On 20/12/2011 15:15, Steven Smolian wrote:
> Has anyone tried using the Izotope phase correcting program on a left/right
> groove transfer of a mono groove to line up both channels?
> > From what I can tell, Izotope's phase correction works at 1/100 of a bit
> rather than the 1 bit as with many other programs and, I am told, makes a
> noticible audible improvement on stereo tape phase issues over programs in a
> similar price range.
> Steve Smolian
> -----Original Message-----
> From: Association for Recorded Sound Discussion List
> [mailto:[log in to unmask]] On Behalf Of Richard L. Hess
> Sent: Tuesday, December 20, 2011 9:50 AM
> To: [log in to unmask]
> Subject: Re: [ARSCLIST] Straight Line Tracking was Stanton Turntable
> 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.
> 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.
> On 2011-12-20 8:59 AM, Don Cox wrote:
>> On 18/12/2011, George Brock-Nannestad wrote:
>>>> From: Patent Tactics, George Brock-Nannestad
>>>> Eric Jacobs has given a very full answer to the S- and straight
>>>> arm question.
>>>> However, there is one further aspect of the tangential tracking
>>>> arm question and pivoted arm question that has to be kept in mind.
>>>> The original derivations of the advantages and disadvantages of
>>>> the various pivoted arm geometries was based on mono only, and
>>>> coarse-groove dimensions. Percy Wilson pointed out a special form
>>>> of time distortion: the overhang in his elaborated example meant a
>>>> gradually slower reproduction because in effect the needle tip
>>>> moved along the groove during play. However, he calculated that on
>>>> one revolution at 78rpm the delay only amounted to 1/400,000
>>>> second. That is not discernible to a listener. However, in the
>>>> stereo case, and in particular with line contact or elliptical
>>>> stylii, the situation is different, and the time scale between the
>>>> two channels shifts. With a slower speed and higher recorded
>>>> frequencies there are definite time delay shifts between channels at
> the high frequencies.
>> I think this would be negligible compared to the effect of not being
>> precisely equidistant from the speakers.
I routinely use the Cedar phase program when dubbing from disc and it
neatly sorts this problem out.