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Re: [ARSCLIST] 1937 shellac test pressing outperforms audio CD

On purely earperical evidence, older Victor tests seem to have more highs than their commercial counterparts. I always assumed some definition was lost in the mother-stamper-pressing part of the process. Perhaps because they are usually on noiser material (or what the ageing process has made noisier) they simply sound that way. But many of us on this list can hear clear audio through bacon frying and rice crispies popping (mmmm- breakfast.)

Incidentally, has anyone looked at the the top frequencies in the various series of 78 technical records?

Steve Smolian

----- Original Message ----- From: "Doug Pomeroy" <pomeroyaudio@xxxxxxx>
To: <ARSCLIST@xxxxxxxxxxxx>
Sent: Saturday, April 04, 2009 9:39 AM
Subject: Re: [ARSCLIST] 1937 shellac test pressing outperforms audio CD


According to Moyer's paper (Evolution of a Recording Curve, in the AES Journal, July 1953)
the WE cutter used by RCA Victor rolled off very sharply above 6.5 kHz before 1938.
Improvements in that year extended the range to about 8.5 kHz, and it was extended
still further in 1947. It's safe to say no cutter in 1937 could cut the frequencies you
are seeing, so there must be a playback issue, if you are certain what you are seeing
correlates with musical overtones.

We know experiments were done and that equalizers were used, but the cutter head
would have been the limiting factor in any event, no?



Date:    Thu, 2 Apr 2009 14:09:56 -0400
From:    Michael Biel <mbiel@xxxxxxxxx>
Subject: Re: 1937 shellac test pressing outperforms audio CD

Eric Jacobs wrote:

I apologize in advance for cross posting.

Likewise excuse the cross-posting of my response.

I couldn't help sharing this - I am regularly measuring 27.2 kHz
harmonics and occasionally as high as 43.6 kHz harmonics (violin)
from a series of 1937 RCA Victor test pressings - nearly 72 years
old.  I'm pretty fastidious about accurate cartridge loading, so I
don't think we're seeing ringing of the transducer.

But they could be harmonic ringing of the mechanics of the cutter head--the other mechanical device in the chain. You have to consider the source feeding the recording head--the microphones and amplifiers. If they were using RCA 44-BX Ribbon Velocity microphones, their top end is 13K to maybe 16K depending on the condition of the ribbon. There also are limitations of the impedance matching transformer in the base of the microphone. Then what are the top ends of the RCA pre-amps and amps in use in 1937? I would think they would be rolling off by at least 20K if not lower. We probably can't be sure even if we check the spec sheets because I doubt they were measuring any higher.

While you are at it, I'd like to see what you measusre on Western Electrtic Wide Range Vertical Recordings such as used by World, Associated, and Muzak. They claimed 13K around 1933-34. I have a matched pair of World test pressings of the same broadcast on a lateral and a vertical, and while the lateral is great, the vertical IS better! I mentioned yesterday on the 78-L a 1932 Victor of Astaire with George Hall's orch on the Buddha CD "Time Capsule" which has highs that are unbelievable. Vince Giordano produced it. I think this side was done off a vinyl test from the Victor Vintage series era, or maybe even a metal. Victor and other companies routinely polished their masters or stampers with jeweler's rouge which probably removed the rough edges of the sound wave -- namely the high frequencies. George Brock-Nannestad discovered a document at EMI that discussed Victor running a knurling tool thru the grooves to likewise smooth them out. Victor subjected tests to wear tests to make sure the records wouldn't wear out prematurely. Rough grooves wore out faster. GOOD RECORDINGS wore out faster!! There is evidence that Victor "dumbed down" their recordings, so it is important that you have access to those test pressings which might not have been compromised. But maybe some of the things Victor was polishing off were cutter-head transient ringings.

Mike Biel mbiel@xxxxxxxxx

Never mind that we've invested nearly $60k in our analog disc

playback and digitization system, pushing the limits of what is
possible, but I was astounded by the recording quality and performance
of these particular discs that long preceeded modern formats like
magnetic tape and LP, let alone CD.

For those who have the ability to measure this sort of thing,

I can email 1-second and 2-second samples (24/96 WAVE files).
For those that do not have access to a high-resolution spectrogram, I
can send jpegs taken from ours.  The WAVE files altogether are
2.3 MB - not especially large - but you should still make sure that your
email software and internet connection can handle email
of this size.

Eric Jacobs

The Audio Archive, Inc.

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