Turn table speed variation question

Piano's toughest, but oboe can also be.

Speaking generally, authentic/original instrument recordings are acid tests for TT pitch stability.

Many orchestral instruments were redesigned in the 19th C. to produce a more forceful, projective tone. This was done to make them audible in the larger concert halls being built to accommodate an expanding middle class audience. To my ears, these more modern instruments place more energy behind the fundamental, at the relative expense of harmonics. (Lew and I discussed this before in another context.)

The older version of such instruments had a stronger harmonic envelope relative to the fundamental. This harmonic envelope is easily distorted into an inharmonious squawk by TT speed instabilities, even if the instabilities occur over very short time frames. Speed variations that occur between strobe measurements can be audibly destructive, yet not detectable by commonly used TT speed measuring instruments.

Play a selection of Hogwood, Harnoncourt and the like. If the TT speed isn't rock solid over all time spans, you'll hear it.

However, you are quite correct about original instrument recordings being an "acid test" for speed stability. But, IMO, the main reason for this is what I pointed out in my previous post; the presence or absence of vibrato.

Excellent point, Frogman.

Thanks for confirming my impression of the difference in harmonic structure between modern and older instruments. I spent 8+ years getting my system to the point where it can play (nearly) all my authentic intrument recordings without distracting levels of distortion. It requires a speed-stable TT of course, and much more. Densely packed waveforms in complex harmonic structures are ruined by almost any sort of distortion, anywhere in the system.