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Quiet piezo's

Hello everyone, this is my first post here at CBN, although I've read through quite a few threads here.

Yesterday I decided to build some surface mount piezos for an archtop I have, the plan being to wire the output to the existing one so I could blend the transducers and the p90 already installed. My problem is while testing, ( soldered to its own output jack for test purposes) the pickups are VERY quiet, I had to turn my 40A tube amp up to 100% to get loud volumes out of them, they sounded fine but are unuseable due to this volume issue. Second test, I plugged them into a di box into garage band. Again way too quiet to be useable, even with all settings maxed. (not a good start) I used small disks inside on beer caps encased in silicone, audio cable from some old pedal connector cables, a 500k pot. Another test I did was to remove all insulation from the disk and I mounted it directly to the surface of the guit. louder. but still unuseable. Any sugestions? did I chose the wrong disks? wrong pot? any help could be VERY helpful on the matter. Thanks guys/gals.

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Permalink Reply by EzMac on April 14, 2013 at 2:43am

here is a photo of the pickup, (no insulation on the disks) and the disks I used, beside a dime for size ref. (10 cents canadain...)

Hope this pics work...

Attachments:

IMG_0313.JPG, 1.9 MB
IMG_0315.JPG, 2 MB

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Permalink Reply by darren brown on April 14, 2013 at 2:47am

a disk piezo noisey i find ,maybe a rod piezo under the saddle be the way to go .

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Permalink Reply by t-belly johnson on April 14, 2013 at 4:57am

A rod piezo is the way forward.I`ve used them alongside single coil pickups with volume and tone pots to good effect.No issues with volume but I would certainly copper foil insulate.

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Permalink Reply by Ron "Oily" Sprague on April 14, 2013 at 5:15am

Your issue, most likely, is that to play it properly (e.g., with sufficient volume) through a 40-watt amp ( or most any other amp) you need a pre-amp. You gotta boost that low voltage that a piezo generates just from string vibration bending the quartz crystal structure, to something the amp can work with. Most commercial gits that have piezos installed, even ones with rod or ribbon piezos directly under the saddle, have a 9-V battery-powered pre amp built into them, often as part of a combined tuner and EQ system. Pre amps are cheap. They can be sourced direct from China, or you can build your own. There are stomp boxes that can do this as well. There's likely nothing wrong with your discs (although you should make sure of your solder joints, just in case).

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Permalink Reply by Darren Wolbold on April 15, 2013 at 7:43am

It sounds quite odd as they usually but out quite a health signal and you usually ahve to dampen them abit

hot glue on the disk is good

Is there more than one pick up in there and how did you wire them ?

I guess they could be over damped

http://darrenscigarboxguitars.blogspot.co.uk/

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Permalink Reply by Skeesix on April 15, 2013 at 6:54pm

The closer to the bridge (where there is more downward pressure and string energy), the louder the piezo will get. Directly under the bridge or saddle would be the best spot.

An archtop bridge is a little different animal. I have an archtop I was experimenting with. I sandwiched two disc piezos in series between the saddle and the base with some cork. It seemed to work pretty well and be loud enough. You have to make the cork exactly the right height to allow some pressure on the discs. That particular archtop is acoustic, so I haven't tested putting it in a circuit with a regular pickup.

I was using typical Radio Shack piezos. Something that fits inside of a bottle cap sounds smaller than that? Where did you get the piezos?

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Permalink Reply by Brian Dechant on April 16, 2013 at 7:22am

Try a Tillman FET pre-amp. Google it for build instructions. You could either build it into the guitar (requires a 9v battery), or into a separate box, but in any case, blending with mag pickups may be difficult. You may want to consider a separate jack for the piezos to go to a separate amp channel.

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Permalink Reply by EzMac on April 16, 2013 at 2:57pm

hey folks thanks for the replys, I assumed (wrongly) that I didnt need a preamp,when using a firewire sound interface, as if that WAS the preamp. I will probably try and build a simple preamp next. These are my first builds, and Im having a fun time doing so. Also just curious, Ive seen acoustic guitar built in preamps, but as far as pedal preamps, is this one, I know its not the most reputable brand, but they are cheap. http://www.behringer.com/EN/Products/ADI21.aspx, thanks again!

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Permalink Reply by David McQueen on April 16, 2013 at 2:57pm

It sounds like something isn't right. Disc piezos generally have really good volume. I'm wondering if there is a cold solder joint or an almost broken wire. It is rod piezos that generally need a preamp with some gain.

When soldering, make sure your wires are pre tinned. You put a drop of solder onto the piezo disc. Then you set the tinned wire on the drop and put the soldering iron on top,of that until,the wire dropps into the solder drop. Then quickly remove the iron.

You have to be careful the solder does not go from the brass exterior to the white center.

The white center is your positive. Brass exterior is negative.

On preamps, with disc piezo they are more used for impedance matching than for gain. The discs are much higher impedance than a standard pickup. You get a much better sound.

The Tillman preamp is a classic. It only has 7 parts. You may have a problem getting the transistor for it locally. It is obsolete and not everyone carries it. There is also a quick and dirty preamp by Francis Deck. I have built this one and it works. I was able to buy all the parts locally. It only has 6 parts.