I didn't know about the permanent magnet erase head. That would help explain the high noise level. But, the transport must have pulled the head well away from the tape in playback, to avoid erasing the tape. I've never seen a Soundmirror in action.


Gary Galo
Audio Engineer Emeritus
The Crane School of Music
SUNY at Potsdam, NY 13676

"Great art presupposes the alert mind of the educated listener."
Arnold Schoenberg

"A true artist doesn't want to be admired, he wants to be believed."
Igor Markevitch

"If you design an audio system based on the premise that nothing is audible,
on that system nothing will be audible."
G. Galo

From: Association for Recorded Sound Discussion List <[log in to unmask]> on behalf of Tim Gillett <[log in to unmask]>
Sent: Monday, October 29, 2018 10:26:55 AM
To: [log in to unmask]
Subject: Re: [ARSCLIST] Soundmirror tapes

Thanks Douglas,

It seems then that so far, the sticking winds is an isolated case.

I mentioned earlier that the very high noise floor seems confined to the
actual recording. I suspect the machine used initially (early 1950's) was a
Soundmirror which apparently used a permanent magnet erase head.   When I
made a new recording on an unused piece of the paper tape, on a modern era
machine (Nagra 4.2), the noise was  much lower than on the original

Tim Gillett

----- Original Message -----
From: "Douglas Pomeroy" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, October 29, 2018 12:14 AM
Subject: [ARSCLIST] Soundmirror tapes


i have several of those paper-backed tapes, stored unprofessionally in
Californian and New York
since they were recorded in January 1948. None of them have the problem you
describe, and they
all play well, and I wouldn't call them unusually noisy either.

Date: Tue, 16 Oct 2018 20:32:39 +0800
From: Tim Gillett <[log in to unmask]>
Subject: Soundmirror paper 1/4" tape


I'm having problems with some very early Soundmirror tapes using a paper
backing, circa late 40's early fifties I guess. I suspect they havent been
wound or played for many decades. They contain live recordings of mainly
classical oratorio concerts.

The tape wind is semi sticking to the next wind in varying degrees depending
on the tape in question. With a couple I've been able to slowly wind them
off without tape breakage or loss of oxide. Once they have been unstuck and
spooled onto the take up reel they remain unstuck and play well. I've been
able to repair old splices and clean off old spreading adhesive.

But this one is more sticky and further into the reel I go it has started to
really stick to the next wind and rip off small pieces of oxide (I guess
more tension from being under a constant torque wind for many years has made
the inner layers stick more to each other).

Any hints on treating the tape to help it wind off without damage, or with
less damage? Heat, humidity etc?


Tim Gillett
Western Australia

Douglas Pomeroy
Audio Restoration and Mastering Services
193 Baltic St
Brooklyn, NY 11201-6173
(718) 855-2650
[log in to unmask]
Music Over Business

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