This is topic aiming speakers in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Marco Giustini (Member # 4544) on 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?
Posted by Monte L Fullmer (Member # 2797) on 06-24-2012, 07:53 PM:
2/3rds have usually been the standard for HF horn alignment for uniform coverage.
Posted by Manny Knowles (Member # 1171) on 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?
Posted by Louis Bornwasser (Member # 3063) on 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
Posted by Don Sneed (Member # 955) on 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...
Posted by Sam D. Chavez (Member # 1841) on 06-25-2012, 06:47 PM:
Say What? You are using low main speakers to fill in the seats below the stadium?
Posted by Robert Koch (Member # 3728) on 06-25-2012, 07:49 PM:
Pay attention to Sam
Posted by Samuel Hynds (Member # 2610) on 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
Posted by Louis Bornwasser (Member # 3063) on 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
Posted by Tony Bandiera Jr (Member # 2365) on 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. ![[Smile]](smile.gif)
Oh, did you guys ever get the software changes to the DCM10/30 made as we discussed? PM me please.
Posted by Marco Giustini (Member # 4544) on 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.
Posted by System Notices (Member # 2357) on 01-09-2018, 07:42 AM:
It has been 2021 days since the last post.
Posted by Brian Vetter (Member # 9763) on 01-09-2018, 07:42 AM:
I found this on the QSC Cinema web site:
QSC Cinema Tech Tip - 'No Tilt Required'
