What can you tell me about the JCM 900 SLX 2100??

[Ascension]

Re: What can you tell me about the JCM 900 SLX 2100??

Here is a tip for playing through any JCM 900 Dual Master variant including the SLX. Pre amp volume is the tube circuit and the Gain sensitivity control brings in the SS clip diodes. If you want a more organic JCM 800 like pure tube tone run the Pre amp gain high and Gain sensitivity low. For a more saturated modern rock and metal tone run the pre amp volume lower and the gain Sensitivity higher. Once you understand how they work and get the drill down with these JCM 900 dual master series amps you will find that these are some of the best pure rock amps on the planet.
They have to be set up and tubed right though or they fall apart. What you use in V-1 is CRITICAL on these amps to getting the best tone. My little 2501 is running a NOS USA Baldwin labled Silvania 12AX7 in V-1 and is flat a tone MONSTER!!!

 

[King IzzO)))]

Re: What can you tell me about the JCM 900 SLX 2100??

Bill Steer used one to make good metal sounds... and a 5150.

 

[Chickenwings]

Re: What can you tell me about the JCM 900 SLX 2100??

i have a MKIII 100w combo. It does rock like hell. And quite versatile as far as rock sounds go. very rich harmonically and responsive. Using the input and the sens. knobs makes a big difference.

 

[NecroPolo]

Re: What can you tell me about the JCM 900 SLX 2100??

Owned one and owning again (the very same amp as a decade ago) I did not quite understand the comments about harshness. My SL-X was anything but harsh. Rather, really close to a JCM800 with different edge, darker texture and about third of the price. There is obvious difference but not as radical as people tells when it comes to a JCM800 vs JCM900 discussion.

JCM800:



JCM900:



Same cab, mic, everything. The only difference is the actual amp.

However, recently I came to an understanding, sort of. I did a reamp session where a 100W SL-X came to the house. Well, I could not get it sounding good. It was like in the descriptions complaining about harshness. I replaced it with my 50watter (it sounded pretty different) and saved the day. Later I examined the 100W head and realised that it had 5881 tubes. My amp is EL34.

I would not come to a quick conclusion or state it as a fact (I have no info about possible circuit differences mods etc between the two) I just guess that this amp was designed for EL34 tubes primarily. For some reason many of these amps employed 5881 tubes later. I guess the amp was not really tuned to these brighter tubes accordingly.

 

[Lake Placid Blues]

Re: What can you tell me about the JCM 900 SLX 2100??

I just guess that this amp was designed for EL34 tubes primarily. For some reason many of these amps employed 5881 tubes later. I guess the amp was not really tuned to these brighter tubes accordingly.

I prefer all Marshalls with EL34s for many of the same reasons. Even the JTM45 with the output transformer impedance mismatch, I like better with EL34s.

The JCM900s were indeed designed and tuned for the EL34, and used the EL34 for the first few years of the series. Marshall briefly went to the 5881 during around 93-95 when their supply for EL34s temporarily dried up. At the time it looked like the Sovtek 5881 was going to being the only suitable current production power tube available in numbers.

Any Marshall set up for EL34s can use 5881/6L6/ KT66 types with just a re-bias. That is as long as the bias pot has enough range. If it doesn't, then some resistor changes by a tech may be required.

Going the other way; from 5881 to EL34 may be more involved. The EL34 requires that pins 1 and 8 be connected together at the tube socket (this doesn't matter to non EL34/6CA7 octal tubes). Also the big screen grid resistors need to be around 1500 ohm instead of the 470 ohm values usually used on amps designed for 5881. I believe the 900s all use 1500 ohm SGRs anyway. Marshall power transformers already handle the greater heater current draw of EL34s so that's not problem. So if you have a 900 with 5881 it is pretty easy to change to EL34.

 

[Securb]

Re: What can you tell me about the JCM 900 SLX 2100??

DSL shares tone controls between the channels. One of the constant frustrations with the amp.

Other than that,, the DSL slays.

That is what I like about the DSL, I can set my EQ and it is consistant across the two channels. Less muss and fuss.

 

[devastone]

Re: What can you tell me about the JCM 900 SLX 2100??

How are you guys randomly digging up 6+ year old threads?

 

[NecroPolo]

Re: What can you tell me about the JCM 900 SLX 2100??

I prefer all Marshalls with EL34s for many of the same reasons. Even the JTM45 with the output transformer impedance mismatch, I like better with EL34s.

The JCM900s were indeed designed and tuned for the EL34, and used the EL34 for the first few years of the series. Marshall briefly went to the 5881 during around 93-95 when their supply for EL34s temporarily dried up. At the time it looked like the Sovtek 5881 was going to being the only suitable current production power tube available in numbers.

Any Marshall set up for EL34s can use 5881/6L6/ KT66 types with just a re-bias. That is as long as the bias pot has enough range. If it doesn't, then some resistor changes by a tech may be required.

Going the other way; from 5881 to EL34 may be more involved. The EL34 requires that pins 1 and 8 be connected together at the tube socket (this doesn't matter to non EL34/6CA7 octal tubes). Also the big screen grid resistors need to be around 1500 ohm instead of the 470 ohm values usually used on amps designed for 5881. I believe the 900s all use 1500 ohm SGRs anyway. Marshall power transformers already handle the greater heater current draw of EL34s so that's not problem. So if you have a 900 with 5881 it is pretty easy to change to EL34.

Wow! Thanks for the useful info!

How are you guys randomly digging up 6+ year old threads?

A question I wonder myself a lot, too I did not understand why I could not get a good sound of the the 5881 SL-X and why it sounded that harsh and different, I was searching for the reason and google spat this ancient thread out on top. SD forum is a win as I haven't found such a full answer like Lake's.

 

[Lake Placid Blues]

Re: What can you tell me about the JCM 900 SLX 2100??

I did not understand why I could not get a good sound of the the 5881 SL-X and why it sounded that harsh and different.

If it is really harsh the bias may be way off-way hot. In that case it might be, that it is an EL34 amp with 5881s and not biased properly.

 

[NecroPolo]

Re: What can you tell me about the JCM 900 SLX 2100??

If it is really harsh the bias may be way off-way hot. In that case it might be, that it is an EL34 amp with 5881s and not biased properly.

Thanks mate, I'll forward this info to the owner. After a proper care his amp can do it so much better I think. I'd also advice him to switch to EL34s the way you described. Kudos!

 

[Lake Placid Blues]

Re: What can you tell me about the JCM 900 SLX 2100??

Yeah, have him take it to a qualified person and get the bias checked. And while at see if the tube sockets are set up for EL-34. Especially the wiring from pins 1 and 8. If it is, then he could have EL34s installed and re-biased.

 

[mrpongo2001]

Re: What can you tell me about the JCM 900 SLX 2100??

It depends on what type of music you do and what tone/sound you are after. I have a 50W 900 DR 2 12 combo and I like it quite a bit. The cleans on it are good, but not great, the OD for rock & blues is decent. If you are looking for an amp to have the best cleans, overdrive & metal tones.... look elsewhere!

I have a SL-X 2100. Probably the best JCM-900 series amp out there. It is not an amp that is made for versatility, so Yes, it is a one trick pony. But if you are interested in just rocking out-full bore, balls to the wall, dime everything and keep trying to go to 11 there is very few amps out there that are better. Massive gain and a much more rounded tone, unlike the DSLs. It says that it is a two channel, but everything is shared, so the B channel is more like a boost, so keep that in mind if you are thinking about having a Clean/Gain on your amp. No reverb either, but with all the 'verb pedals out there, who cares? I lay back on the preamp gain a bit and put an Ibanez TS-9 in front of it... makes it sound MASSIVE!
Keep in mind that it is made to get LOUD. IMO, it is a true 4x12 cab type head. It doesn't sound bad thru a 2x12 with GT-75s, but it is like a stallion that needs to gallop for miles, not just short sprints. It needs a lot of headroom, so anything with V30s in it will make it sound mushy. Best tone I have found for it is the tried and true 1960 A&B cabs with GT-75s stacked, but I have also run it though cabs with Super 65s and it sounds great thru them too.
Mine still has the 5881s in it, but I have tried it out vs. one with the EL34s and I haven't found that much of a difference. Again, more a preference thing.
As far as the DSL goes... Good all-around, will do everything amp with decent tone. Like everyone else has said, it is a much more versatile amp and if you need something that will do everything, get that one. I wouldn't hesitate a second using it live or in the studio. But, if I had one complaint about it, it lacks a bit of character and personality. Jack-of-all-trades, Master of none. IMO, it just doesn't have that definitive tone to it, like other Marshall tube amps do.
You can get either one still reasonably priced aftermarket (though the SL-X is getting much harder to find these days) so it will mainly just boil down to what your needs are. :headbang:

 

[Aceman]

Re: What can you tell me about the JCM 900 SLX 2100??

Yeah...and then they re-released the 2555 Silver Jubilee Head. And then I played a Mesa Stiletto (and bought it!)

Still,

Marshall 900 SL-X 2100
Peavey 5150
Marshall 2555
Mesa Stiletto
Crate Blue Voodoo 60


These are all my wheelhouse. I own the Mesa.