Diagnosing Acoustic Pickup Buzz

[hessodreamy]

I've got this Simon & Patrick acoustic guitar with a b-band new frontier pickup system. A few years ago it started making a terrible buzz. so it sounded 90% buzz and 10% signal. A local guitar tech got out his multimeter and concluded that the pre-amp was fried.

I finally got around to replacing the pre-amp, but the same problem is still there. So I'm trying to figure out a diagnosis myself before I make any more unnecessary purchases like the pickup itself. Any suggestions as to how I go about this?

The pickup is a thin electret film that sits under the saddle. This is wired to the preamp, which has connections to the output jack and the battery.

Any suggestions?

[Ripthorn]

I would say take the output directly from the film pickup and see if there is buzz there. If so, the element is either fried, wiring is frayed, or some other problem with it. If not, there is an issue between the preamp and output jack.

[Ripthorn]

Run the signal to an external amplifier as opposed to the onboard preamp.

[hessodreamy]

Run the signal to an external amplifier as opposed to the onboard preamp.

Ah right - I get you.

OK I tried running the pickup straight into a guitar amp. Didn't really get a signal, but didn't get the nasty buzz like before (more like the hum from holding thinly covered wires).

Then I plugged the pickup into the on-board preamp and took the output straight from there to the guitar amp. I'm not sure I was doing this right because 3 of the 4 output pins are used - 1 ground and 2 to what looks like a stereo output jack. SO I tried connecting the ground and either of the 2 output pins. Still no signal, but a bit of hum. Still no further forward.

Then, while manipulating the wires, I noticed that pulling the wire to the pickup makes the signal toggle from nasty buzz to low-level hum - all without any guitar signal.

I reckon the pickup (or the pickup wiring , which is all closed in) is screwed. Sound about right?

[hessodreamy]

Still looking into this and found something else.

Like I said there are 3 pins from the preamp to the output jack. The output jack looks like a stereo jack in that it has a shield and 2 pins. I can't see what's going in inside the jack itself.

The 3 connections are electrically separated, but when I insert the lead into the socket the ground becomes connected to one of the pins.

Any idea if this is supposed to happen? I presume the output isn't supposed to be stereo, so this 3 pin configuration isn't one I'm familiar with.

Thanks

[KeithHowell]

A stereo jack is used to switch power to the on board pre-amp by breaking/making the ground when inserting a standard mono plug.

From what you have described I would say the socket is wired correctly. Inserting the plug should switch ground onto the ground of the pre-amp turning it on.

It is a standard wiring configuration for most onboard electronics and stomp boxes as well.

Keith

Edited April 5, 2011 by KeithHowell

[hessodreamy]

It is a standard wiring configuration for most onboard electronics and stomp boxes as well.

Thanks for the clarification. Now that I've ordered a new pickup I'm glad to hear it's not the output jack that's dodgy.

I guess this also explains why I got no output why connecting the output of an electric guitar via this output jack?

[KeithHowell]

I guess this also explains why I got no output why connecting the output of an electric guitar via this output jack?

!!???

Why would you connect an output of an electric guitar into the output of your acoustic guitar?

Keith

[hessodreamy]

Why would you connect an output of an electric guitar into the output of your acoustic guitar?

I was trying to check that the output jack works correctly. So I hooked it up directly to the pickup on my electric. It didn't work.

But my new acoustic pickup turned up yesterday and everything works great now. Except I have an extra pre-amp I didn't need to buy!

But thanks for your help, guys!