Alternative tubes for the JCM 900

daemon barbeque

daemon barbeque

Zuhahahaologist
My bandmate uses a JCM 900 ,and it has 5881s in it...Time for some new tubes and we wanted to experiment.
Do you guys have experience with different tubes in 900s?
 
Re: Alternative tubes for the JCM 900

Have you tried Ruby Tubes? Great value for great tone imo. They may be relabeled tubes, but you can't beat the price.
 
Re: Alternative tubes for the JCM 900

Get it retubed/biased with EL34's. You'll both be amazed at the difference in sound. Those amps don't sound that great with 5881's, IMO/IME. EL34's all the way.
 
Re: Alternative tubes for the JCM 900

Thanx bros!
Erik ,I was thinking about the El34s ,or even KT 77s for better tone...
How hard is those things to rebias?
 
Re: Alternative tubes for the JCM 900

ErikH said:
Get it retubed/biased with EL34's. You'll both be amazed at the difference in sound. Those amps don't sound that great with 5881's, IMO/IME. EL34's all the way.
Click to expand...

I just had my 900 retubed with Svetlana EL34's. Of course mine had 34's in it, but the new tubes made a world of difference!
 
Re: Alternative tubes for the JCM 900

Eric, are those amps able to be modded over to EL-34's? Did you have to change a few resistors?

You have a 900 MKIII, not a 900 Dual Reverb, right?
 
Re: Alternative tubes for the JCM 900

daemon barbeque said:
Thanx bros!
Erik ,I was thinking about the El34s ,or even KT 77s for better tone...
How hard is those things to rebias?
Click to expand...

Gearjoneser said:
Eric, are those amps able to be modded over to EL-34's? Did you have to change a few resistors?

You have a 900 MKIII, not a 900 Dual Reverb, right?
Click to expand...

Yes, I have a MkIII and it came with EL34's and only EL34's.

The SL-X and Dual Reverbs came with EL34's then 5881's with the changeover.

I *think* the sockets may be wired up already to except either/or and just need a rebias. Better to have a tech verify that to be 100%. Even if the socket isn't wired for EL34's, they can be modded to accept them easily enough.
 
Re: Alternative tubes for the JCM 900

I was going to ask the same question so thanx Joe and Erik!.
Some guy modded his Marshall , so he should know it.
I'm going to post here or send some PM to you guys about the tech report!
Cheers!
 
Re: Alternative tubes for the JCM 900

From Bob at Eurotubes:
Almost all of the 900’s that we re-tube locally leave with 6L6’s in place of the stock EL34’s. We always ask the owners if they would like to compare the tone of the JJ 6L6 with the JJ E34L or Winged C EL34. We don’t sell the =C=-’s because we like the JJ’s better but we keep them on hand along with every other brand for comparison purposes. I’d say 99% of the 900 players like the more balanced tone that the JJ 6L6’s provide. The KT77's are also a nice option because of their increased low end.
http://www.eurotubes.com
 
Re: Alternative tubes for the JCM 900

marvar said:
From Bob at Eurotubes:
Almost all of the 900’s that we re-tube locally leave with 6L6’s in place of the stock EL34’s. We always ask the owners if they would like to compare the tone of the JJ 6L6 with the JJ E34L or Winged C EL34. We don’t sell the =C=-’s because we like the JJ’s better but we keep them on hand along with every other brand for comparison purposes. I’d say 99% of the 900 players like the more balanced tone that the JJ 6L6’s provide. The KT77's are also a nice option because of their increased low end.
http://www.eurotubes.com
Click to expand...

i was sitting here thinking the same thing, i just read that on Eurotubes this morning. they have complete re-tube kits as well for all different kinds of amps. check out that eurotube site man, if anything it will certainly educate you on sh*t, lol.
 
Re: Alternative tubes for the JCM 900

IMO, my MKIII HATES JJ tubes. Sounds like ass with them, pre or power. Sovtek LPS 12Ax7's are the key to what made it come alive and a good EL34 like a EH works well. Just stay away from JJ's with a 900.
 
Re: Alternative tubes for the JCM 900

ErikH said:
I *think* the sockets may be wired up already to except either/or and just need a rebias. Better to have a tech verify that to be 100%. Even if the socket isn't wired for EL34's, they can be modded to accept them easily enough.
Click to expand...

That is the standard Marshall practice for years and years. Just look (or have a tech look) at the (inside side) tube socket. If it has jumper soldered between pins 1 and 8 it can take both.
 
Re: Alternative tubes for the JCM 900

Tubes for a JCM900? EL34, all the way.



theodie said:
IMO, my MKIII HATES JJ tubes. Sounds like ass with them, pre or power. Sovtek LPS 12Ax7's are the key to what made it come alive and a good EL34 like a EH works well. Just stay away from JJ's with a 900.
Click to expand...


I don't have experience with MKIII but replacing JJ tubes with TAD selected tubes (okay TAD is a distributor not a manufacturer but it's the 4th TAD set in my amp and the sound is pretty consistent) brought a big improvement of sound for me. With JJs my SL-X was dull, kinda "drowned". In my old Selmer T&B amp JJ tubes shine and they sound awesome in my bandmate's JCM800 anyway.
 
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Re: Alternative tubes for the JCM 900

My JCM900 had 6L6's and I never really liked the OD channel so ended up using clean channel with pedals. I was about to install new tubes in it but my mate suggested doing an EL34 conversion - difference in tone is amazing (used Svetlana 34's) - proper Marshall balls at last. I think he only had to change a few resistors as the JCM900 has an adjustable bias pot on the board. I'll find out exactly what component numbers he changed and post it when I can.
 
Re: Alternative tubes for the JCM 900

Anytime you want to put EL-34s in an amp made for other octal power tubes, you need to make sure that pin #1 is connected to ground, the cathode (pin #8) or raw bias. It's the suppressor grid and is internally connected to the cathode on most power tubes, but not in an EL-34.

Sometimes pin #1 on the power tube socket is used as a tie point for other components like grid resistors in some vintage Fender amps. That can make "bad things" happen if you sub EL-34s for 6L6s unless you move that tie point.

You may also have to change the "range resistor" in the bias circuit to get an effective range for EL-34s.

marvar said:
From Bob at Eurotubes:
Almost all of the 900’s that we re-tube locally leave with 6L6’s in place of the stock EL34’s. We always ask the owners if they would like to compare the tone of the JJ 6L6 with the JJ E34L or Winged C EL34. We don’t sell the =C=-’s because we like the JJ’s better but we keep them on hand along with every other brand for comparison purposes. I’d say 99% of the 900 players like the more balanced tone that the JJ 6L6’s provide. The KT77's are also a nice option because of their increased low end.
http://www.eurotubes.com
Click to expand...

[rant on]
Sorry bro' but this is marketing garbage. Bob doesn't sell anything other than JJ tubes. Of course he likes JJ tubes better - that's the only brand he sells.
[/rant off]

This is not to say that JJ EL-34s are worse (or better) than any other brand.

Chip
 
Re: Alternative tubes for the JCM 900

Fresh_Start said:
Anytime you want to put EL-34s in an amp made for other octal power tubes, you need to make sure that pin #1 is connected to ground, the cathode (pin #8) or raw bias. It's the suppressor grid and is internally connected to the cathode on most power tubes, but not in an EL-34.

Sometimes pin #1 on the power tube socket is used as a tie point for other components like grid resistors in some vintage Fender amps. That can make "bad things" happen if you sub EL-34s for 6L6s unless you move that tie point.

You may also have to change the "range resistor" in the bias circuit to get an effective range for EL-34s.



[rant on]
Sorry bro' but this is marketing garbage. Bob doesn't sell anything other than JJ tubes. Of course he likes JJ tubes better - that's the only brand he sells.
[/rant off]

This is not to say that JJ EL-34s are worse (or better) than any other brand.

Chip
Click to expand...

My point was that you can use 6l6 tubes in a 900= I don't work for Bob!
 
Re: Alternative tubes for the JCM 900

Marshalls LOVE the Shunghang 12AX7's in the pre amp! I have had NOS Mullards in V-1 then Shunghangs in the last few I have owned.
I absolutely LOATH JJ preamp tubes (dead dull and lifless they are!)but have had good luck with both the Rec tubes and the power tubes. The JJ-6L6 is tough as nails and one of the few that will live in a Fender Prosonic for any time running in the brutal class A mode.
I ordered both a pair of JJ EL34L's and a pair of Winged C SED's for my TSL 60 head. I wound up using the JJ's due to the meatier tone tighter bottom and better cleans.
 
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