Can you say: "Inverse Square Law"?
Yes, I changed the subject line,
CB
Corey Bailey Audio Engineering
www.baileyzone.net
On 11/19/2020 11:07 PM, Matthew Sohn wrote:
> It seems pretty simple to me. When you apply a liquid, it has mass, which will disturb tape to head contact. You need to find a way to disperse the "lubricant" evenly in a way that does not push the tape away from the head any more than necessary.I know ISO relieves squealing because I have done it, with Q-tips and an eyedropper and I can tell you that I will charge you a lot to do it again, because it is a pain in the ass, but sometimes it is necessary.Suggestion:Try thoroughly immersing a tape in ISO for 5 minutes.Remove it and let it dryPlay it back
>
> On Friday, November 20, 2020, 12:25:30 AM EST, Tim Gillett <[log in to unmask]> 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
|