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Old 9th February 2010, 06:20 PM   #31
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Quote:
Originally Posted by MartinQ View Post
These two measurements look very close to each other to me.
Me too. The LMS plot was done with a Titan48 that had the extended frequency throat mod. So the two cabs are different.
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Old 9th February 2010, 06:31 PM   #32
MartinQ is offline MartinQ  Canada
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Quote:
Originally Posted by davygrvy View Post
Me too. The LMS plot was done with a Titan48 that had the extended frequency throat mod. So the two cabs are different.
Thanks for that added info davygrvy. There is definitely a difference between the two plots but not as significant as it would first appear. To better illustrate this I've cropped and combined the two graphs to approximate the x & y scales.
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Old 9th February 2010, 06:57 PM   #33
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Davy: "Yes, see Danley's graph I posted. He hits 50%..."

Thanks Davy! I stand corrected.
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Old 9th February 2010, 08:18 PM   #34
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Is that the same efficiency peak as found in HR?(below) Or are you saying Danley claims a broadband efficiency of some sort.

28.28v/100w
Click the image to open in full size.Click the image to open in full size.
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Old 9th February 2010, 08:31 PM   #35
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So I found Danley's spl graph and tried it in the sim 100w total into 4 cabs wired series parallel

Click the image to open in full size.

It looks like there is coupling of the TH's
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Old 10th February 2010, 03:50 AM   #36
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Even simple direct radiators may reach 25% in multiples.
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Old 15th March 2012, 11:24 PM   #37
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The thing behind this is the following. In order to get 3 dB more out of a loudspeaker, you need to double the power input. However, two coincident sound sources of similar strength combine to produce 6 dB more as compared to a single one. So, that is 3 dB more for the same increase in wattage. In other words, efficiency doubles. For another doubling in efficiency, you need to double the number of speakers again, so you need four. Start with a 5 % efficient speaker, and a combination of two will be 10%, four 20% and eight 40% efficient. This is only theoretically possible.

'Coincident' requires not only that the sound sources are aligned in time, but also that they emanate from the same point in space. Since this is not possible with real speakers, this latter requirement can only be approximated for wavelengths that are large compared to the size of the stack.
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Old 16th March 2012, 01:04 AM   #38
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A 7" wide LF source fed by multiple drivers for high efficiency.

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Old 16th March 2012, 06:51 PM   #39
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Quote:
Originally Posted by soundhead View Post
So is there any bass horn that can go up against the lab horn. Box per box
Box per box?
No size restrictions?
A bigger FLH box plays louder, the 12Pi is 32.8 cubic feet and can do 131dB at 35 Hz using the same Lab 12 drivers it will be slightly louder than the smaller 26.4 cube Labsub.

Relax your size restrictions even more, and a 100 cubic foot horn driven by just two Lab 12s will get flat response from 38-100Hz at 140dB without exceeding Xmax!

As far as output per driver, FLH generally are the winner, TH are a close second, BP, third, BR forth.

As far as output per enclosed space, the order reverses, so if the question is "how much SPL output can fit in X space", rather than "how much SPL output is possible from driver X", the answer is different.

That said, by relaxing LF requirements by 5 Hz, yesterday messing with Hornresp found one can get 126 dB at 40 Hz rising to 129 dB at 100Hz from a single Lab 12 in a small (7.76 cubic foot) FLH box.

When the conversion from dual BR to single FLH is done, I'll post the results.
This box is smaller than the SS15, nearly as loud, goes way lower, and uses a speaker that costs less.
Will be laying it out later today, it should only use close to one 4x8 foot sheet of plywood.

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Old 16th March 2012, 07:47 PM   #40
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Dam this thread is still alive.

Ok Art I will stay tune
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