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CB Gitty..now what about these piezo sizes?

I'm scanning your online catalog and seeing 20mm/27mm and 41mm piezo sizes. What are

the differences..are there any differences tonewise?

Also..you show a 250K pot and a 500K pot. I have used a piezo tune-o-matic bridge on my homemade

Les Paul types and the volume control supplied by LR Baggs is 5 meg ohm. Piezos are high impedance

devices according to my understanding and tube amps have typically 1 megohm input impedance.

Now a 500k for a humbucker pickup or 250k for a SC (single coil) sounds right, but I would think

that if the piezos are wired directly into a volume control, it should be around 1megohm at least.

Am I correct in this assumption?

What about wiring the two piezo's in parallel. Someone stated that two piezos will sound louder than

1 piezo or two wired in series. Again this appears to be the result of the transducer's very high

input impedance.

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Permalink Reply by Ben "C. B. Gitty" Baker on October 19, 2010 at 9:23am

Carverman - the opinions on this stuff vary widely depending on who you ask, and I don't claim to be the grand oracle on any of it. I can just tell you what I have perceived to be the "average" take. Some guys say that the larger piezos have better volume and bass response, other people say there's no difference. Personally, I think there may be a bit of difference but that your placement and mounting method are MUCH more important than the size of the piezo. I cover all of what I consider to be "piezo gospel" in a two-part article on my site: http://www.cbgitty.com/content/view/34/43/

As for the pots, my understanding is that anything from 250K up through 1M will work. 500K tends to be seen as a good middle-of-the-road and is used by a lot of people in their builds. If you want to get 1M pots though, go right ahead.

I have heard mixed reviews on multiple piezos. Some say that you should ALWAYS wire in parallel for best results, others swear by wiring in series. My understanding is that wiring in series raises the impedance.

As with all of this stuff, the best advice I can give you is to get the different options and try them out for yourself, so that you can get a feel for the differences and find what works best for you. There is no one set rule for CBG electronics, it is about finding your own special blend that makes the sounds you want it to make.

Good luck!

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Permalink Reply by Reverend Hellgood on October 19, 2010 at 6:41pm

Carverman, the good doctor sends his regards.

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Permalink Reply by carverman on October 20, 2010 at 1:58am

Reverend Hellgood said:

Carverman, the good doctor sends his regards.

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Permalink Reply by carverman on October 20, 2010 at 2:03am

Thank you "good doctor/Reverend" for your warm welcome and kindest regards.
I'm finding out a lot of factual information on this site that will make my first CBG build,
not only a unique woodworking project/art form, but a lesson in satisfaction with the
results vs expectations. My first build will be a mini-Diddley 6 string.
There are a few challenges for me already, and I expect some more, I'm sure.

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Permalink Reply by carverman on October 20, 2010 at 2:08am

Ok, I do have a 5 meg control left over from my Les Paul piezo t-o-m bridge build. I will try
using this and a 1 meg that I can get from Stew-Mac, as I need to get some other things from
them as well. I like your 3 pack piezo deals.

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Permalink Reply by carverman on October 20, 2010 at 2:09am

carverman said:

Thank you "good doctor/Rev Feelgood" for your warm welcome and kindest regards.

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Permalink Reply by MichaelS Country Boy Guitars on October 20, 2010 at 2:43am

As far as 2 in parrallel that is how I use them and to me they don't sound louder, just better to my ears and they reduce the feedback from the amp, I don't know how, it just works. I use 2 of CB Gittys 20mm piezos.

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Permalink Reply by Roy Alderman on October 20, 2010 at 4:48am

Wow, carverman - a 6 string for a first build? Quite ambitious. I mad a shitload of mistakes on my 1st two 3 stringers - but then again, I fly by the seat of my pants and do not plan extensively like a lot of the CBG guys here. Good luck with your build! BTW - I use 20mm piezos from CB's and they always sound surprisingly good to me.

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Permalink Reply by carverman on October 20, 2010 at 9:03am

Roy Alderman said:

Wow, carverman - a 6 string for a first build? Quite ambitious. I mad a shitload of mistakes on my 1st two 3 stringers - but then again, I fly by the seat of my pants and do not plan extensively like a lot of the CBG guys here. Good luck with your build! BTW - I use 20mm piezos from CB's and they always sound surprisingly good to me.

No problemo Roy. I have several 6 string guitars, been playing since '65 and have made 3 unique
design Les Pauls (neck through design) with acoustic wings, humbuckers, fretting my own,
and different woods. I usually put together a "Method" ahead of time, (step 1 do this,step 2
do this..etc) so the machining process
in my woodshop/carving room does not end up with one machining operation interfering with
another. Yes, there is the odd little mistake, but nothing that can't be undone with a little
woodworking engine-nuity.
So you use 20mm piezos..you know, I'm gonna get me a 3-pack of 3 different sizes and
see what develops when it's time to install them. I like experimenting with different
types of pickups, so this will be fun doing A/B comparisons on the different sizes.

Personally, I don't think there is going to be a lot of difference in the spectral response
but maybe I will be pleasantly surprised?

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Permalink Reply by carverman on October 20, 2010 at 9:12am

MichaelS said:

As far as 2 in parrallel that is how I use them and to me they don't sound louder, just better to my ears and they reduce the feedback from the amp, I don't know how, it just works. I use 2 of CB Gittys 20mm piezos.

Well if the soundboard vibrates and creates pressure on one, and you get a electrical
a/c signal from that which represents those vibrations, then
two in phase... should add more electrical signal. The impedance lowering is
another thing that
I can't quite understand how it works on piezos. It' certainly works that way on
copper wire pickups.
Ohms law I suppose..if you take two resistors of equal value (10Kohm + 10kohm)
the net result
measured with an ohmmeter is 5kohms.
The current splits down both paths and half goes through each resistor but the
voltage drop across both is the same. Piezos transducers are probably another math equation..but
I would think they should work in a similar fashion.

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Permalink Reply by Reverend Hellgood on October 20, 2010 at 10:15am

I know Carverman from a few other guitar forums. If there's any one that can pull it off, it's him. His guitar building skills are top notch. He's being modest. His custom built guitars are outstanting.

Roy Alderman said:

Wow, carverman - a 6 string for a first build? Quite ambitious. I mad a shitload of mistakes on my 1st two 3 stringers - but then again, I fly by the seat of my pants and do not plan extensively like a lot of the CBG guys here. Good luck with your build! BTW - I use 20mm piezos from CB's and they always sound surprisingly good to me.