Upon recording, equalization modifies both frequency and phase; these are
interrelated. Upon playback, perfect de-equalization would precisely
introduce the opposite frequency and phase modifications. A good preamp
would closely approximate the ideal, correcting both frequency and phase.
Equalization schemes were built upon simple circuitry, and the interrelated
frequency-phase plots are rather simple and easy to reproduce with a few
resistors and capacitors.
Recording hall reverberations are a separate topic, and have been discussed
elsewhere.
Jerry
Media Sciences, Inc.
-----Original Message-----
From: Association for Recorded Sound Discussion List
[mailto:ARSCLIST@xxxxxxx] On Behalf Of steven c
Sent: Friday, September 08, 2006 9:51 PM
To: ARSCLIST@xxxxxxxxxxxxxxxx
Subject: Re: [ARSCLIST] Non-RIAA preamp
----- Original Message -----
From: "Konrad Strauss" <konrad.strauss@xxxxxxxxxxxxx>
on 9/8/06 11:06 AM, Jeff Brown at jeffbro@xxxxxxxxxxxxxx wrote:
But no one addressed the issue of the phase shift correction needed to
compensate for the phase shift introduced by the original recording
EQ.
With
an analog phono preamp the required playback phase correction is
inherently
applied,
Hmm, interesting question. Does the analog phono preamp really correct
for
the phase shift caused by the cutting EQ or does it simply add even more
phase shift? I would suspect the latter.
The "analog phone preamp"...which, one assumes, would have capacitances
and inductances in its circuitry...would (or at least in theory should)
induce phase shifts. To further confuse things, I suspect those phase
shifts would be related to the frequencies involved in the sound signal
being dealt with! However, since any listener is by definition a fixed
distance (and thus a frequency-dependant number of wavelengths, including
fractional quantities) from the sound source...and in an environment
which is NOT free from echo/reverberation (also wavelength-dependent)...
there are phase relations of ALL sorts to be considered!
Steven C. Barr