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Author Topic: aiming speakers Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 06-24-2012 12:23 PM                     Hello, How do you usually aim stage speakers, LF and HF? QSC manuals say to aim the HF horns to point to the center seat of the back row - using the very useful holes on the horn - but JBL say 2/3 of the room. What is your choice when installing/tweaking a sound system?  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 06-24-2012 07:53 PM                     2/3rds have usually been the standard for HF horn alignment for uniform coverage.  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 06-24-2012 08:04 PM                     Before going with the default way that it has "always been done" I'd want to know a little more about the difference(s) between the horn used by JBL vs QSC. QSC may have good reasons for suggesting the back row. Then again, they may not. But how do we know if we don't dig deeper?  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 06-25-2012 07:59 AM                        Certainly the vertical coverage of the horn is the main issue. If the back wall is "live" I have had to aim the horn to minimize echo. (Easier to do than you think: real time mike just above ear level on last row, analyzer at speaker; adjust for good sound, not great sound.) It can look like you are aimed at the front row! Louis  |  IP: Logged Don Sneed Master Film Handler Posts: 451 From: Texas City, TX, USA Registered: Aug 2001 posted 06-25-2012 06:33 PM                        I aim the speakers using a SPL meter to get the lowest DB front to rear...The rear wall or 2/3 or a starting point for me, I fine tune using a SPL meter... if a large stadium seating auditorium, if need be on stadium seating I aim the array or speakers for the stadium seating & add front fill speakers under the speaker platform for the seats in the front of the screen, this allows the main screen speakers to be focus on the stadium seating area & allow the front fill speakers to be focus on the front of the screen seating area....I always get a (.5 to 1.5 db) by using a SPL meter...using this method all seat will hear evenly... with the front fill speaker a couple of amps is needed & outboard equalizers for the fills...for a large aud. this is the system to use...I am surprise more theater are not using doing this...  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 06-25-2012 06:47 PM                       Say What? You are using low main speakers to fill in the seats below the stadium?  |  IP: Logged Robert Koch Film Handler Posts: 93 From: Williams Ca USA Registered: Apr 2006 posted 06-25-2012 07:49 PM                     Pay attention to Sam  |  IP: Logged Samuel Hynds Film Handler Posts: 50 From: Riverside, CA, USA Registered: Aug 2004 posted 06-26-2012 01:09 PM                     just FYI - Our HF horn has a ten degree down angle built into the horn and our MF horn has an eight degree down angle. which is why QSC recommends aiming at the rear of the seating area. (but not with the SC-2150) All other loudspeaker manufactures dont have this down angle - so aiming for them would be around 2/3 of the seating area. but its always a good idea to run pink noise and walk the room, up and down and left to right - to get the most even spl thru out the seating are. Sam Hynds Product Specialist, Cinema QSC Audio Products, LLC  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 06-26-2012 03:39 PM                        Sam: we love ya.' However, years ago JBL came out with a computer program that attempted to level out the sound field in a cinema. I did a lot of random testing to determine why people sit where they do (if given a choice.) This was related to excessive screen size. Sound issues were brought up by nearly half of the public. Sometimes people sit where they do to allow a primitive form of volume control. Note that women of all ages prefer distant seats because of sound. They are unusually unhappy with anything that is shrill or distorted. (Dull is OK.) I ended up NOT supporting the JBL "constant volume" deal since it meant that a large group of people had lost control. Louis  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 06-26-2012 07:33 PM                     Sam H.: Thanks for popping in and clarifying why QSC directs the aiming the way they do. As you know I used the QSC line at UCI for my new screening room..and they still rave about how great they sound. Oh, did you guys ever get the software changes to the DCM10/30 made as we discussed? PM me please.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 06-27-2012 02:25 PM                     Hi Sam, Then I did the right thing, I was aiming the 2150 and I eventually chose 2/3 of the auditorium. In fact, I checked the manuals to see whether there was a note about a prebuilt down angle. I do agree with the walking procedure though, it's possibly the quickest way. I usually find HF aimed to the back row (sometimes the projection porthole!) and I have always wondered whether there was a real reason for that, besides laziness. When I installed the 2150 I did a quick test from behind the screen, and found that actually aiming the horn towards the last row was causing my mike to read a little more HF content. But I like Sam's advice of walking around and judging the HF content by ear, I reckon is more accurate. And yes, my appreciation too. Were my first QSC's, and despite the basic range and the very small auditorium they sounded really great. Was particularly impressed by the subwoofer, I've rarely heard such a deep, clean and undistorted sound, even at high levels. Looking forward to being able to setup a proper auditorium with a proper QSC array.  |  IP: Logged System Notices Forum Watchdog / Soup Nazi Posts: 215 Registered: Apr 2004 posted 01-09-2018 07:42 AM                 It has been 2021 days since the last post.  |  IP: Logged Brian Vetter Film Handler Posts: 1 From: Raleigh, NC, usa Registered: Nov 2016 posted 01-09-2018 07:42 AM                     I found this on the QSC Cinema web site: QSC Cinema Tech Tip - 'No Tilt Required' quote: The mid-high frequency section of most 3- and 4-way QSC screen channel loudspeakers has a pre-set downward tilt. When it is properly elevated to approximately 5/8 image height behind the screen and aimed to the last row in a typical stadium-style cinema, there is no need for additional downward tilt. This allows you to minimize the distance from the horn to the screen, and keep it flush within a baffle wall. -- Brian  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-09-2018 11:09 AM                     I always did what QSC said to do, even with JBL (4675's typically) because that's also close to what THX specified. THX specified 2 feet above the center rear seat in all the THX houses I did. I usually use a pen laser to do aim them. Mark  |  IP: Logged Terry Monohan Master Film Handler Posts: 379 From: San Francisco CA USA Registered: May 2014 posted 01-09-2018 09:18 PM                     One of the worst things for me in the many movie theatres I have gone into all my life is the placement of the stage speakers for stereo sound. Many cinemas even with large wide screens have the 3 L R C speakers all in a group in the middle behind the screen so you don't hear the full width of the stereo sound. While most do a good job of going to the end of the screen or masking many older small screen theatres still have the group of 3 speakers next to one another when the have room to extend to the ends. Who knows what the pitch of the speakers are to the audience in these problem cinemas.  |  IP: Logged

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