Building an acoustic guitar pickup

[David Schwab]

Well, the pickup goes out on a TRS, which terminates in an XLR, so I use that to plug into my mixer. Otherwise, I just plug the XLR into a Radio Shack line transformer, and go into my guitar amp or my effects pedal. I'm a little surprised at how loud it is myself, but the freak out peaks on my DAW don't lie, and my electric never does that. I set the input levels on two adjacent channels identically and there it is. Why isn't everybody into low impedance? I'm totally hooked--the touch sensitivity, clarity and dynamics of this thing just amaze me. Not to mention the fact that hand winding 400 turns took me all of 15 minutes.

OK, the pickup is louder than the Duncan, because you are plugging into a mixer. It's a low Z pickup. The mixer will load down the Duncan, so it wont be so loud, and it will be dull sounding. Same thing if you plug it right into a sound card. They aren't made for high z guitar pickups.

Try that pickup in a regular guitar amp without the transformer, and you will see it's not that loud.

I only asked because I've made a lot of low Z pickups, and they all required a preamp to use with a regular amp, but worked just fine into a mixer. As you noticed, you get a very clear uncolored tone from a low Z pickup.

[Clint Swank]

Yeah, but.....

Well, ok, you're right. I plugged the LoZ (with the line transformer) straight into my Fender and, yes, the Duncan is slightly louder. However, my next question is: Does a line transformer qualify as a preamp? Because the output of my LoZ , with the transformer, is certainly usable as is, though I will, actually, be running it through my pedal board. (Which does qualify as a preamp.)

But in terms of fidelity, there's just no comparison. My LoZ pickup sounds more like my Martin sounds, acoustically, than anything I've ever tried, and I've tried everything. Plus, it's way, way louder than the piezo it's replacing.

Which makes me wonder why LoZ isn't more universally adopted. It reminds me of the situation with independent suspension in American cars. American manufacturers were loath to abandon solid axles for many, many years because they were cheaper, and they assumed (perhaps correctly) that American drivers were morons who didn't care about handling.

I haven't seen a HiZ microphone in a professional situation since I was a teenager (ages ago). So why is HiZ still the sine qua non in guitar pickups? Is it just output? And why does that matter anymore, given the ubiquity of gain sources?

But back to my original question: How much difference will small changes in the number of turns make in the sound, output level, and the amount of noise ? You've obviously made a lot more pickups than I have, David, so, since there's a drastic difference in the number of turns (and the wire gauge) between Hi and LoZ, are we looking at a sort of fractal scale situation here? i.e: Do very small changes on the LoZ scale equal large changes on the HiZ scale?

[Clint Swank]

Thanks, that's a good one

Yeah, even when I had a piezo I was wondering how to do a string ground. The piezo had such a low output that I had to jack the gain astronomically, and the hum was almost equally loud--unless I held onto the output jack. Makes playing a little dificult.
So I'll order one of those puppies, though the hum is really pretty quiet, and my pedalboard gates it right away.

[David Schwab]

Well, ok, you're right. I plugged the LoZ (with the line transformer) straight into my Fender and, yes, the Duncan is slightly louder. However, my next question is: Does a line transformer qualify as a preamp? Because the output of my LoZ , with the transformer, is certainly usable as is, though I will, actually, be running it through my pedal board. (Which does qualify as a preamp.)

Try the pickup without the transformer into the Fender. That's the real output!

Yes, the transformer is boosting the signal. I discovered that back in the 70's when I ran my Rickenbacker 4001 bridge pickup through a mic transformer from a Bogan PA. I was shocked how much louder it was.

The Lace Alumitone and Transsensor pickups are low Z and use integrated step up transformers.

But in terms of fidelity, there's just no comparison. My LoZ pickup sounds more like my Martin sounds, acoustically, than anything I've ever tried, and I've tried everything. Plus, it's way, way louder than the piezo it's replacing.

Yes, it's a very wide and flat response. Hi-z pickups impart their own tone on the instrument.

Which makes me wonder why LoZ isn't more universally adopted. It reminds me of the situation with independent suspension in American cars. American manufacturers were loath to abandon solid axles for many, many years because they were cheaper, and they assumed (perhaps correctly) that American drivers were morons who didn't care about handling.

Les Paul has said this time and time again. But most of the early electric guitars and amps were high z, so that became the norm.

Also, a lot of people don't care for Les' tone... too bright and thin and hi-fi. Guitarists have gotten used to the tone of high Z pickups. The old Gibson Les Paul Recording, Personal, Signature, and Professional models had low Z pickups, as well as the Triumph and Signature basses.

Here's a web pages about them: Gibson Les Paul Recording guitar page

Alembic uses low Z pickups. The Epiphone Jack Casady bass (which is a reissue of the Les Paul Signature bass) has a low Z pickup, and a built in stepup transformer with different taps.

Low Z pickups need a transformer or preamp, and I guess some people don't want to be bothered.

I haven't seen a HiZ microphone in a professional situation since I was a teenager (ages ago). So why is HiZ still the sine qua non in guitar pickups? Is it just output? And why does that matter anymore, given the ubiquity of gain sources?

You can't run a long length of cable with hi-z mics.

But back to my original question: How much difference will small changes in the number of turns make in the sound, output level, and the amount of noise ? You've obviously made a lot more pickups than I have, David, so, since there's a drastic difference in the number of turns (and the wire gauge) between Hi and LoZ, are we looking at a sort of fractal scale situation here? i.e: Do very small changes on the LoZ scale equal large changes on the HiZ scale?

A small number of turns more might not alter the tone much. The more turns, the more output. I noticed the tone started to get fuller sounding with more turns. But I found a formula I liked and then stuck with that.

You can also experiment with different wire gauges. As the wire gets thinner, you get more pronounced mids and a tighter tone. This is true in high Z pickups as well.

bbsailor here posted a few really informative threads on low Z pickups.

[Clint Swank]

Humbucking Version

Latest version is a stacked humbucker. I was getting a bit of noise with the original single coil (especially apparent when recording), but I really loved the original junk pile single coil bobbin, so I built a second bobbin out of plywood. The magnets on the original bobbin are very long rods adjustable with even longer spring-suspended screws (which go right through the bottom of the lower bobbin.)
Ca. 375 turns of AWG 34, bobbins just taped together--voila. Impedance is around 600 ohms.

It sounds even better than the original and it's dead quiet.