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#254022 - 03/27/09 10:46 PM Some new graph fun at the Plex.
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13565
Loc: Iowa
Well, I'm at it again. This time I'm attempting a multi sub setup by Dr Earl Geddes. It is similar to Toole's and Welti's papers in some respects, however, it uses more of a random placement for the subs, versus midwall positions.

http://www.mehlau.net/audio/multisub_geddes/

http://www.gedlee.com/

I don't have all the fancy equipment required, but have found this free program that seems to work well.

http://www.pensa.fr/freqresplot/indexe.htm

Below are some graphs, the first one just my EP600 alone, followed by my twin 350's added. I'm pretty much getting similar results in all 5 seats, so only posting the primary seat.

Not to bad as you can see I'm under a 5dB difference across the frequency range. This graph was done in 1hz increment steps, not some 1/3rd octave type test.


600 only up front left corner


600 up front, one 350 on left side wall about 3/4 back, and the other 350 to the right side of the room.


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M80s-VP180-4xM22ow-4xM3ic-EP600-2xEP350
Anthem AVM60 Outlaw 7700 Emotiva A500 Epson 5040UB



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#254073 - 03/28/09 12:11 PM Re: Some new graph fun at the Plex. [Re: SirQuack]
michael_d Offline
connoisseur

Registered: 07/23/04
Posts: 4191
Loc: Up yonder
So... If I'm understanding these graphs, the addition of the 350's got rid of the 40 hz dip, or just pushed it to 50 hz a wee bit?
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#254080 - 03/28/09 12:27 PM Re: Some new graph fun at the Plex. [Re: michael_d]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13565
Loc: Iowa
yep, not a lot of difference. I'm still messing around with placement and settings. Takes a long time to add each sub in, play around with phase, delay, crossover, etc. In reality, I've heard that if your within 5-10dB's across the frequency range, it is pretty good. If you look at my highest point, and my lowest dip, I'm probably within a 5dB difference.

From what I can tell looking at these graphs:
From 20-25ish there is not much difference.
From about 30-50 everything is seems tighter on the scale.
I create a little dip at about 53, but improved the peak at 56.

that is the thing with doing this, you improve some things, but might change other things.

I just recall back when I was using the Real Traps manually graphing, I had a 10dB swing, so seems with playing around with placement I've helped things.
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M80s-VP180-4xM22ow-4xM3ic-EP600-2xEP350
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#254114 - 03/28/09 04:25 PM Re: Some new graph fun at the Plex. [Re: SirQuack]
grunt Offline
connoisseur

Registered: 12/04/06
Posts: 3569
Loc: Nirvana
Thanks for sharing all the research and experimentation you’ve been doing on this for so long. It’s especially helpful to me since I’ve been bass constrained living in an apartment and all (next week I move).

http://www.mehlau.net/audio/multisub_geddes/

 Originally Posted By: Earl Geddes

Make sure that the main loudspeakers are not high pass filtered as they act as additional low frequency sources. The more the better.


So why do I get crap from some people for saying I run my M80s large because it gives me a flatter frequency response and most importantly sounds better to me? The best thing about the quote from the link you posted is it helps fill in part of an equation I was working on:

Jakewash’s amp thread + sirquack’s multiple sub thread = grunt need an A1400-8. (to drive the M80s full range)

Cheers,
Dean
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3M80 2M22 6QS8 2M2 1EP500 Sony BDP-S590 Panny-7000 Onkyo-3007 Carada-134 Xbox Buttkicker AS-EQ1

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#254115 - 03/28/09 04:29 PM Re: Some new graph fun at the Plex. [Re: grunt]
CV Offline
Founder, Axiom Upgrade Club
shareholder in the making

Registered: 07/20/06
Posts: 11675
Loc: Richland, WA, USA
 Originally Posted By: grunt
Jakewash’s amp thread + sirquack’s multiple sub thread = grunt need an A1400-8. (to drive the M80s full range)


What? The house didn't come with an A1400-8? That's bullcrap!

Are you seriously thinking you'll get one?

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#254116 - 03/28/09 04:33 PM Re: Some new graph fun at the Plex. [Re: grunt]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13565
Loc: Iowa
Yeah Dean, that is one thing I noticed between the Geed/Lee approach and others is he used mains that have big drivers full range, and then tweaks the crossovers/levels/etc. on the subs to fill in the gaps. So, one sub, the main one up front covers the main loww freq's, another one might cover the mid-low range, etc..

For me, I've decided this method is to time consuming. I do have my subs spaced out around the room, kinda randomly like he suggests.

My EP600 is now dead center below the screen in the horizontal position like when I first purchased it. One of my 350's is along the left wall about 3/4th of the way back, and the other one is to the right side near my computer desk/AV rack. All subs are individually calibrated to about 75dB's to match the other speakers, and then when all turned on, the combined levels is about 3-4 dB's higher, which seems to work nicely.

I have found that if I turn my 80's on large, my graph gets HUGE Peaks and Dips, and the frequency is not near as flat. So, I have all speakers to small and the crossover on 80hz.

Some day when I get a different receiver, I may bump the 80's to say 60hz, but still leave them at small.
_________________________
M80s-VP180-4xM22ow-4xM3ic-EP600-2xEP350
Anthem AVM60 Outlaw 7700 Emotiva A500 Epson 5040UB



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#254132 - 03/28/09 05:20 PM Re: Some new graph fun at the Plex. [Re: CV]
grunt Offline
connoisseur

Registered: 12/04/06
Posts: 3569
Loc: Nirvana
 Originally Posted By: CV

Are you seriously thinking you'll get one?


Short answer is yes. Long answer is over in jakewash’s thread so as not to hijack Randy’s.

http://www.axiomaudio.com/boards/ubbthreads.php?ubb=showflat&Number=254130#Post254130

Cheers,
Dean
_________________________
3M80 2M22 6QS8 2M2 1EP500 Sony BDP-S590 Panny-7000 Onkyo-3007 Carada-134 Xbox Buttkicker AS-EQ1

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#254138 - 03/28/09 05:34 PM Re: Some new graph fun at the Plex. [Re: SirQuack]
grunt Offline
connoisseur

Registered: 12/04/06
Posts: 3569
Loc: Nirvana
 Originally Posted By: sirquack

Yeah Dean, that is one thing I noticed between the Geed/Lee approach and others is he used mains that have big drivers full range, and then tweaks the crossovers/levels/etc. on the subs to fill in the gaps. So, one sub, the main one up front covers the main loww freq's, another one might cover the mid-low range, etc

Thanks again Randy, I’ll have to read up on the relative merits of the various approaches. I’m trying to stay focused on projectors, screens and room acoustics and not fly off on some tangent as I’m so prone to doing.

 Quote:

For me, I've decided this method is to time consuming. I do have my subs spaced out around the room, kinda randomly like he suggests.

For me it’s consuming just the right time…yours. ;\) Seriously, thanks for taking the time to share all this. It’s one less thing I have to go out and start researching from the beginning myself.

 Quote:

I have found that if I turn my 80's on large, my graph gets HUGE Peaks and Dips, and the frequency is not near as flat. So, I have all speakers to small and the crossover on 80hz

The room I had was a square so I imagine any other sources would help smooth things out. Now watch in my new room (rectangular) I will get the same results as you have.

 Quote:

Some day when I get a different receiver, I may bump the 80's to say 60hz, but still leave them at small.

I intend to do a lot of experimenting in my new room especially if I get a good amp.

Cheers,
Dean
_________________________
3M80 2M22 6QS8 2M2 1EP500 Sony BDP-S590 Panny-7000 Onkyo-3007 Carada-134 Xbox Buttkicker AS-EQ1

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#254951 - 04/01/09 06:12 PM Re: Some new graph fun at the Plex. [Re: grunt]
bridgman Offline
axiomite

Registered: 08/25/04
Posts: 6026
Loc: Bowmanville, Ontario, Canada
>>Well, I'm at it again. This time I'm attempting a multi sub setup by Dr Earl Geddes. It is similar to Toole's and Welti's papers in some respects, however, it uses more of a random placement for the subs, versus midwall positions.

Nice. I guess the next step is to start plotting response at different points in the room on the same chart. My guess is that you'll see more benefit from multiple subs there than you will in a single response plot.

>>http://www.gedlee.com/

Maybe it's just because I live in Toronto, but when I saw that URL my first thought was "cool, Geddy Lee is into multi-sub setups as well, makes sense" ;\)



Edited by bridgman (04/01/09 06:12 PM)
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John

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#254955 - 04/01/09 06:36 PM Re: Some new graph fun at the Plex. [Re: bridgman]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13565
Loc: Iowa
Yep John, I actually did plot before (1 sub) and after (3 subs) graphs from each seat in my room, to my amazement, there was not a lot of difference between all seats. The graphs did have a different pattern to them, but I was still within a 5-6 dB range in all seats.
_________________________
M80s-VP180-4xM22ow-4xM3ic-EP600-2xEP350
Anthem AVM60 Outlaw 7700 Emotiva A500 Epson 5040UB



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