Down-firing cylindrical sealed servo subs

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donw

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Down-firing cylindrical sealed servo subs
« on: 18 Jan 2020, 08:55 pm »
I'm thinking about building cylindrical, down-firing sealed sub woofers using the servo sub kit 2. Is there anything inherently inferior about either the shape of the enclosure or the direction of the driver? I'd assume the ideal volume would be the same as a sealed box, 1.5 - 1.8 cubic feet.

corndog71

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Re: Down-firing cylindrical sealed servo subs
« Reply #1 on: 18 Jan 2020, 11:24 pm »
As someone who built an upward facing cylindrical servo sub I have to say, good luck!   :lol:

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Saturn94

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Re: Down-firing cylindrical sealed servo subs
« Reply #2 on: 19 Jan 2020, 02:10 am »
As I understand it the cylinder shape offers advantages in rigidity.

I had an SVS cylinder sub for many years (16-46PC+) and loved it!

Jonathon Janusz

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Re: Down-firing cylindrical sealed servo subs
« Reply #3 on: 19 Jan 2020, 02:28 am »
(digging way back in the cobwebs of memory)

I built some speakers with dual 8-ohm servo subs in each speaker years ago, in which the internal cavities were designed as cylinders for the structural advantage described above.  In addition to being cylinders, no further skeleton-izing of the internal cabinets/bracing was done (these were stacked mdf constructed cabinets) so aside from being insanely heavy they were probably as inert from sheer mass as could be built. 

When designing the speaker cabinets, if I am remembering correctly, the only thing Danny mentioned when reviewing the plans was to make sure the length/dimensions of the internal tubes did not create a problematic standing wave situation within the frequency range the subs were needing to play.  I vaguely remember my tube dimensions were the driver cutout diameter by about two feet.  A stiffly built more traditional box of different dimensions would have been (at least on paper) more ideal, but my implementation seemed work work well enough.  However, take that with a grain of salt as I didn't at the time have any way of objectively comparing the performance of the cylinder-based cabinets to a more common box design.

For what it is worth, having now owned front-firing sealed box versions using the parts in that kit, if I were to do it again I would go with a more traditional (and front-firing) box design rather than the cylinder.  It would take less space in the room, less materials, and because I was often playing the subs fairly high up in frequency front firing them seemed to work better integrating them with my mains (when run in stereo pairs).

corndog71

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Re: Down-firing cylindrical sealed servo subs
« Reply #4 on: 19 Jan 2020, 03:43 pm »
Yeah, I'm sort of torn about my tube sub.  On one hand I put a lot of work into building it and I'm not a woodworker but I still have a lot of pride in it.  I cut 38 pieces of MDF into 37 14" wide rings with roughly 13" holes, the baffle and 2 solid pieces for the bottom.  Then I spent several days gluing them together.  I figured 1" thickness would be pretty solid but if you rap on it there is a detectable resonance.  I kind of wish I had made some bracing rings but at the time i just wanted to get it done.  It works well and only weighs about 53 pounds though I still wonder if a traditional box might've performed better.  Not to mention being able to house the amp as well would be nice. 

Tyson

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Re: Down-firing cylindrical sealed servo subs
« Reply #5 on: 19 Jan 2020, 09:03 pm »
I used to have an SVS tube sub and a friend had even bigger DIY tube subs.  IME they put out a lot of bass but were always soft sounding so I have transitioned back to front firing subs.

FullRangeMan

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Re: Down-firing cylindrical sealed servo subs
« Reply #6 on: 20 Jan 2020, 12:26 am »
I'm thinking about building cylindrical, down-firing sealed sub woofers using the servo sub kit 2. Is there anything inherently inferior about either the shape of the enclosure or the direction of the driver? I'd assume the ideal volume would be the same as a sealed box, 1.5 - 1.8 cubic feet.
Is there anything inherently inferior about either the shape of the enclosure or the direction of the driver?
The best enclosure shape is the sphere, the second best are the tube or cylinder, they dont have parallel walls. The worst shape is the cube.
« Last Edit: 20 Jan 2020, 09:08 am by FullRangeMan »

Doublej

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Re: Down-firing cylindrical sealed servo subs
« Reply #7 on: 20 Jan 2020, 12:38 am »
A shorter alternative would be the bucket sub!

Danny Richie

Re: Down-firing cylindrical sealed servo subs
« Reply #8 on: 22 Jan 2020, 02:33 pm »
Is there anything inherently inferior about either the shape of the enclosure or the direction of the driver?
The best enclosure shape is the sphere, the second best are the tube or cylinder, they dont have parallel walls. The worst shape is the cube.

With a sub it really doesn't matter that much. The wavelengths that it plays are far too long to propagate within the space that they are in. The box really just deals with changing pressures.

FullRangeMan

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Re: Down-firing cylindrical sealed servo subs
« Reply #9 on: 22 Jan 2020, 07:34 pm »
With a sub it really doesn't matter that much. The wavelengths that it plays are far too long to propagate within the space that they are in. The box really just deals with changing pressures.
Do you think a sealed box with a big Variovent/Aperiodic will delivery a good sound under 270Hz with a 15'' woofer?  QTS 0.34
https://www.parts-express.com/pedocs/specs/290-597--eminence-kappalite-3015-spec-sheet.pdf

Danny Richie

Re: Down-firing cylindrical sealed servo subs
« Reply #10 on: 25 Jan 2020, 01:43 pm »
Do you think a sealed box with a big Variovent/Aperiodic will delivery a good sound under 270Hz with a 15'' woofer?  QTS 0.34
https://www.parts-express.com/pedocs/specs/290-597--eminence-kappalite-3015-spec-sheet.pdf

I'd be more concerned with cone material and moving mass (stored energy).

FullRangeMan

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Re: Down-firing cylindrical sealed servo subs
« Reply #11 on: 25 Jan 2020, 02:20 pm »
Thanks Danny :thumb: for your valuable help.