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Under the saddle rod piezo disappointment...

Hey all,

I recently completed my first CBG and decided to try a rod piezo under the saddle -vs- using the disc type glued in the box somewhere. From all I read, the under the saddle pickup was the way to go. However, I'm pretty disappointed in the sound.

Did some more reading and discovered that if I'm plugging into a standard electric guitar amp, a piezo "buffer", or preamp is a good thing to have, so I whipped up a little J-FET, impedence matching, buffer with only marginal improvement . OK, it's easier to drive the amp, but the sound really lacks depth and is shrill, sharp, scatchy, clacky... just generally unpleasant.

So I'm thinking to myself that maybe, just maybe, something is amiss with my pickup or wiring, so I do a little experiment and stick a disc piezo to the box with a gob of Silly Putty and run that directly into my little buffer and into my amp. Wow, what a difference - now it sounds more like what I expected. If I use double sided foam tape to stick the disc to the box the sound improves even more. Hmmmm....I then had a Eureka! moment - could it be that my rod piezo is just fine, but it's more likely the relative placement to the string terminations?

You see, I'm using a home-made tail piece to terminate my strings and the saddle is only about 1.5" away from the tailpiece. Is it possible that there's too much pressure on the pickup and that's why the sound quality is surpassed by the lowly, hastily applied, disc piezo?

Before I cut into the box and glue in some discs (yes, the box is glued shut) , I thought I'd run my theory by you all. What do you all think? Did I screw up with my basic geometry?

Oh, but wait, here's the interesting part... took the CBG to my local Guitar Center to test drive some amps in it's current configuration... although it was well received visually, it had that same nasty, shrill, scratchy, clacky, sharp, unpleasant tone... that is until we plugged it into a $360 Fishman Loudbox Mini ACOUSTIC amp, then and only then did it sound friggin' amazing - very much like a nice amped acoustic guitar. Do these amps have a lot of filtering and signal manipulation to deal with this? I mean it was a whole different guitar and the one guy played it for 20 minutes and I stood there in awe.

Sorry for the long post, but I'm really lost here - please, somebody, show me the way to CBG nirvana.

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Replies to This Discussion

Permalink Reply by jawbone on September 29, 2013 at 9:59am

Hey Joe - I find that one piezo, disc or rod, sounds pretty harsh. I usually wire one rod, in the bridge, in parallel with one disc embedded in the neck. I haven't experimented with more than two but what I am going to try on my next build is two rods, parallel in the bridge.
Now, take everything I say with a grain of salt (or oz of scotch) since I don't have a lot of experience.

The last build I did, I embedded the disc in the neck with caulking then covered it with a chunk of plastic so that the license plate would imprint but not stick, parallel with the rod, plugged it in and WEAK, almost no sound at all - I was stumped as that had always worked before, so I messed around and finally changed the disc. The caulking was still wet!! So I'm not sure if the wet caulking shorted things out but when I changed to foam tape - SCREAMER!!!

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Permalink Reply by Clock The Wolf on September 29, 2013 at 10:05am

In another photo of that build it looks like the tailpiece is retaining the strings at or close to the same height as the top of the bridge saddle. Shouldn't the strings be higher at the bridge than at the nut and where the strings are retained? Maybe it's just the photo...

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Permalink Reply by Joe Webster on September 29, 2013 at 10:34am

Thanks for the replies so far guys - if it helps, here's another shot of the bridge & tailpiece.

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Permalink Reply by jawbone on September 29, 2013 at 4:13pm

Just another thought - If the amp that sounded good was meant for an acoustic guitar I wonder if it had some kind of pre amp built in to help with any impedence issues?

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Permalink Reply by Shawn on September 29, 2013 at 12:47pm

The saddle must be as flat on the rod piezo as possible for the vibration to transfer for max output. I made the same error my first time as well. If they are not tight it don't sound right.

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Permalink Reply by Randy S. Bretz on September 29, 2013 at 12:54pm

My basic rod bridges...1/8" wide slot ..you want the rod to be snug in the slot. 1/8" wide bone saddle also snug but not tight in the slot. You want the pressure of the strings pushing down on the saddle -down on the rod.

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Permalink Reply by Randy S. Bretz on September 29, 2013 at 12:56pm

My custom rod bridges.

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Permalink Reply by Randy S. Bretz on September 29, 2013 at 1:07pm

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Permalink Reply by Jim Woods on September 30, 2013 at 2:13am

Joe,

That is a nice looking Ciggy Box you have there.

The rod piezzo needs direct pressure of the vibrating string to work - ie between the saddle and bridge, with the saddle free to vibrate onto the rod.

The disc works from the vibration of what it is attached to. I get much better response from the rod myself. Your description of the "nasty, shrill, scratchy, clacky, sharp, and unpleasant tone" pretty accurately describes my disc piezzo builds. :-)

I did find attaching the disc w/ double sided foam tape under the bridge toned them down a little... maybe you can try externally mounting one on the top by the bridge to see if it gives you a better sound before you start the surgery to get it inside?

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Permalink Reply by Randy S. Bretz on September 30, 2013 at 3:25am

I found over years of experimenting with disc piezo`s the best way I can get them to sound great is to embed it in hot glue in a bridge on top of the box. In my all bone carved saddle bridges they sound awesome. I`ve sold many worldwide through the years with no bad comments from other builders. I carve the bridge out of cow bone and carve a chamber underneath where I place a cut 41mm [1 1/2" diameter] piezo disc. A blop of hot glue press the disc in wait a bit and fill the chamber up with glue.