WTB: Marshall JCM 900 100 Watt

[childeatingsnow]

Looking for a Marshall JCM 900 4100 100 watt head. I am specifically interested in the EL34 version of this head and not the more common 5881/6L6 version.

[Guest gearwhore]

just tube a 6l6 head with el84..give a bias and go...no difference...just what tubes are in. the plate voltage will be low in a 6l6 biased amp for el34..so just turn it up..

I got a head but I dont have a quad of el34 I can let go...or I would set it up before it left....But I can put set in and get bias set for el34s before it leaves and if you get a nice match quad it should be fine..I would keep the 5881s -for $600 shipped and paypal'd... I would let one walk.

[Victor (Fret Friend)]

It's my understanding that a JCM900 Head takes either 6L6s or EL34s (I had one)...

In all fairness, I never really liked Marshall amps & sold my JCM900 to buy a Randall RH-150 [Mosfet Hybrid] which is one of the best metal-amps I've used in over 30 years a player. I now play a US Peavey 212 Classic Chorus which does all styles

[Guest gearwhore]

yep^^^^ some take both...I have bought more than one 5881 badged 900 with 34s in it..mesa's do it..xls-1000 will take anything you can shove in it....I have never had issue..your right the bias point is right at the edge but it works...I have done tons of tube swapping and get great results.....I personally have never had a single issue..a friend or two may have started a fire or two and given me great feedback on what not to do.

[Guest gearwhore]

everybody's doing it.

[Ethanw]

I just sold a 50 watt Dual Reverb on CL and had a hard time getting rid of it, finally took a bunch of trades against it. I would check your local CL and not pay too much. IMO they're a pretty anemic Marshall.

Ethan

[kurtsstuff]

I just sold a 50 watt Dual Reverb on CL and had a hard time getting rid of it, finally took a bunch of trades against it. I would check your local CL and not pay too much. IMO they're a pretty anemic Marshall.

Ethan

There's some very simple mods that take about 15 minutes to do that really change these amps..

1. Remove R7 and R43.

This disables a hardwired tonestack on the gain channel. This tonestack scoops mids, changes the low end and makes the amp sound harsh and sterile.

2. Place a jumper wire over D10.

This will give a smoother, warmer and more organic distortion on the gain channel. It increases the clipping a bit. This one "might" make it a bit too dark and some opt to put a switch on it..kind of a bright switch.

3.Jumper C27. Restores the low end.

also regarding the basically non exsistent "clean channel"..There are 4 LED's behind the gain pot of channel

A..Yank those out and you'll have a really good clean almost all the way through the gain pot throw.

[MCChris]

Good suggestions, Kurt!

I will say that these amps can sound "anemic" on their own, but I've never heard one that didn't sit perfectly in a FOH mix. They don't crowd the frequencies other instruments occupy that can result in a mushy mess. However, a little more smoothness and low end never hurt anybody!

[black magic]

Is the 4100 the one with Reverb?

[kurtsstuff]

Is the 4100 the one with Reverb?

Yes....hence the name "Dual Reverb"....hehehe

[Guest gearwhore]

I just sold a 50 watt Dual Reverb on CL and had a hard time getting rid of it, finally took a bunch of trades against it. I would check your local CL and not pay too much. IMO they're a pretty anemic Marshall.

Ethan

There's some very simple mods that take about 15 minutes to do that really change these amps..

1. Remove R7 and R43.

This disables a hardwired tonestack on the gain channel. This tonestack scoops mids, changes the low end and makes the amp sound harsh and sterile.

2. Place a jumper wire over D10.

This will give a smoother, warmer and more organic distortion on the gain channel. It increases the clipping a bit. This one "might" make it a bit too dark and some opt to put a switch on it..kind of a bright switch.

3.Jumper C27. Restores the low end.

also regarding the basically non exsistent "clean channel"..There are 4 LED's behind the gain pot of channel

A..Yank those out and you'll have a really good clean almost all the way through the gain pot throw.

do you leave the diode and cap in when you jump them?

[childeatingsnow]

Thanks for the input. I ended up snagging a JCM 900 SLX that was originally outfitted with EL34's. I purchased one of these back in the day while on tour and hated it because of the 6L6's. It sounded way too thin and tinny for me and I promptly ditched it. I do like that the SLX eliminates the diode clipping in favor of the extra preamp tube in the gain stage so I guess that we will see.

[kurtsstuff]

I just sold a 50 watt Dual Reverb on CL and had a hard time getting rid of it, finally took a bunch of trades against it. I would check your local CL and not pay too much. IMO they're a pretty anemic Marshall.

Ethan

There's some very simple mods that take about 15 minutes to do that really change these amps..

1. Remove R7 and R43.

This disables a hardwired tonestack on the gain channel. This tonestack scoops mids, changes the low end and makes the amp sound harsh and sterile.

2. Place a jumper wire over D10.

This will give a smoother, warmer and more organic distortion on the gain channel. It increases the clipping a bit. This one "might" make it a bit too dark and some opt to put a switch on it..kind of a bright switch.

3.Jumper C27. Restores the low end.

also regarding the basically non exsistent "clean channel"..There are 4 LED's behind the gain pot of channel

A..Yank those out and you'll have a really good clean almost all the way through the gain pot throw.

do you leave the diode and cap in when you jump them?

I do but..it's "cleaner" to take them out and just run a wire..

[kurtsstuff]

Thanks for the input. I ended up snagging a JCM 900 SLX that was originally outfitted with EL34's. I purchased one of these back in the day while on tour and hated it because of the 6L6's. It sounded way too thin and tinny for me and I promptly ditched it. I do like that the SLX eliminates the diode clipping in favor of the extra preamp tube in the gain stage so I guess that we will see.

The SLX is an actual tube path unlike the 4100/4500 etc that basically have built in..Overdrive for channel A and a built distortion pedal for channel B

[murkat]

I ended up snagging a JCM 900 SLX

\o/

winner.

[Guest gearwhore]

its funny everyone bashes the stock 4100..but its is the most widely used marshall on stage in national touring acts...in 300 shows that had marshall ordered amps on the backline list the 900 is on 2/3 of them...a jcm900 is asked for 3-1 to ANY (not just marshall requests)other head. the only guitar amp asked for as much as jcm900 is fender twin.

And it does not matter genre of music...country,blues,rock,reggae,r-b.

[MCChris]

Like I said, they sound great in a live setting!

I will say that I worked at GC around the time they came out and the build quality was wildly inconsistent. Some really shoddy workmanship out of the box on some of them.

[Guest gearwhore]

the crappy ones must have died quick and got out of circulation I never had a problem other than tubes and minor crap like jacks on any of dozens I have or have had... and I have had some monkey stage hands drop them in their roadcases off back of the truck..end of the stage..down stairs...and never any issue. I would think of them as rugged...durable.I only had to use the spare head I always pack once..and the speaker jack was the reason that one didnt work.

[MCChris]

The amps all worked, but the jacks, pots, fit and finish were all over the place.

[Guest gearwhore]

lol...yeah I cant say there...the finishes are toured...and to use pots and jacks are normal...they are wear parts...but not like its a common monthly issue..every couple of years...shits just wears out when you use it all the time.

[MCChris]

I'm talking brand new, out of the box. Some were embarrassingly bad, not unlike some of the Gibsons we got back then.

I used to schlep a 4502 combo around as a backup. It was pressed into duty a couple times when my Soldano and my bandmate's Mesa went down. Always fired up, always sounded great.

[Guest gearwhore]

then??? the gibsons now are horrendous...I mean nasty...It took 9 guitar returns to get a decent one and it still needed work to be a player..they dont even intonate new guitars anymore

[MCChris]

then??? the gibsons now are horrendous...I mean nasty...It took 9 guitar returns to get a decent one and it still needed work to be a player..they dont even intonate new guitars anymore

I don't doubt it. But I'm not seeing them daily like I was in the early '90s. That experience really turned me off to a few of the iconic guitar brands.

[Guest gearwhore]

It IS the last time I buy a new gibson. I love my 83..and now I think I might just have customs stuff from here on out if its new...but lots of hamers out there need love..so I may never buy new again

[Never2Late]

There's a fully-refurbished Dual-Reverb JCM900 head/cab at my local music store that's virtually brand-new (or better-than-new, depending on how bad it was out of the box)......a customer brought it in to the store for a hefty 'tune-up', and the rig went to my Amp tech who is excellent at what he does (when he's not mellowing his rampant OCD compulsions with copious Mary-Jane). That was over nine years ago.....the half-stack still sits in the shop, fully serviced. The customer never came back and picked-up his amp, he just abandoned it.....? One of these days, I'll wear-down the store owner and let me 'plug-in'....

I don't know much about the 900 - are ALL of them solid-state in the preamp stage, or did the cut-back to tubes?