The Two Towers - 2x30ft^3 - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 140 Old 10-02-2017, 04:22 PM - Thread Starter
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The Two Towers - 2x30ft^3

I am getting ready to finish up the first of two, so I figured it's about time I started a proper build thread and post some photos...

These are going in two corners of my living room, which is connected to a huge space of about 11,000cf. Each one is built with a 24" diameter sonotube @ 11'-1" high, with 4.5" legs on the bottom and 10-3/8" round ports @ 38" long, giving them each a total height of 11'-5.5" and the ports 12" of breathing room above them.

They net out at just over 30cf each, and a designed tune of 12.5Hz, with my expectation that they will come in around 11-11.5Hz at the end of the day.

Each will be fitted with an SI HT18v2, wired in series (4ohm) and powered by an iNuke 6000DSP.

There are 3 pillows stuffed around the port, and 1 pillow stapled and glued to an inner ring at the midpoint of the tube. These should effectively kill any resonances.

Two photos are attached, showing the first tower getting ready for paint. I peeled the outer plastic coating of the sonotube which exposes bare cardboard, so I am going to coat the entire tube with a coat of wood glue to stiffen and seal it, then two coats of paint to match the living room walls.

I'll take some build photos as I build the second one so I can post them here.

Edit: Finished Photo

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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, Custom Tapered Ported Volt-6 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

Last edited by aron7awol; 11-06-2018 at 04:19 PM.
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post #2 of 140 Old 10-02-2017, 05:57 PM
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Epik build!!!!!!!!!!!!!!!!
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post #3 of 140 Old 10-03-2017, 12:25 PM
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You probably have the lightest weight 30cf sub on the forums.
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post #4 of 140 Old 10-03-2017, 05:31 PM - Thread Starter
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Quote:
Originally Posted by kaiforce View Post
You probably have the lightest weight 30cf sub on the forums.
And it's still really freaking heavy. Getting it into the house and into place will be a challenge.
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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, Custom Tapered Ported Volt-6 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 #5 of 140 Old 10-04-2017, 01:13 PM
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That's a big tube build! Any concern about them tipping over with that height?
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post #6 of 140 Old 10-05-2017, 10:45 PM
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You certainly have the title of 'extreme' here.
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post #7 of 140 Old 10-06-2017, 05:37 AM
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Awesome build!! It was my understanding that subs build like this don’t have resonance issues because of the shape? Is this not true? Either way.......should be awesome in the room.

HT: Oppo UHD-203 | Crown Amps | NX3000D | NX6000D | 1299s | Volt 8s | THTs | Crowson Shadow 8s | BOSS riser | Panamax 5300PM | LG OLED 65B6P
Family: Denon AVR-S740 | PSB Alpha AVs | Sony X900F | X1
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post #8 of 140 Old 10-06-2017, 06:24 AM - Thread Starter
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Quote:
Originally Posted by OJ Bartley View Post
That's a big tube build! Any concern about them tipping over with that height?
Definitely some concern. I will likely put a small eye bolt in the top cap and the wall and wire it just to be safe.

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Awesome build!! It was my understanding that subs build like this don’t have resonance issues because of the shape? Is this not true? Either way.......should be awesome in the room.
There are definitely resonances with a bare empty tube, but the pillows seem to totally kill them.

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, Custom Tapered Ported Volt-6 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 140 Old 10-06-2017, 09:30 AM
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I never filled mine and I had no resonances.
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post #10 of 140 Old 10-07-2017, 04:12 AM
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I'd put three more legs on there. The tripod you have now will be very likely to tip over.

Awesome build anyhow.
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post #11 of 140 Old 10-07-2017, 11:37 AM
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I'd put three more legs on there. The tripod you have now will be very likely to tip over.

Awesome build anyhow.
3 legs have inherently more stability than 4 or any other number. If your floor were perfectly level, then perhaps 4, but I would take 3 legs any other time.

Ask your doctor if DIY is right for you. Side effects of DIY may include anxiety, elevated blood pressure, lightheadedness, rapid heartbeat, skeletal muscle flaccidity, euphoria, psychological dependence, insomnia, confusion, blurred vision, impulsivity, uncontrolled or repeated movements.
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post #12 of 140 Old 10-07-2017, 08:26 PM
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Quote:
Originally Posted by MKtheater View Post
I never filled mine and I had no resonances.
The sonotube subwoofers I built many years ago had a terrible end to end resonance that rang like a bell.



Shown another way, treated vs. untreated:


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post #13 of 140 Old 10-08-2017, 06:14 AM
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Quote:
Originally Posted by michael hurd View Post
The sonotube subwoofers I built many years ago had a terrible end to end resonance that rang like a bell.



Shown another way, treated vs. untreated:

How did you measure that? Mic in the port?
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post #14 of 140 Old 10-08-2017, 06:21 AM
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Well, I never had that problem.

Building the room, speakers, and subs.
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post #15 of 140 Old 10-08-2017, 08:00 AM
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Quote:
Originally Posted by corradizo View Post
How did you measure that? Mic in the port?
It's been quite some time ~10 years, and I didn't write a full description with the measurements I took. I think that measurement was 1 meter from the driver, but not certain. I do know when I fired the first one up, it sounded terrible.

Pulling the driver, just speaking into the enclosure you could trigger resonance. A few polyfill pillows took care of it 100%.

I left one treated, one un-treated and pulled out the measurement gear to see how bad it was. The waterfall plot is quite ugly, showing the resonance rings out well past 300 msec with little to no attenuation.

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post #16 of 140 Old 10-08-2017, 08:27 AM
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Originally Posted by MKtheater View Post
Well, I never had that problem.
When you built your ported sonotubes, the only measurement gear you had was your ears and a radio shack SPL meter.

https://www.avsforum.com/forum/155-di...l#post13585401

https://www.avsforum.com/forum/155-diy-speakers-subs/1016979-finished-my-ed-18-inch-sono-s-4.html#post14717224


Based on the dimensions, you would have an end to end resonance, that is not debatable.

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post #17 of 140 Old 10-08-2017, 10:43 AM
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Never heard any, if I can’t hear it I don’t care. They were 6 feet tall and 26 inch round OD. The ports were 7.5 and 8.5. I can’t remember how long though, 38-40 comes to mind. They always were just clean bass with no noises even with my ear to the port. If they were there it was not audible.
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post #18 of 140 Old 10-08-2017, 10:45 AM
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Yes I started measuring once I went sealed. The spl meter with c-weight was as accurate as my calibrated behringer mic from CSL for the bass frequencies. Notnyt measured and tested it for me.
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post #19 of 140 Old 10-08-2017, 10:49 AM
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Originally Posted by michael hurd View Post
3 legs have inherently more stability than 4 or any other number. If your floor were perfectly level, then perhaps 4, but I would take 3 legs any other time.
Did you just make that up ? Your joking right ?
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post #20 of 140 Old 10-08-2017, 10:55 AM
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Never heard any, if I can’t hear it I don’t care. They were 6 feet tall and 26 inch round OD. The ports were 7.5 and 8.5. I can’t remember how long though, 38-40 comes to mind. They always were just clean bass with no noises even with my ear to the port. If they were there it was not audible.
Just because you didn't hear it, doesn't mean it wasn't present.

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post #21 of 140 Old 10-08-2017, 11:00 AM
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Did you just make that up ? Your joking right ?
Not joking in the least.

Is there a particular reason why speaker stands don't have 4 legs?

https://www.parts-express.com/ultima...stand--242-700

Oh my god... that's gotta be unstable as hell.

How about elevating some lighting products?

https://www.parts-express.com/talent...stand--233-080
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Quote:
Originally Posted by michael hurd View Post
Not joking in the least.

Is there a particular reason why speaker stands don't have 4 legs?

https://www.parts-express.com/ultima...stand--242-700

Oh my god... that's gotta be unstable as hell.

How about elevating some lighting products?

https://www.parts-express.com/talent...stand--233-080
Why would you suppose these were banned out of production?


Now all you can buy new is these...
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post #23 of 140 Old 10-08-2017, 11:17 AM
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Why does the tripod of a camera have three legs and not four ? (Which chair is better a four legged chair or a three legged chair )




Thomas Dalton, MMath Mathematics, Durham University (2009)
Answered May 12 2013 · Upvoted by Daniel McLaury, Ph.D. Student in Mathematics at University of Illinois at Chicago







Three legs is the minimum required to be stable in three dimensions (in technical language, each leg constrains one degree of freedom). The problem with four (or more) is that they may not all be able to touch the ground and the same time if either the ground isn't level or the legs aren't all the same length. This causes things with four legs to sometimes wobble (especially desks used when sitting exams...).

I think the reason we use four legs on chairs and tables is that we want the chair or table to be rectangular and having the legs anywhere other than corners would be putting a heavy object on a corner that doesn't have a leg could cause it to tip. That is because the surface of the table would be larger than the base created by its legs.

If you want something stable on uneven ground (like a tripod or a milking stool) then you use three legs and splay them so their base is larger than whatever is on top.

(There is a theorem in topology that, whatever the shape of the ground, subject to certain continuity assumptions, you can always make a four legged table stable simply by rotating it. The surface of the table won't generally be level, though.)
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Is this conversation really happening? I better get on my vest, it's about to get real in hiurrr.
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Quote:
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Why would you suppose these were banned out of production?


Now all you can buy new is these...
Simple. People injured themselves, unfamiliar with the vehicle dynamics, and insurance companies wanted them taken off of the market, to limit their potential claims.

Your argument ad hominem is non sensical, since Bombardier produces the Spyder which is currently road legal and safe.

https://www.brp.ca/spyder/

You could make the same argument that the model T was unsafe, compared to horses. How many people get injured by horses every year? Looks like it worked out well for Christopher Reeve.
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Is this conversation really happening? I better get on my vest, it's about to get real in hiurrr.
My apologies to the thread and OP... please carry on.
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post #27 of 140 Old 10-08-2017, 11:33 AM
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Quote:
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Just because you didn't hear it, doesn't mean it wasn't present.
Yes I understand but I am not going to put extra work in something that won’t effect the cinema experience. If someone has an audible problem then fix it.
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post #28 of 140 Old 10-08-2017, 11:36 AM
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Quote:
Originally Posted by michael hurd View Post
The sonotube subwoofers I built many years ago had a terrible end to end resonance that rang like a bell...

My sonosub had a very obvious end to end resonance as well. Last night I added three pillows, and it's gone.

"The wise understand by themselves; fools follow the reports of others"-Tibetan Proverb
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Oh, and each of my sonosubs has three legs (I designed them like that for stability).

"The wise understand by themselves; fools follow the reports of others"-Tibetan Proverb
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Did you guys hear the resonance? I had 3 legs on mine as well.
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