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Discussion in 'Marshall Amps' started by Kelia, Oct 11, 2020.
I want one , congrats.
I just got one of these a few weeks ago, the 100w version, and it is indeed awesome, enjoy it.
I also got the 50w Mk III and they sound so different they may as well be two different amps, but confusingly they share the same model names.
Differences? I have a jcm800 but really want to try a 900.
I really need to do some comparison clips, because it's easy to hear but harder to describe.
The Mk III has a grittier sound and you can roll the "sensitivity" knob down to 0 and do a pretty reasonable impression of an 800 style MV amp. With the sens knob you can dial in some diode-y fuzz/hair and adds some punch to palm mutes and the like. It's a really flat gain boost, not like a tubescreamer that is focusing on the mids/treble area. Useful but I sometimes wish I could footswitch it on/off.
The SL-X on the other hand is smoother and more polite sounding to me. It has 5 tube gain stages and they are on all the time, if you turn the sensitivity knob down to 0 the amp will have no volume, since it kills the signal off completely. I think - and I could be wrong - but the more tube gain stages the more smoothed out the mids get, so if you like that traditional Marshall angry-mids fizzle kind of sound, the SL-X doesn't do it as well as the Mk III does.
I like them both a lot but for different sounds. The Mk III seems a little more similar to the 800 to me. So if you want something very different from your 800 that will complement it, get the SL-X, if you want kind of the same thing as the 800 but with a different flavor, hunt down a Mk III.
YMMV and etc. I'll try to post some clips up on here. Been working on it for a while but not much to show for it yet but I'll start a thread here once I have something worth sharing.
Really? That much different?
In what way? I wouldn’t think they are, so that’s why I wanna compare them live.
Just installed an old 12AU7 in V2 ,.....this was suggested by someone here
and it really tames the gain at low volume ,....works great !
Yes absolutely, they are seriously different. At least the two examples I have sitting here. Read one post above, I tried to outline the major differences. They share the same model numbers and control knobs etc but they are vastly different sounding. That's why I still think it's worth having both
That's a great idea, I should try that on mine. Since you can't turn the V2 gain stages off you could reduce it with a lower output tube.... interesting idea. I think I have an AU7 somewhere but I'll have to dig for it since I don't usually use them.
My 2100 slx was my main gigging amp for about 10 years, awesome sound and, I agree, volume must but up to get the best tone from these amps.
I bought mine brand new in 1993 with el34's installed. Still have it, I have trouble getting rid of any of my gear lol.
I’ve got the same amp, year and tubes. It’s a beast. One of my favorites.
I’ve owned a 1990 100 watt MKIII head since 1991.
I toured with it for 10 years with no issues.
It looks beat burly still sounds amazing.
Burned through tubes over the years.
I replaced the caps about a year ago.
These are amazing, solid amps!
Marshall only made them from 1990 to 1992.
Then they added a preamp tube and renamed it SL-X to add more gain so they could compete with the Mesa amps that were gaining favor at the time.
like lonewolfsx said, if the sensitivity knob is turned off it sounds like a JCM800.
I personally like the preamp cranked with the sensitivity set around 3 to add just a bit more dirt.
When people were getting their 800’s modded it was to add a bit more gain to push them over the edge.
Marshall knew that and responded with the JCM 900 MKIII.
Some people complain about the diode clipping and then use a dirt pedal in front of the amp.
ITS THE SAME THING!!!
I’ve never played through a SL-X to compare.
But, in my opinion it was the last great Marshall... until the Astoria was introduced.
And that’s what I’m in love with now.
BTW, I own a JTM 45, 1987HW, 1978 JMP and my beloved Astoria dual.
Try some different EL34 style power tubes.
KT77 or 6CA7’s for fun.
Have you A-B-ed the 5881 with EL34's........worthed ?
Those aren’t the same tube type so you might have to swap a resistor or something to make sure they bias up correctly.
The general consensus is that the EL34 amps sound better but my 6100LM has 5881 and I think they sound just fine. They make a difference but really the design of the power amp circuit has a bigger effect than the type of tube used, at least that’s my observation.
That said, I really liked KT77’s in my TSL until one of them popped - actually the reason I tried them was I knew I had floating bias issues and I read that KT77’s are more durable. I have a quad of 6CA7’s I can’t wait to try next. They are such minor flavor differences unless you are playing ungodly loud so I usually just buy whatever is on sale. I think if you had an iso booth or regularly play your 50w or 100w amps at high volume you might care more about the power tube types
edit for grammar...
Thanks for the input!...appreciate
I never tried 5881’s.
‘smoother and more polite’ ― LOL! What you are hearing is Solid-State Clipping Diodes. At least that is what my local Marshall dealer told me back in the 1990s regarding the 900 Series.
I said the SL-X was smoother and more polite, which has no clipping diodes. Diodes definitely do *not* add smoothness haha, that's the whole point of the diodes is to make it more grainy/distorted/impolite.
There are three different amps in the 900 series, don't get them mixed up
SL-X = no diodes, smooth, lots of gain
Mk III = has diodes, a grittier angry 800 type sound but not as bright
Dual Reverbs = has diodes, never played one so I can't comment (yet, it's next on my list
Edit: also if there's anything I've learned playing guitar the last decade, it's that the sales people in music stores don't know shit, especially about technical stuff (99% of time at least)
Hi, i know well this amp, it's my favorite and i own 3 of them, 2 100W with 6L6, 1 50W with EL34. Well I agree thez differnt sound at low volume than at hi volume and i love the two situations. I think I prefers 100W and 6L6, but for me i use them on diffrent cabinet with differnt guitars and they sound very different, it's normal.
The first one, a 100W on V30 (new jubilee cabinet) with washburn N2 or a SG is for metal (scoop mid) tone.
The second one, a 50W on blackback (jmp 70s cab) with a tele for big rock
A the third on 100W with greenback 1960classic acb with a R9 (low power pickups) for clean to metal tone.
I've few marshalls from jmp2203 to vintage modern (and other brands too) and the slx is the perfect marshall amp for a 90s man like me !
And it's the less expensive, so you can buy 3 for 1 jmp !
Just plulled my 50w out the other day, and have been enjoying it. I can get very close to the sound of my old 2203x, and it puts my little SC20H in it's place (just a bigger sounding amp). I agree, prices will eventually start to climb on these underrated Marshall's.
Nice score. Congrats!