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Author
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Topic: Sub EQ
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Antonio Marcheselli
Phenomenal Film Handler
Posts: 1260
From: Florence, Italy
Registered: Mar 2000
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posted 07-26-2002 06:37 AM
Let's say that you have a sub like this on RTA  Equalizing a sub means cut off the main resonance of the room.
Would you cut just the 60hz peak  Or cut up to reach 40Hz 
What is the correct procedure?
Thanks
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Antonio Marcheselli
Florence, Italy
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Antonio Marcheselli
Phenomenal Film Handler
Posts: 1260
From: Florence, Italy
Registered: Mar 2000
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posted 07-26-2002 08:41 AM
Gordon,It isn't what I meant! Both my example are cutting on 60Hz. I wonder if It is better to cut up to have 60Hz = 50Hz or to have 60Hz = 40Hz. This is my Home SW, but one of our theater has +/- the same response (4645C) but with less resonance on 60. Will be better to cut just the 60Hz or the entire 50-70 Hz band? Bye
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Antonio Marcheselli
Florence, Italy
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Antonio Marcheselli
Phenomenal Film Handler
Posts: 1260
From: Florence, Italy
Registered: Mar 2000
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posted 07-26-2002 01:52 PM
Steve,Was SpectraLAB, is it different from spectraplus? Uhm... You're right. Who equalize should know what the speaker can do before equalize. Let's suppose that that graph are about a 4645C sub (without B6). Since 4645C has a flat response up to 35 Hz, means that is not flat up to 35Hz is a room resonance, right? Bye
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Antonio Marcheselli
Florence, Italy
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Oliver Pasch
Film Handler
Posts: 53
From: Europe
Registered: Jun 2002
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posted 07-29-2002 10:35 AM
Hi Antonio,i would always recommend to do as less equalizing on the sub as you can. Answering your question, please don't even try to cut the 60 Hz down to the 40 Hz level, although i believe that you won't be able to have a - 18 dB cut with a regular cinema-processor. What you see on your RTA will mostly be a resonance peak caused by the room-acoustics and not the first audible wave coming from the cabinet. You should firstly go and listen to it, probably using the DOLBY Jiffy-Testfilm, and maybe after that you don't want to equalize anything at all. We use a lot of JBL 4645 down here and from my experience they sound best without any EQing at all. By the way: where and HOW do you put your microphone in the auditorium and what kind of floor is there? Wood? Kind regards
from sunny Germany Oliver
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Antonio Marcheselli
Phenomenal Film Handler
Posts: 1260
From: Florence, Italy
Registered: Mar 2000
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posted 07-29-2002 02:01 PM
Oliver,That graph is not about a 4645B, it is my canton AS25 (HT sub) but our 4x4645B in one of our theater has approx. the same response. Our tech cut gently at 60hz, -4dB. But since that speaker are flat up to 35, I wonder if we can try to cut up to the same level of 40Hz... The floor of the theater is in linoleum. Bye
Antonio
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David Baum
Film Handler
Posts: 90
From: Brussels, Belgium
Registered: Aug 2000
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posted 08-03-2002 05:07 AM
the 4645C sound best not equalized ? ok, they have pretty natural flat response down to 25hz or (from 100hz) but still, they need some EQ. the SF3 module with the QSC DCA amps is one good solution to high pass at 20 or 25 and boost at 25-30hz. But EQ to try to make sound 1 or 2 4645C like 6 or 8 is wrong if that's the target: first, enough subs, stacked, enough power (800-1500Watts, real watts that is), high pass at 20 or 25hz depending on the power used, then EQ to flatten things out.
I use 2 4645C in my HC with a Berhinger parametric EQ and the power amp high pass at 18hz, 18db per octave (it's a small amp for now, 2x250 at 4ohms, AB, cooled). Next will be a QSC DCA 2422 or 3422 with SF3.
Well that does not answer the question  but this chart looks pretty awful, in terms frequency response!
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