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Old 1st February 2011, 05:51 AM   #301
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Quote:
Originally Posted by jbell View Post
fhperez:

Thanks for the update.

Yes these are light. I do installs, and handling a sub 30' in the air makes a person think twice about every pound of weight. I never want to install a heavy weight sub again. I had to go see the chi-o and have my back cracked after my last 150lb sub installation. 42lbs for a sheet of auroco, 7lbs for a 3015lf plus paint and hardware. Basically a 50lb sub. The entire point of this thread for 'single sheet' was primarily due to weight and simple design. I needed a lightweight design I could kick out in part of a day.

Yes, they can walk. The 'bottom' as you have them pictured only has a single brace, which is where the walking is coming from. More bracing would eliminate some cabinet flex and some walking, but then I designed this as an install sub. More bracing = less spl and more weight in my experience, and I am more than willing to allow a 'little' cabinet flex. I would personally bring a small carpet with rubber backing instead of rubber feet. Feet tend to get torn off of a cabinet.

2 tops per sub??? That is blasphemy to many people. There are those who advocate at minimum 2 subs per top. 2 of the SS15's keeping up with 4 EV's at war volume is a pretty good testament to this design. I will repeat scott's comment about TH's. "They bloom at war volume, reflex boxes wilt."

How did the texture gun work out? Couldn't tell much about the finish from your posted pics.

On the osx on 'other' hardware sites, they have listed which motherboards are fully compatible and which aren't. If you want a full size box, start with the motherboard and put it in whatever case you want. The 10v is really a nice little osx machine.... that's why I recognized it

Thanks again for the update -- I really like this design. It's only real downfall is it's a little short in the 40hz department in single cabinets. To hear your dj friend say it was 'loud and low' from across the hall when running pairs made me smile.
Jbell, you state that "more bracing=less spl". Can you elaborate. I'm new to TH. My prior understanding was a stiffer box was always more desirable.

Thanks
DLStryker
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Old 1st February 2011, 09:01 AM   #302
AndrewT is offline AndrewT  Scotland
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less bracing = more vibration of the box walls.
That vibration is sound output. Some of this sound output is at frequencies where the panels have a high Q and this increases the total acoustic power delivered by the "speaker".

For accurate bass reproduction we try to eliminate the resonances and give the speaker a reasonable chance of giving a "flat" output. This reduced distortion output is cleaner but less loud.
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Old 2nd February 2011, 01:36 AM   #303
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Hi there: Without rdesigning JBELL's one sheet box, an experimental stiffer box could be constructed ( with the exact internal volumes ) by using laminated internal components and external walls braced with studs and beams. Using the same driver for both types of construcion, tests could then determine if SPL reduction is caused by panel vibrations or the inclusion of internal bracing ( which reduces internal volumes ). 3/4" laminates could be made from 1/2" plywood with both sides bonded with 12gage sheet steel or fiberglass over 1/2'' ply. ...regards, Michael
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Old 2nd February 2011, 01:52 AM   #304
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Quote:
Originally Posted by j.michael droke View Post
Hi there: Without rdesigning JBELL's one sheet box, an experimental stiffer box could be constructed ( with the exact internal volumes ) by using laminated internal components and external walls braced with studs and beams. Using the same driver for both types of construcion, tests could then determine if SPL reduction is caused by panel vibrations or the inclusion of internal bracing ( which reduces internal volumes ). 3/4" laminates could be made from 1/2" plywood with both sides bonded with 12gage sheet steel or fiberglass over 1/2'' ply. ...regards, Michael
A simpler way, if all we're testing for is the difference caused by panel flex, is to clad the external panels of the box with an additional layer of 3/4 ply. The internal volumes and dimensions will remain the same, but the box should be quite a bit stiffer (and heavier, LOL).
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Old 2nd February 2011, 09:37 AM   #305
AndrewT is offline AndrewT  Scotland
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the internal panels will also vibrate. That is why there is some internal bracing in the single sheet TH.
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Old 2nd February 2011, 01:50 PM   #306
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Quote:
Unfortunately, I do not have SolidWorks, but something similar can be done in SketchUp.
soho; I am now learning SketchUp. Can you share your model of the SS15 with me? Andy
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Old 2nd February 2011, 11:11 PM   #307
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Default I built Jbells ss15

Well, JBells got a real winner with the ss15. And we are all the better for it due to his sharing this amazing design. I just finished the internals this afternoon, used tape and foam to seal the seams and ran a level test. I used a ratshack digital meter, 2.83v at one meter. A few things different. I made the exterior of the box out of 3/4 ply. The extra 1/4" of wood is outside of the plan dimentions so the internal dimensions are too plan. Secondly when I bought my 1/2" ply for the internals a grabbed a 5/8" sheet someone had put on the stack without my realizing it. It wasn't till late this afternoon that I realized the error. Luckily for me I doesn't seem to have hurt a thing. The difference in thickness is evenly divided on each side of the layout lines. I decided to test it first without bracing to see the results. Tomorrow i"ll open it up and brace it, just to see if it affects the results. Maybe do it several times to see how much bracing I can get away with. I think the way it is I can hear panel resonance, but i'm not sure.

MY AMP has a 50hz hi pass filter which I didn't disconnect. So the bottom end will be better than measured, without it.

Here are the results:

40hz 101db
45hz 104db
50hz 108db
55hz 109db
60hz 111db
65hz 111db
70hz 112db
75hz 112db
80hz 110db
85hz 112db
90hz 113db
95hz 112db
100hz 113db
105hz 112db
110hz 112db
115hz 113db
120hz 113db


A couple questions: Is there any reasons to test it at higher frequencies, since i'll probably cross it over around 120hz?

Will putting a speaker jack plate in the back mess with the responce?

I'm assuming cutting a hole to insert a handle is a bad idea?

This is my s**t eating grin:
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Old 3rd February 2011, 12:50 AM   #308
tb46 is offline tb46  United States
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Location: Texas
Hi runrod1948,

I don't think the material thicknesses will adversely affect the performance of this box, it'll be heavier though.

As to your question: "...Is there any reasons to test it at higher frequencies..", it would be nice to see if the upper peaks and valleys we see in Hornresp are there or not, particularly the deep null around 330Hz. Also, well sealed speaker plates or handles (within reason, in the bigger bends) will not affect the performance.

Looking forward to your data with different bracings.

Regards,
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Old 3rd February 2011, 02:27 AM   #309
FlipC is offline FlipC  United States
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I think your test are a bit skewed.

Weighting on the rack shack?
Distance from mouth to meter?
Voltage into speaker?
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Old 3rd February 2011, 07:19 AM   #310
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Quote:
Originally Posted by j.michael droke View Post
Hi there: Without rdesigning JBELL's one sheet box, an experimental stiffer box could be constructed ( with the exact internal volumes ) by using laminated internal components and external walls braced with studs and beams. Using the same driver for both types of construcion, tests could then determine if SPL reduction is caused by panel vibrations or the inclusion of internal bracing ( which reduces internal volumes ). 3/4" laminates could be made from 1/2" plywood with both sides bonded with 12gage sheet steel or fiberglass over 1/2'' ply. ...regards, Michael
Totally have to walk before you can run...

I'd be happy with 1/24 oct freq/phase/impedance charts... done in a repeatable ground plane fashion.

Every time I hear jbell's box measures better than it sims, i'm just curious why the th designs with lots of solid data measure close or very close to an accurate sim.

The boxes I'm thinking of are lilmikes shiva, 6.5" anarchy, th-spud, brians POC, wood1y's 15" tapped horn with RCF all have appeared to be measured accurately and to my eyes are close to the sim.

Last edited by hellonwheels; 3rd February 2011 at 07:29 AM.
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