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Author Topic: Why the move to non horn based speakers? Paul Trimboli Master Film Handler Posts: 274 From: Perth Western Australia Registered: Dec 2002 posted 01-12-2005 03:25 AM                     Why is it that horn based speakers which were the norm for cinemas, like all the old ALTEC range have now moved away from such designs? Is it because its easy to make powerful amps and so speakers don't need to be so effecient? And why have HF horns moved from multicell to C.D styles?  |  IP: Logged Edward Jurich Master Film Handler Posts: 305 From: Las Vegas USA Registered: Jul 2003 posted 01-12-2005 08:58 AM                     I would guess that the old classic horn design is (was) needed for large auditoriums. A small 100 or 200 seat auditorium doesn't require a high efficiency speaker system. Those old Voice Of The Theater speakers are amazing though, a 2000 seat theater I know had one with 2 - 15" woofers and one large horn. Driven with a 50 watt amplifier, that thing could blast you with lots of volume and deep bass.  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 01-12-2005 10:28 AM                     Multicell horns where great for directing sound to a certain point in a large room with a tweeter driver average 15 watts. a problem with multicell is lobing which is a dropoff of sound between cells in different parts of a room...not a great issue with mono sound; Constant directivity horns with 75 - 150 watt driver eliminate this issue. With C.D. set ups using more power with matching flat front bass cabinets are less expensive to make and to time aline between low and high components.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-12-2005 11:08 AM                     Actually, time alignment is easy with horn based sysetms since physically they may be time aligned without electronics. The big move to direct radiating speakers, as opposed to horn based stemmed from THX and the work of Tom Holman. By properly designing a direct radiating system and properly sinking it into a baffle wall you can create a system with flatter response and less distortion (well in some measurements). Horns are inherently more efficient and have better control over the sound. However, the lower the frequencies, the larger the horn must be to control those frequencies. Also, all horns have a sound of their own, either you like it or you dont. Since horns need less power, they normally will win the IM distortion contest since the drivers are not working nearly as hard as in direct radiating systems. In general, if you have a room with live acoustics, the horn based speaker will win most sound contests since it will keep the sound off the walls...if the room is properly made for film acoustics, you are more likely to get into a situation where personal preferences will take over. As to the HF horns...Richard pretty much nailed it. A CD horn provides much more uniform response over the covered area. The CD horn requires more power and it has a notable roll off in its HF response, hence a good sound system will have CD horn compensation somewhere in the processing (often in the crossover). Since you mentioned CD horns and Altec...it was Altec that really had the best CD horn of the all. If you ever get a chance, try to listen to the MR94 horn (similar to JBL 2360 or EV HP9040 in coverage). It is the most uniform coverage I've ever heard or measured and best response too. In fact, I've yet to hear a better HF system than the Altec 288L/MR94. In the little horn category, Altec also had the best with the MRII594A (similar to the JBL 2380, or EV HP940)...it is the only one of its size that can really go down to 500Hz (though 630 will work a tad better) and has very uniform coverage and response. The mentality of today seems to be to make a product that fits a price point or physical profile and then fix for its response in DSP. While it is a way, the best fix is the one you don't need. Steve  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-12-2005 07:17 PM                     quote: Steve Guttag The mentality of today seems to be to make a product that fits a price point or physical profile and then fix for its response in DSP. While it is a way, the best fix is the one you don't need. Probably one of the most meaningful paragraphs ever posted on this site! Mark  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 01-12-2005 08:25 PM                     edward said " Driven with a 50 watt amplifier, that thing could blast you with lots of volume and deep bass. "only parially true the A4 is very efficient but deep bass isn't part of it they typically don't go much below 80hz at the best  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-12-2005 09:25 PM                     An A-4 with its bass-wings is pretty flat down to 40Hz. Without the bass-wings they do indeed drop off rapidly below 80Hz. Steve  |  IP: Logged

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