MONO SVA Sound Tracks and Noise Reduction

[Paul Finn]

Has noise reduction, A-type, always been applied to all SVA optical sound tracks even if the tracks are of a formerly released mono print, variable area or variable density, with both SVA tracks now being identical? It has never been clear with Dolby processors if the MONO Format-01 and the academy filter "in" and noise reduction "out" was intended to be only used with the earlier mono variable density (VD) and mono variable area (VA) sound tracks. I believe Format-02 was also for mono optical sound tracks, but with the academy filter "out" and noise reduction "in". Again, it is not clear if this format was intended for SVA tracks, or, only those recorded as single VA or VD? Were noise reduction processes applied to some VA and VD film sound tracks before stereo variable area came along? Maybe the Dolby old timers here can sort these uncertainties out before the correct intentions and applications are lost.

Thank you, Paul Finn

[Steve Guttag]

Dolby NR only is used IF the print was recorded with Dolby NR. SVA and bilateral tracks appear the same but the "S" in SVA is Stereo. If the tracks are identical, they are not stereo. If the leaders call out mono, it is mono. There were very few Dolby-Mono movies and the print should be appropriately labeled.

NR out and Filter On is the appropriate setting for all mono tracks that do not have NR.

The reason for the academy filter is to "undo" what was done in the A-Chain and B-Chain calibrations for the SVA tracks. Standard, pre-Dolby theatres didn't have much of an EQ (or Warping as it was called back then) to correct for the slit loss of the soundhead nor the frequency response in the cinema using the speakers and acoustics of the day. However, a cinema processor has these variances EQed out. The track will sound excessively bright and potentially have rumble without the Academy Filter applied to such a system.

Mono tracks are normally recorded a bit hotter than an SVA track as a form of noise reduction. in fact, it is not uncommon to see mono tracks where the two lines touch each other...something you should never see on a stereo print. The noise reduction for a stereo print comes from the Dolby NR itself...something lacking on a mono track. Because a mono track is recorded hotter...and Dolby NR does NOTHING above Dolby Level, it will, effectively, be out of circuit except for quieter portions of the track. And, since it was not recorded with NR...how it behaves on those quieter sections will not be predictable as it will be track dependent. That said, some have found that running with Dolby (A) NR on mono tracks to not be very objectionable and it will cut down on some noise when nothing is playing.

However, proper playback of a Mono track is NR out, Academy Filter on. This is true for all mono (non-Dolby) tracks...VD VA or VA bilateral.

Dolby did put images of Mono versus Stereo tracks in their manuals and quick-start cards:

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[Bobby Henderson]

Wasn't "Jaws" a mono "Dolby System" release?

[Leo Enticknap]

I've often found that single bilateral (including RCA duplex) VA and poorly graded, thin VD tracks can be cleaned up nicely by playing them in 02 on processors that support it (e.g. CP200). During the '80s and '90s, there was at least one Indian lab that produced dual unilateral VA tracks (!), for which 02 was an absolute no no - it would obliterate pretty much everything above around 1 KHz. During the mid 90s I worked at an arthouse that regularly showed dual unilateral Bollywood prints, and it was simply impossible to make them sound respectable. Unless there is something wrong with the source signal used to master the track neg, then as Steve notes, dual bilateral mono shouldn't need any help beyond the Academy curve.

[Steve Guttag]

Leo, I found that the original Kintek KT-21 (either yellow or black) dynamic range expander could help with less than optimal tracks. It was definitely a delicate balancing act. Too much expansion and you'd get a notable pumping of the noise. I found that most "good" mono tracks benefited from about 10% Expansion...bad tracks at about 20%...more than that, the negatives outweigh the benefits. The later Kintek (KT-700 and KT-800) were not, in my opinion, as good in this respect though the KT-700 did have a 1.1 and 1.2 position for expansion. The other aspects of the Kintek process varied wildly by print but as far as psudostereo went, they were about as good as it got. Their surround fakerizer was clever in how it identified vocal versus music..they used that circuit to help duct L/R on their Stereo Phoney Izer.

[Marcel Birgelen]

Wasn't "Jaws" a mono "Dolby System" release?

Jaws was Mono Westrex / RCA Photophone, which is a VA format. Unknown to me if it uses any form of noise reduction like Dolby A.

[Gordon McLeod]

In Canada we had many Dolby Mono prints in the early part of optical stereo with dual inventories Sinbad and the Eye of the Tiger and Watership down come to mind I too was a fan of the Yellow box of fun. The Cat 22 can be switched into a DNR type mod that was handy for realy bad prints

[Mitchell Dvoskin]

A number of 1970’s mono prints had “Dolby Stereo” in the credits, but they were standard “Academy” mono. The Dolby Stereo credit referred to the Dolby NR used in mixing the audio, not the release print.

[Pete Naples]

Often you used to see 'Dolby Stereo/SR in Selected Theatre'.

In other words, there were dual-inventory prints available. The 04 or 05 prints were only going to cinemas equipped to play them.

In the 1990s I screened a few prints of the various rep titles, you'd get a Mono print then six months later an 04 print of the same repertory title.

We kept meticulous records of print numbers, formats, condition etc. Sadly the now owners of that cinema ditched it all.

[Steve Guttag]

There was a period of dual-inventory for both Dolby-A and Dolby-SR...by the time "quad" prints came out (with all of the digitals plus SR) the dual-inventory concept ended. BTW...Dolby Stereo was JUST for stereo. The Dolby noise reduction was always "Dolby System" (check your CAT22 cards). Early Dolby Stereo movies, like American Graffiti would have Dolby System in the credits.

The number of actual Dolby-Mono titles was incredibly small. In later years, even with SR...Woody Allen would have essentially a Mono movie but with the SR NR...one just ran it Dolby SR (05). The Stereo decoders back when Dolby Mono was around was not nearly as good as when the CAT150 came out. There wasn't the steering that came along with the CAT150. They just shifted the levels of the stage channels a little bit. Surround was onto itself as a separate decoder (CAT116). It was a very different world.

[Mark Gulbrandsen]

Before the CP-50 many of those early Dolby System labeled films used the original Dolby seperates wired together. NR, Decoder, EQ, Output and a Surround adapter. They were in separate single rack mount units. I used to use a couple models of those on location dailies jobs. Dolby licensed Sansui SQ and those early three channel decoder cards said Sansui SQ right on them. Early CP-50's also continued to use those early decoder boards...

[Sam Chavez]

Dolby Mono used a 364/E2 combination. 364 was the NR with specific front panel switches, E2 was a Cat. 64 in a frame.

Lots of these were installed in Canada at Famous Players locations. Barry Blackburn made a practice to buy enough for the whole circuit. Gotta love him. He repeated this practice during my years at Dolby on other products.

The first stereo processor, CP100 had no surround channel for optical so this was done with various adaptor frames. SA2, SA3, SA4, and SA5.
You could add EQ with a E2, or NR for mag surround channel using a 364. All these features were pretty much incorporated into the CP200.

[Mark Gulbrandsen]

Dolby Mono used a 364/E2 combination. 364 was the NR with specific front panel switches, E2 was a Cat. 64 in a frame.

Lots of these were installed in Canada at Famous Players locations. Barry Blackburn made a practice to buy enough for the whole circuit. Gotta love him. He repeated this practice during my years at Dolby on other products.

The first stereo processor, CP100 had no surround channel for optical so this was done with various adaptor frames. SA2, SA3, SA4, and SA5.
You could add EQ with a E2, or NR for mag surround channel using a 364. All these features were pretty much incorporated into the CP200.

Yea, it was the E3 that I used... For some reason the location sound guys were familiar with it's characterisics, and we usually tuned the room to their liking, or just the 2969 curve, or flat if they didn't care.

[Gordon McLeod]

If anyone has a SA4 I would be interested in it

[Michael Coate]

Wasn't "Jaws" a mono "Dolby System" release?

No, JAWS (1975) was just “regular” mono. I believe Universal’s first usage of Dolby wasn’t until 1978 with FM and the re-issue/re-mix of AMERICAN GRAFFITI. The first time Universal did a 70mm Six-Track Dolby mix was for SGT. PEPPER’S LONELY HEARTS CLUB BAND (also 1978).