What your problem may be, is the Drive Belt? When was the last time it was changed?
The SAMA Motor shouldn't be changing, or fluctuating speed, and the SDS should be providing stable voltage-frequency to the Motor.
But, if your SAMA is using the newer, "stepped drive pulley", that one can adjust speed at the pulley in very small increments by which little groove the Belt is placed on, it is possible that an old, or worn belt is wandering on the Pulley?
Those ridges on the pulley are very small. I'd try this forst before resorting to Motor swap-outs. Mark |
You can easily pick up a new Hurst motor on the web. You don't even have to go through VPI to get it.
On another note, I believe there was some discusison about which motor was actually better. Something to do with the cogging effect, since the number of poles differ on each motor. Maybe someone else who has more knowledge of this will chime in. |
Not sure yet if my first response will be posted, but besides the possible issue with the Belt changing places on the Pulley, another cause could be the possibility of your SAMA not remaining stationary?
I'm finding that out myself with a recent SAMA installation, that the stock rubber SAMA feet seem to be inadequate. My SAMA I note is beginning to pull towards the Platter, that I'm noting inconsistency of Belt Tension due to this "pull", I'm seeing the Rubber feet bend-lean under this pressure, and am in the process of retro-fitting my SAMA with a set of Herbies Tenderfeet.
They are a few mm taller, but a wider foot, at 1.1" x 1.1".
Other devices out there could be used. I think the important thing, will be providing a rock solid anchoring of the SAMA to whatever Shelf-Rack you use. Mark |
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. |
Yes, true, the newer SAMA from what I can see as well, is basically empty. Nothing inside, but a Foam Sheet isolating-seperating the bottom of Motor Case from the Run Capacitor.
But, the 600rpm Motor is not inheritly bad as far as speed stability goes, and if working properly, is not prone to the large degree of speed variation that you are appearing to notice.
So, with that said, yes, the Motor could be at fault, and I imagine if it is doable, one could then possibly opt for either the 300rpm Motor, or otherwise, a new 600rpm Motor should do the trick.
It will be VPI that may have to answer your questions, if the 300rpm Motor will be a simple swap, or will one have to modify the SAMA Case in order for it to fit? We can assume that a different Pulley would indeed be needed. The question is, does VPI have the correct Pulley that will work with a SAMA. Meaning, will it be long enough to protrude far enough, and up through your Plinth to reach alignment with Platter? That is an unknown to me?
Having to glue the pulley, I then assume you once had either slippage, or wobbling of the Pulley, to require gluing it to the Shaft?
I think we can all agree, that the Base on which your Table, and SAMA rest upon should not be an influence of the Motor's speed stability, that this would be caused by something else? But what?
The only other influence that I can think of, in regards to speed fluctuation, would be the VPI SDS at fault? One would have to test the SDS to find if any fluctuations in voltage and/or line frequency are taking place?
Mark |
If you have an SDS then there is one other thing I can highly recommend that you try. Get rid of that vibration prone VPI rubber belt and find some silk thread. Tie a basic knot in the ends and use that instead. You will definitely have to adjust the speed to compensate for the thread's smaller diameter sitting down in the pully groove. You will also definitely need to give the platter a push-start by hand.
The PRAT will increase dramatically, with more detain and better space and air. Not a small improvement and easily one of the best things I did for my VPI. |
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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Please keep in mind, that VPI is on vacation till Jan 11 I believe. Mark |
Here's a thread discussion thread (sorry, I couldn't resist) but there are others and some that have on-line sources quoted.
http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1264987921&openfrom&1&4#1 |
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... |
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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. |
I had a problem with the big rock and got rid of it. I have a TNT Jr. And found temperature changes were effecting the sand in the big rock, and throwing off leveling, effecting a few things. Vpi on my Billy bags rack now and improvement was significant. I have a small custom svelte shelf under the motor. |
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. |
Here is the link to the motor you need for the VPI. Order it over the web and they will expedite. Should ship in 14 days. $84 shipped.
http://www.hurst-motors.com/papbdirectdrive.html |
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? |
O_holter, I did this with a new Hurst motor for my AR table. Not a VPI but it does use a Hurst. I did indeed get lower noise and smoother running by experimenting with lower cap values. But there is a price to pay. If you go too low you run the risk of having the motor randomly start rotating in the wrong direction on power up. You'll have to give up a bit of the lowest noise performance you can get (by upping the cap value from that point) to get reliable start up direction.
By a variety of Sprague "Orange Drop" caps up to just below .22uF and they each one out until you get the best compromise (.047, .1, and .15 are available). Use the 716P series. |
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. |
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 Unfortunately this is an area outside my knowledge base. I can only recommend doing what you're doing - talking to VPI and maybe searching the web to see what other VPI enthusiasts have done. |
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. |
Hello O_holter,
Seems to still have interest, and are persuing the use of the 300rpm Motor.
If it is permissible by the mods, I would like if you could further explain what it is you are not liking with your sound? Is it noise, or vibration from the Motor you're hearing-feeling? Which SAMA is this you have, the newer one, or the older one with round case?
I see you mention PRAT? What other sonic dislikes are you noting? What are you using as a Plinth Suspension? The Pucks, or Springs?
Are you still using the stock Rubber Feet on the Wood Base?
These are two areas, where the chageout to a cone foot for the Wood Base, and using something like Herbies Iso Cups-Balls, or Tenderfeet for a plinth suspension should net you some good, not subtle sonic gains.
As I believe I mentioned earlier in this thread, I too am running a modded HW-19 with newer version SAMA, SDS, 16 lb MK-IV Lead Filled Black Acrylic Platter. My custom HW-19 does not have a seperate Armboard, but uses a custom made solid one piece 1.00" thick Acrylic Plinth secured to the Steel Sub Chassis Plate.
I now use the Herbies Extra Firm Tall Tenderfeet to replace the Sorbo Puck Suspension. I use the short soft Tenderfeet to replace the stock rubber feet on the SAMA, and use Brass Audiopoint Cone Feet to replace the stock Rubber Feet on the Wood Base.
I cannot imagine my Table being any quieter than what it currently is, it is totally dead quiet in operation.
Dislike of sound can maybe be sourced to other components in your chain? Your sound will only sound as good as its weakest link. Mark |
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). |
o_holter, did you ever get the 300rpm motor set up on the 19? I have been having a lot of interest in doing this but everyone I talk to about it at vpi seems to discourage it. |
Four things to look at:
1. Early 600 rpm SAMA came with a flywheel. It looks like a large stainless steel washer that slides over the motor spindle. VPI stopped using it at some point because it wobbles causing speed variations, flutter and rumble. If your SAMA has one ditch it.
2. Worn belts will cause speed fluctuations. Don't get a third party belt. Only a few dollars more to get the VPI belt.
3. Dirty or dry platter bearing will cause speed fluctuations. Clean it out with alcohol and q tips and oil it sparingly with a high quality oil. I like sewing machine oil.
4. I've had a couple generations of the VPI speed controllers (SDS) and was never pleased with any of them. I now use a Phoenix Engineering Eagle and Roadrunner. They keep speed dead on to within about .004. Unfortunately Phoenix recently went out of business but if you can find the pair used for a decent price they are great.
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