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Author
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Topic: Found, new 6 track magnetic heads
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Steve Guttag
We forgot the crackers Gromit!!!
Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 07-17-2018 05:57 AM
Philips continued making the heads, in their various forms, into the 1980s (the ones where the heads were in blue molded plastic). They were available in 6, 10 and 4 track versions.
However, once Teccon and other manufacturers of sendust and other hardened metal heads came out, the original Philips heads, quickly, fell by the wayside.
There was no point in trying for azimuth alignment on an original head, they weren't aligned well enough in the plastic to achieve that accuracy over 70mm (from left to surround though it is advisable not to use track 6 in an alignment in case its inherent delay for surrounds was left on when the test film was recorded).
The wear on the original heads was like butter. In normal usage, I think we got something like 3-months on a head (a summer). Compare that to a Teccon where life space was measured in 10s of millions of feet (or many years of usage). The Teccons didn't cost much more either. Cost per footage of film run on them was a small fraction of the Philips heads.
Kinoton sourced another manufacturer of the heads (also a harden metal) and made available 6 and 10 track (perhaps 4 track, but I never saw any of those for the DP70/75/FP75). They also could supply 4-track heads for FP20/30 projectors. They had the heads available with different inductances too to match with different preamp styles. The name of the company that supplied them to Kinoton escapes me at the moment. It would not surprise me if Kinoton has some heads left though they may have sold them all in their most recent purging of excess parts.
For precision, I liked Teccon heads best. They even made, for us, a version of the DP70 head that allowed for precise azimuth alignment without danger of messing up the zenith alignment. When Teccon went out of business, they had a "last buy" sale. Honestly, there was so little magnetic film after that I'm sure all of those heads will last indefinitely.
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Jim Cassedy
Phenomenal Film Handler
Posts: 1661
From: San Francisco, CA
Registered: Dec 2006
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posted 07-17-2018 10:42 AM
In the late 1980's & 90's I was an engineer at a big video editing facility here in
San Francisco. All of our switchers, TBC's, DVE's & 1" VTR's (VPR-80's - one
of the most amazing 1" VTR's ever made) were all manufactured by AMPEX,
which was located about 25mi South of here.
We had a service contract with AMPEX, who would send a tech out every couple
of months to do the required periodic maintenance. During one visit, he
happened to mention that he had started off his career at AMPEX working in their
cinema sound division, which at this point had been shut down for some years.
So I mentioned that I had a 35mm set-up at home, which was equipped with
AMPEX 4-track mag penthouses, which were working fine, except that the
heads were definitely wearing down.
So he told me that although they were no longer 'in the cinema sound business'
and no longer manufactured the mag heads, when he got back to his office he
would send me the name of a company AMPEX would recommend to former
cinema clients looking to have their old mag-heads re-lapped or even re-built.
I never heard back from him with that info.
- - but, several months later, when the guy came back to our facility for a
scheduled maintenance visit, he gave me two, brand new, still-in-the-box sets
of AMPEX 4track mag heads for my projectors.
The story he told me was that when AMPEX made the corporate decision to no
longer support mag sound systems, somebody forgot to tell the facility that
made their mag heads for several months and as a result, there was "a whole
warehouse" (his words) of the heads "just sitting there", and he managed to
score a couple of 'em for me.
(And just to make this story more 'cute'- the day he showed up and gave
them to me, just happened to be my birthday. awwwwwww...)
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Leo Enticknap
Film God
Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000
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posted 07-19-2018 10:46 AM
quote: Stephen Furley
Presumably a combined 35/70 mm head block. Some machines used these, while others had separate heads for each format.
We had a pair of original Philips ones for the DP-70s at the Egyptian, plus a couple of pairs of Teccon 6-head (70mm only). The six 70mm heads on the OEM ones were worn-out garbage: it was impossible to tune a decent response or get enough gain out of most of them. The 35mm inner heads, however, were near perfect. We were able to tune the MPU using an old THX analyzer to OEM spec response on all but one of the channels (surround, thankfully), which had just a little bit of an HF dropoff. At the final Cinecon at which I worked, we played UCLA's 35mm IB mag print of King of Kings, which sounded great. The picture was scratched and beaten up throughout, but the audio was quite something.
The condition of these heads suggests to me that 70mm mag was in prolonged, mainstream and widespread use, but that 35mm mag never really took off.
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Steve Guttag
We forgot the crackers Gromit!!!
Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 07-20-2018 05:46 AM
35mm mag was in widespread use (more so than 70mm) for a long time. When Dolby Stereo took off, that was, much like 70mm after digital audio) that it dropped like a rock.
Can you imagine the cost difference (both to the studio and the exhibitor) of optical stereo versus 4-track magnetic?
Think about most any "stereo" title before say 1977...odds are, it had a 4-track version, including 70mm titles, there were likely 4-track 35mm versions. Whereas Fox insisted on CinemaScope and 4-track at the onset of CinemaScope, those first few years had 100s of titles.
After Dolby Stereo took hold...I think I handled maybe 5 "new" titles (Blues Brothers, Yentel, Scarface, I think the remix of Fantasia had 4-track.
For retro festivals, we had a set of Norelco 10-track heads where, like you, the 6-tracks were worn out but the 4-tracks were "like-new." I'd put them in for the 4-track movies (mostly musicals) that would show up.
It wouldn't surprise me if some of the extra 10-track heads came from when people order something they keep ordering the same thing. So if they started off ordering 10-track heads to cover everything...when the 4-track prints slowed down...they kept ordering the 10-track heads.
For our "new" 70mm installations in the 1980s, I'd always start them out with the capability of 4-track knowing that we'd never burn through those heads but we were covered for the "festivals" were a 4-track would show up unexpected.
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