EQing Multiple Subs (per Harmon White Paper) - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 9 Old 04-07-2008, 10:33 AM - Thread Starter
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Good Afternoon,

Per slide #25 of the Harmon White Paper (http://www.harman.com/wp/pdf/multsubs.pdf), the optimal placement of subs shows one approach having two subs and two approaches having four subs. I'm looking at the placement consisting of one sub (Maelstrom-X) located in each of the four corners. My question pertains to EQ. Are the subs EQ'd in sum' from the listening position, or is each sub EQ'd individually to the listening position then subsequently the overall level is set?

Btw - My initial approach was going to be something similar to KG's implementation of four units across the front of the room.

Regards,

Larry
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post #2 of 9 Old 04-08-2008, 06:16 AM - Thread Starter
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Wrong forum?
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post #3 of 9 Old 04-08-2008, 03:53 PM
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Larry, I would think that equalizing all four simultaneously from the listening position. I'm running three sealed 12's in a smaller room [two corners and one wall] and don't equalize anything. You might find that by having four, the room is such that you won't need any.

Warmon -
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post #4 of 9 Old 04-08-2008, 03:58 PM
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Warmon is right, with one sub in each corner, little or no EQ is needed, you have to decide if you want colocated subs or mutually coupled subs, its up to you, I'd think that 4 Maelstroms would be able to handle colocation well, but it'd be best to try both ways out.
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post #5 of 9 Old 04-08-2008, 05:02 PM
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It's my understanding they're eq'd in sum.

The point of the positioning in the article, for those who haven't read it, is to find the most uniform FR over a listening area, they weren't looking for the smoothest. If it's uniform, eq will have the same effect over the area, unlike positioning for a specific 'sweet spot".

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post #6 of 9 Old 04-08-2008, 07:06 PM - Thread Starter
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Thanks Jack,

This seems like a logical assessment.

Larry

Quote:
Originally Posted by Jack Gilvey View Post

It's my understanding they're eq'd in sum.

The point of the positioning in the article, for those who haven't read it, is to find the most uniform FR over a listening area, they weren't looking for the smoothest. If it's uniform, eq will have the same effect over the area, unlike positioning for a specific 'sweet spot".

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post #7 of 9 Old 04-08-2008, 11:52 PM
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"Warmon is right, with one sub in each corner, little or no EQ is needed"

Corner placement gives the most output but not the smoothest response.

The mide-side/opposite wall setups give the smoothest response, with the noteworthy attribute of nullifying the odd-order modes.

The paper points out that the results assume EQ is used.

Noah
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post #8 of 9 Old 04-09-2008, 05:26 AM
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Here's my four sub response - located at the 1/3 and 2/3 position on the front and rear wall as integrated with the center speaker at 80Hz xover (top graph).

I compared this to the output of my center channel speaker alone below (which has a rolloff at 50hz - bottom graph).

All measurements at listening position.




The subs is designed with the 20Hz boost seen - I intent to EQ this to taste.

db
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post #9 of 9 Old 04-09-2008, 06:26 AM
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Quote:
Originally Posted by noah katz View Post

The paper points out that the results assume EQ is used.

The paper is based on this assumption. I think most are just looking at the graphs and assuming they're trying to optimize FR flatness, but they're not. They try to find positions that result in uniform FR across an area, not the flattest. Optimizing positioning for unassisted/un-eq'd flat response tends to limit the response to a small spot, while the paper aims for a consistent response across a wide area, the flatness being taken care of by eq.

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