Marshall JCM 900

[mfprh]

Hello all! Haven't been around for a bit...

Anyway, I have an opportunity to pick up a JCM 900 for practically nothing but I'm not well versed on it. It's a 1994 50 watt, dual reverb head.

So far my favorite Marshall is the JCM 800 2210 split channel head, but can't find one in the same price range. How do they compare tonally? I've heard the 900 is an 'improvement' to the 800, but that doesn't really help me much, lol.

Thanks!

 

[CaughtLikeFire]

Re: Marshall JCM 900

Hello all! Haven't been around for a bit...

Anyway, I have an opportunity to pick up a JCM 900 for practically nothing but I'm not well versed on it. It's a 1994 50 watt, dual reverb head.

So far my favorite Marshall is the JCM 800 2210 split channel head, but can't find one in the same price range. How do they compare tonally? I've heard the 900 is an 'improvement' to the 800, but that doesn't really help me much, lol.

Thanks!

the 900 has clipping diodes like the 2205 and 2210 but it's even higher gain (think distortion pedal built-in to the circuitry). it's definitely a love or hate amp. some folks like the fizzier distortion, others don't. the 900 is also a little weak in the low-end. a lot of these drawbacks can be fixed with $10 in parts and a little soldering. a good amp tech can make it really rip for $200 or so. it's an earlier 900, so it might be EL34. if it is, go for it. the ones that came with 5881 take more work and $$ and I'd say skip out on those.

bottom line, the 900 can be a cool amp for hard rock tones but it is not considered an upgrade to the 800 (the 800 is more desirable actually).

 

[mfprh]

Re: Marshall JCM 900

the 900 has clipping diodes like the 2205 and 2210 but it's even higher gain (think distortion pedal built-in to the circuitry). it's definitely a love or hate amp. some folks like the fizzier distortion, others don't. the 900 is also a little weak in the low-end. a lot of these drawbacks can be fixed with $10 in parts and a little soldering. a good amp tech can make it really rip for $200 or so. it's an earlier 900, so it might be EL34. if it is, go for it. the ones that came with 5881 take more work and $$ and I'd say skip out on those.

bottom line, the 900 can be a cool amp for hard rock tones but it is not considered an upgrade to the 800 (the 800 is more desirable actually).

I guess it's always worth picking up a steal, Ebay is great if I hate it lol.

The seller claims it came with 5881's but changed to the EL34 circuit by some tech. Sidenote: I have soldering skills, and know the safety procedures for working on amps, do you know off hand where I can find info on the changes that you are speaking of?

 

[CaughtLikeFire]

Re: Marshall JCM 900

I guess it's always worth picking up a steal, Ebay is great if I hate it lol.

The seller claims it came with 5881's but changed to the EL34 circuit by some tech. Sidenote: I have soldering skills, and know the safety procedures for working on amps, do you know off hand where I can find info on the changes that you are speaking of?

yeah I can look up the small changes with resistors that will make the EQ much better.

just give me a few (I'm stuck working tonight and need a distraction . . . )

here you go: http://web.aoct.org/marshall/jcm900-gain-mod.txt

my buddy has an early 1990s EL34 50W Dual Reverb and did these mods - pretty easy to do and sounded good to me. I would recommend using the lower of the 2 values for R10 that the author suggests. the higher value resistor made the low end boomy and muddy on my buddy's amp. if you plan on playing the amp at a decent (non-bedroom volume), you won't need the extra gain.

a few more notes - the potentiometers are circuit-board mounted and somewhat prone to failure. Antique Electronics carries direct replacements (no need to call Korg. www.tubesandmore.com

the transformers on the earlier models are usually good, but if they do go, Mercury Magnetics makes drop-in replacements for the 900 that will improve your tone and are designed to last forever.

SED Winged C El-34s are great in this amp as are JJ E34L (especially the 30W Groove Tubes-only version). In the preamp, this is one amp where JJ ECC83 hi-gain actually work well although I personally preferred the tone of the Tung-Sol reissues.

hope this helps

 

[Zerberus]

Re: Marshall JCM 900

I love my single channel 800, but the only single channel 900 I liked was the MV switching SL MK III, the forerunner of the SL-X. The others were all too fizzy for me, and the SL-Xs I tried were all mud factories.

I must admit though that I also found the channel switching 800s to fizzy, just not to quite the same extent.

Either way, IMO there is no 900 that sounds better than a comparable 800. While they may be out there somewhere becasue there are tolerances in the components that make some amps magic while others are dogs, and Marshall has a record of this being the case with many production models in the 70s-90s, I haven´t found one

 

[Bludave]

Re: Marshall JCM 900

The 900 gets a bad rap! I have a 50W combo & for many years I A/B'd it with a Super Reverb. Gave me tons of versatility doing that, but the last few yeras I just used the Marshall 900 and a few pedals. I had a DOD TR3 multi effects unit running into the loop. The DOD was the only stomp box style I was able to get into the loop without sucking all the tone out of the amp. I used the Delay & Chorus, but not the OD. I also had a Marshall Bluesbreaker that I used with the clean channel. Then a Wah & tuner.

The Drawbacks to these amps are the effects loop. The loop was not very effective, yet necessary. Keep in mind this amp was designed back in the era where racks were commonly used. so the loop was designed for rack effects not stomp boxes.

The Overdrive can be a little buzzy, but I have always been able to dial in a decent OD tone with mine...... I will still use this to gig with. I like it. The heads I think should have a nice string bottom once you hoke it up to the right speakers. The combo comes with the 75W celestions I would think those in a 4 12 or vintage 30's would do very nicely. I also have a Pevey 4 12 that has Shefeild 1290's & this sounds quite nice with this amp.

 

[Chickenwings]

Re: Marshall JCM 900

I had a jcm 900 dual reverb about 15 years ago. Great for an Ediie VAn HAlen type sound at high volume. BUt its clean channel was not very exciting. I always wished I had an 800 super lead.

 

[ErikH]

Re: Marshall JCM 900

If it does in fact have EL34's in it now, it's be worth checking out. The Dual Reverbs sound best with those, IMO. Like Zerb, my favorite of the 900 series is the often overlooked Master Volume MkIII, and I own one myself, the 2100 head. It's currently being fitted with a new Hammond power transformer, F&T filter caps and new power tubes. The SL-X can get muddy at the higher gain settings, like Zerb said. I agree there too.

If this 900 sounds good to you, go for it.