As you may know, Marie O'Connell provided me an article about her
embodiment of the wet playback machine for my tape restoration notes web
page. It is still available here:
<https://richardhess.com/notes/2006/03/09/wet-playing-of-reel-tapes-with-loss-of-lubricant-a-guest-article-by-marie-oconnell/>
Things to note: she was wiping on the isopropyl alcohol (IPA) from a
felt pad, not placing a drop on the tape, she was using a Studer B67
which, I think, makes your use of an A700 a good analogy, as they are
both similar in transport design, if I remember correctly.
I have found decamethylcyclopentasiloxane (D5) a useful substitute for
IPA. It dries slower, but also completely. I don't think D5 will wash
out capstan lubricants like IPA. Corey Bailey rightfully questions D5's
long-term effects on tape, which are unknown, but seems to be OK, and
prefers to use The Last Factory lubricant which has been formally tested
in this regard (I hope I'm stating Corey's concerns properly).
When I suggested using a syringe to place D5 on the tape, it was not
directly. I inject the D5 into the mass of the head of a cotton swab to
keep it moist and then the D5 is wiped onto the surface of the tape. For
reel-to-reel applications, I variously use an envelope moistener or a
Pellon pad (avoid the fusible kind).
In the end, it seems as if baking is easier/faster than wet playback,
and it is an outside-the-studio process, so it can continue in parallel
with other work, but it does not work for all squealing tapes, and, it
appears may exacerbate squealing with some tapes.
So, for classic sticky shed syndrome, baking, for me, is the default.
For squealing tapes, baking is not a default option by any means.
I attempt to maintain a resource suggesting which treatment to use for
which common recalcitrant audio tape. If you have any suggestions for
updating this page, please let me know:
<https://richardhess.com/notes/formats/magnetic-media/magnetic-tapes/analog-audio/degrading-tapes/>
Cheers,
Richard
On 2020-11-20 12:23 a.m., Tim Gillett wrote:
> Hi all,
>
> Just a followup on my earlier Isopropyl test. It's harder to make the
> test with a cassette tape as the tape is more concealed and
> harder to access. So I made the same test on an open reel tape running
> at 3.75ips on my Revox A700. I put the machine in a basically
> upright position but leaning slightly forward (to help prevent
> Isopropyl from running into the capstan bearing and washing out its
> lubricant).
>
> I played back a tape recorded with white noise which is rich in high
> frequencies. Using a syringe containing Isopropyl I carefully
> applied just one drop to the mag coating just upstream of the repro
> head. The highs dropped markedly on both channels. Then as soon as
> the Iso had passed and the surfaces were dry again, normal full treble
> response returned after a few seconds. I repeated this with a
> succession of single drops and the result was the same each time. I
> guess that with even slower tape speeds the effect would be more
> marked.
>
> Temporarily increasing tape back tension while the tape and head were
> still wet with Iso did seem to recover some of the lost highs but not
> nearly as much as when the Iso had passed through and normal tape to
> head contact was re established.
>
> I could have gone an extra step and quantified the loss in terms of
> db's down at say 5 kHz or 10 kHz but it seemed hardly necessary as the
> loss was not subtle.
>
> Hope this helps and of course happy to discuss this further.
>
> Tim Gillett
>
> ----- Original Message -----
> From: "Association for Recorded Sound Discussion List"
> <[log in to unmask]>
> To:<[log in to unmask]>
> Cc:
> Sent:Fri, 13 Nov 2020 14:36:06 +1100
> Subject:Re: [ARSCLIST] Drying Reel-To-Reel Tape in Food Dehydrators?
>
> Hi Corey,
>
> I've also used Naks with pressure pad lifters for many years but I
> guess it makes sense that they cant hope to press a moderately
> crinkled tape against the head gap as well as a good pressure pad
> can. Even in a Tascam 122 Mk II or III the pressure pad doesnt
> directly press the tape against the repro head gap but presses just a
> little to the left (upstream) of it. This also seems to be the
> reason these model Tascam cassette repro heads tend to have a long
> life. The pressure pad doesnt have the same opportunity to grind away
> the repro head's face. But eventually it makes a mess of the record
> head next to it. I guess for a less than flat tape probably a more
> conventional two head cassette deck with the record/play head
> centred directly opposite the pressure pad would provide better
> tape-to-head contact - at the expense of greatly increased head wear
> of course.
>
> Hi Marie,
>
> Like some others here I've only encountered a few cassettes which
> needed baking. In my limited experience they were Ampex 20+20,
> another Ampex cassette type, a Denon LH90 and two unbranded cassettes
> in white shells. All were helped by baking. I've also read of
> BASF LH SM cassettes benefitting from baking.
>
> A lubricant works by interposing itself between two surfaces
> scraping against each other, separating the surfaces from each other
> just a little. The small spacing and the lubrication go hand in hand.
> I can see that with higher speed tapes such as 7.5 ips or more, a
> small spacing loss might only affect the highs beyond audibility, but
> with slow speed tapes, the same spacing must at some point compromise
> reproduction of the highs.
>
> I just tried a little experiment. Using tape hiss as an audible
> reference, after dropping a little isopropyl onto the mag side of
> the tape, the tape hiss was reduced considerably, and it only
> recovered to full output when the lubricant had cleared. I guess
> there
> has to be a trade off at some point between reducing
> sticking/squealing, and spacing loss (loss of the highs).
>
> Cheers
>
> Tim.
>
> ----- Original Message -----
> From: "Association for Recorded Sound Discussion List"
> <[log in to unmask]>
> To:<[log in to unmask]>
> Cc:
> Sent:Fri, 13 Nov 2020 11:06:20 +1300
> Subject:Re: [ARSCLIST] Drying Reel-To-Reel Tape in Food Dehydrators?
>
> Kia ora all
>
> I have encountered many squealing tapes in the collections I'm
> working
> on in the Archive. Be mindful they have been recorded in locations
> all
> over the Pacific so the climate, humidity and temperature has played
> a
> part.
>
> I have great success with baking the cassettes and leave in the oven
> for at least 2 days. If really bad, I will open up the case and drip
> some isopropyl over the tape. I haven't had any yet that I can't
> reproduce. They are all different brands and lengths also.
>
> Hope that helps.
> Marie
>
> On Fri, Nov 13, 2020 at 10:23 AM Corey Bailey
> <[log in to unmask]> wrote:
> >
> > I've had a few cassettes that suffered from SSS. Storage seemed to
> be
> > the issue. IIRC, in all cases, lubricating the tape proved to be
> enough
> > for good playback. I built an audio cassette tape lubricating
> machine by
> > hacking a cheap cassette transport.
> >
> > Like Lou & others, I generally use Naks for ingest. However,
> Nakamichi
> > brand cassette machines seem to prefer the more expensive brands of
> tape
> > & their tape tension (Factory spec.) seems low compared to other
> brands.
> > For this reason, I have some other cassette machines available for
> when
> > my beloved Nak(s) won't play a tape all of the way through. I
> prefer
> > dual capstan cassette decks for injest because they tend to have
> less
> > azimuth issues. Naks are the only brand, that I know of, that have
> pad
> > lifters. Fast-Forwarding & Rewinding the cassette tape before
> playing
> > will tell you if the shell works, or not. Plus, the tape gets
> exercised.
> > The pressure pad has to be visually inspected.
> >
> > Be safe,
> >
> > CB
> >
> > Corey Bailey Audio Engineering
> > www.baileyzone.net
> >
> > On 11/12/2020 9:55 AM, Lou Judson wrote:
> > > I’ve never had a cassette with sticky shed. I have seen
> problems with cheap shells and possibly warping. I use Nakamichis so
> the pads are not a problem (Naks lift the pad away from the head and
> use dual capstan tension for better contact).
> > >
> > > Have you seen evidence of shedding on the machine after playing?
> or squeaking as they play? I have had cheap casstes and extra long
> ones (such as C-100 and C-120) bind and slow down warbling in speed,
> and usually winding forward and back helps, as well as slapping the
> casstte flat on a desk to re-align the tape pack.
> > >
> > > Re-shelling is not a bad thing either, just have to be careful
> with all the tiny parts.
> > >
> > > Richard Hess might have some deeper wisdom on this, but I have
> never had a casstte need baking.
> > >
> > > <L>
> > > Lou Judson
> > > Intuitive Audio
> > > 415-883-2689
> > >
> > >> On Nov 12, 2020, at 9:37 AM, Malcolm <[log in to unmask]> wrote:
> > >>
> > >> One of these units has been on my wants list for quite a while
> along with a Keith Monks record cleaner, but in both cases life has
> stepped in and said, "No, not yet. I'll get back to you." I have a
> number of cassettes that display sticky shed but before baking them
> I'd like to know whether there may be a problem with the shell
> warping, the pinch pads falling off, etc. Taking the tape pack out of
> the shell is certainly an option, but I'd rather not if I can help
> it.
> Suggestions would be helpful. Thanks!
> > >> Stay safe,
> > >> Malcolm Rockwell
> > >>
> > >> *******
>
> -------------------------
> Email sent using Optus Webmail
>
> -------------------------
> Email sent using Optus Webmail
>
--
Richard L. Hess email: [log in to unmask]
Aurora, Ontario, Canada 647 479 2800
http://www.richardhess.com/tape/contact.htm
Track Format - Speed - Equalization - Azimuth - Noise Reduction
Quality tape transfers -- even from hard-to-play tapes.
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