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Old 27th October 2013, 06:55 PM   #11
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I read that as 2Pi ie half space (infinite baffle), just as the measurements say.
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Old 27th October 2013, 08:17 PM   #12
rigtec is offline rigtec  United States
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Quote:
Originally Posted by Charles Darwin View Post
I read that as 2Pi ie half space (infinite baffle), just as the measurements say.
I see,

Guess it's possible. I interpret that as a pretty close "Omega" symbol. I've never seen PI posted in any of the other pro-audio driver manufacturers "sensitivity spec". Sometimes in the "description" of the testing procedure, they may provide that info, like with *** on the sheet somewhere. Isn't that typically measured in "full field" (non-reverb chamber) environment?

Greg (rigtec)
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Old 27th October 2013, 08:29 PM   #13
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Drivers are usually measured on an IEC baffle like this:

IEC baffle in Anechoic Chamber

But I'm sure I've seen half space measurements from manufacturers other than Beyma.

Last edited by Charles Darwin; 27th October 2013 at 08:31 PM.
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Old 27th October 2013, 08:54 PM   #14
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Originally Posted by rigtec View Post
Sometimes in the "description" of the testing procedure, they may provide that info, like with *** on the sheet somewhere. Isn't that typically measured in "full field" (non-reverb chamber) environment?
Greg,

The 18G50 does specify the measurement is taken with it on an infinite baffle in an anechoic chamber, which is the equivalent of 2 pi, half space.
It's DCR of 6.1 ohms is a bit on the low side for a nominal 8 ohm speaker, but "close enough for rock and roll".

Low frequency enclosures are often tested outdoors, as making an anechoic chamber anechoic below 100 Hz is horribly expensive and large.

The outdoor tests are usually done with the cabinet on the ground, half space, though cabinets designed for suspended usage may also include free space measurements as well.
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Old 28th October 2013, 01:58 AM   #15
rigtec is offline rigtec  United States
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To both weltersys and Charles Darwin. I do stand corrected, and offer my sincerest apologies.

Greg, (rigtec)
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Old 28th October 2013, 01:25 PM   #16
hzwart is offline hzwart  South Africa
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Thank you for the reply's. Unfortunately, I have these drivers and would like to use them in an optimum enclosure to get the best out of them.

I have plotted them in TL's and Horns as per EPA's sim. But what is the optimum enclosure that I can still handle with the response I want?

Due to the 18G50 limited power capability, I have to use them in one stack to optimise the output and keep the drivers within the limited xmax. Hence my need to look for the optimum enclosure.

Well, this is maybe to much to ask for seeing that it is always a compromise between low, small and louder?

A reflex will not do it. So can it be a Horn, TL or manifold?

The reason why I require a response from 34Hz is that I can use one enclosure per side for small venues and still get a decent sound of high quality.

Appreciate all your comments seeing that we can never stop learning.

Regards
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Old 28th October 2013, 02:43 PM   #17
bjorno is offline bjorno  Sweden
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Hi,

FYI:

b
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File Type: jpg Beyma18G50.JPG (550.3 KB, 104 views)
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Old 28th October 2013, 02:54 PM   #18
rigtec is offline rigtec  United States
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Quote:
Originally Posted by hzwart View Post

I have plotted them in TL's and Horns as per EPA's sim. But what is the optimum enclosure that I can still handle with the response I want?
Four horns arrayed in a "Block" configuration will give the highest levels per watt. Stacking the horns increases mouth size, raising the efficiency, and lowering the f3. The bass reflex alignment is next, as far as output per watt, and will likely far exceed in low frequency extension, especially when "corner loading" is implemented.

Quote:
Due to the 18G50 limited power capability, I have to use them in one stack to optimise the output and keep the drivers within the limited xmax. Hence my need to look for the optimum enclosure.
Four of these drivers will permit 3,000w RMS/6,000w program! With 9mm xmax each, you should never have a problem, as long as you use your head and watch that your amp's "clip indicator" lights don't stay on; occasional blinking should be okay.

Quote:
"...So can it be a Horn, TL or manifold?"
The TL's and the manifolds are too inefficient to consider for professional, high output (130db+) use, but may do very well in a much more "personal" environment" e.g., backyard bar-B-Q, Tailgate parties, small banquet's...

Hope that helps... "I'm trying to stay out of trouble"

rigtec, regards

Last edited by rigtec; 28th October 2013 at 02:58 PM.
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Old 28th October 2013, 03:19 PM   #19
epa is offline epa  Netherlands
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maybe a hog scoop?
Click the image to open in full size.
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Old 28th October 2013, 08:21 PM   #20
OMNIFEX is offline OMNIFEX  Jamaica
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Quote:
Originally Posted by hzwart View Post

Due to the 18G50 limited power capability, I have to use them in one stack to optimise the output and keep the drivers within the limited xmax. Hence my need to look for the optimum enclosure.

Well, this is maybe to much to ask for seeing that it is always a compromise between low, small and louder?

A reflex will not do it. So can it be a Horn, TL or manifold?

The reason why I require a response from 34Hz is that I can use one enclosure per side for small venues and still get a decent sound of high quality.

Appreciate all your comments seeing that we can never stop learning.

Regards
I hate to give you the bad news but, using one horn per side is not going to give no where near 34 Hz. I think it is time for you to punch in the TS Parameters of the Beyma 18 G50 in Horn Response and face the harsh reality.
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