It's many decades old, but it's pretty rare - why make amps for a tiny number of unusual enthusiasts, which would never sell enough to be worthwhile.
If you want to play with piezos, then build or buy a piezo preamp.
One FET, two resistors, two capacitors - it's not difficult.
I think there impedance is similar like ordinary piezo, because crystal layers from booth sides of brass plate are already so polarized, that are connected in parallel.
It was so far, but I just tried to connect it on, I think Darlington coupled some ordinary transistors like BC547 instead on FET preamp because of higher input impedance and because I had not FET's in that moment. Than I compared it double with few ordinary piezo, and difference was obviously.
So you can to connect it on FET preamp and adjust input impedance, but I think with that what did my namesake Peter Sesselman about mounting piezo on three different points, could be even more better. He showed the mount points, but I did not see how these points applied on the guitar resonator, so it should be experimented to see.
Similarly, I did not tried, but you could to use two ordinary piezo one over other to connect them in serial to see what will get.
It was so far, but I just tried to connect it on, I think Darlington coupled some ordinary transistors like BC547 instead on FET preamp because of higher input impedance and because I had not FET's in that moment. Than I compared it double with few ordinary piezo, and difference was obviously.
So you can to connect it on FET preamp and adjust input impedance, but I think with that what did my namesake Peter Sesselman about mounting piezo on three different points, could be even more better. He showed the mount points, but I did not see how these points applied on the guitar resonator, so it should be experimented to see.
Similarly, I did not tried, but you could to use two ordinary piezo one over other to connect them in serial to see what will get.
It is probably possible to do many improvements because we can remember how big signal had on example earlier piezo turntable pickups. But in real I can not see that any piezoelectric device in audio applications offer higher quality of sound. Probably it is because of rough changes in excited hard piezo crystal.
I never heard better way to recording any acoustic instrument than just to apply in front of them some quality kind of microphone like condenser ... But it is not so practical because musicians are not so free to move when playing except if will mount mic on the instrument. This looking like the best way, but acoustic pickups are most compact and practical way.
I heard that some people made electrodynamic pickups which offer great quality of sound. It is not so hard to make on example: just to mount a similar moving coil like microphone on the guitar resonator, and independently mounting some adequate small (NEO) microphone magnet that voice coil go free in magnet fissure. There are many ways.
Regards
Peter
I never heard better way to recording any acoustic instrument than just to apply in front of them some quality kind of microphone like condenser ... But it is not so practical because musicians are not so free to move when playing except if will mount mic on the instrument. This looking like the best way, but acoustic pickups are most compact and practical way.
I heard that some people made electrodynamic pickups which offer great quality of sound. It is not so hard to make on example: just to mount a similar moving coil like microphone on the guitar resonator, and independently mounting some adequate small (NEO) microphone magnet that voice coil go free in magnet fissure. There are many ways.
Regards
Peter
electric violin have always been a challenge
and today you even have electric violins without any acoustic body, but purely electrical
the new thing with piezo for guitar and bass instrument is that they are placed in the bridge, and directly attached to the strings
but many people don't like them
some say they only work well when combined with ordinary magnetic pickups
instrument preamps for instrument is beginning to become availabe
still a relatively new thing with electric guitar and bass
but it is in devellopment
and today you even have electric violins without any acoustic body, but purely electrical
the new thing with piezo for guitar and bass instrument is that they are placed in the bridge, and directly attached to the strings
but many people don't like them
some say they only work well when combined with ordinary magnetic pickups
instrument preamps for instrument is beginning to become availabe
still a relatively new thing with electric guitar and bass
but it is in devellopment
That's a preamp-ed piezo .
Seems like 30V is a good ballpark for piezo preamps ... all better with 48V
I have to say, you DONT need a pre amp for an acoustic guitar piezo pickup. But bear in mind the level will be low, and Nigel is correct in saying the impedance wont match optimally, so the response could be squewed in favour of the high end response giving a twangy, banjo type percussive sound.
The best way is to use a small charge amp, ie supply a small CC supply ~5mA. This method if done well will give a very very nice sound, with a bit of extra work.
Your point about bending of piezo yielding the best result is correct though. If you could somehow fix half under the bridge/stringnut at bridge, and then have the rest sticking out, either internally or externally. Then make a small clamp for the 'free' half through which you can thread a small screw. with this screw you can pull the piezo one way or the other small amounts and tension the piezo disc (if thats what you are using), and vary it to suit.
yes it is a bimorph. the manner in which it is constructed converts the bending excitation of the crystal into a 'traditional' axial movement. Should be more efficient/better output. still need a good charge amp. plenty of free advice/designs on the web.
I am using a Dean Markley 'tone...something' under bridge piezo, no pre amp. it is a foil strip type of piezo with 6 cubes of crystal, 1 per string. DI'd it is fine and dandy, into my signature120 valve amp, its is not so good. sounds ok, just low level, and needs alot of gain. a small matching transformer helps alot, BUT a charge amp is the way to go...100%
I got my piezos and wire stripper in the mail. I did a test. I put the piezo right on the treble side of my guitar bridge. IT WAS SUPER LOUD!!! I had to keep my amp on two. Honestly, I couldn't get a bad sound. I EQ'd it 7 different ways. I ran it flat, treble, bassy, middy, etc., and it sounded good.
I ran it straight into my Line 6 amp, and I don't think there is any need for a preamp. I will try to get some audio posted up or something.
I ran it straight into my Line 6 amp, and I don't think there is any need for a preamp. I will try to get some audio posted up or something.
It depends on the Piezo capacitance.
If you use some factory made tiny piezo, with a crystal 1/4 the size of your pinky nail, yes, you *will* need a high impedance preamp, and as close as possible to avoid cable capacitance losses, but for a homemade piezo pickup made out of a 1 inch diameter buzzer or tweeter crystal, requirements are much lower.
FWIW I have measured such disks and found between 0.082 and .125uF capacitance, which into a very low input impedance about 100K gives me a low frequency cutoff of around 20Hz, way below what any Guitar or Bass can put out.
Of course a buffer (gain is usually not needed, they are *hot*) lowers output impedance even more and allows for real long cables without trouble.
If you use some factory made tiny piezo, with a crystal 1/4 the size of your pinky nail, yes, you *will* need a high impedance preamp, and as close as possible to avoid cable capacitance losses, but for a homemade piezo pickup made out of a 1 inch diameter buzzer or tweeter crystal, requirements are much lower.
FWIW I have measured such disks and found between 0.082 and .125uF capacitance, which into a very low input impedance about 100K gives me a low frequency cutoff of around 20Hz, way below what any Guitar or Bass can put out.
Of course a buffer (gain is usually not needed, they are *hot*) lowers output impedance even more and allows for real long cables without trouble.
Here's my piezo project:
Adding a Piezo pickup | GuitarNutz 2
Its a buzzer type element, built into a Strat type of guitar. The trem springs are removed and the force of the strings presses the trem block against the back of the cavity, squeezing the piezo. Theres a buffer based on jfets, which can pan between piezo and magnetic sounds.
With this large piezo, I also found it needed to run into quite a low input impedance (150k in my case), just to roll off spurious sub-bass thumps and almost dc pulses tha would block sound for a second or two.
The final version works quite well. A mixed sound with some magnetic is its best tone.
Adding a Piezo pickup | GuitarNutz 2
Its a buzzer type element, built into a Strat type of guitar. The trem springs are removed and the force of the strings presses the trem block against the back of the cavity, squeezing the piezo. Theres a buffer based on jfets, which can pan between piezo and magnetic sounds.
With this large piezo, I also found it needed to run into quite a low input impedance (150k in my case), just to roll off spurious sub-bass thumps and almost dc pulses tha would block sound for a second or two.
The final version works quite well. A mixed sound with some magnetic is its best tone.
the science of piezo pickups
Hi tinitus,
Actually, use of piezo pickups is very OLD Skool. I worked with Les Barcus (half of the Barcus-Berry genius partnership) for a couple of years in the 80's. Les and John (Berry) released records on their own label, Repeat Records, in the 50's, where every instrument, and I'm talking guitar, banjo, fiddle, flute, sax, you name it, were recorded exclusively with piezo contact pickups. And I can tell you that Les used some very odd and original techniques to make piezo pickups produce a lifelike recording, like making a pickup for a drum head where the piezo element was mounted inside a little slot-loaded box!
Here's why piezos are such a challenge as sound pickups: they are not voltage generators, like magnetic guitar pickups, they are called charge generators. They need to be treated differently from what we're used to dealing with if you want decent frequency response.
I found a cool site that explains all this.
check out this site: Home Page
These little beasties can sound amazing in a guitar! I still have a Barcus Berry thinline (AKA Martin thinline back in the day) in my big Guild acoustic, and it still sounds great 30 years after it was installed...
Hi tinitus,
Actually, use of piezo pickups is very OLD Skool. I worked with Les Barcus (half of the Barcus-Berry genius partnership) for a couple of years in the 80's. Les and John (Berry) released records on their own label, Repeat Records, in the 50's, where every instrument, and I'm talking guitar, banjo, fiddle, flute, sax, you name it, were recorded exclusively with piezo contact pickups. And I can tell you that Les used some very odd and original techniques to make piezo pickups produce a lifelike recording, like making a pickup for a drum head where the piezo element was mounted inside a little slot-loaded box!
Here's why piezos are such a challenge as sound pickups: they are not voltage generators, like magnetic guitar pickups, they are called charge generators. They need to be treated differently from what we're used to dealing with if you want decent frequency response.
I found a cool site that explains all this.
check out this site: Home Page
These little beasties can sound amazing in a guitar! I still have a Barcus Berry thinline (AKA Martin thinline back in the day) in my big Guild acoustic, and it still sounds great 30 years after it was installed...
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