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Old 10th February 2015, 11:46 AM   #1
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Default Box design for this driver

I have 4 drivers Beyma 18P1000 (fe)
And would like to know your opinion about recomended box designs where to suit them.

We are about to build some boxes and would like to have opinions about recomended box designs.

Do you think they suit on G-SUB design? http://www.speakerplans.com/index.php?id=gsub
Also have seen USBBASSBIN which seem way more dificult to construct.

Any other options?
Does 18P1000 suits better in BassReflex or what kind of desing?

You can check the Thielle small parameters of our driver here:
http://beyma.com/getpdf.php?pid=18P1000Fe

Vas: 163.2 liters
Qts: 0,39
fs: 40hz

Last edited by Arnau Pro Audio; 10th February 2015 at 12:34 PM.
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Old 11th February 2015, 03:10 AM   #2
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Based on published specs, the G-sub should work fine.

GM
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Old 11th February 2015, 05:44 PM   #3
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I'd probably build a bunch of half-G-subs.

That way, you've got four 1x18" cabinets rather than two double-18"s.
More smaller cabinets means more options for arraying them, or taking a smaller number to smaller gigs.
Downside is slightly more weight/size/cost, but these are very nice drivers and would be worth the effort.

Chris
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Old 11th February 2015, 09:33 PM   #4
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thanks for the responses GM and Chris661.

About buliding 1x18 cabinets i think we will be ok with double-18"s because they are for a fixed install.

Any advices about the litters of the enclosure?
I'm fighting with WinISD but can't say if the results are correct here you can see the prediction of the enclosure volume with two drivers Beyma18p1000 in a Vented box.


Here u can see the prediction: Click the image to open in full size.

With a Vas of 163 liters for each of the two drivers is ok only 144 liters of enclosure? I think that should be 144 litters for each driver dont you think?

Last edited by Arnau Pro Audio; 11th February 2015 at 09:48 PM.
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Old 11th February 2015, 10:10 PM   #5
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Yes just remade it and its 288.20 Liters of enclosure for two beyma 18P1000.
Seems a correct number dont you think?


For example we can build a GSUB
of 95cm x 55cm x 55cm which will give us 287.3 Liters.

What do you think? Someone can mesure it with WinISD too?

Last edited by Arnau Pro Audio; 11th February 2015 at 10:18 PM.
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Old 11th February 2015, 11:11 PM   #6
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I ran the numbers thru the WinISD simulator & got some not so impressive numbers.
First off, the Fs is kinda high at 40 hertz...especially considering it is an Eighteen.
Staying with the Twin driver concept, I get 291.9 liters of volume, but an Fb of only 41.41 hertz. That 300 or so liters, I was expecting that...for a bottom end performance of -3.07 Db at 41.07 hertz.
This is for home use? It's very much like industrial or car driver performance. The statement of 52mm worth of cone travel until mechanical damage occurs is nothing to brag about nor even worth mentioning...unless your the type who will drive it with a KaJillion Watts of power & video the driver cone trying to jump out of its basket.

Retuning for that extra bottom end, I get 600 liters, an Fb of 37 hertz, a final performance of -3.15 Db at 33.16 hertz. The program gets a little confused with 1000 Watts of power as it is asking for a port of 300mm in diameter & 34mm long....trying to keep the Mach numbers down.




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Last edited by Richard Ellis; 11th February 2015 at 11:26 PM.
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Old 12th February 2015, 05:52 AM   #7
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Quote:
Originally Posted by Arnau Pro Audio View Post
For example we can build a GSUB
of 95cm x 55cm x 55cm which will give us 287.3 Liters.

What do you think? Someone can mesure it with WinISD too?
FWIW, I estimated the G-sub at ~330 L tuned to 40 Hz, which is good enough for dual drivers or half that for a single driver assuming the published specs are reasonably accurate and even with its ~Fs tuning its already Xmax limited to ~300 W driver, so going lower will of course mean a larger cab with less peak output.

Note that Vas calculates a bit higher at 166.24 L plus series resistance will be somewhat higher than WinISD's default 0.1 ohm, so will make even the ~330 L cab a little smaller than the 400 L I would recommend/use.

GM
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Old 12th February 2015, 10:08 AM   #8
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Do you recomend make a bigger enclosure than the 290/330 litters you said?
What are the advantages and disadvantages of making a bigger one? Lower Fs but less peak output?

And another question is: When deciding the Liters of the enclosure should be counted the volume displaced by the driver inside the enclosure? Plus the wood refoces and vented port? In example:

300liters + (13liters displaced by driver x2) + 5 liters wood reforces =331 liters total of the enclosure?
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Old 12th February 2015, 02:33 PM   #9
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Yes, that's what I wrote because:

1] actual driver specs are usually off enough to dictate a slightly larger cab than the basic T/S math calculates

2] there's normally more voltage drop [series resistance] in the speaker wiring than what a design program uses unless the amp is very near/in the speaker, which raises the driver's effective Qts

3] for any app where the speakers will be driven at > 1/4 - 1/3 their continuous power rating and/or 'asked' to reproduce high power transients, which causes thermal power compression due to VC heating and in turn increases the driver's effective Qts

Add all this up and in a typical prosound app the cab size could triple and need to be heavily damped and why cabs were so large long ago, but cost/space is a major consideration, so with the advent of high power handling drivers and digital EQ, cabs are normally designed with power handling in mind [mild to severely under-damped under load] and EQ'd as required.

The ~ 330 L is the net figure I quickly estimated for the G-sub, i.e. the net volume [Vb] the drivers will ‘feel’, ditto the 400 L net I recommend based on what little I know about the driver specs, driver power limits and the performance requirements of your app.

If you want to EQ the smallest practical cab and accept that the driver’s service life will likely be shorter, then allow ~115.44 L net/driver tuned to ~40 Hz based on published specs and assuming they don’t need to go any lower.

GM
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Last edited by GM; 12th February 2015 at 02:57 PM.
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Old 12th February 2015, 02:40 PM   #10
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Quote:
Originally Posted by Richard Ellis View Post
I ran the numbers thru the WinISD simulator & got some not so impressive numbers.
First off, the Fs is kinda high at 40 hertz...especially considering it is an Eighteen.
Staying with the Twin driver concept, I get 291.9 liters of volume, but an Fb of only 41.41 hertz. That 300 or so liters, I was expecting that...for a bottom end performance of -3.07 Db at 41.07 hertz.
This is for home use? It's very much like industrial or car driver performance. The statement of 52mm worth of cone travel until mechanical damage occurs is nothing to brag about nor even worth mentioning...unless your the type who will drive it with a KaJillion Watts of power & video the driver cone trying to jump out of its basket.

Retuning for that extra bottom end, I get 600 liters, an Fb of 37 hertz, a final performance of -3.15 Db at 33.16 hertz. The program gets a little confused with 1000 Watts of power as it is asking for a port of 300mm in diameter & 34mm long....trying to keep the Mach numbers down.




________________________________________________Ri ck..........
Its a PA driver - craploads of output to 35Hz, and then nothing below. I've some 15"s from the same line, and they will do 50mm p/p, though HD is rising fast past ~35mm p/p.

Not for bragging, just getting a lot of sound out of a given box.

Chris
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