Cedar Creek Cinema - Page 7 - Home Theater Forum and Systems - HomeTheaterShack.com

Old 08-08-09, 11:13 PM
Elite Shackster

Steve

Join Date: Apr 2006
Posts: 2,398
Re: Cedar Creek Cinema

The EQ will boost the input signal by 8db twice - that's different than taking two subs with the same FR and playing them at the same time.
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Old 08-09-09, 10:09 AM
Elite Shackster
brucek

Join Date: Apr 2006
Posts: 7,514
Re: Cedar Creek Cinema

Quote:
that's different than taking two subs with the same FR and playing them at the same time.
Yeah, that's true. See below.

Quote:
If sub 1 and sub 2 both have an 8db peak around 50hz, assuming no cancellations between them, the summed response would be an 8db peak around 50hz, not 16db.
I got thinking about this, and I must say I was thinking about filters when I said +8dBSPL + 8dBSPL =16dBSPL. That's not correct - my bad. When we add sound pressure you must use the logarithmic calculation. The total sound pressure level is not the algebraic sum of sound pressure levels. It would be as follows:

If I have two signals in a room playing at +75 dBSPL, then the resultant SPL level is +81.02 dBSPL (pressure result is double = +6.02dB higher).
Math is 20 log [10^(SPL1/20) + 10^(SPL2/20)].

And, if I have two signal peaks @50Hz in a room of +8 dBSPL, then the resultant peaks SPL level is +14.02 dBSPL (result is double = +6.02dB higher).
Math is the same 20 log [10^(SPL1/20) + 10^(SPL2/20)].

So both increase by 6dB.

brucek
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Old 08-09-09, 04:47 PM
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Location: Katy, Texas
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Re: Cedar Creek Cinema

Quote:
Sonnie wrote: View Post
Sorry guys... Angie and I were on a road trip yesterday to pick up yet another set of speakers.
What?? More speakers?? Well, if I recall - from where you are, it’s a “road trip” to anywhere!

Quote:
As far as the eq'ing all subs as one... I do not know the technical aspects of it, but I do know it works regardless of the location of the subs. I also know that any time I have tried (and I have tried many times) to equalize two subs independently, that while the individual responses have looked very good, once they are combined, the overall response looks awful. It has never... and I emphatically repeat "NEVER!" worked when I have tried to equalize subs independently for an overall smooth combined response. Quite frankly, I do not recall anyone ever succeeding at doing so... and it does not make sense that it can be done either.
Understood, you EQ’d all the subs as one, presumably from the sweet spot. What I’m trying to find out is, does that technique also gets decent response at the other seats as well?

Regards,
Wayne

Wayne A. Pflughaupt is online now
Old 08-09-09, 05:12 PM
Senior Shackster

Ron

Join Date: Apr 2006
Location: Dallas, Texas
Posts: 568
Re: Cedar Creek Cinema

Sonnie,

If I ever get to Alabama I need to stop by.

Dallas, Texas

Downstairs: Oak Klipschorns, LaScala (center), Cornwall (sides), Bubinga Heresy I (rear), SVS PB12-Plus/2, Outlaw 990, McIntosh MA6100, (2) MC250, MC2100, Oppo BDP-95, Toshiba HD-A2, Belkin Pure AV PF60, Behringer DSP1124P

Upstairs: McIntosh C2200, MC275 MKIV, Walnut Cornwall I, Oppo BDP-83, Technics SL-1200 M3D, Audio Technica AT150MLX, Richard Gray Power Company 400 Pro
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Old 08-09-09, 05:25 PM
Elite Shackster
brucek

Join Date: Apr 2006
Posts: 7,514
Re: Cedar Creek Cinema

Quote:
Sweet looking HT. Wow.
Yeah, I'm still shaking my head in awe about those F1 Audio 18 towers with the port tuning in the stage..... I would have liked to see more detail in the "Rise of the Eighteens" thread. It seemed to go from concept to finished in a few posts without detail pics......

brucek
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Old 08-09-09, 06:15 PM
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Location: Katy, Texas
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Re: Cedar Creek Cinema

Quote:
brucek wrote: View Post
Quote:
how does the "EQ all the subs as one" thing work
I've wondered this myself.

Scenario:

Sub #1 has an +8dB peak @50Hz at the listening position.
Sub #2 has an +8dB peak @50Hz at the listening position.
Total peak at listening position @50Hz is +16dB.
Sonnie applies a single -16dB cut and all is well.

Would it have been better to apply a more reasonable -8db cut @50 Hz to both subs?
Quote:
brucek wrote: View Post
And, if I have two signal peaks @50Hz in a room of +8 dBSPL, then the resultant peaks SPL level is +14.02 dBSPL (result is double = +6.02dB higher).
Math is the same 20 log [10^(SPL1/20) + 10^(SPL2/20)].
Nothing like a "real live" experiment; maybe this will help clear things up. My DIY sub has two drivers, each powered by an independent amplifier channel. So, I can run both drivers together, or only one at a time. Does this meet the “all things being equal” requirement? Ideal to the discussion, I have a honkin’ peak at ~42 Hz.

Here’s a graph I took today. The blue trace is both drivers running (no EQ). The red trace is one driver only. As you can see, the only thing that changes running both is overall gain. I suppose you could say the peak is “worse,” but its relation to the rest of the curve is the same.

Regards,
Wayne

Wayne A. Pflughaupt is online now
Old 08-09-09, 07:13 PM
Elite Shackster
brucek

Join Date: Apr 2006
Posts: 7,514
Re: Cedar Creek Cinema

Guess you're right - I'm not thinkin' today...........

Sorry for the hi-jack Sonnie...
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Old 08-12-09, 08:19 PM
HTS Senior Moderator

Join Date: Apr 2006
Location: Katy, Texas
Posts: 8,809
Re: Cedar Creek Cinema

So - how 'bout it, Sonnie?

Quote:
Wayne A. Pflughaupt wrote: View Post

Quote:
As far as the eq'ing all subs as one... I do not know the technical aspects of it, but I do know it works regardless of the location of the subs. I also know that any time I have tried (and I have tried many times) to equalize two subs independently, that while the individual responses have looked very good, once they are combined, the overall response looks awful. It has never... and I emphatically repeat "NEVER!" worked when I have tried to equalize subs independently for an overall smooth combined response. Quite frankly, I do not recall anyone ever succeeding at doing so... and it does not make sense that it can be done either.

Understood, you EQ’d all the subs as one, presumably from the sweet spot. What I’m trying to find out is, does that technique also gets decent response at the other seats as well?

Regards,
Wayne

Wayne A. Pflughaupt is online now
Old 08-13-09, 09:00 AM Thread Starter
HTS Hillbilly

I'm a redneck!

Join Date: Apr 2006
Location: L.A. (Lower Alabama)
Posts: 22,554
My System
Re: Cedar Creek Cinema

Quote:
brucek wrote: View Post
Yeah, I'm still shaking my head in awe about those F1 Audio 18 towers with the port tuning in the stage..... I would have liked to see more detail in the "Rise of the Eighteens" thread. It seemed to go from concept to finished in a few posts without detail pics......

brucek
Well... sorry about that. You know how it can be sometimes when you have fifty-eleven things going on at one time. I did include pics of most of the framing though. I wish I had remembered to take more.

Quote:
Wayne A. Pflughaupt wrote: View Post
Quote:
Understood, you EQ’d all the subs as one, presumably from the sweet spot. What I’m trying to find out is, does that technique also gets decent response at the other seats as well?
So - how 'bout it, Sonnie?
I know I answered this somewhere, just cannot figure out where, musta been in another thread. Anyway... the response from others seats is no better and no worse when equalizing from the main listening position than it is when equalizing from all positions. The only difference being that when you equalize from the main listening position, at least that one position is pretty much spot on... however, when you equalize from all positions, none are spot on. This may not work in every situation, but something tells me that it will probably be the case in most situations and it is what I would be recommending if I were writing the manufacturer manuals. They can say and write what they want, the the proof is in the measurements. Maybe sometime when I have extra hours available I will redo the entire comparison and save all the measurements. I probably have them saved, but I have so many, I am not sure I can decipher what is what.

Ahhh... and yes... more speakers. I swapped out my ML Spires for ML Prodigy's... I like the sound of the old style ML's better than I do the new style.

Cedar Creek Cinema

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Sonnie is offline
Old 08-20-09, 11:36 AM Thread Starter
HTS Hillbilly

I'm a redneck!

Join Date: Apr 2006
Location: L.A. (Lower Alabama)
Posts: 22,554
My System
Re: Cedar Creek Cinema

New pics...

Cedar Creek Cinema

PremierHomeAudio: Denon, Marantz, Onkyo, Yamaha, Sony, Pioneer, Def Tech and more. Shoot me a PM!
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