Subwoofer Enclosure Tuning

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I am building a dual 18 inch sub woofer enclosure with a volume of 12.75 cu.ft
using the KAPPA PRO 18LF-8 which has a usable frequency range of 38 Hz - 0.7 kHz , a resonance of 32 Hz and it also has a recommended box tuning frequency of 40Hz but i feel 40Hz wont hit the low notes just right .what frequency should i tune the box i am building to ,32Hz, 38Hz or stick to the recommended frequency of 40Hz?

Link to the driver
Speaker Detail | Eminence Speaker

Link to enclosure design https://i.pinimg.com/originals/9e/bf/5e/9ebf5ef3b42c66906a64e7986aee28fa.jpg
 
Depends how much power you want to throw at these things. Even with a 6cuft box tuned to 40hz the driver is several mm over Xmax at 800w input, there is no real danger with that it's just that the motor is beginning to lose control over the cone and distortion is increasing rapidly. And the speaker will still produce output below tuning just at a lower level but you must have a low cut filter in place or you could easily destroy the driver with high power below tuning.


All of this data is available to see with a modeling program such as WinISD.
 
will that be ok tho?even tho the usable frequency is 38hz-0.7khz?

Well, had your 'recommended box tuning frequency of 40Hz' been correct, yes, but for high power prosound apps it's actually 47 Hz tuning WITH a 20 Hz high-pass and 120 Hz low pass, so the 38 Hz min. is based on these conditions.

For HIFI/HT apps, tuning to Fs [and lower] is an option due to lower power requirements combined with room gain, so if in my room I'd initially tune to ~27.5 Hz and adjust from there if need be, though in each case I recommend a much larger ~19.2 ft^3 net cab for dual.

GM
 
...but i feel 40Hz wont hit the low notes just right .what frequency should i tune the box i am building to ,32Hz, 38Hz or stick to the recommended frequency of 40Hz?

As is often the case at this forum, you have a choice of pretty good "answers" despite not explaining what the question is.

What is your application? What music or HT?

if you bought those "pro" drivers and are talking about a "pro sound" setting, "low" has a very different meaning than for audiophiles playing organ music. Playing real loud at 70 Hz (typical big double bass boost on pop recordings) might be what you want for a club. And with a LF protective filter. For home HiFi and if you've already bought those drivers, the solutions are very different and includes DSP.

B.
 
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The correct link to the speaker you mention is this:


Speaker Detail | Eminence Speaker


And enclosures Eminence for PA :

http://www.eminence.com/pdf/Kappa_Pro_18LF_8_cab.pdf

Look at the graphics of the two models,
12.74 ft. 2x18 - 15db at 30 hertz
and 10.34 ft. 1x 18 -12db at 30 hertz

That difference of 3 db will allow you to use half the power of the amplifier.

If you are looking for deeper bass, the single-speaker box is better, and if you are looking for more power handling, you can build two boxes.

To my way of seeing the original designs of the manufacturer are a guarantee for use PA
 
Hi All,

FYI:

b:Popworm::)
 

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