why is my amp acting up??

[rashayritto]

Hey guys,
I run a Livewire Metal pickup through a boss GE-7 and then into my 5 watt valve jr head. The cab is the one made for the head with an Eminence Lady Luck speaker. I was playing earlier today and noticed that when i have the volume fully cranked, the amp sorta craps out on the higher registers of the B and G strings.

i figured it was my tubes to i changed them out. Now the same problem arises but it has spread to power chords played on the A and D strings. It sounds almost like the amp is being "overloaded" or something. Though i've NEVER had this problem before. Under normal use i have the amp on full and use the EQ pedal for a boost or tone change when needed. I also changed the batteries for my pickup.

can anyone tell me whats going on? is it my speaker? if so, why am i having the problem just now?

 

[Dr.Mavashi]

Re: why is my amp acting up??

Did you check the guitar for fret buzz when its completely unplugged?

 

[rashayritto]

Re: why is my amp acting up??

yeah my guitar is set up perfectly. what happens is when i play say the 14th fret on the B string, it sounds really choppy and broken at first and then eventually the sustain sounds normal. the strange breakup effect doest sound musical. it almost sounds like major fret buzz too. i'm really scratching my head over this.

 

[d1dsj]

Re: why is my amp acting up??

Have you tried a different cab?

 

[muttonchopsrule]

Re: why is my amp acting up??

this could be kind of a tough one to diagnose. when i was building a kit in the past, i had similar symptoms upon firing it up and couldn't figure out what the cause was. after rebuilding the entire circuit 3 times over thinking i had wired something wrong, my master volume pot turned out to be faulty and wasn't passing signal as it should.

with that said, i'd start by cleaning your jacks and tube sockets with some contact cleaner. if you have a meter, test for all your pots for the right resistance and make sure you don't have any bad solder joints or bad grounds.

beware of high voltages too! don't poke around in there unless you know how to discharge the caps and a meter to verify that they don't have any voltage still stored in them!