leafcutterjohn.com

Great idea. Been using cheap piezoes in various cheap instruments, ukuleles and the Bogdon Box bass http://www.edencompanies.com/bogdon/

Guess there is less of a need to buy those expensive transducers like http://barcusberry.com/product.cfm?ProductID=11

Thanks. Now to see if I can solder without burning my fingers off.

I’m glad you found my circuit useful.

I’m not totally sure what the source of the background noise in you watch recording is, it may simply be that the signal from the watch was very small and needed a lot of gain so the noise is from the pre-amp in your mixer/recorder.

The main thing that causes the piezo-pre to make noise like that is too much/little current through the current source — i found about 0.5 – 0.7 mA was best, much below that and it starts to get noticeably noisier; much above 1.5mA and the voltage from the phantom power will start to droop. Experiment by replacing R3 with a 2k potentiometer, adjust the pot for least noise and then replace it with a fixed resistor of similar value.

I’ll also let you in on a bit of a secret. There are two piezos inside each of my microphones, they’re both glued side by side to a strip of metal, connected in series with one having it’s + wire connected to ground and the other having the – wire connected to ground. The effect is to significantly boost the sensitivity of the microphone. Both piezos have to be electrically isolated from the grounded metal strip.

Another hint is that the wire itself can be a source of noise. Try hitting a section of cable — you’ll find that it is microphonic. I try and keep the distance between the piezo and it’s pre-amp nice and short which is easy with a phantom powered preamp.

[...] on a canal boat soon so I wanted to make myself a new hydrophone which includes the pre-amp I made here. I have made hydrophones using piezo elements before but I never tried using a pre-amp which tends [...]

Hi,

Don’t suppose you have a copy of the schematic for the preamp? Alex’s site appears to be down…

Oh no, the site has gone!

There are plenty of circuits suitable for this project on the web. Try looking HERE. There are links at the bottom of the page for two easy to build buffer/amps. These circuits are not phantom powered though – I’ll see what i can do to get the original schematic up here.

hello John, i’m really interested in building the tin can piezo hydrophone with pre amp but i have no idea on what components i need to purchase in order to build the circuit…

would you mind sending me a shopping list by any chance???

thankyou.

Alex’s site is back up now so you should find all you need to know here:

http://www.alexrice.co.uk/content/piezo-preamp

Good Luck!

J.

Alex’s site is down once again. Do you have the schematic for this project?

Theres a good explanantion as to the bass loss & how to solve it, with a circuit diagram (its an impedance matching issue)

http://www.suite101.com/content/get-better-sound-from-piezo-mics-and-pickups-a72764

I gave away some of my contact mic recordings as a xmas present, have a listen/download here:

http://hissandaroar.com/contact-mic-xmas/

hi john, fascinated by your diy hydrophone and am going to make it my *first* project! i’m wanting to order the bits online for both the pre-amp, and the hydrophone – any chance you have a copy of the parts list + some basic instructions/doodles, i’ve checked the site you link to but it seems to be down, cheers!

Hello everyone, you’ll be glad to know that someone has started a page with the full details of alex’s preamp. The new link is in my post. If you want to go there now: http://www.zachpoff.com/diy-resources/alex-rice-piezo-preamplifier/

[...] from Leafcutter John: Leafcutter’s DIY Steel Can Hydrophone & Preamp. Step-by-step guide Shit I’m a Geek / The joy of Piezoelectricity [good background on the [...]

Hi John,

I have a question regarding the resistor R3 in the preamp diagram. It says 1-2K. Is this the same as 1.2K (1.2000 ohms)or does it mean that R3 could be 1K or 2K? Thanks a lot. Great info and thanks for sharing it. Best, james.

Honestly I’m not sure, It’s Alex’s diagram. I imagine it means anywhere between 1k and 2k, or tune to taste maybe. If it’s a typo then 1.2k I doubt you’ll blow anything up by selecting a 1.2k resistor here. If you test the circuit on protoboard you can change the value and see what happens.

Thanks John.
and please regarding Q3, if I use two 2N3819 for Q1 and Q2, which part list would be Q3?
regards, james

[...] making my own, here are some links that helped my decide. Social sound design Leafcutterjohn.com furious contact mic assemble” This entry was posted in work by richbate. Bookmark the [...]