Question About JCM 900 SLX with 5881s

[Jeff5]

What is the difference between these and the ones with EL34 tubes? I'm thinking about picking up a used one but want to be sure I'm not getting a dog. What are 5881s? 6L6s? Not sure! Any help or experience with these would be appreciated. Tried Harmony Central, but most reviews don't talk about the 5881 model. Anyone know if I can get it rebiased to EL34s if I wanted to?

[STRATDELUXER97]

Re: Question About JCM 900 SLX with 5881s

The SLX was voiced specifically around the 5881 tube during a time where every EL34 being made was complete unreliable garbage...This was during the time that the Tesla EL34s weren't being made anymore...

The 5881s are good tubes...They are a smaller based military spec version of a 6L6 tube...Well way back when tubes were alot better,the 5881 was used as a more rugged version of the 6L6G....G stands for glass...

The 5881/6L6 tube generally gives you a rounder tone with more clean headroom and remains tighter at higher volumes..The EL34 compresses and loses it's headroom faster and this is also due in part to the EL34s skinnier bottle size....I'm comparing a Mullard EL34 to a Black Plate 6L6 RCA though...You can put your EL34s in the 5881 slot but you need to make sure pins 1 and 8 are tied together for the EL34s to work...You then need a rebias...This is techie stuff...

If you are wanting the british tone that only a Marshall does better than any other copy of a marshall,then that tone is based all around the EL34 tubes..

The 5881/6L6 tube is all about Fender/Boogie and the clean american tones..Think a nice warm and thick sounding BF Fender amp and that's the 6L6 tone...And this is a very generalized statement of course...

John

[Jeff5]

Re: Question About JCM 900 SLX with 5881s

John. That helps immensely thanks so much. I suppose I can always have it rebiased if I want EL34s.

[STRATDELUXER97]

Re: Question About JCM 900 SLX with 5881s

John. That helps immensely thanks so much. I suppose I can always have it rebiased if I want EL34s.

Yes you can use the EL34s,just make sure to hook up with a tech that knows Marshalls...If the output tube sockets aren't wired for EL34s(They probably are though) then you need to have the sockets rewired....If it is wired to use EL34s then you'll just pop the tubes in and have them biased or a possible bias resistor value change might be needed also...Pretty easy stuff for a competent tech to handle..

John