Traps vs Equalizers vs Placement? - Page 8 - Home Theater Forum and Systems - HomeTheaterShack.com

Old 12-15-09, 10:55 AM
Elite Shackster

Greg

Join Date: Nov 2007
Location: NY
Posts: 2,601
Re: Traps vs Equalizers vs Placement?

Quote:
Lonely Raven wrote: View Post
I love when Bryan gets set loose on threads like this...I learn so much just reading his responses to other peoples questions.

Thanks Bryan!
Agreed. Sometimes I have to remind myself to just shut up and let him teach me!

-Greg

Don't worry... nothing new here, I've already made that mistake. Trust me.
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Old 12-15-09, 01:29 PM Thread Starter
Senior Shackster
Bob

Join Date: Sep 2008
Location: Oregon
Posts: 152
Re: Traps vs Equalizers vs Placement?

Here is some data. To see the room itself, go to the first page of the thread. The speakers and sub are drawn in.
Here is a sketch of the room, the calculated room modes, and the modes to the listening position.
Next I will post some recent experiments with adding the sub and changing the cross-over.
Attached Thumbnails

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Old 12-15-09, 02:24 PM Thread Starter
Senior Shackster
Bob

Join Date: Sep 2008
Location: Oregon
Posts: 152
Re: Traps vs Equalizers vs Placement?

I like your idea of finding a good spot for the sub before adding in the speakers. However, before I read that I tried a couple of runs by just adjusting volume at a given "roll-off frequency" (the REL manual does not call it cross-over). Apparently the frequency of nulls is strongly dependent on volume! I didn't expect that! I am thinking it is time for a multi-variate analysis rather than one variable at a time. Adjust the sub position, roll-off frequency, and volume in a matrix. The problem is what to measure? A mathematical sum of the null peaks?

black is 32Hz vol4, red is 32Hz vol5, blue is 32Hz vol6

PS: what is the difference between cross-over and roll-off?
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Last edited by hrpschrd; 12-15-09 at 06:06 PM.
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Old 12-15-09, 02:44 PM Thread Starter
Senior Shackster
Bob

Join Date: Sep 2008
Location: Oregon
Posts: 152
Re: Traps vs Equalizers vs Placement?

And here are the rest of those trials with the sub. Seems a lower roll-off reduces the severe nulls. (I still want a room curve that has a little stronger bass in the <80Hz region.)

purple = 28Hz vol6
green = 25Hz vol6
red = 25Hz vol 7
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Last edited by hrpschrd; 12-15-09 at 06:02 PM.
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Old 12-15-09, 02:53 PM
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brucek

Join Date: Apr 2006
Posts: 7,514
Re: Traps vs Equalizers vs Placement?

Quote:
And here are the rest of those trials with the sub
It's somewhat difficult for most people to get a feel for the graphs when you continue to post them with LIN (linear) axis. Would it be possible to use the LOG (logarithmic) axis.

brucek
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Old 12-15-09, 02:58 PM Thread Starter
Senior Shackster
Bob

Join Date: Sep 2008
Location: Oregon
Posts: 152
Re: Traps vs Equalizers vs Placement?

Aack! I didn't notice. I am just saving the graphs from REW by clicking on the disk icon at the bottom left. I don't see a menu that gives me a choice of linear or log. What am I doing wrong and I will fix them all.
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Old 12-15-09, 04:35 PM
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brucek

Join Date: Apr 2006
Posts: 7,514
Re: Traps vs Equalizers vs Placement?

The FreqAxis button is in the top right corner of REW. It toggles between LOG and LIN.

brucek
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Old 12-15-09, 05:56 PM Thread Starter
Senior Shackster
Bob

Join Date: Sep 2008
Location: Oregon
Posts: 152
Re: Traps vs Equalizers vs Placement?

I knew that but I guess I've just been careless. I'll fix them, thanks.
hrpschrd is offline
Old 12-15-09, 08:18 PM
Senior Shackster

Jerry

Join Date: Dec 2009
Location: Tampa, FL
Posts: 267
Re: Traps vs Equalizers vs Placement?

This continues to be a very enlightening thread for me. Accoustic treatments is still something I'm very much a neophyte at. Thank you all for all of this wonderful information.

Jerry
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Old 12-15-09, 08:30 PM
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Bryan Pape

Join Date: Sep 2006
Location: Wildwood, MO (St. Loui
Posts: 5,209
Re: Traps vs Equalizers vs Placement?

Something is very wrong. Changing the volume (gain) of the sub should do absolutely nothing in terms of shifting nulls if frequency response. Are you sure you're not adjusting phase instead?

Bryan

I am serious... and don't call me Shirley.

Bryan Pape
GIK Acoustics
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