I've been experimenting with piezo elements to amplify one of my CBG's and a mic and i get the same issue with both...they feedback like a bitch!
I've tried a couple of variations of tape, glue etc and i can reduce the hiss but when im anywhere near my amp i just get acres of squeal!!
is there any particular method of attachment or placement that im missing out on?
thanks in advance
dom
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Linear taper potentiometer
A linear taper potentiometer (uses the letter 'B' in the designation eg 100kB) has a resistive element of constant cross-section, resulting in a device where the resistance between the contact (wiper) and one end terminal is proportional to the distance between them. Linear taper describes the electrical characteristic of the device, not the geometry of the resistive element. Linear taper potentiometers are used when an approximately proportional relation is desired between shaft rotation and the division ratio of the potentiometer; for example, controls used for adjusting the centering of (an analog) cathode-ray oscilloscope.
[edit] Logarithmic potentiometer
A logarithmic taper potentiometer (uses the letter A in the designation eg 100kA)has a resistive element that either 'tapers' in from one end to the other, or is made from a material whose resistivity varies from one end to the other. This results in a device where output voltage is a logarithmic (or inverse logarithmic depending on type) function of the mechanical angle of the pot.
Most (cheaper) "log" pots are actually not logarithmic, but use two regions of different resistance (but constant resistivity) to approximate a logarithmic law. A log pot can also be simulated with a linear pot and an external resistor. True log pots are significantly more expensive.
Logarithmic taper potentiometers are often used in connection with audio amplifiers.
I've found that using a Radio shack potentiometer (I think it's linear) the volume doesn't really kick in until around 9 or 10.
jason peterson said:
I have used unshielded wire on over 150 piezo equiped cbgs with no feedback issues, once the installation issue was settled...
I doubt that the issue of interference, which can be a wiring thing is in play here either like it can be on a wound pup... the difference in the way a piezo works, just doesn't seem to lend itself to this problem... The only time I've had noise issues is a result of a bad solder or a stray wire....
again, just opinion based on 200+ builds...
the best,
Wichita Sam
cite>jeremy james a scriver said:
grizzly.com/products/Samba-Acoustic-Transducer-End-Pin/H6054
You'll have to cut and paste this. Not sure how to make a link.
No soldering. Ready to go. Might help with the feedback the way it's encased.
The easier and more common way to handle the problem is to affix the piezo (brass disc side) to the underside of the top with CA glue and then encapsulate the open back (the ceramic side of the piezo) with some insulating material such as hot glue, silicone caulk or a piece of mouse pad....
hope this helps,
the best,
Wichita Sam
Braxton Nagle said:
Wichita Sam said:
But, when it is so easy to limit feedback in ways that don't kill acoustic volume of the instrument, why not do it a better way?
No rules,
JMHO,
the best,
Wichita Sam
Travis "SlackJack" Woodall said: