Acoustic Guitar Pickup

Step 2 Specifications:

Transducer Type: Piezo-electric
Transducer Size: 1.1"
Audio Range: 106 dB
Noise Level less than -111 dB
Output: 1/4" Female Audio Jack
Wiring: High quality shielded audio cable
Installation Time: about 1 Hour

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The first graph shows a guitar with my pickups installed vs. an Alvarez Yari 12 string (This guitar is a professional model and has individual pickups for each couplet of strings. That's 6 pickups in all), and a Fender Stratocaster. The Fender Strat. is included because it is known for its full vintage sound with professional pickups.

From the graph you can see that the Alvarez is the best due to its overall amplitude and trend. It does however seem to be somewhat inconsistant above 6.0kHz. The Fender electric guitar has a very smooth curve, but as you can see, the high frequency response is low and the overall amplitude is well below the Alvarez. The green curve shows the frequency response spectrum of my piezo-electric pickup installed on an inexpensive guitar. While the amplitude is slightly lower from .4 - 1.0kHz, it more than makes up for this by its great mid. and hi frequency amplitudes. It sounds great plugged-in and lets you turn up the amp pretty loud before giving any feedback.

The second graph shows the difference between our piezo pickup and a generic piezo pickup installed on a guitar.

The green curve on the top is my homemade pickup while the pink curve on the bottom is the spectrum of a generic piezo element. It can easily be seen that getting an element with good specifications is very important. The piezo element I chose has a fuller sound across the entire spectrum. Also notice that the generic pickup lacks smoothness.

This is why it is important to choose wisely from all of the parts at your local electronics store. Getting a piezo element with the specs above will help to get you on the curve we obtained from our pickup, making sure you get a full, rich sound every time you plug-in.

Comments

[asimmonds]

how many prongs is the 1/4" female supposed to have, 2 or 3?

[wobbler]

1/4" mono sockets usually have 2 or 4 connectors (one for the earth/body/sleeve, one for the live/tip). If they have 2, the earth/body (outer of a shielded cable) is theconnector closest to the nut usually. Sometimes they will have 4. This is when the socket is a switched mono socket and is used when you want the insertion of plug to swith something off, usually a speaker. In this case, there are only two which you would use and these are usually easy to spot as they are the ones which will be in touch with the plug when it is inserted, a little like two levers on top.

You can also use a stereo jack socket for a mono one (shown here: http://www.vhipe.com/product-private/Stereo%20jack%20plug%20socket.jpg). Stereo sockets usually have 3 connectors, the one closest the nut for the sleeve, the next for the ring and the last for the tip. To use this as a mono connector, simply either ignore the sleeve connection or connect the ring connection to the sleeve (both are ok and will work) and use the sleeve and tip connections as the earth and live connection.

[mrmerino]

Guitars are generally mono, so You probably need one with 2 prongs. I have an extra one from when I did this (my radioshack sells them in two-packs)

[Glockenator]

the number of prongs varies

[spark master]

can you put 3 of them in parallel (or series) so you cover more of the strings w/o a mixer circuit? My use is in a kalimba. I can make them on a box, the low notes are hard to hear, so after seeing a bunch of electric Kalimbas but on a piece of plank they are solid body and need amplification I thought this would be very very useful cause now I can get more tones.

thanks
Sparkie

[rbneville]

If you go to Parallax website they sell just the piezo film for $1.79 US and i believe it is the same type used in most commercial applications.

[ski4jesus]

Ok, i have a question, can you take a headphone speaker apart and find the piezo buzzer, reverse it and use it? or do you have to buy one? that would be sick if i could, cause i am greatly in need of being able to plug in my acoustic. :P

[mdgrover]

Headphones use dynamic (electromagnetic) speakers, not piezos. However, piezo elements are often used as speakers in small electronic toys - you may be able to find one inside one of those. If not, a new piezo will only cost a buck or two and they sound great.

[trebor_29]

Could anyone send me a link to a suitable buzzer, as I can't seem to find one with the correct specifications, thanks.

[FirstAttempt]

If you can't find a pizo buzzer element with 106db audio range, but can find others with lower and higher ranges, such as 96db and 115db, should you go lower or higher?

[adamkumpf]

For the buzzer, the db rating is how loud the sound will be when used as a speaker. If the internal circuitry and power was identical, a larger db rating would indicate higher efficiency (probably a good thing). I would imagine that there are too many variables (unless you are digging through detailed specification sheets) to know for sure from the db rating alone. If getting the right tone/volume is very important to you, you should probably try them both. Otherwise, you can use a rule-of-thumb that larger/thinner elements will have better low frequency response and smaller/thicker elements will give a better high-end tone.

[jmpearson]

Adam, This looks great; I'm going to give it a shot over the weekend. Question - what tool did you use to measure the freq response? I'd like to make the same kind of measurements and I can't afford the $20K Audio Precision system I used to use in my old career.

[adamkumpf]

Most audio editing software allows you to take the FFT and produce a similar spectrum. For example, the open source program Audacity has a Frequency Analysis tool under the Analyze menu. If you strum a large set of chords and record them on a couple different guitars you can probably get a nice relative comparison of their frequency responses (ideally, you would perform a uniform frequency sweep).

[eriklares]

wow, it really gives the companies a run for their money