Extreme Feedback on my LPC '76

[triple6]

Hi All,

A while ago I posted a NGD with this beautiful black beauty from 1976

http://www.mylespaul.com/forums/norlin-years/338991-hngd-les-paul-custom-76-black-beauty.html

Now, the guitar plays great, looks nice - in a nutshell: I love her. There is only one thing about her, that is really annoying. Compared to other old guitars, like my LPC from 1980, she causes extreme feedback. It is true, that I play quite loud with a 100W stack, but I never experienced such feedback with any other guitar. It makes it not just difficult, but almost impossible to play with a loud stack, (which is a shame, cause this lady would need to be played loud).

As the PUs are the same like in my 1980 silverburst (t-tops) I dont really know what causes the feedback.

Should I shield with an additional grounding on the pots? (see pictures in original thread above)

Does anyone of you has an idea what I could check for or what I could do to make this disapear?

Thanks in advance!

 

[chasenblues]

.

 

[triple6]

Possible that your pickup's might be microphonic..
How much gain do you use?



Microphonic Pickups: Vintage or Modern Sounds?

It actually is much worse with high gain - and I usually play with gain with that stack.

 

[HardCore Troubadour]

I would bet microphonic....could be as simple as something (cover etc) touching....wax potting might fix it right up.

 

[69 Goldtop]

I would bet microphonic....could be as simple as something (cover etc) touching....wax potting might fix it right up.

 

[triple6]

Thanks for your info. The symptoms really look like microphonic. I will check if it also happens at higher volumes with lower gain. Because with clean and soft crunch they really sound very very nice - and I would think twice if I would be willing to change that clean / crunch sound of the PUs.

hmmm decisions, decisions...

 

[brianbzed]

get 'em potted......should fix the problem........worked for Eddie Van Halen....extreme volume and PAF's in his original homebuilt guitars...

 

[moreles]

One more vote for microphonic pickups, since the covers are still on. Had the same problem. Making sure the covers were soldered solidly, and repotting (I did a pretty careless job repotting, but it still worked fine) did the trick. At high gain, a PU cover can vibrate and work like a vocal mic, and that sounds like the story here. Good luck. Should be no biggie. Nice looking guitar!

 

[triple6]

Thanks to you guys!

Am I right in saying that potting the PUs will probably affect the current clean and crunch tone as well? Because I really like that tone (without gain) as it is at the moment.

 

[Zenatty1]

Thanks to you guys!

Am I right in saying that potting the PUs will probably affect the current clean and crunch tone as well? Because I really like that tone (without gain) as it is at the moment.

make sure the tailpiece/bridge is grounded! I had this problem on my '78 LPC

https://www.youtube.com/watch?v=ZrpcRxX8q1I

 

[HardCore Troubadour]

I don't see how it could NOT change the tone a little, because by the nature of what you are doing the vibrations of the windings will decrease a little...

is it really enough to be concerned about or to assume it will be a drastic difference?

I do not believe so....

talk to some of these guys....

Pickups - MyLesPaul.com

 

[Lucidsounds]

Try tapping the pickup covers with something non-metallic and see what that sounds like, that should tell you if it's microphonic or not.

 

[triple6]

Try tapping the pickup covers with something non-metallic and see what that sounds like, that should tell you if it's microphonic or not.

If I get you right - they should be silent when I touch the PU covers (if they are microphonic).

If the noise does not stop when touching the PU covers, it might be that something is not grounded correctly - eg the bridge.

Is this assumption more or less correct?




I am just a little irritated at the moment, - I had a look at the wiring again (see link above, there is a picture of the cavity attached), and I see there, that the pots are not grounded. Most of circuits I saw have grounded pots. Or are the pots grounded by the metal plate?

 

[HardCore Troubadour]

there should be a small channel for a ground wire to go to your bridge from the pots.

you can see it here on my 76 (it was NOT connected when I got it).

if it is not there just get you a small gauge ground, fish it through to the post hole and soldier to pot casing.

the other thing is you can run a wire across the top from the pot to the bridge...don't laugh, LOT'S of people used to do it.

Notice the red wire when I got my 76

BUT I had several people tell me that it lost a LOT of tone when I removed the wire across the top....

 

[69 Goldtop]

That ground wire should go to the stud for the tailpiece.Not bridge. FWIW
I jump all pots with wire on my players. Can`t hurt

 

[HardCore Troubadour]

correct, tail piece.

 

[triple6]

yes, sorry, tp of course.

I actually did check and the grounding wire is there (you can probably see it in the picture attached) - I still might need to remove the studs to see if there is a contact to the TP of if it maybe have lost its contact to the stud.

So chances are high that its the PUs that are microphonic

 

[HardCore Troubadour]

no need to remove them.....put a meter on it and take an ohm reading between the exposed wire and the tail piece.....if it reads zero, it is ok....if you get a resistance reading, there is a problem.