Mook Posted April 22, 2014 Posted April 22, 2014 Hey all.... My MB fusion head has started making a weird buzzing sound. I thought it was a tweeter blown first but tried different cabs, leads, basses and the same with all of them... Used a different head and no weird buzzing noise. I'm guessing it's something electrical but thought I'd see if anyone's come across the same thing....I did a short YouTube clip... Hope you can hear what I'm talking about Buzzy bass head: http://youtu.be/w_0IL0SZZpY Quote
Phil Starr Posted April 24, 2014 Posted April 24, 2014 you are probably in the wrong part of the forum, repairs and technical would be better. Which Fusion is it, one with a valve or one without? Really hard to tell but if it was a conventional amp I'd look at biasing or at something overloading. You could try putting a signal into the effects in channel and seeing if the buzz disappears. If it does the power amp is OK. Alternatively you could take a line out into another amp, if the buzz remains it is before the line out and I'd be looking at a valve swap if yours has a valve. In the end you are probably looking at taking it to a tech I'm afraid. Quote
Merton Posted April 25, 2014 Posted April 25, 2014 [quote name='Phil Starr' timestamp='1398374141' post='2433573'] Which Fusion is it, one with a valve or one without? [/quote] Both the Fusion 550 and the MB Fusion have a three-valve preamp, there isn't a Fusion without valves The 550 is the big rack mount amp with old school power supply and amp, the MB is the Class D SMPS jobbie Quote
Phil Starr Posted April 25, 2014 Posted April 25, 2014 OK thanks, misread GK's website. It's probably still worth the OP trying to find out if it is the pre amp or the amp. If it is the pre amp then check the valve, if it is the amp it's probably beyond home fixes. The 550 will have large storage capacitors in it which could make it dangerous to poke around in, even when unplugged. I doubt there is anything user serviceable in the class D power amp which would cause this sound. I've never worked on a GK but no-one else answered so I thought I'd give my penny's worth. Quote
Merton Posted April 25, 2014 Posted April 25, 2014 [quote name='Phil Starr' timestamp='1398407106' post='2433725'] OK thanks, misread GK's website. It's probably still worth the OP trying to find out if it is the pre amp or the amp. If it is the pre amp then check the valve, if it is the amp it's probably beyond home fixes. The 550 will have large storage capacitors in it which could make it dangerous to poke around in, even when unplugged. I doubt there is anything user serviceable in the class D power amp which would cause this sound. I've never worked on a GK but no-one else answered so I thought I'd give my penny's worth. [/quote] Yeah sorry I wasn't really being very helpful to anyone was I?! Your penny's worth is always relevant and sensible advice so apologies for being facetious about a quite irrelvant part of your response Quote
Mook Posted April 26, 2014 Author Posted April 26, 2014 Thank you so much for that advice. It's really appreciated. It does have the 3 valve preamp so hopefully it's just one of the valves playing up. I'll do all the testing that you suggested Phil. Thanks again Quote
Mook Posted April 26, 2014 Author Posted April 26, 2014 I'll repost to the other repairs and technical forum too. cheers Quote
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