Amp making guitar pot scratch?

General discussion area for tube amps.

Moderators: pompeiisneaks, Colossal

Post Reply
matt h
Posts: 1224
Joined: Fri May 12, 2006 2:26 am
Location: New England

Re: Amp making guitar pot scratch?

Post by matt h »

(deleted)
Last edited by matt h on Fri Mar 27, 2015 4:02 am, edited 1 time in total.
Top
maxwedge
Posts: 12
Joined: Sun Mar 23, 2014 6:28 pm
Location: Concord, Ca USA

Re: Amp making guitar pot scratch?

Post by maxwedge »

Cliff Schecht wrote: Also why not place a DC blocking cap at the input? Somewhere around 0.022uF places your cutoff a decade below where the guitar even picks up (7Hz cutoff for an ~80Hz signal). I've done this on plenty of amps and it doesn't ever hurt the sound but it has stopped amps from shocking themselves (when someone is playing guitar and singing through multiple amps on the same power circuit).
I built a simple io box with the cap in it. It works great.
I built a JTM45 that causes the same problem and different tubes didn't help. Besides the scratchy guitar pot, switching pick ups on my LP made an awful snap sound!
I suppose I could put the cap in the amp.... :lol:
Scott
Top
User avatar
Ken Moon
Posts: 610
Joined: Tue May 08, 2007 2:41 pm
Location: Denver

Re: Amp making guitar pot scratch?

Post by Ken Moon »

Someone needs to sell a pedal with just a cap in it - you could call it the "Scratch Remover".

8)
Top
User avatar
Colossal
Posts: 5205
Joined: Sat Oct 20, 2007 9:04 pm
Location: Moving through Kashmir

Re: Amp making guitar pot scratch?

Post by Colossal »

Ken Moon wrote:Someone needs to sell a pedal with just a cap in it - you could call it the "Scratch Remover".

8)
Haha, brilliant Ken. You better patent that.
Top
Stevem
Posts: 5144
Joined: Fri Jan 24, 2014 3:01 pm
Location: 1/3rd the way out one of the arms of the Milkyway.

Re: Amp making guitar pot scratch?

Post by Stevem »

I put a cap off the input jack of every guitar I work on! My God it's like life insurance for less than a buck and when I think about it that blows my mind that a ant guitar you pay over 500 bucks for can't come with one!!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!

Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Top
User avatar
M Fowler
Posts: 14036
Joined: Wed Jan 16, 2008 2:19 am
Location: Walcott ND

Re: Amp making guitar pot scratch?

Post by M Fowler »

I started isolating all the jacks in my amps. Isolated input jack along with the B+ filter caps for the preamp to a grounding tab near input jack.

PI/filter cap, B+2 filter cap and B+1 main filter cap to separate grounding tab along with the CT's.

That has solved all the problems I've encountered with guitar buzz or hum.

I tried that cap off input jack and didn't get anywhere with that?
Last edited by M Fowler on Fri Sep 19, 2014 4:36 am, edited 1 time in total.
Top
User avatar
angelodp
Posts: 2157
Joined: Tue Jan 15, 2008 2:45 am
Location: L.A.

isolated jack

Post by angelodp »

Delete. No worries.

M Fowler wrote:I started isolating all the jacks in my amps with B+ filter caps for preamp to grounding tab near input jack.

PI/filter cap, B+2 filter cap and B+1 main filter cap to separate grounding tab along with the CT's.

That has solved all the problems I've encountered with guitar buzz or hum.

I tried that cap off input jack and didn't get anywhere with that?
Top
Post Reply

Return to “Technical Discussion”