How much does rock-solid speed stability cost?

Psychicanimal, I thought you might be interested in a recent development. I've been using a Shure V15VMR with the SL1200. I had been using the VTF set at 1.5g, as recommended, when using the dynamic stabilizer and a target VTF of 1g is desired. With this setup I could hear pitch variations on pretty much every record.

Next, I tried disabling the stabilizer and setting the VTF to 1g. Whoa! Much better. Tracking is not so good on warped records, though. This got me to thinking, maybe the stabilizer in subtracting more than .5g. I re-enabled the stabilizer and set the VTF to 1.7g which should give a net VTF of 1.2g, which is near the top of the recommended range for the V15. I suspect the actual VTF is less, but I don't know of a way to verify this. Anyway, the pitch variation is almost completely gone! I still hear it on records with off-center holes, but a good record sounds fine. I've changed my mind on the SL1200. I think I'll keep it:)

Anybody know why this is so? I know the V15 is high compliance. Could the suspension, in a lightly loaded state, been resonating to cause a sound like flutter?

Nighthawk,

I also use the v15vxmr and have noticed the difference the tracking force can make when using the stabilizer. I could be way off, but I think of it much like the loading of the suspension on a car. I think of the little brush as a spring. If the tracking force is light, as shure recommends, there is less loading on the stabilizer and it's "shock absorbtion" is slower to react or has a greater distance to move, however you want to look at it, but the effect is that some of the load is taken off the cantelever. When we set the VTF higher we have forced the loading on the stabilizer and also the cantelever so the whole mechanism is quicker to react and get back down in the groove because it doesn't move as far vertically. BTW, I also notice more sibilance with the lighter VTF.

In anycase, I agree that it does sound better with the stabilizer in place and with the higher VTF.

interesting thread. there is a review by Peter Moncrieff that will tell you (in his opinion) way more than you might want to know about speed issues with turntables.

turntable speed

the review is about the Rockport Sirius III. after owning a few very good turntables, including the VPI TNT and the Basis 2500, i can say that when the speed is perfect IT does make an astonishing difference in the basic reality of the music. if you read the review it will give you a deeper understanding of some of the issues involved.....even if you don't completely agree with some of what he writes.

whichever turntable you choose, consider a product such as the VPI SDS, which will allow you to correct the speed on A/C syncronous motors.

to answer your question......it costs alot to truely achieve rock-solid speed stability. i would add that there are many very good turntables that do a very good job in this area.....but any/every belt driven tt has it's limitations.

I always tought that a brush attached to any cartridge had to have some deleterious effects...

I knew the 1200 couldn't be at fault unless it was defective. The issue of speed/rotational stability to me is sooo important--you guys see me posting it over and over and over.

Yesterday I oiled my 1200 and the audible improvement was nothing short of stunning! The manual states every 2000 hrs, and I've had the TT working for 1-1/2 years (put away for the last six months). There's no way I could have played 3,000 records on both sides, but I saw a post in the Asylum stating that oiling should be done every year, so I went ahead and used 3 in 1 (with Kevin's approval). WOW! I was playing a salsa record which I know very well and the before and after was stunning!!! The bass was fuller and tighter, the percussion was snappy and with a very fast attack (especially the timbales!), the voices were sharp and well defined; sibilinace was softer. The soundstage became bigger and overall, the music was more penetrating and intense. Member Jahaira had told me a few weeks ago that he oiled his platter and the servo arm in his JVC TT and had a similar experience.

The way I look at it is that there was still oil in the bottom of the spindle, but that oiling the bronze bushing damped the rotation, providing a smoother operation, less noise and less speed correction from the Quartz lock drive. I also noticed that female voices were getting raspier towards the end of records and Kevin had suggested me I coud have damaged my modded Groovemaster by using it the first week @ 2g tracking weight. Not so. Now the voices and the overall presentation are smoother and extended.

Nighthawk, my suggestion is to get rid of the Type V damper and get yourself the KAB tonearm fluid damper. Zaikesman wrote a review and he's using a Benz Glider MC with his 1200:

http://forum.audiogon.com/cgi-bin/frr.pl?raccs&1033259530&read&3&4&

This issue of the platter providing the time domain is really important. The belt drive crowd doesn't seem to get it. I've gone through all these efforts of modding the 1200 because there is simply no TT around it that can deliver the needed speed/rotational stability. After this experience with oiling the bearing I truly believe the 1200's outboard power supply is going to be a very welcome addition to my system.

Just wondering, is there anything out (current production model) in between the Rockport and the Technics 1200?

Now, before this direct-drive love-fest gets too out of control, let's talk about some other issues.

First, the "belt-drive crowd" does get it, and there are turntables out there that do not succumb to any of the things that Moncrieff points out in his turntable article.

For example, a quality ironless-core, non-cogging DC motor provides a perfectly smooth output. So using a motor of that type takes you a good part of the way there. Next, using a non-suspended turntable takes the subchassis interaction out of the equation. Third, having a non-stretch belt, combined with the above 2 things, eliminates the "stretch-release-stretch-release" syndrome that Moncrieff talks about. So no cog, no platter/belt interaction, no RC-tank effect interaction with belt and subchassis. What's left? Motor speed control. And heavy platters provide the momentum needed to reduce/eliminate the effects of stylus drag, making speed adjustment very infrequent, and maybe not even needed during the play of the LP. If speed adjustment is required, slow application of this adjustment will make it nearly or totally unnoticeable. A quartz-lock mechanism will not allow slow applications of change, and make immediate changes in a very small variation tolerance, so speed does not vary alot in amplitude, but it does vary alot in frequency. It "hunts" for speed. Up and down and up and down. This is true in either belt-drive or direct drive. Some may say it is perfect because of tight specs, some may disagree. So, as you can see, there are belt systems which do not suffer from these "demons" that Moncrieff waxes so epically about.

Now, direct-drive motors are inherently directly connected to the platter by their shafts, and all motors vibrate. ALL. When the motor vibrates, this vibration is directly coupled to the platter, and the platter vibrates. The vibration of the platter during play can and will cause information loss or distortion, since the record is moving microscopically under the stylus in directions other than the time axis. Better main bearings can minimize this effect. So can heavy, well damped platters.

Belt-drives on the other hand, have the motor somewhat isolated from the platter by the belt, and much of the motor vibrations are damped by the belt, and gone by the time they reach the platter. Since they invariably have some reasonably heavy platter weight, any vibrations coming into the platter will be of low magnitude, and easy for the platter to damp.

As I tried to show here, a well thought out belt drive table has much to recommend it, including good speed control and high vibration isolation, and there are a number of belt drive turntables that perform at extremely high levels. Poor belt drive tables are not an accurate representation of what belt-drive can do, just as poor direct drive tables aren't a good representation of what direct drive can do.

The absolute worst combination possible, is a cheap direct drive, cogging motor, quartz-locked, light platter turntable. These were typical in the late 70s mass-market units. They vibrate, cog, and hunt, with very little compensation from platter weight. Next up is a a cheap belt drive with a poorly designed subchassis, rubber belt, AC cogging motor, and cheap light platter. Neither of these is a very good choice. These are primarily what Moncrieff was talking about. IMO.

At the highest levels, both technologies may be good, but the execution of each design will determine how great it is.

Speed control is very important, but it does not exist in a vacuum. Vibration induced into the platter is also an important aspect of the design. They should not be considered as separate from each other, since the overall performance of the turntable is dependent upon BOTH of these parameters, and not just one or the other. This is why bearing design, platter design, motor and speed control, and vibration control and damping, are included in turntable design. Failure at any one of these criteria will result in a poor sounding turntable. The steps up the scale of performance reflect the proper addressing of all these points together.