Hi everyone, I want to be able to perform noise and vibration analysis on high end audio turntables. Does anyone have any ideas on a cheap piezo transducer and the interface required?
In the video, he's probably using a Brüel&Kjaer 4370 piezoelectric transducer (sensitiviy of 10 pC/(m/s²), very sensitive), along with a charge amplifier (probably B&K type 2525 or similar). He's also measuring vibrations in one direction (one axis), I hope he's not rendering wrong conclusions from this experiment ;-)
B&K 4370 goes for like 100-150 EUR on eBay, the charge amplifier goes for 100-250 EUR. If you're lucky, you will get the special low noise cable with your transducer, otherwise the microdot UNF 10-32 cables go for 60ish EUR per piece. I wouldn't suggest microdot cables from China.
MEMS sensors can be used as a cheap option, although they are very limited in the use. Their cutoff frequency is in the range of few hundred Hertz so you won't be able to see higher harmonics. The sampling frequency is in the order of 1 kHz so you won't be able to measure frequencies reliably past 400-500 Hz. You also have to adjust the measuring range of the MEMS sensor in order to measure small vibrations...
For signal analysis, you don't need a spectrum analyzer. Use either your sound card (for analogue signals) or in case of a MEMS sensor any free availible scientific software (GNU Octave, Python/Numpy, ...) to do a FFT analysis.
I'd like to mention that a usage of different springs or rubber bands does not eliminate the mechanical problems (bad construction or design), it's just helps mitigating the interference or to move the disturbance in a different frequency band where it's not critical.
Good piezoelectric transducer manufacturers are Brüel&Kjaer, Endevco/Meggitt, PCB Piezotronics and Kistler, just to name a few. If you can borrow a laser interferometer (e. g. Polytec), you will be even happier