I recently bought a Vibraplane isolation platform for under my turntable. It replaced the Townshend Seismic Sink which I then put under my SME motor controller. Isolating the motor controller from vibrations made a remarkable change to the sound of the system.
I understand why isolation under the tt would improve the sound, but I was surprised by the improvement under the motor controller. Could someone explain to me what is going on there?
Also, does anyone have any experience with replacing the rubber belt with a thread on an SME table? Thanks. |
Thanks Doug. I have heard three turntables with you and your partner and none drove Paul out of the room screaming. I guess that means the two Teres turntables and the VPI Aries we all listened to together had absolutely no speed variations. I believe two were tape drive and one was a belt drive.
A red car is more likely to be seen in a snow storm than is a white car, and if either has four wheel drive, it is less likely to get stuck. |
Thuchan,
I don't know what happened to the Wave Kinetics NVS thread. I enjoyed that thread because with such a new design, there is very little information in the popular press, so forums like these can be very helpful.
I started this thread because that NVS thread was going off topic and becoming a discussion about speed stability and different drive types. I wanted it to go back to its original focus. And yes, this thread is wonderful and I've learned a lot about the topic of speed, how to maintain it and how it effects the sound.
Threads have a way of disappearing and it is not always by accident. I have no information. Perhaps Jtinn knows something. |
Lewm,
That is a good point about belt contact with the platter. My SME 10 has about one inch of exposed/free belt before and after the motor pulley leaving the vast majority of the belt in contact with the platter. This is in great contrast to some other designs which have a motor on a remote platform 9" or more away from the record platter. Tables like the Walker, the Raven and the Micro Seiki all have a lot of exposed/free belt which is why some owners have switched to thread, I think.
I have not tried the Timeline on my SME or read of anyone else doing so, but the SME tables have a reputation for having pretty constant speed stability and accuracy.
I started this thread a while ago, and I appreciate all of the contributions to it. I have learned a lot. Thank you to all those who have participated. |
Hello Dev,
Yes, I had read that now deleted NVS thread, but I forgot about your particular post. Do you remember how far off the speed was for each of the tables?
According to my KAB strobe, my SME is 0.18% fast, as determined by the fact that four (4) "33" numbers drift out of the red strobe light during a 1 minute test. This was while a record was playing. Unfortunately, my SME motor controller does not have a speed adjustment, so I change belts after about one year and that reduces the error.
I would guess that if you found one SME table too fast and the other too slow that the belts were probably stretched to different degrees. Were these models with adjustable speed on their controllers? If so, did you try to adjust the speed on the controllers to get a more accurate speed? Also, did you listen to each to see if you could hear a difference? |
Grr6001, Someone did indeed imply that the NVS is the best and he compared it to Rockport, Walker, SME 30 and many others. It was JTinn on his website. I also read that MLavigne thinks his NVS, Telos and Anna cartridge are the best he's ever heard. These seem to be absolute statements or at least the strong opinions of these two members of Audiogon.
I agree with you that if one hasn't heard it, he shouldn't have an opinion, but many of us certainly do. It's a part of these forums for better or for worse.
As this is a thread about turntable speed accuracy, I'm curios to know if Albert or anyone has tested the NVS with a TimeLIne? |
SME30/12Here is a video of the SME 30/12 with the Sutherland TimeLine. The only other videos that I have seen with the TimeLine are Halcro's Victor TT and the Sutherland website. |
Albert, Thanks for the specifics on the TimeLine tests. That Mk 3 must be something and perhaps "best of DD breed". I'd love to hear it someday. Pity it's no longer made.
I witnessed a TimeLine demo on a DD table last weekend. The owner held an envelope 12" from the laser and yes, the spot did not move during the 30 second test. When I asked him what the result would be if he let the laser hit the wall six feet behind the table, he admitted it would not maintain its fixed position. Now that table does have speed adjustments for fine tuning, and I presume better results could be attained, though we did not spend the time. I appreciate and respect the thoroughness with which you seem to be doing your evaluations.
The remainder of your post is thorough and well reasoned, it seems to me. Thank you for summarizing the issues to clearly. It's very helpful. |
I have just tried the Fieldpiece SRPM2. It is a laser digital tachometer. It works by pointing a laser at a piece of tape on side of the platter, or any other rotating object in other fields. It purports to have a high level of accuracy and it can be found on Ebay for about $75. I thought this would be an inexpensive device and more accurate than a strobe disk as it goes to three decimal points. The other advantage is that one can play an entire side of an LP while doing the test.
Well, I found it quite disappointing. The reading seemed accurate at first: 33.436. My table speed is finely adjustable so I thought I could just get it to read 33.333 by adjusting the motor controller. Well, I found that the Fieldpiece readings were not repeatable and by just moving the device closer to or further away from the platter, the reading changed, though I know the platter speed remained constant.
So I am going back to the KAB strobe disk which indicates that my table is operating at the correct speed. Perhaps this device is accurate enough for HVAC technicians and people working with motors who need to know RPMs or the total number of rotations from some equipment, but I plan to stick with dedicated tools for turntables. I just can't convince myself to spend the $400 for a Timeline. |
Yes, and I did. I guess I was not clear enough. I placed the Fieldpiece on a stand and took the reading. I then took a second reading from the exact same spot and they were not the same. I then tried about three different locations each at a slightly different distance from the reflective tape on the platter, and at different angles and these readings also did not match. They varied +/- 1 RPM, ie 33.845, 34.352, 33.908 etc. Each time the device was fixed and never moved. I had the KAB strobe on the platter and it did not waver, so I assume the platter was not changing speed. The stylus was not on a record and I did not adjust the speed on the motor controller.
For such a device to be useful, I would think that any reading from any distance within say 2-5 feet from the platter should be extremely close if not exactly the same. The point is that without getting consistent readings, there is no way of telling exactly how fast the platter is spinning. My conclusion is that for me, this device failed the test.
If anyone would like to buy this mint condition device for perhaps a different use, please contact me. |
HI Lewm, the Fieldpiece is powered by three AAA batteries. I will accept your proposition that I don't know for sure that the platter remained at a constant speed during the trial. I do know that within the resolving capabilities of my eyes, the numbers on the KAB did not move relative to the leading edge of my headshell which was placed over the numbers when I did that test for a period of 60 seconds.
I also know that I could not repeat a reading using the Fieldpiece when I took separate measurements within 10 seconds of each other. The unit was not hand held, but placed on a platform. The location remained constant (perhaps not precisely the same, but one that seemed to me to be the same). If one reading is 33.845 RPM and the next reading is 34.520 RPM taken from the same location, that is a variation of about 2%, if my math is close. I have confidence that if the platter speed varied by as much 2% within a few rotations, that my eyes would notice that by looking at the KAB. According to the KAB instructions (6.5 drifts per minute = 0.2% too fast or slow), I was easily able to notice a speed variation of 0.2%, 1/10th of the variation indicated by the Fieldpiece. I did not see this variation with the KAB.
I also presume that my ears could detect a speed variation of 2% as indicated by the Fieldpiece. I am able to hear a speed variation of 0.2% (based on the KAB) which was the case with my old turntable. So I agree with you that I can not know that the platter speed is constant with the KAB. But based on my observations of both the KAB and the Fieldpiece and assuming that my math calculations are correct, then I must conclude that my particular Fieldpiece unit is not very accurate, at least relative to the KAB.
I do know someone who has a Timeline. Perhaps I can ask him to bring it the next time he comes by for a listen. We could then do a direct comparison between the Timeline and the Fieldpiece on my turntable. That will tell me something about the Fieldpiece and my turntable. Or, I think he has a DD turntable and I should take the Fieldpiece to him for testing. |
Hello Tony, You are correct in observing the slight drift to the left over the length of the video. I just measured the relevant distances and they are: drift from right edge of "Philips" label to center of label is 1/2" (0.5"). The distance from the spindle to the laser slash line is 13.5". That should change your calculations slightly.
The SME motor controller has incremental settings of, I believe, 0.1%. I can't remember where I read that though. The line does move slightly when lifting the stylus out of the groove. Halcros Victor TT video is very impressive in this regard. The SME belt drive table should be set for correct speed while playing an LP to account for stylus drag.
You are most observant to catch the slight drift to the left, which means the table is very slightly too slow. I can not hear this. A close examination of Halcro's DD Victor video also reveals a slight drift to the left of about the same 1/2". Note the laser dash is centered on the blue tack and by the end of the 4 minute video, it is just barely touching the blue tack as it has drifted to the left. This video has been held up as the gold standard reference for DD turntable speed accuracy. I have found no others on the net except the Sutherland website videos in which none of the turntables hold correct speed.
In the interest of collecting data on different turntable performance, and learning in the process, I borrowed Albert Porter's TimeLine and decided to share the results.
I'd be very interested in seeing your calculations and translating them into the actual speed, ie. 33.4 or so RPM. Thanks. |
Thank you Tony. So, if I understand you correctly, my table is slow by roughly 6/1000th of a rotation out of 173 rotations or 0.0000346 per rotation. Said another way, 0.003% slow is 0.00003 RPM slow. So my table in this video is running at 33.3333333-0.00003 = 33.333303 RPM. Is that correct?
The precision of the Sutherland TimeLine is such that is can clearly show this deviation. I'm sure that SME and most other designers do not use such fine measuring tools when testing the results of their designs. I've mentioned elsewhere that my turntable shows correct speed while using both the KAB strobe and the paper disk supplied with the turntable.
I am perfectly satisfied with setting the speed with the KAB. But this experiment with the TimeLine has been very informative. The motor controller increments are course enough to be detected by the TimeLine. I've tested the number of increments I can hear, and it is somewhere between 4-5, either too fast or too slow. I can not detect by listening a variation of 1-3 increments on the motor controller in either direction. Perhaps others with perfect pitch could hear this.
The new TechDas turntable has "passed the TimeLine test." It would be interesting to see that video and the video results of other tables which have different drive types using a similar methodology to my and Halcro's test.
I have heard of some tables showing even better results, but without video documentation. |
Hi Tony,
The TimeLine device that I borrowed from Albert Porter is the older model. The new/current one has, I think, six strobe lights/flashes spread equidistant around its perimeter. I know it is different in some meaningful way.
It would also be interesting if the duration of the strobe itself would be quicker on and off. Then the strobe slash or line on the wall would be of shorter length. As it is now, because the device is rotating on the platter, the length of time that the light is on smears what would be a dot into what appears to be a line. This is consistent with my observation that the further away the wall is from the spindle, the longer is the strobe line/slash.
It is an incredibly interesting device and I think one could study what happens to the line with a slow speed camera and thus detect different behavior between belt drive and DD tables during the moment of flash, i.e. during very short durations, and perhaps detect visually deviations of speed consistency. Some listeners claim to hear this earlier in this thread.
If you look closely at Halcro's video, the strobe line looks different than it does on my video and the quality of my line changes slightly during the course of my video. So something else is going on.
As was mentioned earlier in this thread, there is also a distinction to be made between speed accuracy and speed consistency. I agree with those who think the latter is more easily heard. |
I am hoping to establish a video database of various turntable speed test results. The thread is over on WhatsBestForum. Here is a link:
http://www.whatsbestforum.com/showthread.php?13137-Turntable-Speed-What-matters&p=239164#post239164
So far, I've only posted Halcro's excellent Victor T101 video and my own video of the SME 30/12. Perhaps in time, there will be more turntables added. If anyone wants to upload such videos to YouTube, I will gladly add those links to the WBF thread in a list in post #1. |
