jlaflamme
jlaflamme
Join date: Mar 2011
290 IQ
#1
I just purchased a used JCM 900 2x12 100 watt combo model 4102. It has EL34's in there now but Im thinking about changing them out for some 6L6's because I heard they are better for projecting more bottom end to the tone. Anyone have a opinion or experience with this? Thanks Jim.
Cathbard
Grumpy Old Tech
Join date: Oct 2009
2,565 IQ
#2
The screen resistor is a tad big for a 6L6. It will work but it isn't good. Don't bother. Instead throw a set of JJ EL34L tubes in there. They have a bigger bottom end than normal EL34's.

Retube the preamp with JJ ecc83s tubes - that will make more of an impact by far.
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Last edited by Cathbard at Dec 2, 2012,
Robbgnarly
Tab Contributor
Join date: Feb 2011
1,177 IQ
#3
Quote by jlaflamme
I just purchased a used JCM 900 2x12 100 watt combo model 4102. It has EL34's in there now but Im thinking about changing them out for some 6L6's because I heard they are better for projecting more bottom end to the tone. Anyone have a opinion or experience with this? Thanks Jim.

Unless your amp has been modified previously DO NOT PUT 6L6's IN IT you will fry the power section.

SED=C= tube are gonna be your best tubes, but they are extremley expensive ($170USD for a matched quad of EL34's) I run these in my Marshall JCM2000 and they sound awesome

JJ tubes are also very good and much cheaper ($75 USD for a matched quad)


Now there are several EL34 type tube you can substitute in your amp. KT77 will get you a bigger beefier tone than a standard EL34. JJ also Makes an E34L which has a bigger bass response than the typical EL34. JJ aslo has the 6CA7 which is soposed to be similar to an EL34 and 6L6 in the same tube (I have no experience with these)


www.eurotubes.com

I order tubes from them all the time

Thanks for the NINJA Cath
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
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Last edited by Robbgnarly at Dec 2, 2012,
Cathbard
Grumpy Old Tech
Join date: Oct 2009
2,565 IQ
#4
You're welcome.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
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BCKRedBaron
Registrar'd Loser
Join date: Jan 2012
131 IQ
#6
Cath and robb nailed it, so it's not like my help is really needed, but I just wanted to add that the 6CA7 robb mentioned would do quite well if you're looking for darker tone and more low end. It has more low-mids than the other EL34 types and deeper bass. I use them in my Mesa Stiletto and I feel that they help balance out what can be a harshly bright amp. KT77s are pretty bassy/chunky compared to 34s as well, but I don't care much for the top-end sizzle those things have, particularly in a JCM900. But that might be your thing, so you could check those out too.

If not those, then +1 to Cath's recommendation of the E34L.
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Cathbard
Grumpy Old Tech
Join date: Oct 2009
2,565 IQ
#7
I suspect that this isn't a power tube issue anyway. Those crappy clipper diodes make it sound quite fizzy, especially the ones on channel 2. That can trick your mind into thinking that it's lacking bass.
So here's the question - is channel 1 annoying you as much as channel 2? If not there is a solution. It does require removing the board and doing a bit of soldering but you can improve the sound of a 4102 quite a lot by reversing a design error.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
jlaflamme
jlaflamme
Join date: Mar 2011
290 IQ
#8
Thanks, I went with a matched set of JJ EL34's. They were the same price as Electro Harmonix. I had this amp about 15 yrs ago and really liked it so I decided to buy another. I've heard others say these are lousy amps but I'm not jumping on that bandwagon. I can't really complain since the amp only cost me $250. Needed new tubes, a cleaning, and a new grill cloth. I think I did ok!
Robbgnarly
Tab Contributor
Join date: Feb 2011
1,177 IQ
#9
Yeah I'm not a fan of the JCM900 DR, but for $250 even I would have bought it. Killer deal man
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
Cathbard
Grumpy Old Tech
Join date: Oct 2009
2,565 IQ
#10
That's about what I paid for mine. I don't really like the 4102 but for that sort of money I wasn't going to turn it down. Only took an hour to make it sound decent anyway. All it took was cutting one track and soldering in a resistor.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band