I just put together a nice little barn wood CBG and I used one of the Teisco pickups because it looks great on this CBG. This one is a resonator and I did it like I always do with a three way switch and a piezo also.
This time the whole box went super microphonic. I disconnected the piezo and it was still there. Has to be coming from the Teisco. The sound from touching any part of the instrument is louder than the PU output by far. So I'm wondering, are these potted, did I get one that wasn't? Are there other explanations?
I saw that Wayfinder wrote a nice review of these and didn't mention anything like I'm getting so I'm thinking it's not just the pickups but something I screwed up, but the wiring is simple and I can't guess what it might be.
If I can't make this PU work or find another the same size I will have to trash the box and it is beautifully aged with two nice knot holes for sound holes so I really don't want to loose it.
The vintage / Japanese gold foils aren't wax potted. Pretty sure the modern 'acoustic sound hole' gold foils aren't potted either. I used to scavenge pawn shops for Japanese pickups back in the 1990's. They do vary a lot as to how microphonic they are.
I have a vintage one I'm going to use on a resonator, but I'm planning on it being right up at the neck over a solid part of the guitar to avoid microphonics.
GFS / Guitar Fetish gold foils are potted, they have p-90, humbucker and strat sizes. Likely the P-90 sized one would cover your route and still give you some gold foil classiness and be far less prone to noise. If the humbucker would cover the route, you'd get even less noise.
Also; PICS PLEASE. :)
If you've ever taken apart one of these modern Chinese acoustic soundhole pickups you'll see the coil is not even wound onto a bobbin and it's simply wrapped in tissue paper, it's a crazily crude way of making a pickup, but it works, and it's also going to contribute to them being microphonic.
Put shielding tape in the box and run a ground wire to the bridge ground. Can't solder to aluminum tape if you go with that, so you'll need to use a screw instead to hook the ground wire and shielding tape. Copper tape for guitar shielding can be expensive, a cheap alternative is copper "slug tape" found in garden centers or online which can be soldered. There's also Cavity Shielding Paint.
Another option is to make a small box around and under the pickup simulating a solid body pickup cavity to reduce the feedback or line it with shielding.
Shielding is good practice and great for minimising hum and RF interference but will do nothing to reduce feedback. Feedback problems are caused purely by soundwaves generated by a loudspeaker acting on the strings and the guitar causing them to vibrate sympathetically and generating an increased electrical signal, but there's no relationship between feedback and sheilding/grounding issues.
True about not doing anything about feedback, but most cases of reported feedback problems have a lot to do with RF problems or at least half of the problem.
Have a 60's MIJ semi-hollow body guitar that came with unpotted single coil pickups. If that guitar was within 3 feet of the amp it would squeal like Ted Nudgent was in the house, which was good sometimes. Once it even picked up CB radio chatter. I lined the inside cavity with shielding and got rid of half of my problems. Later those pickups were put in a Poplar solid body guitar that sounded great and had no problems at all, which is why I mentioned the small cavity like box around the pickup.
Humbuckers/double coil pickups don't have those problems. I've made it a practice to shield the cavity or inside the box on anything with single coils regardless of the pups being potted or not just to be sure.
Wayfinder, reducing feedback isn't the reason for manufacturers using pickup covers. If anything metal covers increase the likelihood of feedback because if the possibility of introducing another vibrating element into the pickup assembly...well, that's what Seymour Duncan reckons anyway.
Thank you all for all the good thoughts and info. This thing isn't feeding back, just amplifying every touch or movement of the entire instrument just like a piezo does but way louder than any piezo I've used. I agree that that can be a nice sound, but this is over the top. I got busy for a few days but will pull the pickup out and have a look inside. I'm thinking some hot glue in there might be a quick fix. If not I'll look at making something else fit with a bit of a frame if needed.
Really appreciate all the ideas. Will get pictures out pretty soon. I'm trying something new and making four at a time. It's been really good for me to, say, make four necks in a row. I'm getting a lot quicker and surer in my cuts that way.
Thanks again to all.
What you've got is a microphonic pickup. Don't put hot glue in it, that won't penetrate into the coil...it may help a little by stoping it jiggling around, but look at wax potting it if you want to seriously try to reduce the microphonic effect. There's plenty of info on how to do it out on the web...whether it's worth the time and effort is another matter. Again, shielding it is good practice but it won't affect the pickups tendency to be microphonic.
Yeah, I was hoping that the jiggling was most of it but you're right, if I have it apart I might as well pot it.
You don't need to open up the pickup to pot it.
Yeah, but I do want to do a close inspection. Might be some piece of factory junk floating around in there. I'll post if I find anything unusual.
this may be a dumb idea, but does it get better if you hold the resonator's diaphragm with your hand/fingers?