In the process of trying to get the right design for 21sw115. I want the size to be more compact and willing to lose a few db for the tuning to stay low. Dose anyone have advice with trying to sim curved ports?
My original idea is going for a bass reflex design, but I'm sure I can enhance the tuning with new ideas. Hornresp and winisd aren't cutting it at the moment. If anyone has any other ideas or box builds that sound right. Frequency response and size over all else!
Thank you in advance.
My original idea is going for a bass reflex design, but I'm sure I can enhance the tuning with new ideas. Hornresp and winisd aren't cutting it at the moment. If anyone has any other ideas or box builds that sound right. Frequency response and size over all else!
Thank you in advance.
B&C?
From a quick look at the data even a smalll box will be LARGE. Do you have EQ to adjust a too small a sealed box.
Do you already have said woofer?
Putting 2 woofers push-push dramatically eases the box build. And 2, or 4 woofers can be used to acostically deal with peaks and mules that form at low frequencies. Not possible with a single woofer. (ref Toole/Geddes)
dave
Well, size is relative lol. something a little bigger then a ks21, but smaller than a horn loaded 21. I have a quality mixer from A&H. I don't have the woofer yet, but I'm hoping to get around 130db since the tops I built can comfortably reach 120. Sealed would loose quite a bit of db im thinking. I wouldn't have to worry about xmax but I'd like to keep efficiency.
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Would I be able to eq a higher tuned bass reflex box to lower frequency with success? Is that a bad idea due to phase problems or port resonance?
Yeah, even @ 220.83 L/30 Hz Fb the vent bumps it to 282.15 L and even then vent mach is 30 ms/Xmax @ 127.6 dB mid band eff..
Eq on your subs crumbles phase alignment? Also, xmax worries. Just wondering if you also underpower your sub Maybe it's possible to eq. But box tune would it up in the end:/
No, excursion rises rapidly below Fb (box tuning).
Port (pipe) resonance should be well above the subwoofer range.
A few Hz below Fb, a ported box drops at ~24dB per octave due to the port output being 180 degrees out of phase with the speaker output.
The KS21's Fb is around 35Hz (-3dB) at 29Hz it has dropped to -10dB (useless, sounds less than 1/4 as loud).
More compact than what?
How low do you want the response to go?
If you are looking for "more compact", the B&C 21SW152 is a better choice due to its smaller VAS and larger excursion and power handling, a bit more output in a 190L than the 21sw115 in a 250L (internal volume) box in these simulations:
https://data-bass.com/systems/5b11bfe651412e00047d6693
This is what the measured response looks like for the B&C SW152-4 in a 14.9 cubic foot external volume, (423L) cabinet with a 25Hz Fb, note how much larger the cabinet must be for the lower tuning at similar senstivity:
The dips at 150 and 170Hz are pipe resonance due to the long port needed for low tuning.
This is it's real world output at 2meters (add +6dB for one meter equivalent):
You could get more 3-6dB more output per driver using tapped horn designs, but the cabinet would be larger..
Art
Quick models in WinISD.
Top three, ported, all tuned to 30Hz, 12, 9, and 6 cubic feet. The bottom line in blue, sealed, 6 cubic feet. Xmax is hit at 800 watts with 2db bump@30Hz, Q=2.
All high passed at 24Hz 8th order BW. Low passed at 125Hz 4th order LR.
Top three, ported, all tuned to 30Hz, 12, 9, and 6 cubic feet. The bottom line in blue, sealed, 6 cubic feet. Xmax is hit at 800 watts with 2db bump@30Hz, Q=2.
All high passed at 24Hz 8th order BW. Low passed at 125Hz 4th order LR.
Attachments
If a small enclosure is a huge deal to you, the 21sw152 will require more power, but can work in half the volume.
What is the F3 that you are after? And what's the enclosure volume, Vb, that you are willing to use?
Here is my design for a Vb = 160 litres (5.65 cu.ft.) vented-box enclosure, tuned to Fb = 24Hz. This design has a 2nd-order high-pass peaking filter applied, with a frequency setting of 23Hz and Q=2.0. There is also a modicum of parametric EQ applied, −2.0dB at 50Hz with Q=1.0. A 4th-order Linkwitz–Riley low-pass filter set to 80Hz has also been included.
The above design seems quite promising, with the vent air velocity reaching the warning level at a nominal power input of 105 watts re 8 ohms. The peak power required to achieve 114dB maximum SPL is around 675W. The maximum displacement value falls well below the Xmax of this driver, so it can accept higher short-term power peaks while still working relatively linearly.
Here is a 160-litre closed-box enclosure design for the 21SW115 4-ohm driver. Parametric EQ has been applied, with +11dB applied centred on 24Hz with Q=1.70. A 4th-order Linkwitz–Riley low-pass filter set to 80Hz has also been included. Peak power input of 600W produces a maximum SPL of around 113dB, and the F3 is quite reasonable 22.4Hz. The roll-off is a gradual 2nd-order slope, so it will help with transient response. The closed-box system has considerably more output at 10Hz than the earlier vented-box system, and it will make much better use of room gain as well.
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Thank you so much for this detailed response, I will definitely change my driver choice to the sw152. Around 200L is definitely compact enough for my requirements.
