From: Patent Tactics, George Brock-Nannestad
Eric Jacobs, Parker Dinkins et al. have discussed various ways of obtaining
EQ and Eric comes back to the use of a partiuclar switch:
> > How many of you use your mono/stereo switch on your phono preamp
> > when doing transfer or remastering work?
In my view, any summing, switch or computer, will contribute to a smearing in
time of the signal, because the left and right channel of mechanical mono
records are not synchronous. This is caused among other things by rotation of
the cutting stylus on its axis (deliberate in the case of instantaneous
recordings, and as reported by Bill Klinger and myself at the 2005 ARSC
Conference), and certainly even with an optimally adjusted offset radial
tonearm. That has two minima across the record surface where there is true
synchrony. It does not really matter if you click-reduce right and left
separately and then add or if you add first and work on the combination. In
all cases I prefer the first.
However, the real remedy is to use the CEDAR AZX Azimuth corrector, which is
a misnomer. It will correct the inter-channel time delay of a tape played
with an azimuth different from the original headstack, but obviously it
cannot sensibly recreate the treble removed by the scanning loss. So it is
actually an inter-channel re-synchronizer, and it works to a fraction of a
sample. This means that you can click-reduce your right and left as
previously, and then you use the CEDAR box to obtain a signal that may then
be added and subsequently suitably EQd. I have only heard rumours that one or
the other sound restorer uses this feature, but I find it essential (and have
There are various modifications to the process, but try it without click
removal: suddenly some clicks disappear just because they are now able to be
subtracted properly in time when making a lateral mono.
Just my $500 worth.