I can tell you much easier way to reduce the hum. Use two sensors and balanced cable and input. Wide circles should be connected to a shield, internal pads -- to the cold and hot wires of the cable. And then you need to just stack your sensors to each other with pads oriented outside. So you get a para-phase signal from them that will be amplified and sinphase hum will be subtracted. And you don't need any monstrous shielding on your sensors.
This reduces the noise, but does not reduce the sensitivity of the mic. So whatever low frequencies you are trying to record won't be affected negatively, just unwanted noise will be removed. Metal Marshmallow actually has excellent subsonic response, I have a blog post about it metalmarshmallow.com/blog_post.php?id=12
with string instruments, even "bass" string instruments, you're not getting much output below 50 or 60Hz anyway; that "40Hz" open low E string on a bass is really mostly vibrating at its octave harmonic at 80Hz even a 5-string bass's "31Hz" low B is really mostly vibrating at the 62Hz octave of that besides, most bass amps and PA system subs are chopping off everything below 35-40Hz anyway
Hola, para que evites ese problema necesitas alimentar tu circuito con un DC to dc converter. Así aislas ese molesto ruido de la alimentacion electrica. Ya que el dc cuenta con un filtro de carbon entre sus placas para que el salto de electrones no cause esas interferencias que hacen al moverse a 60 hz. son 60 hz porque asi oscila la frecuencia de la energía del cableado. Saludos desde México.
Supongo que esta utilizando un circuito para adaptar impedancias y amplificar la señal, me pregunto que tal funcionaría aquí un transformador de audio (con una calidad decente por supuesto). Transformadores de audio del tipo que utilizan las cajas reamp, tendrías la posibilidad de balancear la señal además de adaptar la impedancia aunque es bien sabido que la impedancia con las cuales trabajan los piezoeléctricos suelen ser muy altas, cercanas a los 10 Mega Ohm. También podría utilizar cera de abeja como es de habitual uso en los acelerómetros para fijar el piezo en el gabinete, esto aseguraría que no haya espacios de aire entre el piezoeléctrico y el gabinete.
If you're living in America 60Hz (and its harmonics) noize is probably there due to AC frequency and all electronics radiating it and probably resonating.
I can tell you much easier way to reduce the hum. Use two sensors and balanced cable and input. Wide circles should be connected to a shield, internal pads -- to the cold and hot wires of the cable. And then you need to just stack your sensors to each other with pads oriented outside. So you get a para-phase signal from them that will be amplified and sinphase hum will be subtracted. And you don't need any monstrous shielding on your sensors.
I cant stop watching these videos. Such valuable information. Thank you for making these tests available for us. Great gob, please keep making!
Great instructional voice so clear almost always answering my questions seconds after I think them…
Keep em coming!
there is also a massive dip on the 30 hz, it wouldn't do much for a bass ukelele or anything with low frequencies
This reduces the noise, but does not reduce the sensitivity of the mic. So whatever low frequencies you are trying to record won't be affected negatively, just unwanted noise will be removed. Metal Marshmallow actually has excellent subsonic response, I have a blog post about it metalmarshmallow.com/blog_post.php?id=12
with string instruments, even "bass" string instruments, you're not getting much output below 50 or 60Hz anyway; that "40Hz" open low E string on a bass is really mostly vibrating at its octave harmonic at 80Hz
even a 5-string bass's "31Hz" low B is really mostly vibrating at the 62Hz octave of that
besides, most bass amps and PA system subs are chopping off everything below 35-40Hz anyway
Hola, para que evites ese problema necesitas alimentar tu circuito con un DC to dc converter. Así aislas ese molesto ruido de la alimentacion electrica. Ya que el dc cuenta con un filtro de carbon entre sus placas para que el salto de electrones no cause esas interferencias que hacen al moverse a 60 hz. son 60 hz porque asi oscila la frecuencia de la energía del cableado. Saludos desde México.
Supongo que esta utilizando un circuito para adaptar impedancias y amplificar la señal, me pregunto que tal funcionaría aquí un transformador de audio (con una calidad decente por supuesto). Transformadores de audio del tipo que utilizan las cajas reamp, tendrías la posibilidad de balancear la señal además de adaptar la impedancia aunque es bien sabido que la impedancia con las cuales trabajan los piezoeléctricos suelen ser muy altas, cercanas a los 10 Mega Ohm. También podría utilizar cera de abeja como es de habitual uso en los acelerómetros para fijar el piezo en el gabinete, esto aseguraría que no haya espacios de aire entre el piezoeléctrico y el gabinete.
Thanks!
If you're living in America 60Hz (and its harmonics) noize is probably there due to AC frequency and all electronics radiating it and probably resonating.
True
do you know if shielding paint, used in some guitar builds, would do the same as the tin foil? I assume so. Cheers!
Huh. Cool.
60 Cycle HUM ! So , piezo elements are not unlike single coil electromagnetic guitar pickups !!!