Solos have noisy motors. This noise is reduced by replacing the original bearings in the motors.
To document the improvement the sound from each motor was recorded before and after replacing the bearings.
The recording was done by placing a quality microphone within 1/4" of the motor (no propellor) and recording during the start-up period (about 9 seconds). The mic was connected to a mixer board and Audacity software.
Audacity plots the spectrum of the sound. The peak Hz dB was used to compare the sound.
Original Bearings New bearings
Motor 1 817 hz -16 dB 998 hz -33 dB
Motor 2 750 hz -21 dB 1016 hz -31 dB
Motor 3 796 hz -19 dB 1011 hz -31 dB
Motor 4 747 hz -17 dB 1012 hz -31 dB
The average reduction is 13 dB.
I was a little disappointed in the results - I had hoped for a much quieter result. The bearings I used were from McMaster Carr.
New Bearings:
57155K368
ABEC-5
3759T47
ABEC-7
What else about these motors is generating noise? I can post the spectrum graphs if anyone is interested.
To document the improvement the sound from each motor was recorded before and after replacing the bearings.
The recording was done by placing a quality microphone within 1/4" of the motor (no propellor) and recording during the start-up period (about 9 seconds). The mic was connected to a mixer board and Audacity software.
Audacity plots the spectrum of the sound. The peak Hz dB was used to compare the sound.
Original Bearings New bearings
Motor 1 817 hz -16 dB 998 hz -33 dB
Motor 2 750 hz -21 dB 1016 hz -31 dB
Motor 3 796 hz -19 dB 1011 hz -31 dB
Motor 4 747 hz -17 dB 1012 hz -31 dB
The average reduction is 13 dB.
I was a little disappointed in the results - I had hoped for a much quieter result. The bearings I used were from McMaster Carr.
New Bearings:
57155K368
ABEC-5
3759T47
ABEC-7
What else about these motors is generating noise? I can post the spectrum graphs if anyone is interested.