UM18 Sonotube - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 13 Old 11-16-2019, 01:44 AM - Thread Starter
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UM18 Sonotube/Amp suggestions...

I want to build a ported sonotube using an Ultimax 18”. I want to use a 20” diameter tube. The top will be 3/4” MDF and have the port(s). It will be flush mounted (meaning inside the tube). The speaker baffle will be 1 1/2” MDF also inside the tube. The sub driver will be surface mounted, not flush. So how long does the tube need to be and what diameter(s) and length(s) will port(s) need to be [take into consideration the displacement of driver/port(s)/port flared end(s)]???

Also any suggestions on an amp???

Bass. Is. My. Passion.

Last edited by Bazzheyd; 11-16-2019 at 02:01 AM.
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post #2 of 13 Old 11-16-2019, 08:52 AM
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It can be whatever meets your requirements and goals. How tall are you willing to build it? How low are you looking to tune?

A bridged NX3000D is always a good match for a UM18, or a single channel of a NX6000D if you want another channel for future use.
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Take the Red Pill (BassEQ) BassEQ Demo Clips
Video: Sony 85" X900F @ 80" eyes-to-screen (49.4° viewing angle)
Audio: Denon AVR-X4400H 7.2.4 Atmos
Mains: Fusion-15 LR, Fusion-8 Center, Ported Volt-10 Surrounds, Custom 45°/45° Double-Angled Ported Volt-6 Atmos
Subs: The Two Towers (HT18 32cf 11.5Hz x 2), UM18 4cf x 2, Crowson MAs x 4

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post #3 of 13 Old 11-16-2019, 11:58 AM
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20" tube with an 18" driver? You'l barely have any meat on the endcaps for driver mounting. You should consider a 24" tube.
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post #4 of 13 Old 11-16-2019, 03:01 PM
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A 20" tube is a tight fit for an 18" driver, and would need to be taller for the same volume as a larger tube. This could cause problems with a lower resonant frequency. A 24" tube would work well. I used a 22" tube for mine, with no issues.

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post #5 of 13 Old 11-16-2019, 09:38 PM - Thread Starter
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I can go up to 7 foot tall at 20 inch diameter and that’s why I’d stated the driver wouldn’t be flush mounted but instead surface mounted. A 22 or 24 inch diameter I can go 6 foot max.

I’d like an amp bridged that preferably has dsp.
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post #6 of 13 Old 11-16-2019, 10:08 PM
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24" @ 6' is my favorite sweet spot. I already modeled a whole bunch of different tuning options in that size, which I've called the SonnySub:




Take the Red Pill (BassEQ) BassEQ Demo Clips
Video: Sony 85" X900F @ 80" eyes-to-screen (49.4° viewing angle)
Audio: Denon AVR-X4400H 7.2.4 Atmos
Mains: Fusion-15 LR, Fusion-8 Center, Ported Volt-10 Surrounds, Custom 45°/45° Double-Angled Ported Volt-6 Atmos
Subs: The Two Towers (HT18 32cf 11.5Hz x 2), UM18 4cf x 2, Crowson MAs x 4
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post #7 of 13 Old 11-16-2019, 10:30 PM - Thread Starter
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Is that 6’ internal length? Keep in mind I want both ends inset into the tube. And what size port (will use flared ends).

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post #8 of 13 Old 11-16-2019, 10:38 PM
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Those are all a 6' tube with 1.5" endcaps with half of their thickness inside the tube. Each option is a different port size using the cheap form tubes that they sell at Home Depot or Lowe's @ 48" long. Flares aren't necessary with ports of these sizes, but if you want to go multiple smaller ports to flare them more easily you can.

Take the Red Pill (BassEQ) BassEQ Demo Clips
Video: Sony 85" X900F @ 80" eyes-to-screen (49.4° viewing angle)
Audio: Denon AVR-X4400H 7.2.4 Atmos
Mains: Fusion-15 LR, Fusion-8 Center, Ported Volt-10 Surrounds, Custom 45°/45° Double-Angled Ported Volt-6 Atmos
Subs: The Two Towers (HT18 32cf 11.5Hz x 2), UM18 4cf x 2, Crowson MAs x 4
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post #9 of 13 Old 11-16-2019, 10:55 PM - Thread Starter
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What schedule/size pvc has 7.375” I.D.? Also how far does driver need to be from floor or base?

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post #10 of 13 Old 11-17-2019, 09:13 AM
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Flares are always beneficial. 8” diameter ports are typically used for 18” drivers, and 8” diameter pvc flares can be found online. If those are too pricey, even a 1” roundover in the endcap and internally made from wooden rings helps.
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post #11 of 13 Old 11-17-2019, 03:09 PM
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Quote:
Originally Posted by Bazzheyd View Post
What schedule/size pvc has 7.375” I.D.? Also how far does driver need to be from floor or base?
It's not pipe, it's a form tube similar to a Sonotube but thinner and cheaper.

Take the Red Pill (BassEQ) BassEQ Demo Clips
Video: Sony 85" X900F @ 80" eyes-to-screen (49.4° viewing angle)
Audio: Denon AVR-X4400H 7.2.4 Atmos
Mains: Fusion-15 LR, Fusion-8 Center, Ported Volt-10 Surrounds, Custom 45°/45° Double-Angled Ported Volt-6 Atmos
Subs: The Two Towers (HT18 32cf 11.5Hz x 2), UM18 4cf x 2, Crowson MAs x 4
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post #12 of 13 Old 11-17-2019, 08:05 PM - Thread Starter
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How much spacing needed between the floor (or base) and the driver?
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post #13 of 13 Old 11-17-2019, 08:08 PM
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I did 4.5" on mine.

Take the Red Pill (BassEQ) BassEQ Demo Clips
Video: Sony 85" X900F @ 80" eyes-to-screen (49.4° viewing angle)
Audio: Denon AVR-X4400H 7.2.4 Atmos
Mains: Fusion-15 LR, Fusion-8 Center, Ported Volt-10 Surrounds, Custom 45°/45° Double-Angled Ported Volt-6 Atmos
Subs: The Two Towers (HT18 32cf 11.5Hz x 2), UM18 4cf x 2, Crowson MAs x 4
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