After getting the BLDC motor up and running, I'm interested in replicating Bill's vibration test on the Hurst 300rpm vs the BLWS. I removed the Hurst motor from my VPI Classic 4 and let it free standing on the plinth to measure it, just as I was letting the BLWS free standing when making the measurement. Even though I'm reconfirming Bill's result, I'm still appalled by the performance of the Hurst. I'm using a ADXL337 affixed to the motor and captured using Audacity with a Focusrite Forte USB soundcard at 96KHz, then run FFT on the signal. Both tests has the same gain settings. I'm measuring X and Y using the two channels.
For the BLWS, the peak is 120Hz@-66.5dB(-87dB), 240Hz@-80db(-101dB), 60Hz@-73dB(-78dB) (later two included for comparison as there is only 1 obvious peak).
For the Hurst, the peaks are 120Hz@-34dB(-92dB), 240Hz@-55dB(-98dB), 60Hz@-50dB(-64.5dB)
The value in bracket is the background value when motor is not running. The difference between the two motor is so huge that it swamp out any potential measurement tolerance problem.
I have always been complaining to VPI that I can hear the motor humming. After a lot of back and forth, there doesn't seem to be any solution. Not sure if my motor is any worse than the norm but this is the first turntable that I can hear the motor noise even from a couple of feet away (from the numerous belt drive and direct drive turntables that I have owned in the past), and this is supposed to be a Stereophile Class A component! At least now I have the proof that I'm not crazy.
For the BLWS, the peak is 120Hz@-66.5dB(-87dB), 240Hz@-80db(-101dB), 60Hz@-73dB(-78dB) (later two included for comparison as there is only 1 obvious peak).
For the Hurst, the peaks are 120Hz@-34dB(-92dB), 240Hz@-55dB(-98dB), 60Hz@-50dB(-64.5dB)
The value in bracket is the background value when motor is not running. The difference between the two motor is so huge that it swamp out any potential measurement tolerance problem.
I have always been complaining to VPI that I can hear the motor humming. After a lot of back and forth, there doesn't seem to be any solution. Not sure if my motor is any worse than the norm but this is the first turntable that I can hear the motor noise even from a couple of feet away (from the numerous belt drive and direct drive turntables that I have owned in the past), and this is supposed to be a Stereophile Class A component! At least now I have the proof that I'm not crazy.
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An externally hosted image should be here but it was not working when we last tested it.
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I couldn't get your attachments to open but I've had 4 VPI Tables with both 300 and 600 rpm motors and I'd have to say that is not the norm. While the Hurst aren't exactly great, I think you got a extra noisy one. I've only had one that I found to be particularity noisy but a bit of super lube under the brass collar solved it.
Got it! I just saw the drawing on AA page. And now another question: I’ve decided to build this controller and the SG4, so gracefully offered to us by Bill. Are parts still available from Mouser? Does anybody else need boards? I know they are sold in multiples of 3.
I just checked the Mouser buckets for both SG4 and controller. Both are missing some parts but nothing critical. All can be substituted.
I have extra boards. PM me your address and I'll send them. Extra parts too, let me know.
Here are the parts that are not available from Mouser in the project cart anymore; carbon film resistors, 39K and 10ohms, both 5% (what can they be substituted with?); 15v wall switching 15W supply, I imagine this can be easily found; 1000uf 35v electrolytics - not a problem, I imagine; 100uH Coilcraft inductors - these I have to look for and see.