my profile | my password | search | faq & rules | forum home

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » EQ'ing a poor auditorium (Page 1)

This topic comprises 2 pages: 1  2

Author Topic: EQ'ing a poor auditorium Ken McFall Jedi Master Film Handler Posts: 615 From: Haringey, London. Registered: Apr 2001 posted 02-13-2010 01:14 PM                     Here's a problem I've got with a small independant who runs a cinema in a multi use hall. The hall is on two levels and is rectangular with seating on the two long sides and one short end. An organ is at the other short end. The lower floor is similar ecept the stage is under the organ. A very tall roller screen is dropped down from the rafters. The ceiling is pitched with exposed rafters. Speakers are JBL's all round (Not too sure of the model but supplied by a reputable cinema supplier. Westar 2002 sound head and 2001 picture head. CP65 processor. The acoustics of the hall were a known problem when I installed the projection system some years ago. The local film society had ran there for some years and that was their main problem. However recently the complaints have been worse than ever so I made a service trip yesterday. Did a full A chain and no problems with the sound head at all. Flat illumination and responce. B chain was pretty good and I didn't have to force anything at all. Here's the problem. End of last year they had a fault with the transformer card in the cp65 which I repaired. While waiting for me to get there thay ran in bypass and the sound was much more intelligable but very raw as there was no noise reduction or processing at all. So it was mono from all stage speakers. This past week they have started to use bypass more because of the complaints. I've dome more eq's than I care to remember but this is the most difficult auditorium I've ever come across. I suspect the reason that bypass sounds better is becuase the sound isspread across the three stage speakers which may be negating some of the acoustic properties if the building. Similar to the reason they use lots of smaller speakers in large train stations... Acoustics is a very specialised science that I know practically nothing about so I'm always happy to learn. So anyone got any ideas.  |  IP: Logged Demetris Thoupis Phenomenal Film Handler Posts: 1240 From: Aradippou, Larnaca, Cyprus Registered: Apr 2001 posted 02-13-2010 01:26 PM                     When doing a two floor cinema its always best if you have a multiplexer to place two mics at the ground level and two mics at the floor level. You'll be suprised how different things will sound. Also don't rely too much on the analyzer. While you may be getting good responses from the eq, it does not mean that its fine. You most probably have a lot of reverberation in that room and thus the result of lack of intelligebility you are mentioning. The other factor is that something might be happening when you are not there that you are unaware off. What kind of symptoms do they mention? Did you try leaving just the centre speaker amp on and walk around the auditorium to listen to how it sounds and then add one channel at a time to see how it changes? Wall carpet and wall treatment like curtains is a good way to kill reverberation. On the other hand, you could go with Renkus Heinz digital steerable beam Iconyx range to solve reverberation and direct the sound beams directly at the listeners ear. Renkus Heinz Iconyx Live Demetris  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 02-13-2010 01:30 PM                     Center channel EQ levels: turn down the LF's, keep the mid range levels where they are at, and roll off the HF's after 4k. Voice is reproduced mainly in the mid range, thus why do you need the other two sides hot of the EQ spectrum? Works pretty good in halls and houses with acoustical problems. -Monte  |  IP: Logged Ken McFall Jedi Master Film Handler Posts: 615 From: Haringey, London. Registered: Apr 2001 posted 02-13-2010 01:38 PM                     They don't use the top floor so that's not an issue but yes there is a lot of reverb. I've done all of the usual checks and some of as you have suggested. As I've said this is a long term difficulty and I'm not the only person who has tried eq'ing this place. I was toying with the idea of bridging the left center right outputs so all stage speakers were giving the same output... The other difficulty I have to contend with is that the guy who runs the place has an hearing aid so is totally reliant on the comments of others as he cannot hear what everyone else does. Many of the complaints have been contradictory... muffled sound and too sharpe hf etc etc. Speach too low compared to the effects. I know some of the complaints are simply different audiences, sound tracks and age groups but the overall problem is the auditorium. Nothing jumps out as being a fault.  |  IP: Logged Demetris Thoupis Phenomenal Film Handler Posts: 1240 From: Aradippou, Larnaca, Cyprus Registered: Apr 2001 posted 02-13-2010 01:50 PM                     Ken did you try listening the Dolby Jiffy test film? It can help with realising some problems in the auditorium. Again the Renkus Heinz seem to be a solution but prepare of a big cheque for each speaker! The other possibility is a bad 2:4 card in the Dolby unit. Demetris  |  IP: Logged Ken McFall Jedi Master Film Handler Posts: 615 From: Haringey, London. Registered: Apr 2001 posted 02-13-2010 01:58 PM                     Demetris running my jiffy film was the VERY first thing I did so I knew exactly where I was starting from. No problems were evident with the speakers or matrix. I'll give Montys suggestion another try and maybe be a bit more aggresive with the roll off's than I have been before.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 02-13-2010 02:11 PM                     I would first look at the positioning of your stage speakers and their horns position and aiming to minimise reverb will help  |  IP: Logged Demetris Thoupis Phenomenal Film Handler Posts: 1240 From: Aradippou, Larnaca, Cyprus Registered: Apr 2001 posted 02-13-2010 02:19 PM                     Ken. It's good some times to suggest obvious things in case your search has blinded you!  |  IP: Logged Ken McFall Jedi Master Film Handler Posts: 615 From: Haringey, London. Registered: Apr 2001 posted 02-13-2010 02:20 PM                     Hi Gordon, The speakers are positioned as close to the rear of the screen surface as possible. Unfortuatly the lower roller of the screen is at the rear so they are not as close as I'd like. Also they have to be on stands that are easy to remove as required. The horns are aimed downward to direct the hf to the audience as much as possible. Maybe I could try aiming them very sharply downwards to minimise the hf spread upwards? There is some open space behind the lower half of the screen that has a grand piano but it is curtained. However, the top part of the screen is fully open behind, up to the rafters, where the organ is. If you can follow my descriptions its FAR from an ideal situation for film sound.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 02-13-2010 02:53 PM                     It may be that a narrower horn would be desirable it would also be interesting to see what a TEFF anaylzer would show on the room as the decay of the reverb sounds like part of the issue  |  IP: Logged Ken McFall Jedi Master Film Handler Posts: 615 From: Haringey, London. Registered: Apr 2001 posted 02-13-2010 03:09 PM                     Gordon. I don't think I'd be able to get agreement on much of a spend to investigate the issues with an acoustoc engineer or other. I certainly don't have the skills to persue things much further than I have done so far. Demetris, you are quite right in that you sometimes don't see the trees for the woods... That's why I posted the question. I can at leats show the posts to the guy and try a few things suggested and see what happens. I have explained that at the end of the day he may well be stuck with things as they are. It's not his building so spending a lot of money is out of the question especially with the current finacial situation. I'll give it a couple of weeks and maybe spend another day there just working on the sound possibly even working overnight. Thanks everyone so far for your help.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 02-13-2010 03:26 PM                     First off...you can't fix a bad room with EQ....but here are some things to consider.... If have a reverberant room...try to stay away from direct-radiator speakers...you really want horn-loaded speakers (Altec, Klipsch, JBL PD5000 series...etc)...you want to keep the sound off the walls as much as possible. Do NOT over-eq...particularly the HF...you will find that if you do a TEFF analysis that you probably have too much HF boost despite you using the X-curve...the X-curve presumes a normal amount of reverberation...which you do not have. A couple of things to try...lower Left/Right by at least 3dB. They are playing mostly music...which will build up in a live room and drown out dialog...which is a series of short bursts. Don't go crazy with the bass either...watch out in the 150-250Hz range as well...don't over emphasize as everyone will sound tubby. In the States...we also have a problem with British accents in live rooms...but I suppose your people have overcome that . Not to worry...Aussie accents are even worse (witness that Mad Max had to be dubbed on its original release). This is a case where having a DSP for EQ with a wireless router and a laptop with wireless Ethernet can be a God-send since you can sweeten the sound to the room based on actual material. With tough rooms...you have to use more than just Pink Noise...you have to listen to actual voices (male and female) and listen for what is getting muddied. Steve  |  IP: Logged Ken McFall Jedi Master Film Handler Posts: 615 From: Haringey, London. Registered: Apr 2001 posted 02-13-2010 03:34 PM                     Thanks Steve some great pointers. May see if I can rig up at entesion for my cat 67 E2 Alignment Extender. Would not need to be too long and I could sit in the auditorium and hear 'real' film sound live. I'm sure I can improve on the sound but it's getting input from you guys that is invaluable given your experience. Thanks again.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 02-13-2010 03:46 PM                       Don't discount that there may be a card problem, so if you have not already done so, listen to the sound in bypass and then normal, but with flat EQ and subwoofer off, and see what you hear. Might be a bad 222 card if I was to choose one most likely at fault.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 02-13-2010 03:48 PM                     Remember too...when in bypass...you have a compressed track and that will improve dialog in a live room as the problems are less exaggerated. There are times when good mono really does beat stereo. Steve  |  IP: Logged

All times are Central (GMT -6:00)

This topic comprises 2 pages: 1  2

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.