#1
alright so my two modules were perfectly fine before i swapped out the power tubes in my randall to EL34s, then after biasing and letting the amp warm up for a few minutes, i played the 'Brown' module and it sounds great, but the 'clean' module is really farty and sounds like the volume's quivering. if i hit the strings harder the volume increases (obviously) but sounds like the notes are trying to break up, but not in the nice tube-like way. instead they fart out and sound like a SS amp turned up to high.

maybe it's just coincidence that it happened after the bias, could it be preamp tubes? the power tubes are brand new.

thanks in advance for any help.
My MAIN Gear
____________
"They call him the 'Sand Spider.' -Why? -Probably because it sounds scary"
*Agile AL3000 Les Paul w/ Alnico IIs
*Randall RM50
*Dunlop CFH
*fellow LEO feel free to give a shout out
#2
yeah definetly sounds lke a bias problem...get it done or do it urself....it ll sound good after biasing trust me
#3
well i don't understand why the dirty module wouldn't be having similar problems...it's only happening in the 'clean' module. the preamp tubes are fine cuz i swapped them to check. unless it's just a lot more noticeable in the clean channel when it comes to a biasing problem.
My MAIN Gear
____________
"They call him the 'Sand Spider.' -Why? -Probably because it sounds scary"
*Agile AL3000 Les Paul w/ Alnico IIs
*Randall RM50
*Dunlop CFH
*fellow LEO feel free to give a shout out
#4
look man if the bias is ****ed it ll simply add some abnormal/nasty clipping....you just wont realise this clipping on the dirty channel because its already clipping into distortion.

on the clean channel you get a pure unclipped tone from your guitar and the bias problem is just sending into that nasty clipping sound you hear...dude if you changed the tubes without biasing its gonna sound like that...just get it biased.
#5
^yea sorry i went and put it on the 'brown' module and lowered the gain to a clean sound but it still did the nasty clipping and volume quivering.

and i attempted to bias myself, but my multimeter i borrowed from my friend reads in Volts, not mV, and the last number never shows up on that POS, so i need to go get a new one from radioshack or something.

so i suppose that prolly made the bias way more than it needed to be.

thanks for the info though, sounds like you were spot on.
My MAIN Gear
____________
"They call him the 'Sand Spider.' -Why? -Probably because it sounds scary"
*Agile AL3000 Les Paul w/ Alnico IIs
*Randall RM50
*Dunlop CFH
*fellow LEO feel free to give a shout out
#6
yeah no...either get a new multimeter that you can count mV or then get if fixed...personally learning to do it is a useful thing.
#7
^i agree wholeheartedly. i tackle all my mods and problems/fixes myself, and i was sure that this wasn't an impossible task even for my limited electronics knowledge.
My MAIN Gear
____________
"They call him the 'Sand Spider.' -Why? -Probably because it sounds scary"
*Agile AL3000 Les Paul w/ Alnico IIs
*Randall RM50
*Dunlop CFH
*fellow LEO feel free to give a shout out
#9
My MAIN Gear
____________
"They call him the 'Sand Spider.' -Why? -Probably because it sounds scary"
*Agile AL3000 Les Paul w/ Alnico IIs
*Randall RM50
*Dunlop CFH
*fellow LEO feel free to give a shout out
#10
final update: purchased a good multimeter and biased it correctly, no more farty sound.

that's my good news for the night, my amp is finally a british EL34 powered monster!! can't wait to crank this sucker!!!!
My MAIN Gear
____________
"They call him the 'Sand Spider.' -Why? -Probably because it sounds scary"
*Agile AL3000 Les Paul w/ Alnico IIs
*Randall RM50
*Dunlop CFH
*fellow LEO feel free to give a shout out
#11
Quote by georgakis187
look man if the bias is ****ed it ll simply add some abnormal/nasty clipping....you just wont realise this clipping on the dirty channel because its already clipping into distortion.

on the clean channel you get a pure unclipped tone from your guitar and the bias problem is just sending into that nasty clipping sound you hear...dude if you changed the tubes without biasing its gonna sound like that...just get it biased.



...You can hear crossover distortion when there is already preamp distortion

Example: stock 5150...5-15mA per tube = fail
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#12
Quote by slash_rocks2005
final update: purchased a good multimeter and biased it correctly, no more farty sound.

that's my good news for the night, my amp is finally a british EL34 powered monster!! can't wait to crank this sucker!!!!
How did you bias your amp? Did you have to remove it from the chasis to access the bias trim pot dial?
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