Stylus Drag

As far as stylus drag's affect on speed control, let me also explain that platter mass is part of the entire speed control system. The speed control system is designed around the motor and platter inertia. Turntable designers, especially belt drive tt's use platter mass for dampening. Mass is commonly used for dampening. Your car engine and even your car body has mass dampers to minimize the vibrations that you feel and hear in the car. A massive platter requires more torque to control speed- and so belt drive tables use the small motor pulley and large platter outside diameter as a torque multiplier. A direct drive tt has a relatively low mass platter and as many on this forum will attest, also has excellent speed control. The speed control system is different for the low mass DD tables as compared to a belt drive table. DD turntables simply use a different control system for the lower inertia platter. DD turntables were originally designed for DJs so they could stop/start the platter quickly. My personal preference is the massive platter on a belt drive table because the mass doesn't just dampen torque variations, but also external vibrations from the floor and the air. The massive platter makes a great sink for the record. DD turntable users have to admit that they must work hard to isolate their DD turntables and platters from vibrations.

Dear Toniwinsc, I nearly sold my Kuzma Stabi Reference (8kgr platter, two motors, one belt) in order not 'to stay behind'. Lucky me there was no Kenwood 07D available during
my 'intention time' otherwise I would make a mistake. Thanks for your 'grounded' explanation. I want mention the the packaging and posting of the 'monster from Slovenia'.

Regards,

Hi,

As this is verging on speed stability, i'll post some new comments on the turntable speed accuracy thread.

Andrew

****But it apprears Halcro has observed changes in speed with havily modulated sections of the record using the TimeLine. The key question is whether or not this small change is audible.****

Well, Halcro is correct, but I suppose that the key question is wether this "small" change is audible to YOU, and wether you are particularly sensitive to the effects of subtle speed instability effects. I disagree with Atmasphere that these changes are heard only as effects on sound staging as opposed to speed stability. Yes, there can be decreased sound staging stability, but also (and more important to me) varying degrees of instability in the swagger or groove of the music compared to the rock-
solid stability of live music; that is, assuming that the musicians were playing with a rock-solid groove.

To put this in a musical perspective look at some of Tonywinsc's great comments and stats:

****So let's say someone using the timeline with a 500mm radius to the wall observes a 2mm shift in the red line when they drop the needle onto the record. At 500mm that is a 0.06% change or 0.02 rpm shift. If you were playing a 3150Hz test tone, that would cause a 1.9Hz change.****

When an orchestra tunes to A:440 it is not uncommon for musicians to comment among themselves that the pitch being given (usually the oboe) sounds a bit high or a bit low. This, even though the digital tuner being used tell the oboist that the A he/she is playing is a true 440. What is the point? That the trained ear can hear subtle pitch changes that even the TYPICAL PORTABLE digital tuner can not identify. Now, consider Tonywinsc's comment, and I realize that the comment doesn't address the effects of heavily modulated passages on stylus drag. A change in pitch of 1.9Hz is easily audible. Orchestras make the choice to tune to A:440 or 441, 442, etc. for very real, and musically important reasons. Additionally, players are constantly making minute changes in their respective pitch centers. So, when one considers that due to the mechanical nature of LP playback a change in speed stability means a change in pitch and a change in the musical impetus of the music, it is not difficult to understand how stylus drag can be an important issue. Now, where we choose to try and perfect our very imperfect sound systems, and which of these imperfections we are each most sensitive to is a very personal matter, but there is no doubt that the music is very vulnerable to all these effects.

I had used my little strobodisc for years on my turntable. When I used the 3150Hz tone and the iPad app, I found that my speed was low by a few Hz. I didn't hear it as a pitch change, but as a rhythm and pace improvement. I'm hearing all of my records as new just from getting the speed dialed in correctly. That was a learning experience; don't rely on the little stobodiscs. I hear a pitch variation only when playing a pure sinewave. The record runout causes a small but noticable warbling in the pure tone. Improving record runout (filed the hole out and centered the record on the platter) directly reduced the pitch variation.