Incoming JCM 900 Mkiii

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griff
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Incoming JCM 900 Mkiii

Post by griff »

Struck a good deal on one, basically a straight swap for some gear I'm not using. This one apparently is a '91 or '92, 2501 and is a higher gain circuit of the 800's that came out in the 80's, but very similar.
Supposed to be more desirable than the Dual Reverbs that came out after.
If it can get similar to what an 800 can do I'll be very happy.
Lockdown is sorted for me I guess.
Any of you fine folk own/owned/played one?
How good is the loop on these things? I see it has a level control, so that's a good start.

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Re: Incoming JCM 900 Mkiii

Post by Reg18 »

I’ve played a few but many years ago, I remember not particularly liking the dual reverb versions, but my favourite was one called an SLX or something. In fact my friend had a JCM800 at the time and I preferred the JCM900. Although his 800 was the later dual channel 800 which I never loved.

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Re: Incoming JCM 900 Mkiii

Post by Kris »

the slx was marshall's answer to the hot rodding of the time-Had an extra gain stage..I hated the 900's back in the day but that was prob because i was trying to use the treble and prescence. A well travelled engineer friend told me "bass and mid on 10,treble and presence on 0"
its worked for me ever since:) you used to be able to get them for next to nothing.

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Re: Incoming JCM 900 Mkiii

Post by griff »

Yeah it'll be a bit of a test for me as I'm not used to amps with so much high end. But it could end up beig a blessing in disguise as a live rig.. all that high end should cut through the mix pretty well. Could always try a 10 band in the loop too

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Re: Incoming JCM 900 Mkiii

Post by willow13 »

wow I had one of these in the mid 90's ... I thought it was awesome. Single channel no reverb so suited my plug straight in with no effects approach of the time
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Re: Incoming JCM 900 Mkiii

Post by DongHua »

had a 50w version of Mk3 JCM900, it was surprisingly good and I paid almost nothing 15yrs ago, I am still looking to pick up a SLX whenever one shows up locally for a right price.

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Re: Incoming JCM 900 Mkiii

Post by griff »

DongHua wrote:had a 50w version of Mk3 JCM900, it was surprisingly good and I paid almost nothing 15yrs ago, I am still looking to pick up a SLX whenever one shows up locally for a right price.
No diodes in this model I believe, but moar gain than the previous models. They get good reviews also. Good luck with your search!

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Re: Incoming JCM 900 Mkiii

Post by griff »

willow13 wrote:wow I had one of these in the mid 90's ... I thought it was awesome. Single channel no reverb so suited my plug straight in with no effects approach of the time
Looking forward to seeing what I can get out of an amp with no frills.. might not be cover band material but defo could be a recording/originals unit eventually. I know it needs new tubes for starters.

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Re: Incoming JCM 900 Mkiii

Post by Kris »

thats a good point about the diodes-i forgot the mk3 was like that.I had a (plain)jubilee for a while and i could never get the fizz away.Ended up using it as a poweramp (pre master volume insert was handy) and selling it because it seemed a waste

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Re: Incoming JCM 900 Mkiii

Post by Optical »

The 250x is basically the jcm800 split channel (2205 etc) preamp with a solid state (opamp) FX loop and standard marshall tone controls.

Not the same diode config as the jubes, but agree with cutting the treble to the 0-3 region and mids on 10, can usually tune out the fizz that way.

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Re: Incoming JCM 900 Mkiii

Post by handsoffmatt »

The 900 mkIII is an awesome amp. It's essentially just a 2203 with an additional gain stage and footswitchable dual master volumes (i.e. solo boost). Great sounding amp! I liked them a LOT more than the much more common Dual Reverbs
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Re: Incoming JCM 900 Mkiii

Post by handsoffmatt »

For those that don't know BTW. The Marshall tone lineage is pretty damn linear all the way up the line of their flagship amps, because in a lot of ways they are VERY similar throughout the years in the core models. After the switch to EL34's and solid state rectifiers you can pretty much draw a straight line between Plexi 1959 up to the current JVM models:

Super Lead "Plexi" 1959 (100W) / 1987 (50W) models (these are model numbers, not years). 4-input, 2-channel (parralel) non master volume. The quintessential Marshall sound.

Master Volume 2203 (100W) / 2204 (50W) models. These started out in the classic headshell design, but later became the JCM800 series. They are essentially identical to the 1959/1987, but with a factory "mod" performed to cascade ch1 into ch2, resulting in increased gain, and the second channel volume became a rudimentary master volume control.

JCM900 mkIII 2100(100W) / 2500 (50W) models. These are essentially identical circuit to 2203/2204 but with a diode clipper added for more gain and footswtichable dual master volumes. Later on, the 2100 / 2500 became known as the SL-X, which removed the diode clipper and added an extra preamp tube gain stage.

After that came the era of incorporating multiple amp "designs" into one chassis. Starting with the 30th Anniversary, Marshall then produced amps that had a JTM45 circuit (slightly different to the amps above), a "plexi"circuit and "hotrodded (JCM800+) circuits all in one box. So, any of these amps can get you the classic Marshall sounds:

Marshall 30th Anniversary
JCM2000 (all models)
JVM (all models)

Of course, ALL of the amps had feel differences, due to things like different transformers, power filtering differences (for safety regulations and reduced noise) and, some would say, capacitor differences. They all though have the same essential Marshall voice.

There have been a number of models through the years though, that have strayed outside of this formula.

JTM45 is the most notable. Of course it was the FIRST Marshall design, and has a slightly different voice and very different feel.

The 25th Jubilee Series had their own unique voice, though still undeniably Marshall.

The JTM amps of the 90's were definitely more like modernised JTM45's (but manufactured more cheaply)

The Mode 4 was a completely different beast......SS power amp and one channel that was intentionally voiced to be more "Mesa"

These are all the "flagship" Marshall amp ranges. Of course there have been any number of sub-ranges over the years (Valvestate, MOSFET, AVT, Haze, MG etc etc) all designed to deliver Marshall-esque tone, by whatever means, on a budget.
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Re: Incoming JCM 900 Mkiii

Post by griff »

Thanks Matt, very cool!

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Re: Incoming JCM 900 Mkiii

Post by hamo »

Nice score man.
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Re: Incoming JCM 900 Mkiii

Post by Optical »

handsoffmatt wrote:
JCM900 mkIII 2100(100W) / 2500 (50W) models. These are essentially identical circuit to 2203/2204 but with a diode clipper added for more gain and footswtichable dual master volumes. Later on, the 2100 / 2500 became known as the SL-X, which removed the diode clipper and added an extra preamp tube gain stage.
?? that's not right at all...
It has less gain stages than a 2203/4, and the SLX has two more gain stages than the 2500 and shares almost nothing in common circuit-wise...

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