Turntable Speed

I use the Phoenix Engineering Eagle and Roadrunner to control the motor on my Lenco.  PE designed the Eclipse system for SOTA and certainly it is wonderful for any turntable with an AC synchronous motor, but now we are talking nearly $1000 in cost.  (SOTA includes a proper motor in the total cost of the Eclipse, which does ease the pain a bit.)  For comparison, KAB strobe kit that includes a wide diameter disc and a battery powered strobe light is about $100 and won't correct platter speed; it just tells you where you are.  The Sutherland Timeline is about $400 and not worth 4X the cost of the KAB kit, IMO.  If I owned a vintage DD turntable (whoops, turns out I own 4 of them), I would check speed even if the built-in strobe suggests it is spot on.  I am not so sure that those built-in devices are sensitive to speed variation due to stylus drag, etc, or slight errors in set speed.

Timeline itself is accurate. The problem with it is that it relies on a human being to assess its accuracy by following a laser dot on a wall. Probably the timeline is better than the observers of the timeline.

The operative word is "pretty", as in "pretty accurate".  Most of us are looking for speed errors or more importantly speed variation of less than 0.1 RPM against a background of 33.XX RPM.  I am mostly basing my claim on reports of others who first monitored speed with a cell phone and then used other more accurate methods, e.g. the Sutherland Timeline or the Phoenix Engineering Roadrunner or even the KAB, and found that the cell phone app in question was off a bit.  I don't think absolute exact 33.333 rpm is a necessary goal. I do think that keeping speed constant within a very small bandwidth is much more important, as we are much more sensitive to warble than to absolute pitch.  For starters, the cell phone itself does not match the actual load of an LP being dragged by the stylus, neither in weight nor in distribution of mass.

Those iPhone apps for platter speed are notoriously inaccurate at the level audiophiles want them to be accurate. What you get is the false satisfaction that you’ve seen a digital readout on the screen. I would recommend the KAB strobe system instead. Uses a large diameter strobe disc and a battery powered strobe light for constant frequency. But you don’t get a digital readout. Strobes built into turntables and any plug-in strobe light are subject to variations in AC line frequency.