[78-L] Frequency Response/Range for 78's

[Don Cox]

On 28/07/2012, Doug Pomeroy wrote:

> Hi,
> 
> As Mike says, Nick Bergh is doing valuable research on this subject.
> Nick has first-hand knowledge of the equipment used from the very
> beginning of electrical recording.
> 
> The July 1953 issue of Audio Engineering magazine reprints two figures
> showing (1) the frequency response of the original Western Electric
> wax recorder and the modifications to it by WE and RCA (in 1938), and
> (2) the recording characteristics of Victor records from 1925 to the
> present:
> 
> The curves are not "written in stone" because most record companies
> did some experimenting, especially with bass filters. But in general
> they show the high frequency capability of the original cutter was
> about 4 kHz and it went out to 6 kHz after improvements to the rubber
> line cutter, and out to about 8 kHz with the 1938 improvements, and
> out to about 10 kHz by 1947. By 1952, the New Orthophonic system
> extended the response to beyond 12 kHz.
> 
> I the early years, Victor and Columbia were using the same WE cutters,
> and their records reflect this. Other companies used a variety of
> other equipment, and may sound different (often worse).
> 
> Some collectors of 78s have claimed to hear "overtones" far higher in
> frequency than the cutter known to have been used could possibly have
> cut (even at a very low level), ignoring the elementary laws of
> physics.
> 

I think we should distinguish clearly between the frequency range - the
highest and lowest that get usably recorded - and the EQ within that
range.

Two discs can have the same frequency range but different EQ, and vice
versa.

Tolerances on components such as capacitors were very high and this would
give different EQ from one studio to another even if the circuits were
the same. How accurate was measuring equipment in the 1930s ? How could
an engineer produce sounds of various frequencies at identical levels
for testing?

I think "use your ears" is the best practical advice.

Regards
-- 
Don Cox
doncox at enterprise.net