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» Film-Tech Forum   » Operations   » Film Handlers' Forum   » Suggestions on EQ-inga small room (Page 1)

 
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Author Topic: Suggestions on EQ-inga small room
Bernie Anderson Jr
Master Film Handler

Posts: 435
From: Woodbridge, New Jersey
Registered: Apr 2000


 - posted 12-03-2008 04:57 PM      Profile for Bernie Anderson Jr   Author's Homepage   Email Bernie Anderson Jr   Send New Private Message       Edit/Delete Post 
I've talked to different people about this, but is there any rule of thumb for EQ-ing small theatres or screening rooms? I've been told to roll off the low end sooner and don't drop off the high end as much compaired to the recommended academy curve. Any thoughts on that?

Bernie

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Louis Bornwasser
Film God

Posts: 4435
From: prospect ky usa
Registered: Mar 2005


 - posted 12-03-2008 09:20 PM      Profile for Louis Bornwasser   Author's Homepage   Email Louis Bornwasser   Send New Private Message       Edit/Delete Post 
The roll off specified is designed for all rooms. That is the point of the specification.

The only exception is "large" rooms with special circumstances. In fact your small room and the mixing suite should be the same; life is easier in a small room. Louis

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Christos Mitsakis
Expert Film Handler

Posts: 242
From: Ag.Paraskevi, ATHENS, GREECE
Registered: Sep 1999


 - posted 12-04-2008 01:35 AM      Profile for Christos Mitsakis   Email Christos Mitsakis   Send New Private Message       Edit/Delete Post 
Eq flat up to 2KHz falling 1.5dB per octave afterwards, or go up to 4KHz flat, then fall 3dB per octave. Both will give you acceptable responce for small rooms.

Christos.

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Tony Bandiera Jr
Film God

Posts: 3016
From: Moreland Idaho
Registered: Apr 2004


 - posted 12-05-2008 02:25 PM      Profile for Tony Bandiera Jr   Email Tony Bandiera Jr   Send New Private Message       Edit/Delete Post 
quote: Louis Bornwasser
The roll off specified is designed for all rooms.
And that is a problem. Smaller rooms, when using an RTA and pink niose, require {LESS} roll-off to avoid sounding {dull}.

Edited text in {}

The manual for a Goldline RTA goes into detail explaining the differences in roll off for large and small rooms, and the reasons why. (Has to do a lot with reflection times affecting the response at higher frequencies.)

I think there is a Goldline manual in our "Manuals" section here.. unfortunately, I sold my Goldline and don't have the manual anymore.

[ 12-05-2008, 07:08 PM: Message edited by: Tony Bandiera Jr ]

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Max Biela
Film Handler

Posts: 89
From: Dortmund, Germany
Registered: Sep 2003


 - posted 12-05-2008 02:56 PM      Profile for Max Biela   Email Max Biela   Send New Private Message       Edit/Delete Post 
It is the other way around: very small rooms require an almost flat EQ with very little roll off. See SMPTE paper published in the "Technical Guidelines for Dolby Stereo Theaters" in the manual section.

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Cameron Glendinning
Jedi Master Film Handler

Posts: 844
From: West Ryde, Sydney, NSW Australia
Registered: Dec 2005


 - posted 12-05-2008 03:05 PM      Profile for Cameron Glendinning   Email Cameron Glendinning   Send New Private Message       Edit/Delete Post 
I agree with Max, close to flat in a small room

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Tony Bandiera Jr
Film God

Posts: 3016
From: Moreland Idaho
Registered: Apr 2004


 - posted 12-05-2008 07:06 PM      Profile for Tony Bandiera Jr   Email Tony Bandiera Jr   Send New Private Message       Edit/Delete Post 
Yep, Max is right, I had that backwards.. my bad.. I'll edit the original post.. [Smile]

Sucks getting old...

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Pete Naples
Phenomenal Film Handler

Posts: 1548
From: Dunfermline, Scotland
Registered: Feb 2001


 - posted 12-09-2008 03:39 AM      Profile for Pete Naples   Email Pete Naples   Send New Private Message       Edit/Delete Post 
OK Here's a quandry.

Define a small room?

Dimensions/Volume, or Nº of seats?

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Bernie Anderson Jr
Master Film Handler

Posts: 435
From: Woodbridge, New Jersey
Registered: Apr 2000


 - posted 12-11-2008 06:44 PM      Profile for Bernie Anderson Jr   Author's Homepage   Email Bernie Anderson Jr   Send New Private Message       Edit/Delete Post 
Small room: small screening room with maybe 10 seats to a small multiplex auditorium with maybe 50 seats (35'x50')

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12300
From: Annapolis, MD
Registered: Dec 1999


 - posted 12-11-2008 07:06 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
I tend to sub-divide the small rooms into the less than 40-feet from screen to rear wall. The Very-Small room for me is on the order of 20-feet from screen to rear-wall.

Like any EQ...use the analyzer but you best listen to your result with known film (a track you have heard in several rooms) and preferrably with several different pieces of material and dialog as well as music better be part of the material.

Steve

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Scott Norwood
Film God

Posts: 8002
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99


 - posted 12-12-2008 08:09 AM      Profile for Scott Norwood   Author's Homepage   Email Scott Norwood   Send New Private Message       Edit/Delete Post 
Semi-related question: some setups and rooms seem to sound really great for music and lousy for dialogue, while others are the opposite. Why? Is it the extend to which the room is "too live" or "too dead" (what is the technical term for this?)? Is it the setup (EQ, crossover points, etc.) of the system?

Large rooms also seem to have low-frequency issues. I'm familiar with one (large 1920s house) that has a nasty bump at around 200-250Hz. How does one go about fixing something like this? Is it wrong to try to fix these issues with EQ alone? Is there material that absorbs certain frequencies that can be installed and, if so, how does one know where to install it and how much to use? Is it just a matter of trial-and-error? What about rooms that have dips at certain frequencies?

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Louis Bornwasser
Film God

Posts: 4435
From: prospect ky usa
Registered: Mar 2005


 - posted 12-12-2008 10:12 AM      Profile for Louis Bornwasser   Author's Homepage   Email Louis Bornwasser   Send New Private Message       Edit/Delete Post 
The larger, the more reflective room; you will have dialog problems. (if it is really large and reflective, you may have to EQ the normal way, then corrupt the eq to aid articulation.) You do this with all channels off except center; work only with dialog; when finished eq the other channels normally. Lastly, raise the center only 3-6 db if needed.

I feel like a real old timer on this since this was normal procedure in the 1930-1950's. Louis

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Robert Minichino
Master Film Handler

Posts: 350
From: Haskell, NJ, USA
Registered: Dec 2005


 - posted 12-12-2008 01:04 PM      Profile for Robert Minichino   Author's Homepage   Email Robert Minichino   Send New Private Message       Edit/Delete Post 
From the opposite perspective (3000 seat house), Louis is absolutely right. Our theatre sounds great on music with minimal EQ, but dialog is unintelligible without a substantial and wide hump around 400Hz in the center channel.

For deciding what a small room is, my guide would be a combination of the largest dimension and room volume. The larger the largest dimension is, the lower in frequency the lowest room mode is, so that dictates your bass frequency response. The larger the volume of the room the less high frequency reverberation there is with respect to low frequencies.

In almost any conceivable home theatre or equivalently-sized screening room I'd run without EQ (or EQ so speaker's near field response is flat) on the high frequencies, and use a combination of room treatments and EQ to get a slightly rising response as you go down in frequency from 120Hz (3dB/oct) with no obvious interaction from room modes. It's been my experience that this combination gives the most "real" bass response in smaller rooms.

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John Hawkinson
Film God

Posts: 2273
From: Cambridge, MA, USA
Registered: Feb 2002


 - posted 12-12-2008 05:12 PM      Profile for John Hawkinson   Author's Homepage   Email John Hawkinson   Send New Private Message       Edit/Delete Post 
So, err, why are people asking what defines a small room? EQ the room to the curve and see how it sounds!

--jhawk

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Pete Naples
Phenomenal Film Handler

Posts: 1548
From: Dunfermline, Scotland
Registered: Feb 2001


 - posted 12-13-2008 02:26 AM      Profile for Pete Naples   Email Pete Naples   Send New Private Message       Edit/Delete Post 
Just interested in what people consider a small room, nothing more.

I've got one tiddler in the Republic of Ireland, it aligns with very little action from the equalizers and sounds great. I put a lot of this down to the fact that you are sitting practically in the throat of the speakers. You are hearing more direct sounds as opposed to the predominantly reverberant field you would hear in a large room. The room being very well damped is helping matters too.

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