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Multiple Small Subs - Geddes Approach
Multiple Small Subs - Geddes Approach
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Old 18th May 2016, 12:21 AM   #1841
gedlee is offline gedlee  United States
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Originally Posted by Mindsource View Post
Thanks for the explanation Dr. Geddes and for the clarification Joe.
That was so stupid of me! The poster was Matt, not Joe. Too much Vicodin!
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Old 18th May 2016, 12:25 AM   #1842
gedlee is offline gedlee  United States
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I'm curious, people have talked about failed attempts at multiple subs, issues of localization. At first I assumed the subs were not blended properly. But now I wonder this. Is it possible that although the subs are exiting modes equally that because of their placement in room that they are exciting resonances of structure, furniture, etc unevenly?
Someone will always fail at any suggestion.

Structural excitement should always be small, otherwise all bets are off.
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I think of when you mention a sub is only necessary in one of the two front corners, modally you've proved this, but what if the sub is localizable because of some resonance in the corner, and if placing a sub in each corner alleviates this?

I don't know much and I'm pulling this out of my imagination, but let me know if I'm on to something please.
Yea, I don't see this as likely. Could happen I suppose, but it would be rare.
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Old 18th May 2016, 12:30 AM   #1843
gedlee is offline gedlee  United States
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Hi MATT!

My money is on this:
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Finally it could be that it's a an effect in their head, they want to believe it's a worse approach and their skepticism is creating made up ideas.
I setup my LFs in the steady state. In that case phase doesn't really have any meaning, since it is tied to the frequency response via being minimum phase. Hence, get the amplitude right and the phase will be right. A phase delay of 90 degrees at 50 Hz is about 1 ms. we can't resolve that kind of phase at those frequencies.
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Old 18th May 2016, 01:18 AM   #1844
pjpoes is offline pjpoes  United States
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Originally Posted by gedlee View Post
Hi MATT!

My money is on this:


I setup my LFs in the steady state. In that case phase doesn't really have any meaning, since it is tied to the frequency response via being minimum phase. Hence, get the amplitude right and the phase will be right. A phase delay of 90 degrees at 50 Hz is about 1 ms. we can't resolve that kind of phase at those frequencies.
Alright Alright, I guess that makes perfect sense and I should just leave those poor guys alone who use frequency optimization to get the subs aligned.
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Old 18th May 2016, 01:23 AM   #1845
pjpoes is offline pjpoes  United States
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Oh and yes, my name IS Matt. I can't be that upset, for some reason half of the federal employees I consult for call me Mike. My name isn't Mike, nobody ever introduced me as Mike, the only thing that name has in common is the number of letters and first letter, yet it persists. My middle name is Joe I guess, we can go with that if you like!

As for your agreement that people just don't want to believe, I've seen some really strong evidence of that bias too. I saw someone who took ONE measurement at ONE location after connecting four subs and doing a little bit of optimization. There was a raised area in the response. Not even a rough or peaky response, just that instead of being flat, it had a very broad bump around 80hz. They showed that as proof the method didn't work. I took one look and thought, that looks like a really easy bump to eq out (and in fact, some adjustments of the phase and volume might have helped, who knows, it was very low Q). To me it provided direct evidence of just how well it worked. My guess is if they bothered to take 4 or 5 more measurements at other locations, they would see just how much smoother the bass is at other frequencies.
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Old 3rd February 2017, 01:12 PM   #1846
nugat is offline nugat  Europe
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Originally Posted by gedlee View Post

Why is Audio so sexist? I don't understand.
When a man's hearing fails, he pricks up his ... ears.
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Old 11th June 2018, 11:16 AM   #1847
darkmatter is offline darkmatter  United Kingdom
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An interesting thread which I will be going through.

Likely I will be subscribing to this approach with 4 subs
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