I need some amp help

[adrianlee]

Ok, this is kind of a gripe/bitch session as well as a place to get input from all who understand the technical side of amps (as I honestly do not).

I have a music man HD130. I love this amp. It might be the most ideal amp for me. Got for super cheap at Guitar Center for $250+tax during the summer of '10.

At some point the amp started to crackle, fizz and pop to an unbearable point...I figured it needed retubed/biased and MAYBE a cap job. I finally get around to taking to a tech (I'd been using my Twin until now) and the cost to get all of the work done (tubes, biased, cap job) comes to $310. OK, a little steep IMHO, but, the guy did numbers on mauerkraut's SVT (something two amp techs couldn't figure out) so, I went ahead with the job. $310 later, I get a call stating my amp is finished. I storm on over to his place after work $310 in hand with a huge grin on my face. I call him, he comes down with my amp (he didn't let Vin, er, mauerkraut play his amp either, so, i assumed all was well), we chit chatted a bit, i handed him cash and we were off. He was telling me about how hard it was to find parts for my amp, how long the job took, etc...

RIGHT at the end of the conversation, he mentioned that he biased with an 8 ohm load and he asked me what i used (4 ohms). I ASSUMED that it wouldn't be a large problem....

I get to my studio with mauerkraut and begin to play and it sounds (at all volumes) completely fucked up (like a fuzz being super choked out gated fuzz--Albeit, we love fuzz, but, I want a CLEAN amp).

I proceed to call amp tech and he tells me that I'm going to need new transistors and that they're very rare and that's the reason for my amp sounding like this (it never sounded like that before, all it did was crackle and pop, not sound like a gated fuzz).

SO, what went wrong? What happened? Am I getting taken for a ride here? Shouldn't a cold bias fix this problem? Why was my amp clean before with the transistors that were already in it? Please, help.

[Hybrid]

Is it some random guy? Or a legit business? Get your money back, either way.

If he fucked up a piece of YOUR equipment, doing the OPPOSITE of what he was hired to do, he should not get paid.

[Ironbird13]

so, the amp was set to 8Ohms and you ran a 4Ohm cab?
if so thats a dangerous mismatch and might have blown something (its safeish to run a higher load cab but not a lower load)
when you told him you were running a 4Ohm cab he SHOULD"VE changed it then

[sonidero]

This is from the webs... It's the ohms issue... ^

you are seriously overloading the amp!
if you did the same thing to a transistorized one it would be toast in the first 5 minutes of use
i don't know for sure how you have got away with this for so long but you are asking for trouble
increase the resistance in the output load by running 2 *4ohm speakers in series [amp+out to speaker1+, speaker 1- to speaker2+ speaker2- to amp-out]

or 2 16 ohm speakers in parallel [amp+ out to speaker 1 and 2 + amp- out to speaker1 and speaker2 - out]

good luck
Andy

[Ironbird13]

if you did the same thing to a transistorized one it would be toast in the first 5 minutes of use

Andy

?? i thought solid state amps where alot more forgiving of mismatch?

[sonidero]

Not sure, makes sense... I just copied that out of another thread from Mesa Boogie... I'm not Andy, probably should have cut that out...

[dubkitty]

have the tubes been properly burned in? new tubes need to be run for at least 12-24 hours at full power before being used. tubes that haven't been properly broken in will sometimes sound fuzzy and gated.

in any case, i'd go back to the guy and in a calm and cooperative manner explain that i'd spent a lot of money on the assumption that i'd get equivalent results to my friends' SVT, hadn't gotten same, and expected that the tech guy would do the right thing and correct the problem if i gave him the opportunity to do so. sometimes techs fumble when dealing with amps that aren't typical--you should have seen the fun i had getting my Electar Tube 10 worked on!--and they're usually going to want to work it out. he doesn't want bad word of mouth, and you can use that.