small amp for percission - help


2010-12-14 9:05 am
Hey all, need a little help.

Trying to build a small amp (see attachment)

Basically i want to build a box i stomp on, with a piezo transducer in it

i want out the big bass thump sound similar to a bass drum

output from the (small) amp will be to my gig setup amp.

Any help would be madly appreciated...

i have built this circuit on the breadboard it works well with a small speaker but when i plug it into my peavy 100w amp i get really bad humm.

once again any help will be madly appreciated.



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Ground loop maybe How are you powering the stomp box? from a wall-wart?
Try on battery power first, if its quiet then look to the power unit. This can a problem when connected to the Peavy as thats grounded as well as the power supply. In this case running on the internal speaker it will not hum.

For a mains power supply try a regulator (7809?) and some caps to tame the hum. Good luck
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2010-12-14 9:05 am
Lol, Sorry for my poor writing skillz, it does say Piezo..

Andrew, Yes i am trying to generate a sound similar to a bass drum from the box.
the piezo and the "little amp" will be mounted in the box, output via 6.5mm mono to my 110 watt amp.

Firechief. Yes i have 3, 45mm piezo discs $5 from eBay. Not sure on the specs. perhaps would be advantageous to change the sound, maybe even get some sort of resonance / reverb if this is possible (and not above the skill level of a beginner diy). suggestions?

Spiny. I have been powering it from a 9v pp3 battery, all ground lines shown on the schematic are linked to the - terminal of the battery ( i think this is my problem as there is no "actual earth" basically i get an ok sound, but i get some "MAD" humm even at low volume levels.

out of interest i have also been trying to duplicate a similar device from a TL072 opamp with no success.