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
 > >>
 > >> *******

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