Sound Mirror Tapes. Value?

[sennsai]

A friend has acquired several of these on metal spools in their red boxes, although some have spots of light rust under the paintwork. Don't think there is any content of interest on them. What he wants to know is of course, are they worth much?

[camtechman]

Size (Diameter) ?

[sennsai]

Right, they are 7 inch, one is some kind of brown plastic.

[Ted Kendall]

Nearly all the value is in the content, which check carefully - even fragments from seventy-odd years ago can be precious. These reels don't easily fit later machines, and the paper tape is best forgotten. Somebody preserving a Soundmirror may want some correct spools, I suppose...

[ricard]

I don't really want to disagree with Ted in any way, but I would think that just because of their connection with the Soundmirror, which I think means they're a bit different to later tape formulations, the tapes would be interesting for a Soundmirror collector, more so than other tapes if similar (or, realistically, slightly younger) vintage.

[sennsai]

OK, thanks for the views. There's a recording of "The Sounds of Time" but these are available anyway. Also someone demonstrating how to pronounce Russian words, possibly off the radio. I'm going to go through them and see if anything interesting. My Philips N4520 played one back ok on 7.5, but as mentioned could really do with a true 4-track player.

[Ted Kendall]

The lower track should be good enough to identify content - the original Soundmirror head recorded one track of about 4mm down the middle of the tape.

Fair point about the tape formulation, although the Soundmirror could happily use the acetate tape of the time.

[kalee20]

Originally Posted by Ted Kendall

Nearly all the value is in the content, which check carefully - even fragments from seventy-odd years ago can be precious. These reels don't easily fit later machines, and the paper tape is best forgotten. Somebody preserving a Soundmirror may want some correct spools, I suppose...

The Soundmirror reels I have, will fit later machines (centre hole with 3 anti-rotation slots), but they also have a large cut-out to engage with the drive features on the hub which is peculiar to the soundmirror. So you can use these reels on a non-Soundmirror, but you have to butcher non-Soundmirror reels to use them on the Soundmirror.

[Ted Kendall]

I said they don't easily fit other machines - the trident slots are so narrow that fitting them on a Revox turntable, for example, is difficult.

[kalee20]

Thanks for clarifying, Ted - I had wondered if there was an earlier version of the Soundmirror reels than mine, with no triple slots, perhaps before this became the de facto standard? And later, to make the reels compatible with nearly every other machine, they were introduced on the Soundmirror reel?

But now, all is clear!

[radiotechnician]

Soundmirror and 'Russian words' twigged a memory.

I have worked on these machines and have manual on file.

Close to 60 years ago a shop I worked at acquired a great
'plentitude' of Russian magnetic tape to sell. The reels were in
sleeves made of a pulpy cardboard. I think I remember that
it was wound oxide-out.

The tape was sold very cheaply, and it worked on machines but not
well.

I remember the comment that it might make a very fine abrasive to
polish things with.

[brenellic2000]

Suffice to say there are two distinct spools: those early ones designed for the original American pattern using upturned flanges on the turntable spools (which prevent DIN spools being used); and the later offset spigot drive 'universal' DIN pattern. These are variously in steel, Formica/Melamine and clear plastic. The original paper tape cups badly which affects the centre-section recording. The later plastic tape is fine. There was a later 2-track high and low speed version, to order.

The UK license-built Thermionic Products BK.411 Soundmirror was contract built for TP by Walter Instruments who later modelled their own Walter deck on it... The Tandberg and Carad also have their origins in the BK.411, and Revox in the earlier BK.401 Soundmirror.

[ricard]

A lot of spools (3M comes to mind, but also other manufacturers, I think also some vintages of BASF, under the center sticker, for instance) have a one or three holes around the center of the hub, and which would fit a reel table having a corresponding stud. Are these compatible with the Soundmirror in any way, or are they intended for some other standard?

[brenellic2000]

Hi Ricard,

I think the short-lived upturned flange drive was unique to America (Brush/Soundmirror, Webster) - it wasn't common in Europe where the DIN cine-spool standard prevailed, usually with a offset spigot pin rather than tri-wing drive. 'Ferrovoice' tape was also offered on a Soundmirror compatible/universal spool.

[sennsai]

I was under the impression that early tape reels copied the standards used by the cine projector reel (presuming there was a standard).

[kalee20]

Yes - 1/4" tape reels certainly fit Standard 8mm cine projector spindles, and vice-versa.

The Soundmirror upturned-flange drive certainly seems unique. I guess we're lucky that the spindle diameter is not outlandish too!

And I also recall seeing a 'Ferrovoice' reel, many years ago, which was moulded plastic rather than resin-bonded fibre, but featured apertures to fit the Soundmirror.

[ricard]

Does anyone have a picture of the 'upturned flanges' - I can't envisage what they look like and Google didn't help much either.

[kalee20]

Here.

And the corresponding drive.

[ricard]

Excellent pictures. Thank you.

So it's basically the same principle as having an offset spigot, but executed differently (and incompatibly).