Earl Geddes On Bass live on 1/19/2013 (Video) - AVS Forum
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Old 01-25-2013, 10:32 AM - Thread Starter
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Earl Geddes On Bass live on 1/19/2013 (Video)

http://www.ustream.tv/recorded/28637776

Click the shortcut to "Earl Geddes on multiple subwoofers"

or skip 1:30 into the recording.

Also see this thread that is based on the same event

http://www.avsforum.com/t/1453585/earl-geddes-on-bass-and-subwoofers-1-19-2013#post_22869090
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Old 01-25-2013, 12:51 PM
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I'm only half way through, but Earl says that bass traps don't work at all...?? Wuzzup wit dat?

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Old 01-25-2013, 02:50 PM
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Originally Posted by Alan P View Post

I'm only half way through, but Earl says that bass traps don't work at all...?? Wuzzup wit dat?
I haven't looked at it, but even without doing so, he's right, sort of. Most products marketed as bass traps actually damp midbass reflections. That's OK, as what most people call 'boomy bass' is actually excess midbass. FWIW, if you used enough damping material on a wall to have any real effect below 60Hz or so there probably wouldn't be any room left over to sit down.

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Old 01-25-2013, 03:22 PM
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He talks about constructive damping built into the room, twin Sheetrock walls with a damping layer in between, and absorptive springs behind being one example, as being the only way to add "good LF damping" into a room. I always assumed my carpet was doing an ok job of LF damping but I guess that was naive.

He also mentions things like room gain doesn't exist. Corner loading doesn't actually add extra output in the LF, we all hear that boundary loading can give extra "free output", Geddes mentions it excites room modes and it does add energy above the "modal region", which I assume is around 300hz and below, so it just seems like we get extra output in the LF range. Just an interesting point.
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Old 01-25-2013, 03:51 PM
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Originally Posted by hermeslyre View Post

He talks about constructive damping built into the room, twin Sheetrock walls with a damping layer in between, and absorptive springs behind being one example, as being the only way to add "good LF damping" into a room.
Those are examples of how you reduce bleed-through, not how you damp the room. It would be interesting to see him and Ethan Winer debate the issue.
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He also mentions things like room gain doesn't exist.
Tell that to the guys who've measured it, like me, though there are dozens more over in our own DIY section, let alone engineers going back to at least Paul Klipsch and Harry Olson.
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Corner loading doesn't actually add extra output in the LF
It's not a matter of adding extra output, it's a matter of eliminating destructive reflections that occur when a boundary is 1/4 wavelength or more distant, though the net result is the same.
One thing about Earl is that his pronouncements never stray far from what he's marketing. I wouldn't say that he tries to break the laws of acoustics when it suits him if it will sell more of his products, but he has been known to bend them.

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Old 01-25-2013, 05:30 PM
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He's only talking about small rooms. ~12' across. The first 10 minutes are technical difficulty.

He is also talking ONLY about nuetral bass
I haven't watched the whole thing yet - but he has these disclaimers up front.

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Old 01-25-2013, 06:05 PM
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If i am not mistaken, his subs are bandpass design with 40Hz LF cut off. They indeed may have to be put in a car for appreciable cabin gain.
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Old 01-25-2013, 06:25 PM
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Wayne Parham has posted about the presentation on the ART forum

http://audioroundtable.com/forum/index.php?t=msg&th=17930&prevloaded=1&&start=10#msg_num_9

It's kind of funny to watch the two continue the old argument, though not face-to-face any more. I am fairly sure Dr. Geddes had Wayne and his flanking subs meme in mind when he dismissed any need for modal smoothing above 100Hz
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