[78-L] Acoustical 78s in Spectra-Sonic Sound^

[Michael Biel]

From: Royal Pemberton <ampex354 at gmail.com>


I bought a copy of THE BIX BEIDERBECKE STORY, VOLUME 3: WHITEMAN DAYS
(Columbia CL 846) in the early 1980s that was definitely a recent
pressing,
obviously mastered with their celebrated DisComputer pitch control.
('COLUMBIA NY' stamped into the dead wax on side 1 as well.) The tape
transfer was obviously done in stereo as the 'image' wanders a little
now
and again, and is usually a bit right of centre! (Someone didn't know
how
to handle 1952-vintage tapes....) And the sleeve was dodgy as well, one
corner chewed off, and the title and catalogue number print normally
seen
on the sleeve's spine omitted.

I have a pressing from the 70s of Victor Borge's "Comedy in Music" where
the splices at the beginning section make whole sections fade in and
out, but it was not because it was transferred in stereo.  See below. 
(I have heard later pressings and CDs of this without the problem.)

> I'd hate to see the state the tapes to INTRODUCING PETE RUGOLO are in,
> based on the transfers in the Collectables CD that has that album plus his
> ADVENTURES IN RHYTHM LP material (Collectables COL 5893; also labelled
> 'Sony A-28821'). More than a few of the IPR cuts have that strange effect
> of the high frequencies rapidly fading in and out that are due to trying to
> play back furiously skewing cupped acetate tapes with a stereo playback
> head stack with both channels summed to mono.

That is not necessarily what is happening.  Most engineers are taught to
never play back mono tapes with a summed stereo head.  This
comb-filtering can also happen by playing a warped full track tape with
a mono full track head.  What has happened is the razorblade-straight
original recording  has now become a curve with several bends from top
to bottom, so if you use a full-track mono head it works just like the
comb-filtering you get when you do play a mono tape with a stereo head
like you describe.   

Textbooks say that tapes should be played back on the same type of heads
that recorded it, but actually old tapes should be played back on
narrower width heads that are placed in an area of the tape that is less
warped, usually the center.  One of the easiest ways they do it is to
get a 4-channel quad head and use ONE of the tracks which sounds most
consistent when re-alligned to the azimuth that now exists on the tape.
What I used to do was use my old Wollensak with a "Head-track selector"
which raised and lowered the two-channel quarter-track head.  I was also
able to pull out audio that was incompletely erased when a full track
tape was recorded over with a half- or quarter-track recorder. 

Mike Biel  mbiel at mbiel.com