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Tim,
I haven't preserved a Soundmirror tape for about 3 years but your
observations and experience with the noise is similar to what I had.

All the tapes were in Soundmirror boxes and the reels were a deep red metal.

Most of the ones I worked on were poorly spooled on the reels and the
tension was all over the place.

Splices were difficult as the glue seeped through to a few layers which
resulted in the magnetic layer coming off as the reel turned.

I'll see if I can find photos of a unique soundmirror and reel and send it
through.

Cheers,
Marie

On Thu, Oct 25, 2018 at 5:10 PM Tim Gillett <[log in to unmask]>
wrote:

> Another observation about these apparently rare paper tape recordings
> made,
> I assume, on a Soundmirror machine. (the red tape boxes are all
> Soundmirror
> labelled). These recordings are very noisy. I'd read that paper based
> tapes
> were noisy partly because of the roughness of the paper backing, and I
> dont
> doubt  that's true.   But when one of the recordings finished and it went
> to
> blank unrecorded tape  I noticed a large drop in background noise.
>
> Maybe the initial recorder had a magnetised tape path? I made a test
> recording on a blank piece of tape on a good modern recorder and while
> there
> was the expected extra "bias noise", the total noise was much lower than
> on
> the old recordings. Then I read somewhere that the original Soundmirror
> recorders used a permanent magnet erase head. I guess this would also
> explain the very high background noise.
>
> Has anyone else experienced this much higher background noise on
> recordings
> made on Soundmirror machines?
>
> Tim Gillett
> Perth,
> Western Australia
>
>
> ----- Original Message -----
> From: "Richard L. Hess" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Wednesday, October 17, 2018 8:08 AM
> Subject: Re: [ARSCLIST] Soundmirror paper 1/4" tape
>
>
> > Hi, Tim,
> >
> > The only thought I had is that there was moisture intrusion into the
> tape
> > pack at some point to cause this. This could have been moisture on its
> own
> > or with biological or chemical contaminants that acted like an adhesive
> or
> > caused the tape coatings to act like an adhesive.
> >
> > It is just a guess with no real science to back it up.
> >
> > Yes, I would try baking to separate, but that's not always useful,
> either.
> >
> > The other thing that has occasionally worked with blocked tapes is
> > chilling them for a while, both to drive out moisture and get some
> > micro-movement layer to layer which may "unhook" the little bonds.
> >
> > If you hear a zipper noise, you are damaging tape.
> >
> > Good Luck!
> >
> > Richard
> >
> >
> >
> >
> > On 2018-10-16 4:58 PM, Tim Gillett wrote:
> >> Hi Corey,
> >>
> >> No, definitely not normal sticky shed or even any stickiness.
> >>
> >> My tentative guess is that with time and pressure the rough surface of
> >> the paper backing has imprinted itself onto the adjacent layer's
> smoother
> >> oxide surface so that many tiny "interlock" or clasp points have
> formed.
> >> On the sections where the winds have separated without damage, the
> >> interlocks have released and now there is no longer a stiction in those
> >> sections. I can rewind the tape back from where the tape stopped and it
> >> winds perfectly. No stiction. For a paper tape, the pack is quite good.
> >> When I run the tape forward, as soon as it gets to the point where I
> >> stopped separating the wind, the adhesion resumes.
> >>
> >> It's complicated by various sticky tape splices which have gone gooey
> and
> >> oozed, causing adhesions at those points but that's a separate issue.
> >>
> >> Yes there are unrecorded sections which I can experiment with.
> >>
> >> Thanks,
> >> Tim
> >>
> >>
> >> ----- Original Message ----- From: "Corey Bailey"
> >> <[log in to unmask]>
> >> To: <[log in to unmask]>
> >> Sent: Wednesday, October 17, 2018 4:12 AM
> >> Subject: Re: [ARSCLIST] Soundmirror paper 1/4" tape
> >>
> >>
> >>> Hi Tim,
> >>>
> >>> It's hard to recommend a solution without visually assessing the
> >>> problem. For polyester base tapes that have layer-to-layer adhesion, I
> >>> usually have to bake them at a lowered temperature (118° F. or less)
> for
> >>> 6 to 8 hours and then I will check the tape again. For paper backed
> >>> tape, baking may not work. Is there an unrecorded section that you
> could
> >>> use for testing? For me, baking audio tape is reserved as a last
> resort.
> >>> Layer-to-layer adhesion is the one exception.
> >>>
> >>> Cheers!
> >>>
> >>> Corey
> >>>
> >>> Corey Bailey Audio Engineering
> >>> www.baileyzone.net
> >>>
> >>> On 10/16/2018 6:11 AM, Tim Gillett wrote:
> >>>> Thanks Gary,
> >>>>
> >>>> Yes having had experience with one tape like this 15 years ago (from
> >>>> the same person's archive) I'm aware of the centre track, the tracks
> 2
> >>>> and 3 capture and the azimuth corrector technique. It's just a shame
> I
> >>>> wasnt aware of this sticking problem back then as I guess if I'd
> >>>> unwound them then it wouldnt have been as much of a problem as has
> now
> >>>> become 15 years on.
> >>>>
> >>>> I only recently discovered that the tapes have been stored in less
> than
> >>>> ideal conditions with high humidity and evidence of mould on some
> tapes
> >>>> (but apparently not on any of these Soundmirror tapes that I can see.
> >>>>
> >>>> Yes hoping Richard Hess or maybe Peter Brothers might have experience
> >>>> with this sticky problem.
> >>>>
> >>>> Regards,
> >>>>
> >>>> Tim.
> >>>>
> >>>>
> >>>> ----- Original Message ----- From: "Gary A. Galo" <[log in to unmask]
> >
> >>>> To: <[log in to unmask]>
> >>>> Sent: Tuesday, October 16, 2018 8:57 PM
> >>>> Subject: Re: [ARSCLIST] Soundmirror paper 1/4" tape
> >>>>
> >>>>
> >>>> Hi Tim,
> >>>>
> >>>> This is a strange problem. I've worked with quite a few Brush
> >>>> Soundmirror tapes in our archive, and the only spots where I found
> any
> >>>> sticking was on a couple that had leader tape spliced on at the
> >>>> beginning. But, it was confined to that spot, and not all the way
> >>>> through.
> >>>>
> >>>> Regarding playback on modern equipment, I use tracks 2 and 3 of a
> >>>> 4-channel head. They fit right over that single half track on the
> >>>> Soundmirror tapes. The stereo playback allows proper azimuth
> >>>> adjustment, and gets you inside of most of the edge curl that may
> have
> >>>> occurred. It may also get you inside any oxide shedding that may
> >>>> happen, if that stickiness is confined to the edges. Then I put the
> two
> >>>> channels through a phase corrector before summing them to mono.
> >>>>
> >>>> Richard Hess may be able to better address the sticking problem.
> >>>>
> >>>> Best
> >>>> Gary
> >>>>
> >>>> Gary Galo
> >>>> Audio Engineer Emeritus
> >>>> The Crane School of Music
> >>>> SUNY at Potsdam, NY 13676
> >>>>
> >>>> ________________________________
> >>>> From: Association for Recorded Sound Discussion List
> >>>> <[log in to unmask]> on behalf of Tim Gillett
> >>>> <[log in to unmask]>
> >>>> Sent: Tuesday, October 16, 2018 8:32:39 AM
> >>>> To: [log in to unmask]
> >>>> Subject: [ARSCLIST] Soundmirror paper 1/4" tape
> >>>>
> >>>> Hello,
> >>>>
> >>>> 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?
> >>>>
> >>>> Thanks,
> >>>>
> >>>> Tim Gillett
> >>>> Perth,
> >>>> Western Australia
> >>
> >>
> >> ---
> >> This email has been checked for viruses by Avast antivirus software.
> >> https://www.avast.com/antivirus
> >>
> > --
> > Richard L. Hess                   email: [log in to unmask]
> > Aurora, Ontario, Canada                             647 479 2800
> > http://www.richardhess.com/tape/contact.htm
> > Quality tape transfers -- even from hard-to-play tapes.
>