SDS question

Hello friends,
I was checking my turntable speed today using my KAB speed strobe and found that my table was running quite slow. I had the VPI SDS calibrated at 59.85hz and I thought I had the speed perfect. Today, I needed to adjust it to 60.03hz to get it dead accurate again.
What might cause such a big change to have to be made? I was wondering if it might be the weather (it has turned cold recently here in Chicago)?
Any thoughts would be appreciated.
Weather's a possibility. Generally, needing a higher frequency suggests that system friction has increased. Perhaps your bearing lubrication has dried out a little. Another possibility would be that your motor is starting to wear or needs more lubrication and thus become a little weaker. Unless it keeps getting worse, I wouldn't really worry about it.
That's quite a bit of a jump in hz, considering it was dead on before.

As James suggests, it may be a Lube issue? When was the last time you Lubed the bearing? If you're using VPI Grease, maybe a drop of Mobil 1 to cut it ever so slightly?

Or it might be Belt slippage? When was the last time you replaced the Belt? At least try cleaning the Belt, and edge of Platter (Windex), and see what happens?

There was a recent thread about the SDS slightly wandering, but very doubtful you're wandering as much as .18hz

Let us know if you find anything? Mark

are you plugging the sds into the wall or a power conditioner? House power can vary +/- 10 volts at times. I realize the sds is suppose to handle that but I find using my PS audio 300 power plant eliminates this prolem
Its been a while since I was up to date on TT technology. What kind of motor is used? A synchronous motor, common decades ago, would assure that the rpm was exact ("dead nuts" is the technical term). Bearing lubrication, temperature or phase of the moon would have no effect. Only a change in line frequency would affect speed.
Start with the lube and proceed to the belt. I think keeping the bearing lubed may be the most overlooked "tweak" or maintenance procedure. Throwing a few drops of factory-approved oil in the bearing made my near-new Technics SL12x0 spin much nicer and a little quieter.

Belt wear and slippage is a continuous process and usually doesn't get addressed until it's obviously audible. By then it makes the turntable sound like it's seriously broken. But one would think intuitively that a belt could wear and slip the equivalent of .18Hz over time, and one wouldn't notice unless strobing it.
Just following up on Starcons' comments, I was at 60.54 before hooking up my PS Audio PPP. Now the SDS is at 60.00 and my turntable sound is noticeably improved.
OK...I forgot belt slipage. I am a DD guy where the speed of the platter is the same as the motor, and the motor is exact. I really don't think that there should be any belt probably need a new belt.
Thanks for all the responses. I lubricated the bearing with white lithium grease about 6 months ago, so I should be good there.
The belt is the original belt so it is about 3 years old. Time for a change?
The motor is also original, and it does seem a tiny bit noisier than it was 3 years ago. How long should a motor be expected to last?
Actually, I was wondering if the how much an acrylic platter would expand/contract with temperature changes. Is this a possibility? The room containing my TT gets very cold when I'm not home and the heat is off.
You could try boiling the belt for about a minute, then re-talc'ing it. That's what VPI recommends should be done every year. If that doesn't work a new replacement isn't much.

..just for your information. When my Superscoutmaster needed oil it made a ch,ch,ch,sound. When I called Harry, he said it needed oil and is sending some to me
Hello, Your Motor should last considerably longer than 3 years. And I also doubt your house is getting that cold, that it's affecting-changing Platter Diameter.

I have thought I once read a post, where VPI themselves had recommended a drop of Oil where the Motor Shaft meets the Motor Housing. A call to your Dealer, or VPI themselves will know. If your Dealer in Chicago was MusicDirect, Bes Nivera will also know as well.

Three years is a bit of a stretch (pun intended of course! lol) for your Belt. I recommend getting a new one. Belt Slippage is tough to actually see, but your SDS may be confirming this.

Lastly, doubtful if Voltage has went down in the Chicago-land area this time of year. Usually, it's the Summer, where the miilions of AC Units are running across the City, thus slightly lowering Voltage at the Mains. Hope this helps. Mark
What kind of motor is this, and how is the speed regulated?
Variation of line voltage (but not the frequency) is common, and I would be surprised if a TT was sensitive to voltage variation (within reason).

For example, my DD turntable has a strip of magnetic recording media on the underside of the platter which is recorded with a HF signal. A head (like a tape recorder) reads this signal which is compared with a quartz crystal generated signal and the difference (if any) regulates the speed. It works great.

I believe (based on prior threads) that Tfkaudio may have a VPI Scoutmaster, which uses a synchronous motor with a relatively small (1 to 2 inch diameter) plastic pulley on the end of its shaft, driving a rubber belt that goes around the outer rim of a full 12 inch plastic platter. I trust someone will correct me if I'm wrong.

The SDS is basically a monobloc amplifier that takes wall power and "plays" a single tone. That tone is a sine wave with frequency of approximately 60 herz. This frequency is adjustable, i.e., you can set it somewhat plus or minus from 60 herz. We can observe the effect on platter rotation by using a strobe disc on the platter and accordingly adjust the SDS frequency so the platter rotates at the correct speed.

The reasons why the frequency might need to be adjusted include system friction and reduced motor effectiveness. For example, if I press my finger against the outer rim of the rotating platter, it will slow down. This may be due to slippage somewhere in the system, most likely from the belt, or it may be due to insufficient power from the motor (just like pinching the rotating motor shaft hard enough can slow the rotation). As you can see, this configuration has some vulnerabilities compared to your direct drive.

If, for example, there were too much friction and the belt were slipping slightly, increasing the SDS frequency would offset this by setting a faster pace from which the slippage would reduce the rotation back to the desired speed. Admittedly, not the most elegant solution, but it works.

Slippage may be variable, depending on belt material characteristics relative to environmental factors. The Scoutmaster configuration requires the belt to flex and stretch a little as it goes around the pulley and platter. Perhaps the belt gets stiffer when it is cold, and this could result in greater slippage. Or, the slippage may be a function of the humidity of the air, which could effectively lubricate the belt where it meets the pulley or the platter. Another possibility is that the platter's bearing lubricant has temperature dependant viscosity. (I might guess that his lithium grease is not the lubricant recommended by the manufacturer.) Maybe Tfkaudio has a bit of foreign matter in his bearing that requires low viscosity lubrication to overcome. Obviously, I really don't know.

If his turntable's performance does not change significantly from where it is now, I would think knowing the cause is not so important. If it keeps changing, I would recommend contacting VPI and having them deal with it. Perhaps they may have encountered this before.
Jameswei...Thanks for the info. Of course my synchronous motor can slip has to when it starts up. However, when it "locks in" to synchronous operation this is indicated by a LED.
Hello, and thanks again for the input.

I am going to order a new belt. 3 years is a good run for the old one.

Stringreen, regarding oil for the motor, you said that Harry is sending you some... does that mean that any old motor oil won't do?

Thanks again.


P.S. Yes, I have a VPI Scoutmaster. I was surprised to see that I failed to mention that up front.
Tom, I'm thinking that these newer VPI Tables with Inverted Bearings are recommended to use Grease, rather than Oil? Somebody with a Scoutmaster please confirm if you can.

A simple call to VPI, ot a quick call to MusicDirect in Chicago should confirm whether this is true, or not?
Since they are a VPI Dealer, they should have the proper Bearing Lubricants in stock. Probably best to stick to what VPI recommends. Hope this helps, and do let us know if the new Belt has improved your speed stability? Mark
Hi Tom. When I spoke to Harry about the Che,Che sound (he actually heard it on the telephone), he said there is an adjustment if there is too much play in the shaft. This can be checked by pulling up on the pulley. There should be a little play, but not too much. The play on mine was about equal, so the next step Harry said would be to put oil on the shaft. He didnt mention what kind of oil, but he said he would send some to me. I havent received it yet..this was only a few days ago. If you call VPI, they could surely answer your questions. ..Just for your information, VPI is closed on Mondays and a couple of other days. I called Tuesday and was able to get through. Stan
I've been using Phil's Tenacious Oil, a bicycle oil, for several years now after it was recommended on the Vinyl Asylum. Used it on my Scout, and have been using it on my Scoutmaster with excellent results.

Here's a link:
According to my manual, the bearing is lubricated with white lithium grease. So that is what I use.

The motor would be lubricated with oil. I'm going to call VPI and ask for some, or what kind to buy.

I went to the VPI website and looked at the Scoutmaster manual. Tfkaudio is clearly on the right track with his lubrication.

"After at least one year of use, the platter bearing and motor will need to be lubricated. For the platter bearing, use .25 teaspoon of white lithium grease. For the motor, use 1 drop of 40-weight motor oil below the brass piece." the "brass piece" they mean the shaft of the pulley? and if so, how do you get oil on that shaft, it being under the wide pulley
Seems like a poor description at best by VPI, but I would assume a Scoutmaster owner would know what to look for.

I had mentioned these very same lubrication needs earlier in this thread, but I cannot take the credit, as I believe this information was provided right here, that I mysekf read once in Agon archives from another user-owner.

These Archives are sure a godsend for all!

Perhaps like my own VPI Motor, acess would most likely need to be gotten under the Motor Pulley, and dependent on jusy how far down the Pulley Shaft that the Pulley is situated may dictate removal of the Pulley?

No doubt attached with an Allen Set Screw, and I imagine the most important thing to remember here if there's a need to do this, is just make sure yu replace the pulley in the exact same manner as it was before.

If the Pulley is removed, this would be a good time to perhaps clean the pulley with a bit of Alcohol, or Windex? Hope this helps, and again, please do let us know how all turns out. Your findings, and information will be valuable to other owners who come along in the future here in Agon. Mark

I would have to agree that "the brass piece" is the motor shaft, especially since you said Harry recommended putting oil on the shaft. I don't have a Scoutmaster, so I have only looked at web images of the motor, and they seem to support the brass piece being the shaft, too.

As Markd51 noted, one may need to remove the pulley by loosening an Allen Set Screw in order to get the oil to the shaft.
That's exactly what I did. It's actually 3 set screws, 2 in the shaft, and, once the shaft is removed, a very small one to lift out the brass nut. I then dabbed a swab with motor oil and brushed. Not that simple, but there it is. I hadn't even given thought to doing this since I acquired the motor a couple of years ago, so it was certainly about time.
Thanks again to everybody. I had always wondered how to go about oiling the motor, since there is almost no space between the pulley shaft and the motor base. The VPI manual really should have explained it just like Sberger did!