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Discussion Starter · #1 · (Edited)
seeing how my sealed enclosure is nearly finished and i'm now quite comfortable with a sub build, i would like to hear any feedback on my next multituned slot ported enclosure.

i'll be using mach 5 ixl15.2.2 with a behringer ep4000 to drive them. each driver will get one channel. i'm guessing the max size that my wife will tolerate is about 6 cuft.


the box will be 21.65" x 18.11" x 41.73" (55cm x 46cm x 106cm), double baffled with cross bracing using 18mm MDF.
any idea to help improve the design? read that the back port should be at least 1.5" from the back wall. how important would that be?





and would it make any difference to use the 45 degree guide at the port bend or i could stick to the usual 90 degree bend? i'm guessing this 45 degree port guide will be hard to clamp during gluing.
if it's important to have the back port elevated from the back wall, could i get away with a angled guide at the port end?

any advises would be much appreciated
 

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Welcome to HTS!

To my knowledge the fewer bends, the better as far as ports go (less risk of reduced SPL contribution). Full U-shape bends can be okay as well but are less desireable than L-shape bends.

I wouldn't bother with the 45 degree inserts. The rule of thumb for end of port clearance is to allow at least one diameter of distance. For a slot port I'd go by the narrowest dimension, the height of the slot. Be sure that you are precisely calculating your slot port length to include the bends and/or thickness of the wood.
 

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Discussion Starter · #3 ·
guess i missed the 5 post forum rule. that's why my pictures doesn't show even after i moved them to photobucket. :wave:

Welcome to HTS!

To my knowledge the fewer bends, the better as far as ports go (less risk of reduced SPL contribution). Full U-shape bends can be okay as well but are less desireable than L-shape bends.

I wouldn't bother with the 45 degree inserts. The rule of thumb for end of port clearance is to allow at least one diameter of distance. For a slot port I'd go by the narrowest dimension, the height of the slot. Be sure that you are precisely calculating your slot port length to include the bends and/or thickness of the wood.
the ports are L shaped. it would easier to explain if the pictures show up.

port height is 5.5cm, width is 15.93cm, 3 ports side by side. i have 23.16cm clearance from the top panel. i'll try and pad my post count so that pictures will show
 

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Discussion Starter · #4 ·
after minus the 0.17 cuft driver, 0.3014 cuft bracing and port i got a nett volume of 5.55 cuft. each port takes 0.353 cuft of space increasing the internal volume to 5.90 cuft with 1 port closed and 6.26 cuft with 2 ports closed.


3 port open i got a tuning of 20.27 Hz (blue line)
2 port open i got 16.06 Hz (cyan line)
1 port open i got a tuning 11.02 Hz


cone excursion are kept in check by a 2nd order high pass filter provided by minidsp (if it's able to reach that low, else will resort to opamps) and -3db rolloff at 4Hz from the EP4000.


air velocity are kept below 35m/s and i'll be rounding over the ports at the ends.

anything else that i need be aware of? any comments would be much appreciated before i start cutting the panels.
 

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Looks good to me. It will certainly dig deep! One more thing you could check is apparent amplifier power, but if you aren't boosting anything I'm sure it's plenty safe.

Also, do you know Xlim/Xmech/Xsusp on the IXL or do you only have Xmax?
 

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Discussion Starter · #6 ·
Looks good to me. It will certainly dig deep! One more thing you could check is apparent amplifier power, but if you aren't boosting anything I'm sure it's plenty safe.

Also, do you know Xlim/Xmech/Xsusp on the IXL or do you only have Xmax?
running with 4 ohm the ep4000 are rated for 950W rms, peak at 1400W burst in the brochure. with sine wave it's measured to be good for 650W continuous.

i simulated the drivers with 950w, but with 650w the excursion goes down below 22mm (xmax). is that what you're saying about amplifier apparent power?

as for the maximum excursion, it's only the xmax at 22mm that's given in the website.
 

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I see.

Ya, I meant to ask you to check the apparent amp power graph in winISD. That will show you how close and at what frequencies you are coming close to your amp's 650W rated power.
 

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Discussion Starter · #8 ·
I see.

Ya, I meant to ask you to check the apparent amp power graph in winISD. That will show you how close and at what frequencies you are coming close to your amp's 650W rated power.
have never (ever) checked the apparent load power graph in winisd before. never knew they existed as never read any discussion about them in any build threads. maybe i missed some.


the apparent load power maxed out at 500VA at 150hz. i'm probably gonna be crossing them at 100hz. safe to assume that the amp won't see it being loaded more than 450w during operation?
 

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have never (ever) checked the apparent load power graph in winisd before. never knew they existed as never read any discussion about them in any build threads. maybe i missed some.

the apparent load power maxed out at 500VA at 150hz. i'm probably gonna be crossing them at 100hz. safe to assume that the amp won't see it being loaded more than 450w during operation?
Yep, most people don't even think to check. It's usually only a concern when you are using EQ to boost frequencies. Keep in mind it's just an estimate as well, but ya, looks like your amp won't be stressed much :T
 

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paskal

was this sub ever built?
I am trying this approach with new SI 18" drivers and having problems keeping port resonant frequency numbers high enough.
what numbers were you getting in your model?

thank you
 
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