Replies to This Discussion

Permalink Reply by Ottie(Skydog)Noble on July 26, 2010 at 3:31pm

a 3 way switch will make it easy look into that

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Permalink Reply by Jim Birmingham on July 26, 2010 at 3:58pm

Thanks,
Jim

Ottie(Skydog)Noble said:

a 3 way switch will make it easy look into that

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Permalink Reply by Jim Birmingham on July 28, 2010 at 3:16am

Hi David,,What size piezo's do you use and are you able to tell any difference in the sound as related to size????
Jim

David Lloyd said:

Hi Jim,

I hope the piezos behave themselves this time.

So far I only have had a play with different strings on one of the violins (electric or classical guitar strings). I will post some pictures once I have made a proper start on it :O)

David

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Permalink Reply by Jim Birmingham on July 29, 2010 at 3:45am

Hi David, I meant to ask you,,I see the picture of your piezo's inside the box but how did you actually mount them???If you try to play with alot of volume do they feed back??? Jim

David Lloyd said:

Hi Jim,

I hope the piezos behave themselves this time.

So far I only have had a play with different strings on one of the violins (electric or classical guitar strings). I will post some pictures once I have made a proper start on it :O)

David

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Permalink Reply by David L. on July 31, 2010 at 10:37am

Hi Jim,

I haven't compared different sizes for sound - I just glue in 2 or 3 of whatever i have to hand. To fix them I use "serious glue" by Evo Stick I buy it from my local DIY store but here is the product details off another site http://www.rapidonline.com/productinfo.aspx?tier1=Tools%2C+Fastener... but I don't know if it is available in the USA. It is great stuff and I also use it to glue the neck bracing/ bridge block/ anything else that needs sticking. If you put a thick layer down for the piezo it dries a bit like silicone sealant in texture (I think this may help with stopping feedback). I only play at home so the volume is never up too far and I only get feedback if the piezo is preamped too much or I am messing about with overdrive effects (as you would expect).

If you are after a better sound from your piezo pickup it might be worth considering one of these http://www.rapidonline.com/productinfo.aspx?tier1=Tools%2C+Fastener...
At first I was sceptical of a "passive preamp" but having bought one out of curiosity I was really impressed with the sound and also the tone control works well. For $9 it is a cheap product considering it includes the under saddle pickup tone/volume control and an output socket.

David

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Permalink Reply by Jim Birmingham on August 1, 2010 at 5:36am

Hi David, Thanks for the info,,I think you said once before that you wire the piezos in paralell?? When you start adding piezos what difference do you notice??? So far,, I have not been sucessful at using more than one. I just couldn't tell a difference.
Jim

David Lloyd said:

Hi Jim,

I haven't compared different sizes for sound - I just glue in 2 or 3 of whatever i have to hand. To fix them I use "serious glue" by Evo Stick I buy it from my local DIY store but here is the product details off another site http://www.rapidonline.com/productinfo.aspx?tier1=Tools%2C+Fastener... but I don't know if it is available in the USA. It is great stuff and I also use it to glue the neck bracing/ bridge block/ anything else that needs sticking. If you put a thick layer down for the piezo it dries a bit like silicone sealant in texture (I think this may help with stopping feedback). I only play at home so the volume is never up too far and I only get feedback if the piezo is preamped too much or I am messing about with overdrive effects (as you would expect).

If you are after a better sound from your piezo pickup it might be worth considering one of these http://www.rapidonline.com/productinfo.aspx?tier1=Tools%2C+Fastener...
At first I was sceptical of a "passive preamp" but having bought one out of curiosity I was really impressed with the sound and also the tone control works well. For $9 it is a cheap product considering it includes the under saddle pickup tone/volume control and an output socket.

David

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Permalink Reply by David L. on August 2, 2010 at 7:17am

Hi Jim,

A slow day in the UK so I have just spent part of the afternoon messing around with some 25mm and 35mm piezo discs.

I think i said this previously either here or elsewhere but I wire 2 or 3 piezos together in parallel for three reasons -
1. It reduces the high impedance - I don't follow all the theory of impedance mismatch (school seems along time ago) but when I first looked for information on piezos as pickups many other sites made a big deal about the "problems" of the high impedance and how you needed a preamp or it could do something bad. No one ever elaborated on what this bad thing was and clearly from all the piezos used in CBGs by the good people here no one has reported a "bad" event.

2. If one piezo fails the others will still work - belt and braces concept.

3. I thought two or three around the bridge area would increase the odds of finding the elusive "sweet spot" guitars are supposed to have (also some commercial piezo pickups have 2 or 3 pickups).

That said I have found the following using piezos taped to a strat copy body around the bridge and put through a 10W amp

1. No difference in sound between between 25mm and 35mm discs.
2. Changing position of the disc did give a slightly different sound (stick it on the high e string you get more treble and stick it on the lowE you get less treble - no surprise there)
3. No difference in sound between 1 and 2 or 3 piezos wired in parallel
4. intentionally wiring 2 piezos black/red to hot and red/black to earth didn't affect the sound (no sound cancellation to my ear)
5. 2 piezos wired in series sounded poor compared to a single piezo or 2 in parallel.

(please note this is only my view and others may have diferrent opinions which I would gladly like to hear)

Regards,
David

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Permalink Reply by Jim Birmingham on August 2, 2010 at 10:10am

Hi David,,,,Thanks for all the info re piezos. My findings are the same re paralell and series. I thought it was just me not being able to tell any difference but it appears that we both went to the same piezo school. The ones I use are 35mm and seem to work well.

How is the violin coming????

David Lloyd said:

Hi Jim,

A slow day in the UK so I have just spent part of the afternoon messing around with some 25mm and 35mm piezo discs.

I think i said this previously either here or elsewhere but I wire 2 or 3 piezos together in parallel for three reasons -
1. It reduces the high impedance - I don't follow all the theory of impedance mismatch (school seems along time ago) but when I first looked for information on piezos as pickups many other sites made a big deal about the "problems" of the high impedance and how you needed a preamp or it could do something bad. No one ever elaborated on what this bad thing was and clearly from all the piezos used in CBGs by the good people here no one has reported a "bad" event.

2. If one piezo fails the others will still work - belt and braces concept.

3. I thought two or three around the bridge area would increase the odds of finding the elusive "sweet spot" guitars are supposed to have (also some commercial piezo pickups have 2 or 3 pickups).

That said I have found the following using piezos taped to a strat copy body around the bridge and put through a 10W amp

1. No difference in sound between between 25mm and 35mm discs.
2. Changing position of the disc did give a slightly different sound (stick it on the high e string you get more treble and stick it on the lowE you get less treble - no surprise there)
3. No difference in sound between 1 and 2 or 3 piezos wired in parallel
4. intentionally wiring 2 piezos black/red to hot and red/black to earth didn't affect the sound (no sound cancellation to my ear)
5. 2 piezos wired in series sounded poor compared to a single piezo or 2 in parallel.

(please note this is only my view and others may have diferrent opinions which I would gladly like to hear)

Regards,
David

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Permalink Reply by LittleBigOne on August 9, 2010 at 7:31pm

Hi David,

The link to the passive pre-amp you were talking about does not appear, please can you re-post as
I am very interested ; do you have any schematics for this passive pre-amps so I could build my own ?
Thanks

David Lloyd said:

Hi Jim,

If you are after a better sound from your piezo pickup it might be worth considering one of these http://www.rapidonline.com/productinfo.aspx?tier1=Tools%2C+Fastener...
At first I was sceptical of a "passive preamp" but having bought one out of curiosity I was really impressed with the sound and also the tone control works well. For $9 it is a cheap product considering it includes the under saddle pickup tone/volume control and an output socket.

David

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Permalink Reply by LittleBigOne on August 9, 2010 at 10:47pm

Sorry, I finally found it
here :-)

Many thanks

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Permalink Reply by David L. on August 9, 2010 at 11:40pm

Hi,

I didn't realise I had posted the wrong link - there is a link here for the buy it now listing (if you go to the sellers shop you will find it a little cheaper for a bid price) http://cgi.ebay.co.uk/Acoustic-Guitar-Piezo-Pickup-Passive-Preamp-S...
Your link goes to the wiring group on this forum which has pictures for anyone interested.

I bought it out of interest and was really surprised at how good it is and the tone control works well (the first time I have seen/heard this on a passive circuit). Also because it is passive you do not get the feedback/electrical hiss problems that an active circuit gives when the controls are cranked up. I did think of trying to build my own but trying to get hold of just an under saddle piezo nearly costs as much and even if you use a piezo disc once you add in the jack socket and pots it will be way over in price.

Regards,
David

LittleBigOne said:

Sorry, I finally found it
here :-)

Many thanks

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Permalink Reply by LittleBigOne on August 10, 2010 at 4:45am

Hi David, did you finally found the value for the capacitor potentiometer in the passive pre-amp ?

...this discussion make me thinking that maybe we are trying to re-invent the wheel, look, why
not replace the piezo disc with a normal FET transducer that have pre-amp embedded ?! I found
the piezos are very limited compared to a transducer cell from what I have tested. I have some
of these cells and they give incredible response, for a cost far away from piezo + saddle + controls + passive pre-amp...

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