Replies to This Discussion

Permalink Reply by Roosterman on September 28, 2009 at 8:57pm

Mmm.... interesting point - I have no idea!

I would say this though - unless you absolutely HAVE to seal your box, leave it free! The string pressure will hold the lid down if you have built with the box the right way up. If you have built on the bottom (with the box upside down), maybe you could put a catch on it?

Leaving it free means that if there are any problems in the future, or if you want to upgrade it, you can get in without ruining your box.

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Permalink Reply by Diydc on September 28, 2009 at 9:15pm

I`d suggest using some small screws to close the box instead of glueing it all up. This way you can get it back open just about any time you need to.

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Permalink Reply by Erik Ryman on September 28, 2009 at 9:40pm

Hmmm...I've just closed my first one....with nails, glue and a few more nails just to make sure.

Better hope my soldering is OK, I guess.

Diydc said:

I`d suggest using some small screws to close the box instead of glueing it all up. This way you can get it back open just about any time you need to.

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Permalink Reply by David L. on September 28, 2009 at 10:04pm

Hi, I do not know the answer either. The only info I could find was for a piezo transducer fitted into a resin strip and slotted into the road to monitor cars driving over the strip - the lifespan was estimated to be 6 years so a piezo disc in a CBG under much less stress (unless a car rides over it) should last ages. For my CBGs I always use two or more piezos connected in series (all red wires together as one hot output and all black wires together as the other earth output) because then if one fails the others will still work. Here is a resonator I have nearly finished - 2 piezos below the resonator cone and 2 above when it is in position in the soundwell.

I also stick the box lid down using decorative hinges so I can unscrew them again to access inside (just in case)

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Permalink Reply by Erik Ryman on September 28, 2009 at 10:19pm

David - do you use a tone control with that many piezos in series? I've been playing around with the same, but more than a couple starts to get muddy unless I add something to vary the tone..

That's going to be a beautiful guitar - love the look of the neck

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Permalink Reply by David L. on September 28, 2009 at 10:53pm

Hi Erik,

Yes in this case I used a standard telecaster wiring diagram wiring the 3 way switch to the magnetic pickup in the neck position and all 4 piezos (35mm discs) as one in the bridge position. Output then goes to a 500k pot for volume with another 500k pot with a 0.047mF cap as a tone control. Output then to the jack socket. The sound is quite bright but after reading your posting I had a play with this and the other CBGs I have made with 3 piezos and all sound fine but although the tone pot on each works with the magnetic pickups the tone pot has little effect on the piezo sound. I hadn't noticed before as I have found the sound to be what I wanted - also I tend to use the amp settings to alter tone rather than the guitar. Having had a quick play I have noticed even the amp controls have less effect on the tone of the piezos compared to the magnetic pickups. Not sure why - I guess it is linked to the impedance difference, but all the electrical theory goes over my head.
Regards,
David

Erik Ryman said:

David - do you use a tone control with that many piezos in series? I've been playing around with the same, but more than a couple starts to get muddy unless I add something to vary the tone..

That's going to be a beautiful guitar - love the look of the neck

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Permalink Reply by David L. on September 28, 2009 at 11:08pm

Hi again,
I just noticed you say you add the extra piezos in series(only the first piezo is connected to hot terminal then via the other discs until the final disc is connectwed to the earth) - I add mine in parallel (all piezo discs are joined individually to both the earth and hot connector). If this is the case the difference in circuits alters the electrical characteristics and this could be why you get a muddy sound and I get a bright tone.
I would be gratful if you could let me know if this is the case - it means I could play around with the wiring on my next build so I can alter the piezo disc tone by changing the circuit between series and parallel.
Regards,
David

Erik Ryman said:

David - do you use a tone control with that many piezos in series? I've been playing around with the same, but more than a couple starts to get muddy unless I add something to vary the tone..

That's going to be a beautiful guitar - love the look of the neck

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Permalink Reply by Erik Ryman on September 28, 2009 at 11:15pm

Hi David

Thanks for that...and I'm the same, I'm afraid - try it and see - seems to be my main approach.

I've been playing with 10K & 25K pot as tone knobs, which is more a little amp thing really, but seems to work OK on a piezo guitar. I must admit I'm thinking more of using the amps controls too as it is easier that way.

Its good to know that the piezos in series work well though, I guess its down to something I'm doing then..

cheers
Erik


David Lloyd said:

Hi Erik,

Yes in this case I used a standard telecaster wiring diagram wiring the 3 way switch to the magnetic pickup in the neck position and all 4 piezos (35mm discs) as one in the bridge position. Output then goes to a 500k pot for volume with another 500k pot with a 0.047mF cap as a tone control. Output then to the jack socket. The sound is quite bright but after reading your posting I had a play with this and the other CBGs I have made with 3 piezos and all sound fine but although the tone pot on each works with the magnetic pickups the tone pot has little effect on the piezo sound. I hadn't noticed before as I have found the sound to be what I wanted - also I tend to use the amp settings to alter tone rather than the guitar. Having had a quick play I have noticed even the amp controls have less effect on the tone of the piezos compared to the magnetic pickups. Not sure why - I guess it is linked to the impedance difference, but all the electrical theory goes over my head.
Regards,
David

Erik Ryman said:

David - do you use a tone control with that many piezos in series? I've been playing around with the same, but more than a couple starts to get muddy unless I add something to vary the tone..

That's going to be a beautiful guitar - love the look of the neck

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Permalink Reply by HENRY LOWMAN on September 29, 2009 at 1:29am

Like Ben just said, and to put a Janice Joplin spin on it, "Freedom is just another word for nothin' left to lose...!" Leave the top free, or use small screws, as mentioned before. I build my own boxes, and it DOES make it easier to get back in and rework things, if one feels the need. CHEERS!

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Permalink Reply by Erik Ryman on September 29, 2009 at 2:21am

Yes David (sorry missed your post) I've been putting them in series with a small tone pot (10K), which oddly seems to clear things quite a bit. I'll have a try with them in parallel then, thanks for that..

cheers
Erik


David Lloyd said:

I would be gratful if you could let me know if this is the case - it means I could play around with the wiring on my next build so I can alter the piezo disc tone by changing the circuit between series and parallel.
Regards,

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Permalink Reply by Paul Doug on September 29, 2009 at 2:33am

Welcome to the forum, Julian. Back to you original question, I think piezos last a long time, but there is no reason to seal you box. Screws or a latch works well.

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Permalink Reply by Weizel on September 29, 2009 at 2:58am

Mr. Lloyd,
I know this is quite off topic, but what are you using for the cone?

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