VPI motor - upgrade to 300 rpm?
I have not made an unbiased comparison between the 300 and 600 rpm motors, but years ago when I looked up specs for the so-called upgrade, I noticed the 600 has twice the torque - that's quite a difference. Of course, there is probably a price to pay for that, likely vibration, but with all the talk years ago about the torquey idler drives, I kept the 600 and made myself a pulley stabilizer/flywheel which goes in front of the pulley and tensions the belt around the pulley 180 degrees - all without increasing the overall belt tension. I can just turn my motor on, no pushing, and the platter starts to spin at speed immediately, and that's how torquey the 600 motor really is. I have only 1/4" of belt on each side of the pulley/flywheel, which means it will have very little stretch - compare that to the stock 6" length and 40 degrees of contact. And, of course, it sounds way better. Why VPI doesn't do this I don't understand. Sorry, can't link a pic, but I'll try to figure something out. |
Today I got this reply from Mike at VPI: "The 300 RPM motor does not work on the HW-19 so that is not an issue. The 600 RPm motor should work perfectly when you get the capacitor right for your countries voltage and frequency, it is a critical item and if you are willing to play with different values you can fine tune the motor for lowest noise and running smoothness. Mike" No use running after a 300 rpm motor, then. Capacitors, here we come. Has anyone tried? Storyboy, this sounds very interesting, can you explain a bit more ("in front of the pulley and tensions the belt around the pulley 180 degrees")? Amazing what one can achieve with further improvements like these... |
I posted a pic, just follow the link . The brass flywheel comes from an HO scale model train motor, and the rest is rigged. It works. http://trade.audioasylum.com/ca/wtb/listing/Turntables/VPI/Scout/pulley/43555 |
Storyboy, thanks a lot, it looks very effective. For now I am testing threads, one silk, one nylon, both ca 1mm thick. I can tension the thread by adjusting the player feet to widen the distance to the pulley. The platter starts ok and I do notice sound improvements, but I have not managed to get the speed right. Since it had been used with the standard rubber belt, the SDS was tuned to 72 volts / 60.00 hz (for 33 rpm). With the thread it remained too slow even when I turned it up all the way to 66.00 hz, which is the top level for 33 rpm. I tried switching to 45 rpm, but then it went too fast, and remained too fast even when turning the hz fully down. My pulley has two groves, one small-diameter at the top which is correct for the rubber belt, and one larger below it. I tried changing to the larger grove, but this made the speed even faster and did not solve my problem. My experiences were similar with the two threads. I also felt that the speed was a bit fluctuating, but I must get it fairly right before I can tell. Advice welcome. |
