#1
I don't know if this is the right place for this, I haven't been on the forums in a while. But anyway, I have a Crate Blue Voodoo BV60. It was a 1x12 combo I converted into a head/rackmount. Recently the sound began to fade in and out as I play, and it does it no matter how loud the amp is turned. Sometimes it will drop out completely. But it isn't abrupt, it fades out. The tubes are only a couple months old and I don't use it a lot so I doubt its them. Any ideas? I'm looking to upgrade so I need to sell it but i don't want to sell it broken and take a loss.
Call me Roche.

Quote by Dyers
wut is a luthier? im assuming it has to do with the luthern church
#3
Ahh, my amp has started to do this too, I was going to create a thread. My amp is too only a few months old. My guitar teacher said that it was probably going to be the power valves so I've just got some new ones. Once i find out if they need to be re biased I'm going to see if the replacement stops the problem.

So sorry if I jack the thread but, if I have bought the same type of valve (EL34) but different make (EH to JJ) does my amp need to be re biased?
Last edited by a_man at Mar 15, 2009,
#4
Quote by a_man
Ahh, my amp has started to do this too, I was going to create a thread. My amp is too only a few months old. My guitar teacher said that it was probably going to be the power valves so I've just got some new ones. Once i find out if they need to be re biased I'm going to see if the replacement stops the problem.

So sorry if I jack the thread but, if I have bought the same type of valve (EL34) but different make (EH to JJ) does my amp need to be re biased?



Your amp always has to be rebiased when changing power tubes, regardless of make or not.
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#5
Quote by kayman121
Your amp always has to be rebiased when changing power tubes, regardless of make or not.


OK thanks, Ill do that later once I've done this damned report! .
#6
I tryed a BV120 in the store when I was buying my amp and it was fine for a while then it started fading in and out. R they notorious for this?
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#8
Power tube is going bad.
Quote by MightyAl
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#9
Quote by kayman121
Your amp always has to be rebiased when changing power tubes, regardless of make or not.


Not if it's cathode-biased...
#10
Quote by Mitchell?
Not if it's cathode-biased...


How do I check if my amp is cathode-biased?
#11
^Do some searching on it, read the schematics.

TS: I second everyone else, you need need new power tubes.
I don't give a shit if you listen to me or not
#12
Quote by Kevin Saale
^Do some searching on it, read the schematics.

TS: I second everyone else, you need need new power tubes.


OK thanks.
#13
^also, if you told us what kind of amp it is there's a chance we'd know. Seeing that it runs on EL34s tells me it's likely fixed bias (in which case you would need to bias the amp) since most cathode bias amps seem to run el84s and 6v6s.
I don't give a shit if you listen to me or not
#14
Quote by Kevin Saale
^also, if you told us what kind of amp it is there's a chance we'd know. Seeing that it runs on EL34s tells me it's likely fixed bias (in which case you would need to bias the amp) since most cathode bias amps seem to run el84s and 6v6s.


Oh, sorry, it's a Randall RG50TC. Would it just be best to take it to a tech? I don't want to break anything but I have an OK understanding of some electronics.
#15
I'm 99 percent that amp is fixed bias. I don't know if it has an adjustment or not, you'll have to read up a bit. If you read up a biasing a bit and the amp has an adjustment then you can do it yourself with no more than a small flat head screwdriver and a multimeter.
I don't give a shit if you listen to me or not
#16
Quote by Kevin Saale
I'm 99 percent that amp is fixed bias. I don't know if it has an adjustment or not, you'll have to read up a bit. If you read up a biasing a bit and the amp has an adjustment then you can do it yourself with no more than a small flat head screwdriver and a multimeter.


Thanks, I'll get back to this at some other time.
#17
Ahh that's annoying that the tubes are already bad. But ok thanks guys i'll swap them out and see.
Call me Roche.

Quote by Dyers
wut is a luthier? im assuming it has to do with the luthern church