The point, made originally by British engineer Sean Davies, was that
without any high end roll off, the record level would need to be lowered
somewhat to avoid clipping at the time of A/D conversion: "There may
be a bit penalty to allow for headroom in the A/D conversion. For
taking the RIAA curve there is a lift of nearly 20 dB at 20 kHz so
transfer level would have to be reduced by this amount which implies the
loss of 4 bits compared with analog equalization." With 78 rpm discs he
states: "the bit penalty for a constant velocity above 250 Hz curve
be 2 to 3 bits." His AES preprint is Convention Paper 5534, (2002).
A reply to Davies is found in AES Convention Paper 7185 (2007), by
R.S. Robinson of the Channel D Corporation, which advocates flat
transfers and EQ in the digital domain.
Gary Galo gave a talk at the 2009 ARSC Conference: "Phase Equalization
and Its Importance in the Playback of Disc Records", which may be
heard via the web site.
Audio Restoration & Mastering Services
Transfers of metal parts, lacquers,
shellac and vinyl discs & tapes.
193 Baltic St
Brooklyn, NY 11201-6173
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> Date: Thu, 12 Apr 2012 17:53:59 -0500
> From: Parker Dinkins <[log in to unmask]>
> Subject: analog vs digital eq
> Any time you boost levels the headroom is reduced, whether it be in
> the =
> analog or digital domain.
> If any digital audio program material is too high, 1) reduce the
> global =
> level before boosting, 2) cut instead of boosting, or 3) use
> floating =
> point processing and adjust the levels when it goes to fixed point.
> I'm not convinced that analog eq is always desirable with disk =
> transfers; I know the arguments pro and con. It is very helpful to
> have =
> a high quality phono preamp with a variety of curves for quick
> reference =
> in auditioning a disk.
> Parker Dinkins
> On Apr 11, 2012, at 11:00 PM, ARSCLIST automatic digest system wrote:
>> Date: Wed, 11 Apr 2012 16:28:26 -0400
>> From: Doug Pomeroy <[log in to unmask]>
>> Subject: analog vs digital eq
>> I think the short answer is that the recording curve was
>> imposed in the analog domain, in reversing it for playback,
>> only analog eq handles the phase response correctly.
>> Also, applying eq digitally to a truly flat transfer reduces
>> available headroom somewhat.
>> Doug Pomeroy