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This topic comprises 4 pages: 1 2 3 4
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Topic: Anyone got any Sensurround information?
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Don Sneed
Master Film Handler
Posts: 451
From: Texas City, TX, USA
Registered: Aug 2001
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posted 06-07-2003 07:34 AM
Back in the mid 70's when Sensurround came out, I was a young projectionist, Stereo sound for theatres on optical sound track was not out yet, all theatres had Mono sound with 35-100 watts, Subwoofers was not heard of at that time, when Universal Studio, BGW amplifiers, & Cerwin Vega team up to make Sensurround it was an experience !! Then Dolby came out with the CP-50 a couple of years later & change the way we listen to movies...The theatre I worked at had to remove the port glass to run the speaker cables out of the window, if I was on the Telephone when the Sensurround kicked in, my voice would break up or chop on the phone, I had to stop talking until the effect stop...30-years later most theatres now install sub woofers...Thanks to Sensurround & Dolby lead into the sound system we all enjoy today...I am so glad I was part of the history of theatre sound, although at the time no one knew we were part of history...
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Ian Millar
Film Handler
Posts: 8
From: .
Registered: May 2007
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posted 06-04-2007 10:03 AM
Hi everyone. This is my very first posting here. I hope you guys enjoy it and don't mind, but I am not in the cinema industry - just very interested and big on my home cinema hobby. I have wonderful recollections of seeing all of the major Sensurround films that were shown here in Sydney Australia in the 1970's. They were shown in the Forum Cinema at the bottom of George Street Haymarket. The first of course was Eathquake which to a 12 year old kid was nothing short of mind blowingly awesome. It wrenched your guts and made you laugh like crazy with excitement. The forum was an old run down cinema with grey flaky painted walls inside. It was demolished in the eighties (perhaps necessarily after all those Sensurround movies). I recall giant black speakers in the back corners and across the floor under the screen. Then there was (The Battle of) Midway, and (not sure of the order of these:- Rollercoaster, Battlestar Galactica, and Mission Galactica, the Cylon Attack. The Sensurround effect in Rollercoaster was not impressive. I loved the shaking so much in the other films that I went back to see them over and over. I now have all of the movies either on LD or DVD. Apart from the nostalgia and the sound effects they are all pretty lame now by modern standards. The only one with really interesting and true to original sound effects in the LFE channel however, is the latest release of Earthquake on DVD. It's really interesting. In the languages setup on the DVD menu you have a choice of "Dolby Digital 5.1", or "Sensurround 3.1". The Sensurround 3.1 is really wierd. It merely puts the low frequency CONTROL tones into the .1 (sub woofer) output. There are two distinct tones and none of the proper sound effects at all through the sub woffers. These tones were to control ON/OFF and GAIN of the rumble in the cinema which was generated by a "pseudo-random infrasonic noise generator circuit". Hey I am a Patent Attorney by profession and this is what inventors Stumpf et al called them in the US patent specification which was reissued in about 1980. However the most spectacular bass sound that I have ever heard in a home cinema set-up is had when you select the Dolby Digital 5.1 option where they have put the real thing down on the LFE channel. They have also done wonders with the mix on the 5 other channes especially considering that the original was mono. OK you all probably think I'm nuts, but it gets better... Reading the patent document some years ago I found out what speakers and amplifiers were recommended by the inventors of the system. One of two recommended speaker drivers was the 18 inch Cerwin-Vega 189E (which was mounted in a variety of horn cabinets). One recommended amplifier was mentioned as the "Cerwin Vega Model 3000". After ages searching on eBay I found a pair of the drivers in fantastic original (not reconed or otherwise repaired) condition in the States. They both retain the proper stiff linen suspension and none of that feeble foam stuff of more modern drivers. Further homework found that the maximum travel of the cone is only about 6mm and that they had to be mounted in a sealed enclusure of a mere 1 to 1.5 cubic feet and that they MUST be horn loaded! How can you get an 18 inch driver into a small enclosure like that? Easy - forget rectangular. I also found an A-3000I power amp and had it oscilloscope tested and checked-over. My mate who is into low powered tube amps had to keep clicking his little oscilloscope knob up another notch as he said with Brazillian accent: "This is bloooody poooWerfuuul maaate". It put out 351 watts RMS into 8 ohms and with a square wave input had NO overshoot at many frequencies way up to just below maximum where the flat top of the square started to ripple just a bit. After further searching of the Net, I learned that one of these amps was used to drive 4 of the speaker drivers - 2 per channel - each pair in parallel to present each channel of the amp with a 4 ohm load. Anyway I set about building a pair of folded horns in much the same design as the Sensurround Model M horns but bigger and with a longer mouth and much heavier, and with wife-satisfying timber finish. Each one weighs 265 lb! I finished them last week and set them up - one facing into a corner and the other sideways into the room from an entry corridor. I tested them with sine wave tones from 10 Hz up to 100 Hz and they had a few apparent peaks with nothing perceptible below about 15 Hz and lots of power at about 30. I rolled them off over 115 Hz with inductor coils built into the cabinets. So one channel of the amp drives both speakers and the other drives an LFE 4 ohm Buttcicker transducer bolted into my lounge chair which is mouted on rubber suspension pads (The amp is so powerful that it easily bottoms the Butkicker below 15 Hz!). I have not laughed and smiled as much as this in years! I put on the Earthquake DVD and heard/felt that sound the way it was in the 70's precisely as I remember it and nothing like anything that I have heard in between! Forget live rock concerts and night clubs with the pounding bass or any recent films at the cinema. All that is chicken piss compared to this. Its a slamming crunchy sharp edged bass sound that is totally unmusical and nothing like the sound of a sine wave input. The VU needles on the front of the amp jump about quite ramdomly right up to the red area - most unlike a musical note of a sine wave. It's SENSURROUND and it's Blooody poooWerfuuul mate and it makes me smile! Cheers, Ian ![[Smile]](smile.gif)
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Ian Millar
Film Handler
Posts: 8
From: .
Registered: May 2007
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posted 06-05-2007 08:46 AM
Thanks guys...I feel very welcome now
I watched the Midway DVD this afternoon with the 1.1 Dolby Digital and the LFE sounds are very different to those on the Earthquake DVD. On Earthquake its rumble or rumble with gain and very sharp-edged (kinda more square wavy I suppose you could say), but nothing much below 20 Hz or so (an educated guess there). On Midway there is much more variety in the LFE. For example when the LFE indicator illuminates on my processor (A Sony SPD-EP9ES which is about 10 years old now) things happen in different ways. For example there is a low level near monotone drone of about 40 Hz for general background effect to kind of fill the room during long shots of fighter planes and battle ships etc, then when there is an explosion, you get a variety of rumbles - some deep, some not so deep, some loud, some not so loud, but the really good stuff happens just a few times and the Buttkicker in my lounge moves at very low frequencies (guessing about 10 Hz based on previous tone tests I did on it). There are also very short bursts of intense effect for say mid-air explosions that miss their target - you know those little puffs of smoke in mid air with no flame (and there were plenty of those). There is nothing in the LFE quite as viscious as on Earthquake, but its all good stuff. I'll watch Galactica soon and see how that goes.... Lotsa fun.
Oh and Thanks John for the Randwick tip (no pun intended but there is a racecourse there too) and James, my neighbours are fabulous people and one - the closest one - is a retired studio sound tech and has a lot of interest in the system. I love to have all the neighbours over for drinks and dinner to maintain the relationship. Fortunately they are all over 50 yards from the "epicentre" and there are trees everywhere. It's like a forest here. Of course all the windows a shut before cranking it up. Also, I did a walk-around test during the earthquake sequence and nothing outside but bird sounds and a slight hint of something wierd gong on inside. ![[eyes]](graemlins/eyes.gif) Thank goodness for that!!! Cheers for now everyone. Oh can someone tell me how I can put my photo in my profile so I don't look so anonymous? ![[Cool]](cool.gif)
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Frank Angel
Film God
Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999
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posted 06-05-2007 09:27 AM
Ian, welcome....and I LOVED your post. A man of my own heart, and very VERY lucky to have found a woman who can live with Sensurround speakers the livingroom! All I had was a Simplex XL on a pedestal with wheels in the foyer -- you had to squeeze by it to get out the door. My girlfriend was forcing me to go to a dinner party or wedding or some such girlie thing, and as we left the apartment, my beloved Simplex leaked oil all over the back of her dress. ![[Big Grin]](biggrin.gif) She gave me an ultimatum right then and there: "Either that horrid monstrosity goes, or I do!" Can you believe it....she called an XL a monstrosity?!!
I didn't miss her as much as I thought I would.
I too thought Sensurround was indeed an incredible idea in EARTHQUAKE, not so much in the other releases. Sure today's modern subbass systems are good, but I am not sure that even THX cert subbass systems could reproduce the sheer gonad-vibrating air-pressure sensation that the EARTHQUAKE Sensurround system produced (and women wonder why we loved it so ![[thumbsup]](graemlins/thumbsup.gif) )
There were many installations where the system, once calibrated to spec, would actually cause structural damage. Plaster ornamentation, so common in those big single screen palaces, was particularly susceptible, i.e., plaster falling off the walls -- quite appropriate in the middle of the show!
I must have seen EARTHQUAKE four or five times, most times sitting as close to one of the big bins as I could. I recall the one time in a Chicago movie palace type theatre under the el, I sat practically inside the throat of the stage horn.
When I got my "home theatre" setup long before anyone ever heard the term and right after I sent the XL-hating bitch packing, I had stacked 8 BSR 3-way bins - 4 per channel so as to acoustically couple the bass and then 2x KLH6 per channel acoustic suspensions in either rear corner. It was powered by two Phase Linear 350w RMS per channel and a QSC. In my 22ftx15ft living room, this thing certainly approached the Sensurround effect enough to have a mob of my neighbors, halfway thru my private presentation of EARTHQUAKE, come pounding on my door accompanied by two policemen.
The copy of the film that I had back then (pre-VHS) was recorded (Jack Valenti called it piracy in those days) from a single off-air broadcast on a local TV station and simulcast on an FM station. I recorded it on a 3/4in U-Matic deck in stereo. The unique thing is, the FM station had mixed the output from the random LF noise generator into the broadcast at the appropriate times on both L & R channels. It was quite effective.
No one except me and my stoned college chums thought this was a wonderful thing. The cops demanded to know what was going on; the neighbors first thought the apartment boiler was exploding as the bass sound is difficult to localize. It took them awhile to figure out where it was coming from. I told them we were just watching EARTHQUAKE -- they could see the 8ft VideoBeam screen thru the door and that alone made the cops even more suspicious as no one at that time had large screens at home. Then they got really serious and wanted to know why it was so loud and shaking the building -- the windows were rattling. I said "what do you mean it's too loud -- it's an EARTHQUAKE! It's supposed to be loud." My buddies thought this was hysterical; my neighbors and especially the cops did not.
Anyway, I am sure EARTHQUAKE had a stereo track as it did have mag prints. The TV broadcast definitely was stereo, at least L & R. Sensurround trigger tones no doubt were recorded on the surround track 4 on the mag prints cause lawd knows they didn't need a surround channel.
I am fascinated with your statement that the DVD has the trigger tones, since I have a short-lived LP release that they had to pull off the market. The opening cut consisted of just the actual subbass sound recorded directly from the random noise generator; It's about a minute long and the reason Universal had to pull the album was that unsuspecting folks with normal stereo systems would plunk down the needle with the volume at normal level and promptly rip their speakers to shreds. Even though it is only a minute, it takes up as much space as a five minute cut because the grooves have to be spaced far enough apart so the severe undulations don't cut into the grooves walls on either side. It is quite unique. I would love to MIDI sample that LP cut and use the tones on the DVD to regulate the sampled rumble. Maybe I can get the cops to come back....hehe.
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