Author Topic: Guitar Amp Tech Question (Read 311 times)

SirLoin · « **on:** April 28, 2006, 07:02:19 AM »

i know there are quite a few jammers in this forum,i got a problem with my guitar amp and would appreciate any advice.

i got a Kendrick 4212 80w tube combo amp and i took it in to get re-tubed after 14 years of nothing but great sounds...The store i bought the replacement tubes from recommended this "Wild Bill" guy to do the job.(sounds simple enough..retube & bias)

Well this guy talked me into "modding" the amp by disconnecting the ground on the amp and converting the ground switch to a toggle for the prescence knob/negative feedback loop...Apparentley this will "juice" the amp...Said i don't need a ground unless i'm playing in a 100 yr old barn up north.

i get home plug it in and now there is a very loud annying hum that wasn't there wasn't before...i try different cords/guitars/electrical outlets(even ran an extension to bathroom breaker outlett)...Plugged into my peavey 4x10 50w and nice & it's quiet.

Q:is it safe(or legal) to disconnect a ground switch?...I've heard of guitarist's getting electricuted(eg..Keith Richards)

aztec · « **Reply #1 on:** April 28, 2006, 08:02:03 AM »

Everything else aside Sirloin you said you had 14 years of great sound and now humming...take it back and have ol Wild Bill un mod it. ~~Old friend, az~~

Waffle · « **Reply #2 on:** April 28, 2006, 11:08:03 AM »

Any idiot that disconnects the ground from from an amp should have to play with that amp outdoors on a wet stage with a PA system tied into a 400 AMP power service....and then step up to the mic and touch it with his mouth while he tries to sing a note...

That buzz you now have is a direct result from the ground being removed.

Golfer · « **Reply #3 on:** April 28, 2006, 11:19:11 AM »

Quote

Originally posted by Waffle BAS
Any idiot that disconnects the ground from from an amp should have to play with that amp outdoors on a wet stage with a PA system tied into a 400 AMP power service....and then step up to the mic and touch it with his mouth while he tries to sing a note...

That buzz you now have is a direct result from the ground being removed.

I like the tingle...it reminds me of the time I spent in a Soviet prison. Soviet prisons are good. Soviet prisons are good. Soviet prisons are good...

LEDPIG · « **Reply #4 on:** April 28, 2006, 12:11:59 PM »

I'd say you unmod that thing, although i been playing different amps here and there both home and on stage i've never had a problem with grounding but that first problem might be your last problem. Besides you really don't want a guy named Wild Bill modding your amp do you? Haven't you heard how many times Van Halen blew up his amp and almost killed himself. If you want a hotrodded sound just get a hotrodded amp get one of those Krank amps i understand those things are beasts!:aok

nirvana · « **Reply #5 on:** April 28, 2006, 12:39:05 PM »

Put a head of on it, or get something with a little more power if you want earthquake sound. Otherwise take it back.

SirLoin · « **Reply #6 on:** April 28, 2006, 01:09:11 PM »

Found the problem...he replaced the power tubes but not all the preamp tubes and one of them was toast..Runs silent now(except when i crank it to 12..eat that Spinal Tap!)

In talking with Wild Bill he said the amp was still grounded through the plug,but the ground switch on old amps(or handbuilt replicas) essentially do nothing...Well it does something now..holy cow!!! It disables the presence knob but sounds like someone taking a blanket off the amp.

Unlike Blackface twins,this thing starts to breakup at 3 and riding the guitar's volume pot is the thang.Really great Texas tone now~!(and holy cow is it loud!)