New tubes for silver jubilee 2555x? Preamp tube help:

[usablefiber]

Hey guys, my silver jubilee reissue has been sounding bad lately, very tinny and sort of like the low and high frequencies aren’t blending together right. Not pleasant. I’m thinking to try retubing the preamp tubes, I got the power tubes new and serviced about a year ago but a many years Since I replaced the preamp:

I know on the jcm 800 100 watt my tech used to give me a different tube for slot 2 than 1 and 3, saying it was more stressful on the tubes I believe.

I was wondering how the preamp tubes are arranged and used in tbe 2555x, and if there was a recommended order or type, and also what people recommend for new 12ax7 in slot one to get the best tone. I was thinking of getting a JJ 12ax7 or maybe a tung sol, but I know the names and labels are misleading these days.

Any suggestions or info would be appreciated, thanks guys!

 

[Pete Farrington]

on the jcm 800 100 watt my tech used to give me a different tube for slot 2 than 1 and 3, saying it was more stressful on the tubes I believe

Dunno about the x version, but the 2555 doesn’t have that V2 direct coupled cathode follower DCCF circuit used by 5F6A tweed bassman based amps, which puts voltage stress on the valve’s heater insulation.
So other than the usual requirements of good gain, and low noise and microphonics, there’s no particular constraints or considerations, try which valve brands you fancy

https://el34world.com/charts/Schematics/files/Marshall/Marshall_25aniv_silverjubilee_50_100w_2555.pdf

 

[JTM1963]

2555 and 2555x have the same topology..
If it sounds like you descibe it doesn´t sound like just a preamp tube issue.
I run RTF ECC83 NOS in both my 2555 and 255x and they both sound great.
They used to be reasonably priced but as with all NOS are getting harder to find and prices are rising.
Get som current production tubes and see if they make a differenece.

 

[Kuga]

I use 7025 EH on V5 and V6, TAD PI on V7( preamp valves). V1 to V4 are power tubes. Like JTM1963 said could be a preampvalve.

 

[JacksonCharvelAddict]

Mine sounded really weird and it was just the bias being set incorrectly from the factory. Sounds much better now.

 

[PentodeLicious]

I Have this recipe in my 2555X and It sounds glorious:
V1- ENGL shuguang 12AX7
V2- ENGL JJ ECC83
V3- Mesa Boogie JJ ECC83

you can get unbranded versions as well.
The new JJ ECC83 are great. the shaguang 12AX7 have much more variations in performance between each one.
Also Harder to find since they are not made anymore...