Thanks for advice. First of all, my main problem was solved by oiling the motor and glueing the pulley to the shaft, as I wrote. It was not a drive belt problem. I use the SAMA with the SDS and have a special Bright star platform (sand box) with separate support for the SAMA. I have not noticed any "pull" with this arrangement, but will investigate, and agree with you on the "rock solid" goal. In my experience, everything that can be done to dampen the motor and make the belt perform as smoothly as possible is definitively worth it (so my Sama has extra damping, I even found a bit of bluetac under the top ring made a positive difference. I use a stethoscope and my finger to detect noise and vibration for the motor). I have not tried tenderfeet but already have a complex support system including three small bike tires below the sand box (cheap way to air suspension, and yes, it does help). Thanks for the advice on the Hurst. Interesting to open the SAMA and see that 80 percent of it is just the metal support for the tiny motor. Since I probably need a new pulley along with a 300 rpm motor, I may go thru VPI. But the question, is this a sonic benefit, has not been answered. |
Thanks! I think PRAT is what I am looking for, and want to try the silk thread variant. What kind of basic knot do you use? The question remains, what is the best motor, is there a sonic profit with 300 rpm? Since no-one here has answered, I have mailed VPI about this.
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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... |
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. |
Wow, made it with the nylon string! Turns out I had to use more tension, and a double knot (with the knot at the outside of the span). The nylon thread/string creates very interesting sonic changes, the whole thing seem to be clearer the bass more distinct. So thanks a lot for advice, and I will follow up on the other suggestions too. |
I get quite correct 33 rpm (a tiny bit slow) by setting the SDS to 66.00 hz, the top value, and then position the player (or the Samas, but that is harder to do) so that the nylon thread gets a good amount of stretch. The thread is 1 mm thick. For 45 rpm, I get OK speed at 90.00 hz (note, I have 230volts/50hz electricity), although I hear some hum from the motor.
Storyboy, I notice you use a rubber belt rather than a thread in your flywheel system, is this because it sounds better in that configuration? Could you describe the change the flywheel makes to the sound? Is it possible to order the flywheel as a separate part?
Podolaw, thanks, I will check out. |
Mike at VPI writes that changing capacitors will make a difference to motor performance: "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. Begin with .22 microfarads and work your way down in value till the motor stops running." Have anyone tried? |
Tonyptony, thanks a lot. I am a bit confused by looking at the Hurst and Elusivedisc web pages. From the latter it appears that VPI is upgrading towards the lower rpm hurst motors, and that the 250 rpm motor is currently the best regarding low noise, but perhaps it cant be done with the hw-19. I have mailed them, is this correct, and if so, what is the reason (pulley too large?). I'd like to get the best motor in place before other things (pulley size, string type, capacitor type). |
Rubber belt alternatives - debatable? From my experiments so far, using nylon and silk thread versus rubber belts (vpi new grey + translucent original belts), it appears that rubber has a number of good sides, that are only with difficulty improved by the thread solutions. Two nice sides with rubber is fairly robust performance regardless of platter - pulley distance (within limits, not very demanding of setup), and a fair degree of "body" and overall tonality to the music. Even if thread solutions are a step up, if set up right. Silk thread sounds a tiny bit better, I think, compared to nylon, but may be a bit more troublesome also. When things are right they sound better than belts, but they have to be tensioned "just right", and with the VPI Samas arrangement this can be a bother to adjust manually from time to time (more often than with the rubber belt). Possibly the ideal arrangement would have a light spring arrangement pushing the Samas away from the platter to "auto-tension" the thread.
As others on A-gone and elsewhere have noted, this concerns the right balance between stiffness and elasticity, transfer and isolation. We want motion going one way, but no audio noise, and nothing travelling back either.
The more the platter is able to overcome motor and pulley and string weaknesses (noise, pitch variance, statics) by its own momentum, the better. The ideal self-moving platter hasn't been invented. VPI currently offers a very expensive "hrx super platter" upgrade, this is probably a great benefit, but I have gone through three VPI platter upgrades already, and guess my current Black knight platter should do the job fair enough for awhile, there is more benefit to be had by motor tuning and drive adjustment. A direct drive for HW-19 is not available, but a good thread solution is said to be a step up in the same direction. |
Mike at VPI has mailed that if I am able to extend the plinth hole for the pulley, he can ship the 300 rpm motor and new pulley. The hole for the 600 rpm motor is ca 35 millimeter, the pulley is 22. A half rpm motor means a doubling of pulley diameter, so it will need to be 55 to 60 mm including adjustment space. I am searching for ways to do this mechanical adjustment. |
Mark, sorry for not answering. I am ordering a 300 rpm motor and a new pulley from vpi, with the lower groove 10 percent larger than the upper groove, for a silk string. The reason I do this is, mainly, slight speed or pitch variations. For some reason, this problem comes and goes a bit, it is actually less now (having changed back to a clear belt, older type). The player rests on a complex arrangement - Black magic cones, Bright Star sandbox (split top, for the Samas), and even three small bike tyres under the sandbox (the air actually helps). Still using the springs, perhaps Tenderfeet would be better. As for the rest of the chain, it should be good enough (Titan i p-up, Sme V arm, Aesthetix Io preamp, Krell 600 amp, Dynaudio consequence speakers). |