SlashUK

Hi All, this is my first post so any help greatly appreciated. I play for ukgnr (UK Guns N Roses (Formerly Bad Obsession) >> The Top Guns N Roses Tribute Band >> GNR, Rock, Music, Slash, Axl Rose, Duff Mckagan, Izzy Stradlin, Gilby Clarke, Matt Sorum)) and have had my 1988 (Black & Gold) 2555 for 5 years and it has sounded great with my 1979 gold top (seymour duncan jazz) and my 70's tweed 4x12 loaded with Celestion G12H 30w's.

About 12 months ago the amp went reallt thin with no tone. I sent it off to marshall who changed the valves, valve bases and the mid pot, and it came back sounding great. I used it for 1 show and it sounded awesome but the day after that i tried it again in our practice room and it sounded thin again plus volume was now waving up and down, so sent it back to them. They changed Input jack and return loop jack, output transformer and impedance selector. The guy at marshall said it was an intermittant fault with the impedance selector that did not show up first time on the bench.

It now runs constant but still sounds like crap through the cab, seems like the tone is really flat with no bottom end and harsh tops and there is too much distortion even at low gain settings. I've renewed the pickups and had a re-wire on the guitar, so its not that. I'm wondering now if the speakers in the cab may be knackered?

Any ideas please cos im absolutely gutted!!!!

Adwex

Lots of things have been changed, difficult to tell what the problem is. I wouldn't lose any sleep over it, I suggest you send it back to whoever worked on it. Replacing the output transformer I'm sure was expensive, I'd bring it back...or to someone else.

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timstoel

There is an extremely high chance that the resistors around the output tubes are intermittently changing values. This is a very common problem in high powered amps. The resistors get heated and cooled many times over their life. If the bias feed resistors shift in value, you would get exactly the problem you are describing. I'd start there.

Tim

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RagnarMarGunn

Hi,

Was the amp fixed before it went on Ebay?
The discribtion is somewhat different when it comes to sound quality then in this thread!!:
Marshall JCM 2555 Silver Jubilee Slash Amp - No Reserve - eBay (item 140272500725 end time Oct-13-08 06:16:09 PDT)

Ragnar

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'66-'67 Marshall JMP 50W 1986 with GZ 34
Non Marshall 4X12 with '71 Greenbacks
Non Marshall 2X12 custom slant
'90 Ibanez Jem FP77
2007 Epiphone LP Custom with EMG