Help With Mandolin Body Noise
 

Hi all.

I have a JJB installed in my mandolin, and I suspect that one of the wires is now making contact with the back of the instrument. Whatever the cause, there's a ~100hz thuddy sound when I play it.

Before I bother my luthier with this, is there any way I can fix this on my own? Tape? Some of those 3M cable routing things?

Thanks in advance for any advice.

Depends on how you installed it. If you have access to removing the jack you can tie a loose loop in the wire to take up slack. I put an acoustic feather in my F many years ago and was very careful with the installation. It's worked flawlessly for many years when amplification is required.

Is it internal mount or external? I had a lot of noise with external mount K&K and JJB pu's using a carpenter jack. Once I went all internal the noise went away. I'm sure on some of my installs (I've done around 15 or so, internal mount) a wire is touching the back or soundboard, but no noise issues.

Thanks, y'all.

It's internally mounted. Worked fine for a long time and then all of a sudden started with this weird body noise. I can't think of anything else it might be. I hugely prefer the sound of these JJBs on it to the Baggs mandolin pickup, which sounded super boxy to me, so I'm hoping this isn't an issue with the pickup. If I can't get this sorted, I may have to switch to an AT35 on it.

My guess would be something came loose if you didn't notice anything initially when installed. If the transducer mounting material didn't retain the transducer in the same manner that might be the problem. Can you inspect it with a mirror through a sound hole?

I would take a look inside, but also do the most basic troubleshooting of substituting parts of the signal chain. Next time it happens be ready with spare cables, spare preamp, spare amp, etc. Even when these p'ups get loose they're not very noisy. I mount them with low tack putty and it holds for years.

Have you changed anything at all? Bridge, strings, bridge position?

Hi Mandobart. It happens every single time I play and nothing has changed—and my chain is dead simple. Mando into PZ Pre into (submixing) mixer into FOH. I have zero stage volume (no amp, no monitor). I'm pretty sure my luthier superglued them to the top.

Edit: I should add that I run the same JJBs in a couple of banjos with zero trouble. I replaced the one in my main guitar because it had some very odd EQ humps that I found very unpleasant.

OK, after a couple more gigs, it was doing it with my banjo, as well. I'm wondering if something's not set right on my PZ Pre (both run through it).

Battery?
 

Hi Midwinter,

Is your pre-amp battery powered? If so, maybe the battery is almost dead and the signal is clipping. The banjo may have a hotter signal, which may be why it was ok for longer (the quieter mando had to be turned up more?). Just a hunch. Good luck!

Stan

The PZ Pre is the preamp. Both instruments use identical JJB pickups.

So I disengaged the PZB (the piezo buffer) and I think that's solved the problem.