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Author Topic: Who made the first decent professional cinema subwoofer?  (Read 17959 times)

Bob Leonard

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Re: Who made the first decent professional cinema subwoofer?
« Reply #20 on: April 03, 2008, 10:38:01 pm »

For all the kids I would have to beleive the first dedicated sub used in a theatre may well have to be the Sheerer horn.

http://www.audioheritage.org/html/profiles/lmco/shearer.htm
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Mac Kerr

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Re: Who made the first decent professional cinema subwoofer?
« Reply #21 on: April 03, 2008, 11:37:12 pm »

Bob Leonard wrote on Thu, 03 April 2008 22:38

For all the kids I would have to beleive the first dedicated sub used in a theatre may well have to be the Sheerer horn.

http://www.audioheritage.org/html/profiles/lmco/shearer.htm
I think a bass device that covers the range of 50-500 can't really be considered a "sub" even if it actually made it down to 50Hz, which in light of the speakers of the day is doubtful. The only other driver in that system is a compression driver on a 1505 multicell horn.

Mac
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Michael 'Bink' Knowles

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Re: Who made the first decent professional cinema subwoofer?
« Reply #22 on: April 04, 2008, 10:32:46 am »

Mac Kerr wrote on Thu, 03 April 2008 20:37

Bob Leonard wrote on Thu, 03 April 2008 22:38

For all the kids I would have to beleive the first dedicated sub used in a theatre may well have to be the Sheerer horn.

http://www.audioheritage.org/html/profiles/lmco/shearer.htm
I think a bass device that covers the range of 50-500 can't really be considered a "sub" even if it actually made it down to 50Hz, which in light of the speakers of the day is doubtful. The only other driver in that system is a compression driver on a 1505 multicell horn.

Mac




Agreed. The follow-on to the Shearer Horn was the Voice of the Theater, another cinema system that had a large bass bin but not a real subwoofer.

I forget where I read it but certain mainstream audio folks back then thought the total frequency response of the system was supposed to be centered logarithmically around ~500 Hz. If your system went down to 63 Hz (three octaves below 500) then it should go up to 4k (three octaves above 500.) It was thought that higher and lower frequency material wouldn't be missed if you maintained the balance.

A lot of horrible LF noises on film would have been revealed by strong subwoofer capabilities.

-Bink
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TrevorMilburn

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Re: Who made the first decent professional cinema subwoofer?
« Reply #23 on: April 04, 2008, 11:17:02 am »

This Vitavox cinema system from the UK (date unknown) has a claimed response to 35Hz - again, very doubtful for use as a sub. Note the enormous power handling of the bins - a whole 40 English Watts!!!
http://membres.lycos.fr/stephane3000/pdf/vitavox/vitavox_lf. pdf

regards,
Trevor
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Tim McCulloch

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Re: Who made the first decent professional cinema subwoofer?
« Reply #24 on: April 04, 2008, 01:58:32 pm »

Hi Bink-

35mm film runs at 90 feet per minute, which works out to 18ips.  IIRC the width of the optical track and limitations of the phototube and film grain led to a bandwidth spec of about 80Hz-3k..  The variable density soundtrack was a hissy beast, even with a 3k top end.  I found a nitrate reel in storage at a theater I worked at while in highschool, and the head projectionist ran it for me...  Noisy as it could be, and I got a demonstration of nitrate's combustion.

Magnetic tracks arrived in 1953 (CinemaScope 4 track stereo) and extended the bandwidth to 50Hz on the low end and 6k on the top end IIRC...  

Magnetic heads wore quickly, and many smaller exhibitors went back to the variable area optical tracks rather than spend the money to relap or replace the mag heads.

Reproduction was also limited by the A-7s behind the screen and the 20-30 watt Altec tube amps that warmed the booth (along with the arc lamps).  I'd imagine that any contemporary low end would send the amps well into clipping and blown rectifier tubes and launch cones as the required LF drops below resonance.

Nowadays the digital tracks are optical, too.  Kids these days!  For a close up look click here: http://en.wikipedia.org/wiki/Image:35mm_film_audio_macro.jpg

Audience expectations have changed, much has been done to meet those expectations with audio on silver-based imaging.

With the continual conversion to digital cinema, there are nagging questions about how to archive new digital content, and how to deal with "remastering" archived movies that are sitting down in a salt mine 40 miles from me...  Maybe silver ain't so bad after all?  Probably best left to a Basement discussion.

Thanks for the memory jog, Bink!

Tim Mc
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John Roberts {JR}

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Re: Who made the first decent professional cinema subwoofer?
« Reply #25 on: April 04, 2008, 03:45:51 pm »

Tim McCulloch wrote on Fri, 04 April 2008 12:58

Hi Bink-

35mm film runs at 90 feet per minute, which works out to 18ips.  IIRC the width of the optical track and limitations of the phototube and film grain led to a bandwidth spec of about 80Hz-3k..  The variable density soundtrack was a hissy beast, even with a 3k top end.  I found a nitrate reel in storage at a theater I worked at while in highschool, and the head projectionist ran it for me...  Noisy as it could be, and I got a demonstration of nitrate's combustion.

Magnetic tracks arrived in 1953 (CinemaScope 4 track stereo) and extended the bandwidth to 50Hz on the low end and 6k on the top end IIRC...  

Magnetic heads wore quickly, and many smaller exhibitors went back to the variable area optical tracks rather than spend the money to relap or replace the mag heads.

Reproduction was also limited by the A-7s behind the screen and the 20-30 watt Altec tube amps that warmed the booth (along with the arc lamps).  I'd imagine that any contemporary low end would send the amps well into clipping and blown rectifier tubes and launch cones as the required LF drops below resonance.

Nowadays the digital tracks are optical, too.  Kids these days!  For a close up look click here:  http://en.wikipedia.org/wiki/Image:35mm_film_audio_macro.jpg

Audience expectations have changed, much has been done to meet those expectations with audio on silver-based imaging.

With the continual conversion to digital cinema, there are nagging questions about how to archive new digital content, and how to deal with "remastering" archived movies that are sitting down in a salt mine 40 miles from me...  Maybe silver ain't so bad after all?  Probably best left to a Basement discussion.

Thanks for the memory jog, Bink!

Tim Mc


I am almost tempted to slog through my father's old notebooks to see if I can glean any pertinent clues but that would take a few hours. He was the "machinery" guy at Vitaphone the early talking movie joint venture, and I recall seeing some short pieces of film in at least one of his notebooks when they were researching some aspect of the sound reproduction. I recall lots of work with wow and flutter, and mundane things we take for granted. (Note the film stuff was probably much later than the Vitaphone gig, they were still syncing to records IIRC.)

I find the now archaic SMPTE IMD test tones of 60 Hz and 7 kHz instructive. 7 kHz for them then may be like 20kHz for us now.  I suspect the 60 Hz was not as representative of bottom end response as related to mains power frequency (present in lamp light sources). Since I don't know when this IMD spec was dated it does not give me a temporal anchor. SMP(t)E has been around since 1915 or so, while the "t" was added later.

Optical tracks in theory should be capable of response down to DC, but surely didn't. Magnetic tape "could" have been a step backwards in LF response but apparently wasn't in practice. Back then, like now speakers were difficult to get loud, low, and large.

JR


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Antone Atmarama Bajor

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Re: Who made the first decent professional cinema subwoofer?
« Reply #26 on: April 08, 2008, 01:17:22 am »


    I inherited some old Kintek's from Skywalker Ranch.  (The Single 15" versions.  They had their own plate amp and some 4 Ohm RCF 15 200 AK's, apparently the Plate amps were not well matched and one of them had a persistent hum.

    If anyone wants the empty boxes with the Plate amps... they're up for grabs.
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Charlie Zureki

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Re: Who made the first decent professional cinema subwoofer?
« Reply #27 on: April 19, 2008, 09:15:36 pm »

 University Sound manufactured what they called a Bass Horn dating back to the 1940's.

 EV manufactured a 30" driver for Sub/Low Frequencies, in the mid to late 70's , some were sold commercially but, the size of the cabinet housing recommended, made the driver impractical, larger than a refrigerator and few commercially available amps were powerful enough to drive it.

 ALtec Lansing made the models 200-210 vented bass horns early 1971 (painted mostly a beige color, some gray), some of these were huge also!

One of the most common Subwoofers in the seventies was the JBL Scoop. Invented by a Detroit Area Guy,who was/is an un-sung hero in the development of professional, high powered, sound systems,and supplied many theatres with his superb sound systems,one that I know of, still being used today.

Hammer
 
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Mark "Bass Pig" Weiss

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Re: Who made the first decent professional cinema subwoofer?
« Reply #28 on: April 30, 2008, 12:54:10 am »

That 30" driver was actually 29-3/4", and sold by Electro-Voice in the latter half of the 1970s under the model designation "30W". It has a 2.5" voice coil, a 93dB max SPL at 4' with 100W of input, according to the E-V brochure that I have here..

Art Welter

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Re: Who made the first decent professional cinema subwoofer?
« Reply #29 on: April 30, 2008, 02:26:51 am »

Mark,

Please check out the brochure again, though I never have seen the actual specs I would think the 30W  could put out 113 or even 123 dB at 4 foot. With 100 watts and a refrigerator size cabinet, those units could certainly make way more noise than 93 dB max.

Cone sag was a problem for the 30W long term,  a lot of styrofoam hanging on a little voice coil in a narrow gap.

Interesting to look at older specifications, the 1987 EV brochure for the EVM-18B shows:
30 feet at .001 watt input: 51 dB
10 feet at 1 watt input: 91 dB
4 feet at 200 watt input: 122 dB

Takes some math to convert those figures to the 1 watt one meter standard!

Anyway, I have seen unintentional errors in EV brochures, but the 30W was basically an SRO with a humongous flapping cone, so I would expect it to be in the mid 90 dB range at one watt one meter like most of their cones. Someone on the  Lansing Heritage site posted a much higher figure than that, FWIW.

Have not heard any good things about the cone, other than it went damn low, but it was one of the few cones from that era that was able to get down to the low pipe organ notes with appreciable level and efficiency.
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