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Re: [ARSCLIST] Equalizers
----- Original Message -----
From: "George Brock-Nannestad" <pattac@xxxxxxxx>
> > On 18/07/04, Steven C. Barr wrote:
> > > Keep in mind that prior to some point in the 1930's, equalization was
> > > "made up on the spot" by the recording engineer, and there was no
> > > standardization of any type, even within labels.
> ----- I am not sure I agree with this way of looking at things. The
> level was made up at the spot, yes, but the EQ was a function of the
> of the cutterhead on the amplifier and the mechanical damping of the
> cutterhead, and so to a large degree was determined quite precisely by
> components of high precision (number of turns in a magnetic circuit,
> airgaps, rubber or oil of a defined quality). Frequently the microphone
> characteristic went into this as well.
> Temperature would have an influence, though, but it would not vary much in
> studio. On the road that would be different, though. The important EQ,
> of the cross-over between constant-velocity and constant-amplitude, was
> this way. Voigt, who wrote a marvellous paper in Wireless World in (I do
> have it to hand, sh---!) ca. 1941 ("Getting the best from records"), tells
> how the mistake of calibrating HMV's microphone in dry hydrogen made them
> discover an involuntary increase in sensitivity about 3 kHz, i.e. a pre-
> emphasis centering on that frequency.
> The later controls
> > > on amplifiers and pre-amps refer to a fairly-standardized intra-label
> > > curve (one per label). These controls appear on most "hi-fi" gear of
> > > the fifties and early sixties, but apply only to records of their
> > > era...equalization of earlier 78's has to be done "by ear" (unless
> > > someone can decode the cryptic notes found in surviving recording
> > > ledgers if any exist)...
> > Don Cox commented:
> > Also the manufacturing tolerances on resistors and capacitors in those
> > days were very wide, so even if somebody designed a circuit to give some
> > desired EQ, the results could be somewhat diferent.
> ----- the few bodies that worked with an in-house system (off-hand I can
> think of the British Broadcast Corporation) also had calibration discs
> enabled them to control the response from input to output. A disc
> and reproducing chain was just regarded as another black box insert and
> to contribute no change in the transfer. In those days it was long and
> waves, so an upper frequency limit of 4500 Hz was the norm.
Such ledgers I have seen (Victor and Compo) from the early electric era also
include lists of three or four numbers, which appear to describe control
settings...and I would assume these would be various gain/level controls,
as well as cut/attenuation of bass and treble. The Compo ledgers include
page after page of experimental recordings, each with all the settings...
but no description of the circuits or component values, and thus useless...
Based on my own experience as "sound engineer" for my own performances, I
assume these early recording engineers simply adjusted the controls for the
best setting, from the standpoint of audibly pleasant but not creating
groove paths which would wear quickly...and noted the numbers that were
pointed to on each knob...