Replies to This Discussion

Permalink Reply by rusty case on September 29, 2012 at 2:09am

Thanks for bringing this subject to the forefront, Rand.  I've just begun to experiment with pickups and piezos and will post my observations of attempts here.  My own goal would be to include some degree of percussive capability, and not lose the high end of the scale, as you mentioned.  A piezo should be 'brite', yet not over-sensitive, IMO.

Sounds like ETB has an idea, with the piezo placed in a thickened section of wood within the soundbox.

Best

rc

Permalink Reply by Jantan ux on September 29, 2012 at 9:05am

Natural cork is great. Cork under piezo kills screaming and screeching high frequencies. Brings more low frequencies.

 

Permalink Reply by Rand Moore on September 29, 2012 at 2:19pm

Hi All,

Thanks for the suggestions.

To dj.xsusb:
I have no problem with low frequencies. With the bottle cap and hot glue approach I get plenty (too much) bass. What I'm looking for are ways to get the isolation but without loosing much high (treble) and mid-range frequencies. I think for canjos, cookie tin banjos and similar instruments, the bottle cap and hot glue approach would be good, since those instruments have too much treble to begin with, But with an instrument designed around a wooden box, this type of piezo isolation results in an instrument that's too bass-y IMHO. If I can find some cork, I'll see if it is any better than the bottle cap and hot glue approach.

I'm also going to give Ellwood T. Bear's approach a try. I've used wood isolation before, with foam rubber, but the sensitivity was not isolated that well. But maybe following Elwood's construction method and using silicon seal, it might prove the right approach. I need to score a few more piezos pups, first. I'll need to find a source here in China. Wonder how you say "piezo" in Chinese...

Thanks again.

-Rand.

Permalink Reply by frank tennyson on October 28, 2012 at 6:24am

I use a source in Thailand. If you want me to send you that info let me know and I'll send you the info. They are cheap, but the shipping is very slow - three weeks to a month.

I use two piezos with two volumn controls so I control each pick up separately. I place one under the bass and one under the treble. The bass is further away from the bridge and the treble as close to under the bridge as I can get it. Both encased in Balsa sandwiches and glued to the underside of the top of the box. Both piezos are soldered to the jack. I adjust the volumn of the pickups before they are sent to the amp. I have thought of using tone controls as well but have heard this does not have much effect on piezos?

Permalink Reply by Habanera Hal on September 29, 2012 at 2:39pm

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

Permalink Reply by Rand Moore on September 29, 2012 at 8:50pm

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 jí​tā​ dānxiànquān shíyīnqì"). They can also be had pretty cheaply on Taobao.com.

-Rand.

Permalink Reply by Keith Stanford on October 2, 2012 at 7:22pm

Howdy Rand -

I have had similar experiences with Hot Glue = too much bass.

I made two very similar CBGs.

On both of them I placed the Piezo on top of the box directly under the strings and just in front of the Bridge.

(I then drilled a hole into the box for the wires to connect with the Jack wires.)

On one of the CBGs, I glued the Piezo to the box with Hot-glue 'only' on the bottom of the Piezo, i.e. to stick the Piezo to the box. No glue was placed on top of the Piezo.  I hid the Piezo by super-gluing a concave metal disk over it.  This disk was twice as large in diameter as the Piezo, so the Piezo did not touch the disk.  The sound on this CBG is very good with no unwanted extraneous finger sounds.  And no excessive bass.

On the second CBG, I again glued the Piezo to the box with Hot-glue....but on this CBG, I used Hot-Glue to glue the concave metal disk over it.  So basically, the Piezo was completely encased with Hot-Glue.  Again, this CBG had no unwanted extraneous finger sounds.  But........it indeed had excessive bass.  The only way to compensate for that extra bass was with the amp controls.

It'll be November before I can get back to making some more CBGs, but at that time I'll do some more experimenting and report back to y'all.

Kind regards,

kieta

Permalink Reply by Rand Moore on October 3, 2012 at 4:37am

Hi Kieta,
Thanks for the feedback. It seems to confirm my findings. So, I'll have to try your "minimal hot glue approach" and super-glue some kind of cover/casing over it. Maybe a larger bottle top like one of those off a fruit juice bottle. I'll let you all know how this works. Will have to wait for my next build.
-Rand.

Permalink Reply by rusty case on October 3, 2012 at 7:18am

Many thanks to Rand and KS !  Really valuable information to have in advance when contemplating a more advanced build than I am presently fabricating !

It might seem to me that the soundboard is transferring the harmonic vibration to the piezo transducer.

Any excess flexible adhesive must be dampening the higher level tones.

Perhaps the transducer might perform acceptably if placed upon the underside of the soundboard, in that same location, where it might not be necessary to place a cover over it ?

I'm still learning about diddley bow and canjo construction, but look forward to building the more complicated instruments.

Best

rc

Permalink Reply by Keith Stanford on October 3, 2012 at 4:46pm

Yes, Rusty, I would recomend that the Piezo be Hot-Glued to the underside of the SoundBoard, (i.e. place it inside the CigarBox).  That way, it is hidden and no need to place any type of cover over the Piezo to hide it.

My purpose of putting the Piezo on the top of the CigarBox was that I was trying to place the Piezo directly under the strings and directly in front of the Bridge.  That would be difficult to accomplish when the Piezo is placed inside the CigarBox, as the CBG Neck extends down the middle of the inside of the CigarBox.  Hence, the Piezo would need to be placed just to the side of the Neck, and would not be under the strings and not in front of the Bridge.

 

Just to throw another concept into the discussion here, I understand that some folks glue the Piezo to the Neck instead of the CigarBox.  I wonder how that works out for them?

 

Great discussion here on this topic....I hope others will share their experiences on "Piezo Location Placement", and results.

 

Stay tuned....

kieta

Permalink Reply by rusty case on October 3, 2012 at 5:00pm

Yes.

I guess a good option here would be to enlist a geek with a sillyscope and see what the picture says with the piezo mounted in a number of different positions, and using varying methods, along with trying multiple piezos...   to cover all the angles!   :-)

Best

rc

Permalink Reply by Keith Stanford on October 3, 2012 at 5:13pm

rc - Then that would take all the fun out of experimenting and tryng to come up with our own 'best' Piezo location. <grin>

 

I am guessing that that every CBG will be slightly different as the CigarBoxes are all different in size and how they are made.

 

As easy and inexpensive as they are to make, I plan on making 'many' and trying a lot of the techniques and ideas that are posted here on CigarBoxNation.  The ones that end up sounding "really' good will end up in my personal collection.  The others will be 'gifted' to my kids, relatives, friends, co-workers, strangers, etc....

 

kieta

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