Replies to This Discussion

Permalink Reply by Dan Sleep on November 5, 2012 at 5:59am

Here is a picture from a Telecaster forum:

http://www.bing.com/images/search?q=copper+lined+pickup+cavity&...

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Permalink Reply by ron carlson on November 5, 2012 at 6:12am

Thanks Dan! I may just be able to pull that off in one fashion or another.  

Just to clarify, Do I need to ground to that, or that and then the pot, or is it just shielding for the pickup?

Thanks,

RC

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Permalink Reply by Dan Sleep on November 5, 2012 at 6:24am

Ummm.. I am not totally sure if it needs to be grounded or not, but I think it does. You just want to be sure you don't inadvertently introduce a "ground loop", which is a condition where a signal is able to take more than one path to ground.

This is an example of what you want to avoid:

http://www.bing.com/images/search?q=ground+loop+guitar+wiring&v...

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Permalink Reply by ron carlson on November 5, 2012 at 7:01am

Hmm,.. All I'm doing is adding a volume pot into the mix between the jack and pickup. Nothing too elaborate. I have not had any issues with hum from Piezo's but this is my first go around with a Mag Pickup. I suppose I might have to experiment a bit.

RC

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Permalink Reply by ron carlson on November 23, 2012 at 4:08am

Back to this again,..

A few days back, I decided to go in and modify my existing bridge to lower the action a bit on the 3-stringer I built.  It was pretty much "quiet" before but did notice that I could drop a very slight (and I mean slight) background hum that I was detecting at moderate and higher volumes.  This would completely go away if I touched the pickup or the base of the jack cord. While I was at it, I figured that I would try grounding the strings by soldering a grounding wire to the bridge rod and ground it to the back of the volume pot.

This just made things worse and I'm not sure if it was lowering the strings so that they are closer to the pickup or the bridge/ string grounding I added.  Now when I palm mute on or slightly behind the bridge it's dead silent. The fireworks now happen when I'm not physically grounding the strings with my body.  In effect, my efforts to drop this very slight background hum that existed made it worse :)

I initially was going to solder to the jack ground lug but decided to solder to the back of the vol. pot where all my other grounding was located anyway. I'm thinking that this might has been a bad decision and actually have created a ground loop issue by doing this. No big deal opening it up again to re-locate the grounding wire to the jack ground lug but I lose a set of strings every time I open it up. 

Anyone care to comment on whether or not they think that moving the ground wire from the back of the volume pot to the Jack ground is going to fix this or am I chasing the wrong thing?

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Permalink Reply by Michael Cuell on November 24, 2012 at 5:23pm

You can get copper shielding tape pretty cheaply on ebay. You can also get slug tape from Lee Valley, which looks like the same thing.

Slug Repellent Tape

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Permalink Reply by ron carlson on November 25, 2012 at 3:38am

I suppose I'm going to have to give this a go. I've got a roll of Al. tape so hopefully using that will improve things. Isolating the pickup is going to be the hard part, though. It's not too difficult in a solidbody where the pup is sitting in it's own recess but a completely different thing in a CBG.

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Permalink Reply by Dan Sleep on November 25, 2012 at 3:42am

Can't you use the self adhesive copper tape, and just wrap the bottom part of the pickup with it?

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Permalink Reply by ron carlson on November 25, 2012 at 4:03am

I could do that I suppose but I would need to pull the screws that fasten it down in order to do so. I have it mounted to the thru neck inside the box and not the lid if that makes any sense.

I guess I'm still trying to understand what I'm trying to isolate the pickup from. I'm only working with a pickup, volume control and jack here and I haven't created a ground loop with my ground wiring that I can see.  My pickup is grounded to the back of the volume pot as is the jack. The only addition to that is the bridge which is also now grounded to the back of the volume pot in the same fashion.

If I "enclose" the back of the pickup and also ground to vol. pot it would be just more of the same I would think. <head scratch>

The thing I'm trying to understand here is if this is a grounding problem, a pickup isolation problem or if they are one in the same.  

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Permalink Reply by ron carlson on November 26, 2012 at 2:31am

This was going to be my next move but was hoping someone would drop by and confirm that it worked for them. It's not a big deal to move the ground wire but like I said, every time I open it up, I end up restringing it with new. I'm running out of string packs ;)

I'm going to give it a shot, Jim, and I will report back. Thanks.

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Permalink Reply by Mungo Park on November 29, 2012 at 5:31am

Ground the bridge, ground the foil, which ultimatly grounds to the jack and you should be good to go. If you are good then you should get a slight drop in hum when you touch the strings.

Ron

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Permalink Reply by ron carlson on November 29, 2012 at 6:15am

I went in yesterday and relocated the bridge ground to the jack (-).  Being a glutton for punishment and experimentation, I wanted to see where that would get me before going the foil tape route.

Got it re-strung up late last night and gave it a go.  Bingo!  I'm still getting a little noise when not palm muting but it's greatly reduced. I inadvertently discovered one thing that seemed to help also. Setting my amp gain higher and backing off the vol. control on the guit seems to help quite a bit also.

As we speak, everything is fired up with my guitar is sitting on a stand not even 2 from the amp and everything is dead silent. As weird as it sounds, I can play standing up in close proximity to my amp hardly get any hum and no feedback.  When I sit in my chair and play, I need to pay more attention to palm muting or I get a bit of unwanted noise.  

I'm now thinking my big comfy chair my be possessed by the debbil ;)

Thanks for all the help guys!  

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