software

I used the SEARCH button. The Iommi pickup in my Epi LP is great for high frequency feedback supression, but last night I found out that I can get a low frequency feedback (in the upper frequency range of an electric bass).

It almost seems as if the entire pickup is vibrating, as I can put some finger pressure on the pickup, and it stops.

Can the stock mounting springs be weak? Should I stuff the pickup pocket with spongy foam?

Thanks all, in advance.


Originally Posted by SludgenutzI used the SEARCH button. The Iommi pickup in my Epi LP is great for high frequency feedback supression, but last night I found out that I can get a low frequency feedback (in the upper frequency range of an electric bass). It almost seems as if the entire pickup is vibrating, as I can put some finger pressure on the pickup, and it stops. Can the stock mounting springs be weak? Should I stuff the pickup pocket with spongy foam? Thanks all, in advance.

Might be some grounding issues. Make sure that everything in there is grounded to the bridge wire (wire that runs under the bridge that helps everything be grounded to the bridge). If you have to, have it taken into a shop.

But honestly, there's always going to be a very small amount of feedback. Get a noise suppressor after you have the other problem fixed.

Thanks, but I needed to make myself more clear. This is an quot;acousticquot; problem. The bridge is grounded. The low howl I hear more on the order of a semi-hollow body howl. I have seen the inside of the control cavity, and the bridge wire ground wire is grounded.

does the feedback change/fade/grow when you walk anywhere? Feedback is subjective to your pickup's position to your speaker(s).

Also, have you tried turning down the bass freq. on your amp (or graphic EQ if you have one), since you say it's a quot;lowquot; feedback?

I think it could be weaker springs. Try bigger/stronger springs and see if that helps, and foam under the pickup couldn't hurt either. It's quite possible that the low end is just shaking the pickup and creating a loop. It SHOULD go away if you face away from the amp or walk across the room with the guitar.

Okay, here's what you have to do. You say that when you apply finger pressure on the pick-up the feedback goes away so what you have to do is keep constant pressure on the pick-ups to eliminate or at least suppress the coils from vibrating. This is done by filling the pick-up cavities with lots of foam. Enough so that you have to force the pick-ups back down in the cavity but not so much that you can't back away on the pick-up height if nesessary. I like to adjust my pick-ups as close as I can get away with it so that leaves plenty of room for lots of foam so you might want to try this as well.
It's a hit or miss type of thing when narrowing down the amount of foam needed so try it and let us know how it turns out.

If you have good quality pups that have been potted well, this will surely eliminate your feedback issues.

Frehley is right - I've had the same problem before on various LPs. Packed the pup cavity with foam (a hard foam - to really hold the pup tight) and it sorts it.