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SI18D2 vented box design help

2111 Views 21 Replies 12 Participants Last post by pursuerOfBass, Sep 22, 2014

pursuerOfBass

Discussion Starter · Feb 15, 2014

I have a SI18D2 that's going to be powered by a inuke 1000DSP in bridged mode. I'm having trouble calculating port length for a 20hz tune. I've come up with 3 slot ports that are 32.75" deep x 7" wide x 3" high. The bracing and driver displace .907 ft^3. I'm not sure what to do from here, or how to calculate port length? can anyone offer some suggestions? Thanks for looking.

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chalugadp

· #2 · Feb 15, 2014

The martycube has a 20hz tune and its smaller then your design . Your vertical bracing has one extra piece needed.

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steve nn

· #3 · Feb 15, 2014

Plug in your internal volume, plug in your tune in the box tab. Bring up air velocity and then go to your vent tab and work from there. Use this link to fig out displacement http://www.avsforum.com/t/1516043/my-ported-uxl-18-in-9-9cf-x2 In a sense you're kind of working backwards but you should pick up on it.

mhutchins

· #4 · Feb 15, 2014

I would add a vertical and horizontal brace to the back panel. Otherwise, it looks great !!!

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cessna1466u

· #5 · Feb 15, 2014

Quote:
Originally Posted by pursuerOfBass /t/1517877/si18d2-vented-box-design-help#post_24359646

I have a SI18D2 that's going to be powered by a inuke 1000DSP in bridged mode. I'm having trouble calculating port length for a 20hz tune. I've come up with 3 slot ports that are 32.75" deep x 7" wide x 3" high. The bracing and driver displace .907 ft^3. I'm not sure what to do from here, or how to calculate port length? can anyone offer some suggestions? Thanks for looking.

Just wanted to let you know that I hope you don't mind but I want to borrow one of your pictures to ask a question in the Martycube thread. Hope its ok.

LTD02

· #6 · Feb 15, 2014

so what you have is roughly a full size martysub. about 10.5 cubic feet or so of internal volume.

a 32" long port will probably come in at about 19hz. i'd push it to 36" long.

in your drawing, it looks like it is pretty close the 36" long as it is.

the measurement is taken from the very front of the cab.

so at 36" long, the port starts at the front of the cab, extends 36" long, then has a 3.25" air gap to the rear panel, then the rear panel is 0.75" thick, which all summed up is 40" front to back.

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LTD02

· #7 · Feb 15, 2014

nice rendering by the way.

Flynnr

· #8 · Feb 16, 2014

How about instead of putting those blocks in the corner of the sub, put them in the corners on the back of the speaker grille with the magnets in them so they will be fixed to the grill instead?

pursuerOfBass

Discussion Starter · #9 · Feb 16, 2014

Thanks for the input everyone. I have followed some suggestions and extended the port length to 36" and added vertical and horizontal bracing to the back panel. Does everything check out? as i'm planning on building the cabinet tomorrow!

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steve nn

· #10 · Feb 16, 2014

Everything looks good at 36" like LTD suggested. You're good to go! Sorry I misunderstood your question earlier and see the link I posted seems to be a link that was stuck in my browser or something? (most likely the user lol) I did the same thing in another thread. Anyway this was the link http://www.hometheatershack.com/forums/enclosure-volume-calculator/ Your rendering/mock is definitely very well done.

steve nn

· #11 · Feb 16, 2014

If you wanted too, you could run a strip side to side, top to bottom, and front to back to tie everything in nicely. It can't hurt and will only add to the integrity of your bracing.

pursuerOfBass

Discussion Starter · #12 · Apr 6, 2014

Thought i would update this with some pics of the completed build. It sounds great, but its really not enough bass for my very large open room. So i'm considering selling it along with the inuke 1000dsp and building two smaller 18's powered by an inuke 6000dsp. My question is does diy audio have a market and how much could i sell this for?

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brian6751

· #13 · Apr 6, 2014

How big is your space? Why joy just build another one if those?

cessna1466u

· #14 · Apr 6, 2014

That looks awesome. What material did you use to build it. It looks like solid wood or is it plywood with veneer? Love the dark color, what color stain is it?

Trepidati0n

· #15 · Apr 6, 2014

Quote:
Originally Posted by pursuerOfBass /t/1517877/si18d2-vented-box-design-help#post_24575432

Thought i would update this with some pics of the completed build. It sounds great, but its really not enough bass for my very large open room. So i'm considering selling it along with the inuke 1000dsp and building two smaller 18's powered by an inuke 6000dsp. My question is does diy audio have a market and how much could i sell this for?

Where is your "gap" in terms of bass? Is it below 50 Hz or higher? You aren't going to gain much by putting in two 18's with smaller enclosure if aiming below. Remember that "hoffman's iron law" is pretty much in play here. To put this in perspective...NOTNYT is pretty much the poster child example of the trade between ported/sealed for the lower content.

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Bob7145

· #16 · Apr 7, 2014

Price? You'ld be fortunate to get back what you have in it. It's huge, heavy and you'ld have to explain to anyone interested what it is and how to use the amp. Not sure many folks trust something "Homemade".

pursuerOfBass

Discussion Starter · #17 · Apr 8, 2014

Quote:
Originally Posted by brian6751 /t/1517877/si18d2-vented-box-design-help#post_24575468

How big is your space? Why joy just build another one if those?

Roughly a 27" cube. I would but "someone else" in the house does not like anything about this subwoofer...

Quote:
Originally Posted by cessna1466u /t/1517877/si18d2-vented-box-design-help#post_24575562

That looks awesome. What material did you use to build it. It looks like solid wood or is it plywood with veneer? Love the dark color, what color stain is it?

I used 3/4" MDF to build it, then glued 1/4" birch plywood on the outside. I stained it with minwax dark walnut on the sides and finished the front, back and top with spray on bed liner.

Quote:
Originally Posted by Trepidati0n /t/1517877/si18d2-vented-box-design-help#post_24575689

Where is your "gap" in terms of bass? Is it below 50 Hz or higher? You aren't going to gain much by putting in two 18's with smaller enclosure if aiming below. Remember that "hoffman's iron law" is pretty much in play here. To put this in perspective...NOTNYT is pretty much the poster child example of the trade between ported/sealed for the lower content.

Not exactly sure yet, i just want more bass, especially with music. I'm going to buy a UMIK-1 and play around with REW and make some filters to try and see if that improves anything. The only other reason i'd side/down grade to two smaller 18's is so i could put my klipsch heresy's on them and have them at ear level.

Quote:
Originally Posted by Bob7145 /t/1517877/si18d2-vented-box-design-help#post_24578884

Price? You'ld be fortunate to get back what you have in it. It's huge, heavy and you'ld have to explain to anyone interested what it is and how to use the amp. Not sure many folks trust something "Homemade".

Gotcha, that's what i figured. I'll probably just hold on to it then, as it completely blows my klipsch ksw-12 out of the water.

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Bob7145

· #18 · Apr 8, 2014

It's a killer sub! Beautiful too. Somebody local that can come over and hear it would love it and probably buy it.

pursuerOfBass

Discussion Starter · #19 · Sep 20, 2014

Another update and i could use some help troubleshooting a potential problem

Here is a synopsis of what happened:

I had to move the sub and inuke into another room to do some work, so i hooked it up to another older AV receiver i had. It didn't work at first and then was extremely loud for a few seconds until i was able to turn it off. I think that receiver is now broken and hopefully it didn't take the sub or inuke down with it. I moved it back to its main location and hooked it back up to my Yamaha RX-A1020 and now the bass is nowhere near the level it was before. I have checked all the connections, the knobs on the front of the inuke and my presets, ran YPAO again which set the sub level at +3.5 compared to the -3 it set it at before. The signal lights on the front are not lighting as high as they use too either, It seems i have to turn the volume up on my receiver much higher to achieve the same amount of bass that i had before. My brother also commented that there is a lot less bass than before.

I'm at a loss for what the problem could be, does anyone have any suggestions?

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Samps

· #20 · Sep 21, 2014

Hook a multimeter up to the terminal on the box and check the ohms. It's possible that when you moved it, one of the speaker wires came loose and you ended up running a 2 ohm load using 1 voice coil. I'm not sure if the inuke would shut down immediately from a 2 ohm load?

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