Replies to This Discussion

Permalink Reply by BrianQ. on December 7, 2019 at 10:46pm

You could do it either way, but if you stack them , you would have to insulate the back of the top one, right?

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Permalink Reply by Jeff 'Bones' Reilly on December 7, 2019 at 10:46pm

I place mine one under the bridge area and the other under the neck area so I guess side by side .. Hope that helps Rat . 

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Permalink Reply by Cause the Blue rat on December 8, 2019 at 12:59am

Thanks folks!

Yes BrianQ. I'd have to insulate between them. 

Jeff. I wasn't sure if folks kept them together. Of how far apart they could go. 

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Permalink Reply by Taffy Evans on December 8, 2019 at 8:29am

Hi Blue rat, the piezos surface has to have a good firm contact with the vibrating surface to work efficiently, the sensor piggy backing the other would not respond well to top vibrations. Insulating  them apart would further decrease efficiency. I have not tried it but that is my understanding.

Taff

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Permalink Reply by Cause the Blue rat on December 8, 2019 at 9:25am

Thanks Taffy. Having to insulate between the two would farther dampen it's response. 

I commented on another post on how I will never get that awesome CBG sound out of a quality pup. I have a one pickup guitar build that is glued together but not set up yet. The only good spots I can reach would be directly in front or behind the bridge. 

The back of the guitar is 1/2 plywood. There's less than a 1/2 inch of space between the old door wood and face of the guitar in front of the bridge. And access behind the bridge is tight. Because of the jack support block. That piece of ply marked "E". Yes I mark each piece as it's cut now. Keeps me from cutting a piece out of an already cut piece. Real good at doing that. :) The only other step I'll need to do is drill a third hole for the piezo volume knob. Both pup types will be wired for independent operation so I wont need a switch.  

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Permalink Reply by Taffy Evans on December 8, 2019 at 10:31am

Hi, in the acoustic six string guitars I build the piezo sensors ,three in total, are recommended by the manufacturer to go under the saddle in between strings 1-2, 3-4 and 5-6 glued to the bridge plate. So the area you mention for your guitar should be good.

Taff

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Permalink Reply by Cause the Blue rat on December 8, 2019 at 12:47pm

Thanks again Taffy. Any idea of the impedance of three piezo in a row? I was going to slap a Duncan Vintage rail. After getting the idea of finally using piezo the pickup will be the middle pickup from the Fender 69's that'll go into the body I just cut apart. It's output imp is only 6.5. 

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Permalink Reply by Taffy Evans on December 8, 2019 at 7:34pm

SorryBR, I'm not into that sort of info, can't help you there.

Taff

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Permalink Reply by Cause the Blue rat on December 14, 2019 at 10:09am

Thanks Taffy. Don't sweat it. Been all over the web looking for info. Haven't found a single direct answer. Yes I understand that an 8 ohm speaker actual ohm reading depends on the frequency going through it. The average is 8 ohms. For a piezo? Not a strait answer or average anywhere. Plenty of charts with lots of X's and Y's. But with no value given to a single one of them. All you end up with is badly spelt words.  I did find out that most upright bass preamps have an impute (the connection between the piezo and preamp ) of 1Mohm. So I can guess with some success that two in parallel will be 500Kohm and three would be ( not quite right ) 330K ohms. And so on. I did read years ago that there is a number of piezo you can't go past. But there was no reason given. 

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Permalink Reply by Taffy Evans on December 14, 2019 at 11:14am

Hi BR, also maybe the quality of the piezo my affect your calculations, like three off one brand may be different to three of another brand.

Taff

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Permalink Reply by Jim Saraceno on December 14, 2019 at 4:34am

I generally try to place mine close to but on the neck side of the bridge. One just outside of the bass string and one just outside of the high string. I shoot for those spots but often have to move them a little to accommodate sound holes or braces.

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Permalink Reply by Cause the Blue rat on December 14, 2019 at 10:14am

Thanks again everyone for your responses. 

What I'll end up doing is first glueing them to a piece of foam. That will be glued to a small piece of ply. Lather to the top sides with lots of hot glue and stick em in place. One shot. 

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