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Hi Tim and Marie,

The Soundmirror tapes that we have in our archive are also very noisy. I suspect that it's a combination of things - the rough paper backing, the rough oxide coating, and noise inherent in the Soundmirror's record electronics. The oxide coating on those tapes looks like someone slapped it on with a paint brush - pretty unrefined!

Our Soundmirror tapes were all made on Scotch 100 paper-backed tape. The plastic reels have very small center hubs, and large (roughly 1/4-inch) slots that wrinkle the tape. The amount of torque that's required to pull the tape off the small center hub when you get near the end is very stressful on the tape. I wound all of our paper tapes onto 10 1/2-inch reels, which results in smoother motion and less physical stress on the tape. All of our Soundmirror tapes suffer from wandering pitch from the beginning to the end of the reel, a problem you probably wouldn't notice if you played the tapes back on the same machine they were recorded on. But, no one would want to use the primitive transport, playback head and electronics in one of those machines. Better to play the tapes on a good, modern tape machine and deal with the wandering pitch with software.  

We don't have any Soundmirror brand tape in our archive. I would be interested to know if anyone has any Scotch 111 acetate tapes that were made on a Soundmirror. Honestly, I don't know if this was ever done. I would bet that they would be somewhat quieter, but probably still suffer from noise from the record electronics. 

Best,
Gary



____________________________

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

-----Original Message-----
From: Association for Recorded Sound Discussion List [mailto:[log in to unmask]] On Behalf Of Marie O'Connell
Sent: Thursday, October 25, 2018 2:15 AM
To: [log in to unmask]
Subject: Re: [ARSCLIST] Soundmirror paper 1/4" tape

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.
>