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On 20/12/2011, Richard L. Hess wrote:

> Hi, Don,
> 
> The time/phase error at the stylus tip could cause significant
> problems if an attempt was made to create a mono sum of the signal.
> It's the same thing we see with tape azimuth.
> 

Yes, but why would anyone want to create a mono sum of the signals?

The old reason was for broadcasting, but nobody is broadcasting from
vinyl now. And did this effect cause any problems in practice when they
were?

> The 1/400,000 of a second at 78 rpm would translate to approximately
> 32 degrees of electrical phase angle difference at 15 kHz at 33.3 rpm,
> which is not huge, but significant. This is the order-of-magnitude of
> azimuth wander seen on less-than-ideal, but not horrid 3.75 and 7.5
> in/s tapes.
> 
> But you are certainly correct that a one foot path length difference
> would produce an error of a full cycle at about 1120 Hz, but somehow
> we don't hear that path length difference in the same way we hear a
> mono sum before the signal is fed to the speakers.
> 

Regards
-- 
Don Cox
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