5150 bias mod

gbdweller · Jan 14, 2006

Has anyone tried the 5150 bias mod? I just completed mine and played out with it last night. Oh my god!...What a difference! The clean channel was alive and resembled a great sounding twin without the reverb. The lead channel was on fire with sustain and a ton of life in the tone. That annoying, sterile sounding 'buzziness' is gone. The parts cost me about $10.00 but the change it made was like getting a new amp.

6gun · Jan 14, 2006

gbdweller said:
Has anyone tried the 5150 bias mod? I just completed mine and played out with it last night. Oh my god!...What a difference! The clean channel was alive and resembled a great sounding twin without the reverb. The lead channel was on fire with sustain and a ton of life in the tone. That annoying, sterile sounding 'buzziness' is gone. The parts cost me about $10.00 but the change it made was like getting a new amp.

Ok, for 10.00 I'd look into it, or do you have to be a guitar tech also to get it done? Any more info is appreciated.

gbdweller · Jan 14, 2006

If you don't have electronics knowledge or skills, have it done by a tech. If you have the skills, check it out at www.fjamods.com . You can find the link to the description in the mods section of the the fja forum. Tube amps do have lethal voltage present even when the power is disconnected. The 5150 does have resistors that bleed off this voltage, assuming of course, that everything is working properly. The amp will have to be biased when the job is complete, and everytime you change the power tubes thereafter. Please don't attempt this if you don't know how or are unsure of your ability.

6gun · Jan 14, 2006

gbdweller said:
If you don't have electronics knowledge or skills, have it done by a tech. If you have the skills, check it out at www.fjamods.com . You can find the link to the description in the mods section of the the fja forum. Tube amps do have lethal voltage present even when the power is disconnected. The 5150 does have resistors that bleed off this voltage, assuming of course, that everything is working properly. The amp will have to be biased when the job is complete, and everytime you change the power tubes thereafter. Please don't attempt this if you don't know how or are unsure of your ability.

That's what I thought <takes screwdriver out of back of plugged in amp and places quickly in pocket>.

Thanks for the info though, I'll still look into it.