EVH 5150 help !!!

jaysmith

I have a 5150 III and matching 2x12 cab. I have gigged this amp for 3 years, though not every week.
Last year i noticed a difference in the tone.
    I use mostly the blue channel and a lot of the gain seems to have gone from this to more of a mild overdriven tone instead of the higher gain sound it once had.
    Also, the amp doesn't have quite the volume it once had and the over all tone is more shrill or " spikey" sounding than it was before.... the huge bottom end in tone has also dissappeared from the amp.
    So, i went to a couple of guitar shops to play through brand new models of my amp and matching 2x12 speaker just to make sure it wasn't something i was imagining.
    They all sounded like my amp used to before the problem started.
The next thing i thought of was that the amp probably needed a service and valve/ tube change.
So i took it to a very well known and respected amp tech to take a look at it.
    He told me there was nothing wrong with the amp or valves/ tubes.
    When i politely asked what could possibly cause such an issue that i was experiencing he became quite rude and repeated that the amp was fine.
Although i certainly am not in a position to question his profession, i don't want to use his services again.
I am left not knowing what to do and don't want to throw away another £40 for somebody to look at it and tell me the same.
    It's a shame really, as i love the sound of these amps.

MattFGBI

It absolutely sounds like a valve related issue.  I'd imagine that one or more of them are past their best.

Do you have a spare 12AX7 or ECC83? You could try swapping it one by one with the ones in there to see if it makes a difference.  

Drew_TNBD

Dicky t00b.

Buy some 12AX7's and replace them one by one in the amp. Start with the 1st one and work your way through the set.

Question - Are the blue and red channels experiencing the same thing?

ICBM

You don't need a tech to fix this. As Matt and Drew said, buy one new 12AX7, and substitute it for each of the preamp valves in turn until you find the one that's causing the problem. It possibly wouldn't be completely unnecessary to change all of them, although I don't without identifying which of the old ones is faulty first. (It's just possible more than one could be, if they're getting old.)

You don't need to worry about biasing or anything like that with preamp valves. All you have to do is gently pull the old one out - a wiggling/rotating motion helps - and put the new one in making sure the gap in the ring of pins line up in the right place. You don't need to spend a fortune on valves either, the standard cheap Chinese 12AX7s for under a tenner are fine. (And quite likely what the amp has in it now anyway.)

jaysmith

Thanks for the advice folks. It's very much appreciated.
Tube/ valve replacement was what i thought too.
I mentioned that to the amp tech and he nearly bit my head off... his exact words were "LOOK !!! i've just told you there is nothing wrong with the amp or the valves" ... i can't understand how this person has such a high reputation at all... does he treat all his customers ( many of them famous guitarists) like this ?