2.1 triamped system crossover and 2 way box design

karolis94

Member
2013-01-19 2:59 pm
2 way + subwoofer (crossover and 2 way box design)

Hello, I am planning to make a pair of 2-way speakers for indoor use (mainly as home theater and occasionally for music). The 12" subwoofer that I currently have should reproduce the lower frequencies below main speakers. Whole setup would look like this:

*24 dB/Octave 3-Way Linkwitz-Riley Electronic Crossover from ESP;
(3100 Hz crossover from mid to high; ??? Hz crossover from low (subwoofer) to mid)

*Eight Band Sub-Woofer Graphic Equaliser from ESP;
*Active Sub-Woofer and Controller from ESP;
(for 47l sealed 200W subwoofer with adjustable 50 - 150 Hz 2nd order Butterworth crossover)

I have two questions after running a few simulations on WinISD:
What crossover frequency would be a better choice, given that the excursion of mid woofer is over the limit at 200 Hz with 70 W applied? (Speaker parameters: Prms = 100 W, XMAX = 1 mm, linear XLIM = 2.5 mm)
If I set the XO to 123 Hz, XMAX peaks at 2 mm;
If I set the XO to 150 Hz, XMAX peaks at 1.5 mm;
excursion.jpg

After enabling the XO in WinISD there seems to be almost no difference between box sizing. Next photos should illustrate what I mean:
box1.jpg box2.jpg
So does this mean that I can ignore the XO and simulate the box with XO disabled OR there is no difference what size box to choose?

I will be thankful for everybody with any ideas.

More about the mid driver is written in description at this page: G?o?nik basowy 21 cm BASS 200 Watt ALPHARD PS-8 ! (5504303122) - Allegro.pl - Wi?cej ni? aukcje.
 
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karolis94

Member
2013-01-19 2:59 pm
After whole day of simulations I have decided to build 2.5 way system out of it. Main speaker would go down as low as they possibly can without over excursion, to achieve this I will add a shelving high pass filter or a Linkwitz transform with -8 dB gain. I could use some info about shelving filters or other bass cut/boost equalizers.

I presumed that main speaker box will be based on Chebyshev alignment, this way frequency rolls down rather nicely with limiting filter enabled. Does this tuning frequency looks right to you?

BGnEGYi.png


I would like to hear from you guys what you think about my idea.
 
Hi,

The woofer actually seems to be a classic PA midrange driver where Xmax limits the maximum SPL below 250 Hz. Unfortunately there's nothing you can do, a vent doesn't help at all. My advise is a closed box of 15-20 liters and a crossover frequency of 150 Hz. 1 mm excursion gives an SPL of 99 dB at 150 Hz, that's certainly at the limit, but I assume and hope it does work in practice anyway, unless you listen very loud. 2.5 mm excursion gives 107 dB. :)

Attached my simulation results including baffle step. Impedance and frequency response of the driver is unknown (estimated).
 

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eriksquires

Member
2013-05-10 4:11 pm
Just FYI, with a sealed cabinet, a 2nd order high pass will give a LR 4 electro-acoustic response. :) This is the traditional THX alignment if done at 80 Hz. A subwoofer with a low pass 4th order LR alignment would match up perfectly if time aligned.

Look in other threads for measuring speaker impedances with Room EQ Wizard.

Lastly, if you want really good bass, invest in room treatment. Best price performance so far are GIK Acoustics Soffit Traps. I see people routinely throw away tens of thousands of dollars getting mediocre bass. I also see people throw away hundreds of dollars getting mediocre bass. Don't be one of those. :)

Best,

Erik
 
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