanent gig. A 1970s LP into an old Traynor into a 1960. He has a killer rock tone.  

I have a 1960a with GT12-75s. It was ok with my prior amps. With the Mark V, I tried a quick hookup without adjusting the EQ enough and was rewarded with a thin & piercing earball-blinding tone. The cab, along with most of my amps (5150 212, 50 Caliber+, Peavey older Transtube) all are back in storage while I await a house with adequate room. Have barely picked up a guitar in months.

Nice find, OP! I still sometimes miss my Marshall JCM900 SL-X head.

IMHO, the 5150 and G12T-75s are made for each other. For some reason that combo really works.

One of those days, though, I hope to have G12K-100s in my 1960a. I tried some out at a local guitar shop in an Orange cab, and I fell in love with those speakers. Nice sparkly top end, just the right amount of mids and a nice big, yet tight low end, and there was nothing harsh about them.

If that Traynor head is a YBA-1 Bass Master... that might explain something as well.
One of the most underrated heads ever built IMHO.  That thing is somewhere between a 59 Bassman and a Plexi in tone.  I own several (surprise! ) and am always on the hunt for MOAR! (at a decent price).

Its a Bass Master that's been suitably massaged by a good tech. Mojo added in the form of a master volume.