Members Never_Grew_Up Posted February 13, 2005 Members Share Posted February 13, 2005 There's an article floating around HC about making a homebrew piezo pickup out of a Radio Shack or equivalent piezo buzzer element. I've made a few of these and been generally happy with the result. Definitely better with a preamp.Has anyone tried putting these on a grand piano? I'm doing sound for a production of Chicago and I'm thinking these would be less feedback prone than micing the piano from underneath since the piano player will have a monitor near his feet. Link to comment Share on other sites More sharing options...
Members Brad Harris Posted February 13, 2005 Members Share Posted February 13, 2005 You already have some right? No better way than to find out (I doubt many here have even built one). The best sound I've ever gotten once out of a baby grand (with the lid in the #2 position), was with an AKG C418, sounded beautiful, had all the lows, mids and highs balanced nicely from the reflection of the lid. The mic was on a boom stand, just past centre of the piano, 1/2 between the lid and the strings, about 1 1/2' from the hammers. Hasn't worked since! Must have been a blue moon! Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 13, 2005 Members Share Posted February 13, 2005 Many years ago, I manufactured and sold a line of acoustic instrument pickups and active DI's based on a similar concept (but with customized OEM piezo crystal blanks) and they will work ok on piano as well as guitar. Some important things to consider for maximizing sound quality: 1. The interface between the pickup and the piano's sound board is important. It acts as a filter, so different materials (adhesives) will sound very different. We used a calking putty (non-drying) that was removeable and cleaned up with low volitility mineral spirits like turpentine. 2. Different positions on the sound board will have greatly differing sound quality. I preferred closer to the bridge, and not in the middle of the sound board panel. Close to the pin block is another posssibility, mixing the two may be better. 3. You will need to use a high impedance input, around 500k - 1M. This is vastly higher than a typical mixer input. An active direct box will solve this problem. 4. The pickup's tonal response will vary with input impedance of the DI. Nothing you can do about this, but it's another variable. 5. The compound that you pot the back of the pickup with will also change the response of the pickup. we cast a thin coating of epoxy over the back in a dome shape, that seemed to be the best. It will also reduce the sensitivity, so it's a compromise between tayloring sound quality and output level. It's mechanical eq. Do you have a link to the project? Link to comment Share on other sites More sharing options...
Members Never_Grew_Up Posted February 13, 2005 Author Members Share Posted February 13, 2005 We're a public high school drama department, not a lot of website access. The piano lid will I believe be closed as there may be performers on it. (It's "Chigago" after all). I was thinking of putting the piezos underneath, but I could put them inside with a small diameter cable. I was thinking at least 2 pickups, 1 on the high end, 1 on the low. May 1 in the middle as well. I have an old Fishman model G beltpack preamp that I use with the other piezos I've mounted in guitars. I'm thinking of a small passive mixer in front of that so I can blend low & High (and mid if I use one there). I hadn't thought about potting the back with anything, but for something as potent as a piano, I don't think the loss in output level will be much of a problem, and the likely high end attenuation would actually be a good thing, thanks for the tip on that. Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 14, 2005 Members Share Posted February 14, 2005 They need to be in contact with the soudboard, not the lid. Link to comment Share on other sites More sharing options...
Members Never_Grew_Up Posted February 14, 2005 Author Members Share Posted February 14, 2005 Yes, I meant underneath the piano, not under the lid. Link to comment Share on other sites More sharing options...
Members Scodiddly Posted February 14, 2005 Members Share Posted February 14, 2005 I'm getting mighty interested in the repurposed piezo buzzer thing myself, so maybe I'll have some more stuff to share in a few months. In the meantime, I can tell you this much. Barcus Berry has a piano system, the 4000-something. I've got some serious beefs with the preamp/DI they include with it, but the pickup works pretty well. They claim that it doesn't respond to up & down vibrations on the soundboard, reducing feedback - so it gets side-to-side ("transverse") vibrations. The one that I use at the local folk club sits right in the middle of the soundboard*, and I modified the preamp for a higher input impedance. I still think it really needs a mic on the strings to sound good, but since a lot of the sound comes from the pickup there's still a lot less feedback than with just a mic. *Yahama small grand - 5 or 6 feet long? I found that things were a bit clangy with the pickup close to the hammers, a bit too dead close to the pin blocks. Right in the middle was the best compromise, especially since the default setup includes a couple mics on the strings. Link to comment Share on other sites More sharing options...
Members moody Posted February 14, 2005 Members Share Posted February 14, 2005 I've done it for bass (no preamp), I've been told it works reasonably on guitar, never tried it on piano. The epoxy idea sounds pretty good - when I've done it it was just wrapped in tape and wedged under the (tunematic) bridge. Link to comment Share on other sites More sharing options...
Members Terry Allan Hall Posted February 20, 2005 Members Share Posted February 20, 2005 Actually, we whipped up a homebrew set-up for a Yamaha Baby Grand (isn't that a contradiction of terms? ) that a buddy of mine has in his studio... We took 6 of these and daisey-chained them together, so we could spread them out about 6" apart, across the sound board...plugged into a good pre-amp (I think he's using an older Barcus-Berry unit), and then into the board, it sounds surprisingly "natural". Only problem, and he considers it very minor, is that it also picks up mechanical noises (the sound of the hammers moving, just before striking the strings, etc.), from the piano, as well...but a mic would probably do the same. Counting the BB preamp and a tube of silicone adherent, he's got about $25 invested into it...I'd think a similar set-up would work about equally well on a full grand. HTH Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 20, 2005 Members Share Posted February 20, 2005 The more pickups you use, the more the possibility of phase interference, like multiple micing. The sound board contains a lot of information which is co-mingled all over the surface. This may or may not be a problem. Link to comment Share on other sites More sharing options...
Members Scodiddly Posted February 20, 2005 Members Share Posted February 20, 2005 Originally posted by agedhorse The more pickups you use, the more the possibility of phase interference, like multiple micing. The sound board contains a lot of information which is co-mingled all over the surface.This may or may not be a problem. A while back I spent some time with a baby grand, a mic, and headphones. The sound of a piano is remarkably diffuse. I've been playing with the idea of a bar with mic capsules every few inches, for live use. Link to comment Share on other sites More sharing options...
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