Built: a dual-opposed, sealed, sonotube-based servo sub. And lamp!

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dayneger

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A while ago I posted a couple of questions regarding a sonotube/concrete form-based subwoofer.

The early design concept looked like this:



I wouldn't say the feedback I got was particularly encouraging, but then @WGH suggested a vertical orientation, which I quite liked!

And sometimes you decide to build something "anyway".  Not to spite anyone, of course, but simply because it's a vision you want to realize.

Fast forward several months and here it is!

The day mode:



And then the dimmable evening mode:




dayneger

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I wrote up a fairly lengthy build thread on diyaudio.com if you'd like to see all the details: 

https://www.diyaudio.com/community/threads/built-a-dual-opposed-sealed-sonotube-based-servo-sub-and-lamp.419347/

The super short version is that I wanted a clean, hopefully family pleasing design with serious power and musicality.  I also wanted to explore the idea of having 2 separate monopole sources on a single footprint to hopefully even out the room loading a bit, as well as have dual-opposed drivers to not directly shake our living room's suspended floor.

The subwoofer:

- Stands 73" (1.85m) tall and is based off of 14" (35.6 cm) inner diameter cardboard concrete form (like sonotube)

- Has two 12" GR Research 4 ohm drivers with servo coils with baffles 60" (1.52m) apart, powered by a Rythmik HX800 servo amp with 2x400W Hypex outputs

- Leverages a 32' (10m) cobb style light strip with a dimmer and 2700K light color

So far it sounds pretty kick-butt!  I don't have the gear for proper measurements yet, but I was able to get it to blend with my Avinci Studio monitors quite easily.  It effortlessly plays well below 20 Hz without too much booming (better than my prior single sub on the floor in the same spot) and feels quite light on its feet.  The rounded, matte, white form also lets the eye slide by... it feels smaller and less obtrusive than it is.

Finally, I've really enjoyed the additional utility of the indirect lamp lighting!  Particularly the strip up the back makes it feels like it's floating against the wall.  Not sure why it's coming in sideways, but you get the idea.



I also just rebuild the monitors as white towers and was surprised (and pleased) to discover that something about the sound is slightly better!

Tyson

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That’s freaking cool 😎

Also, you might paint the speaker stand white to match the rest of the color scheme.

JCarney

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That’s freaking cool 😎

Also, you might paint the speaker stand white to match the rest of the color scheme.

I disagree. It is exactly as it should be. The base matches the floor, the tube matches the walls. Very cool build dayneger, well done.

JCarney

hk29

Beautiful!  thanks for sharing!  Inspiring!  I wish one day I could build stuff like this! 

YEEEEGZ

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That’s really cool, nice job!

corndog71

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Nicely done!

Here’s mine.





Early B.

Very cool! 8)

dayneger

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Thanks for the feedback, appreciated!  It was definitely a fun project to plan and build, and I'm enjoying both the visual and sonic impacts.

Regarding the stand and spine color, I went back and forth a few times.  At the end I felt that keeping the volumes separate architectural elements would feel more intriguing and allow the tube to float/feel lighter to a greater degree than having the stand color anchor it more firmly to the floor.

The first version also had a downlight around the lower driver, but rather than my vision of the light elevating the tube, it simply made a bright hotspot on the floor that drew the eye down to the base and cables.  It's much better without it.

Nice work on yours, @corndog71!  Thanks for sharing.

dayneger

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Beautiful!  thanks for sharing!  Inspiring!  I wish one day I could build stuff like this!

Thanks!  I'm sure you could build your own things--the sub wasn't "actually" rocket science 8) and I made up some of the parts as I went.  Mostly it's about being willing to just start and learn as you go.  It's amazing what you can achieve even with just a few handheld power tools and a positive attitude!

The other aspect is not choosing to learn with project implementations that require too much perfection.  An example here is that I wanted an ugly cardboard tube to look modern and elegant, and I didn't want to spend my life filling and sanding and fighting painting drips.  While it had its own challenges in handling (see the build thread), the laminate ironed out almost the entire tube in one feel swoop, likely adding additional damping and stiffness via the rubbery contact cement and stiff laminate material at the same time. 

I knew it would be hopeless to get the edges of the laminate to line up almost perfectly where they joined, so I deliberately designed my stand to allow tons of slop and clean it all up with essentially no further effort.

Here you can see what I mean... lots of gap that massively reduced the need for precision.  This aspect of planning ahead can save massive headaches later.



The laminate and tube were also cut a bit long, then (carefully) trimmed back to the desired length at the last possible moment, which also helps avoid damage to the ends in handling.  It's super easy to bash the ends of a 6' tube into anything and everything.



The spine covered up the laminate gap just by attaching its 4 bolts, and poof, gone.  Then the power and signal cables got routed up the interior of the spine to keep things clean externally while avoiding the addition effort/hassle/limitation of routing them inside the sub chamber (which I did consider).



Plan to make your life easier on yourself and just go for it!


dayneger

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Dang, not again!  If someone could tell me how to have my vertical shots not get autorotated to horizontal by the forum platform, I'd appreciate it.  :scratch:

GentleBender

I don’t know the answer, but I can do this. It looks really cool.





Danny Richie

Looks like that turned out really well.

artur9

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Can you make me 3-4?  I'd like one in every room corner...

How do you turn it on?  Trigger?  auto sense? leave it on?

dayneger

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I don’t know the answer, but I can do this. It looks really cool.

Thanks, on both accounts!

dayneger

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Can you make me 3-4?  I'd like one in every room corner...

How do you turn it on?  Trigger?  auto sense? leave it on?

With sufficient financial motivation, sure!   8)

The Rythmik HX800 amp, like many of its ilk, has off, on, and auto. So far the auto has worked flawlessly.

Zuman

This is really cool - excellent work! I feel that this project is likely to be in my future!
I currently use a REL S/50 sub with their Longbow wireless system. The Longbow transmits 24-bit data up to 45 feet via uncompressed 48kHz signals and it's very fast. I must admit I can't tell the difference between using it and a wired connection. Now I need to research an equivalent system to use with your design...
Thanks for posting this.

E-Zee

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Thank you for sharing.   It is well designed, well implemented. I think it is a beautiful piece in every aspect.

dayneger

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This is really cool - excellent work! I feel that this project is likely to be in my future!
I currently use a REL S/50 sub with their Longbow wireless system. The Longbow transmits 24-bit data up to 45 feet via uncompressed 48kHz signals and it's very fast. I must admit I can't tell the difference between using it and a wired connection. Now I need to research an equivalent system to use with your design...
Thanks for posting this.

Thanks for the feedback!  It would be terrific to see you make your own version.

I'm afraid I can't help much with wireless transmission... I just put in a long RCA and called it a day.  If you were ok deviating from using the Rythmik servo system, you might be able to migrate the guts of your REL over to this form factor?

artur9

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... Longbow wireless system. ...
Both Emotiva and SVS make wireless subwoofer connections, and I'm sure others do as well. 

I thought REL also sold their Longbow transmitter/receivers separately?