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.
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
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
>> > Hello,
>> > 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.
Richard L. Hess email: [log in to unmask]
Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX
Quality tape transfers -- even from hard-to-play tapes.