Hi Guys.
I have gotten back into messing around with piezo pickups after rejecting them a couple of years ago because I was unable to sufficiently isolate them -- they were too sensitive, picking up fingering and handling noise, etc. You know the story... Anyways, recently I built 2 instruments using the 20mm (2cm) diameter piezos that CB Gitty sells. To isolate them, I filled half a coke bottle cap with hot glue, letting it pool. After is cooled, I put the piezo pup in the middle of the bottle cap, and filled the rest with hot glue, making sure the piezo did not touch the edge of the bottle cap. Once that cooled, I applied a liberal dab of hot glue to the top side of the bottle cap and stuck that to the underside of the soundboard near where the bridge is located. I then added the jack, and finished up the two instruments. The result was two instruments (a CBG and a paddle box dulcimer) that have minimal sensitivity to fingering and handling (a BIG improvement over by earlier attempts), but the resulting instrument seems to favor the Bass side of the spectrum. So, I'm thinking that my method of isolating the pickup is causing the treble side to be attenuated (decreased like I was using a low pass filter). Have any of you experienced this? Do you have a work around (one that also allows me to minimize sensitivity to finger and handling noise)? By the way, my piezo pup isolation technique using the bottle cap is something I read elsewhere on CBN. I don't really want to have to pass it through an external preamp with equalizer to filter the lower (bass) frequencies and, in so doing, boost the high (treble) frequencies. I do have a guitar amp with 3 band equalizer. Turning down the bass, turning mid range part way up and turning treble way up only helps a little, but adds a lot of electric buzz to the sound coming out the speakers, so I usually turn it down. I'm not very knowledgeable when it comes to electric guitars, so any productive suggestions would be appreciated.
-Rand.
Replies
Similar to mounting the piezo on, or within a piece of wood added to the soundboard might just be something such as the bass bar and soundpost within a fiddle/violin.
...I've been off on a tangent, studying up on fiddles/violins, and they are fascinating!
What I have been studying just might apply to our piezo discussion, here.
A violin/fiddle uses a soundboard of tonewood, and a harder wood for the back and sides, for strength.
Upon that soundboard, a floating bridge is used, which has two 'feet' on it, that set atop the soundboard.
Beneath the treble side of the bridge's foot, slightly towards the tail, there is a post between the face, or soundboard of the fiddle, and the back. It is called the 'soundpost' or, 'soul post'.
It is critical in the tone of the instrument.
Also, inside the body of the instrument, beneath the foot on the bass side of the bridge, is a structural member called the 'bass bar'. It extends fore and aft of the bridge, and is just as important as the soulpost.
It occurs to me, that if these elements were incorporated in a CBG design, along with placement of the piezo, or combination of piezos, much could be done with influencing the tone of a CBG.
Best
rc
Hi Rusty Case,
Seems I've read a discussion on this before on CBN regarding the use of sound posts and bass bars, but I don't recall if there was a conclusion. Based on my personal experience in building sound boxes, almost any box I build sounds better than the average wooden cigar box. For a sound box I typically use a 5cm by 0.5cm length of wood (cherry or shapelli) that I typically cut as follows: two 9" lengths and two 6" lengths, So, I end up with a box 9" x 6" x 2". I use butt joints with corner post re-enforcement to strengthen the boxes. Then for the sound board and the back board, I use two appropriately sized pieces of 2mm thick plywood veneer. The resulting boxes always sound better than the cigar boxes I've used in the past, even the CBG I built this past summer in the States. My recommendation would be first to develop a consistently good sounding box design, and then experiment with that design to test the effectiveness of sound posts and bass bars. In my own designs, I wish I could find a 2mm thick hardwood back board which I think may improve the loudness of my instruments, as this is what Bob McNally does on his strumsticks (tm). He also uses solid tone wood (maybe spruce) for the soundboard. I don't want to reproduce the high pitch of his instrument, but making mine sound louder would be nice.
-Rand.
Here's a link to the discussion I was thinking of: Discussion of using bass bar and sound post on CBGs.
Maybe all further discussion of bass bars and sound posts should be posted there so as not to side track this discussion thread. Also, here is a photo someone posted showing what he did. You can probably find similar info by searching CBN using the keywords "bass bar" and "sound post". There are also a couple CBF (F for fiddle) groups on CBN whose members probably knows about these things.
-Rand.
Sure Rand, and tnx for the direction to that thread over there...
It seems they are primarily interested in 'unplugged', and I am most interested in implementing piezos without getting all the extra baggage of scratches and thumps in an excessive amount.
Oh well, orphaned again. :-)
Best
rc
I tested a clip-on piezo with my can-on-a-stick, and my can-in-a-stick. The clip-on has a urethane pad on it already, and with the amp gain turned up, pumps a lot of the clicks and scratches.
Then I tried a small bit of this 1/8" polyethylene closed cell foam sheet on either side of the clip.
All it does is prevent the high freqs from coming through.
Basically, a muffled tone.
NOT good! lol
I'm thinking it is the nature of a piezo to capture that high freq vibration caused by any movement on the surfaces of the instrument.
Perhaps the best step is to go with a magnetic pup if those are objectionable???
Best
rc
poly.jpg
mmmm, how about trying both methods together ,one enclosed in the foam(I found 1mm 'craft foam over the piezo directly under the bridge with strings pressing down gave a good deep tone- but i never tried another piezo to pick up the high tones. perhaps 2 vol pots or a blend pot -if you wanna get flash . it's worth a go . or of course get a couple of mag pups from Suntek for a few £...lol----chasing a specific tone could drive you mad .HAHAHAHAHA!!
I suspect you are on the right track, jabes.
A pair, or three piezos, each mounted differently, with an onboard mixer.
my samick uses an onboard active pre-amp with EQ that works quite well. the same device is available cheaply on the bay...
...composition, tone, style... that's what it's all about, right? :-)
Best
rc
gotta be worth a go Rusty, i did one rod piezo in the bridge,that worked pretty well but needed a preamp to 'lift' it a bit .
good luck, J
Rand-
Are you centering the piezo between the strings? Moving the pup to the treble side of the box might compensate for the loss you're describing. Also, I've had good success (is that an oxymoron?) using dual piezos wired in parallel, widely spaced apart and buried in hot glue, Your bottle top method might work even better doing that.
Best regards
Hi Habanera Hal.
On my CBG with the bottle cap & hot glue piezo pup, the piezo is placed on the treble-side of the sound board because that instrument was a neck-thru design w/o any special cutout for a neck-mounted (or neck-clearing) pup. Compared to my paddle-box dulcimer with its center-mounted piezo (located under the soundboard below where the bridge is located), there is not much noticeable difference in terms of treble response. It's a good idea, though. Maybe I need to reduce the amount of hot glue I use and try placing it on the treble side to see if that helps. That will have to wait until my next build with a piezo pup.
Also, if anyone is interested, "piezo pickup" in Chinese is "压电拾音器" ("yādiàn shíyīn qì") and it literally means "pressure-electricity pick up device"). This will come in handy when I search Taobao.com for piezo pups in earnest. And "Electric guitar single coil pickups" translates to "电吉他 单线圈 拾音器" ("diàn jítā dānxiànquān shíyīnqì"). They can also be had pretty cheaply on Taobao.com.
-Rand.
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