Single sheet TH challenge

I read that 45 degree deflectors are no good, your thoughts?
That statement (I was one of them) was based on the wrong assumption that they were working as sound-wave reflectors. The main role for corner bracing is to optimise corner volumes. That’s why I prefer to call them optimisers instead of ‘de-or-re-flectors’.

Should I do the corners of the other 180 degree bend as well? Would it be worth it to use one half of a 10" pipe in that bend?
I shouldn’t do the 180 degree corners. I only changed your 180 degree bend in your example as you drawing showed a minor error in expansion at this point. Maybe it's just the drawing but in Oliver new drawing that would show up. Your 10” pipe suggestion is something you can try although I prefer to keep my cabs out of wood.

So you are saying the additional deflectors would keep the air molecules moving faster around the outside of the bends?
Nope, these optimisers have almost no effect on the higher speed air molecules that are passing along the outside of a bend and that is exactly what you want! Corners without optimisers can have a negative effect on the speed of the air molecules along the outside of a corner. So it is not just the volume error that is involved here. Also the positions of these corners are related to their corresponding wavelength. The only problem is that the wavelength isn’t always the same but that needs a much longer explanation or Akakbak if you want practical results...
 
andy -- I'll repeat myself... if you are going to prototype a cabinet that has never been built -- don't waste your baltic birch prototyping.

Go buy 3/4" flakeboard subfloor or cdx or something like that... Don't glue your second side on and don't glue your additional braces/boards until you are positive they have the effect you want. 3/8" door gasket foam and screws will get you an air tight seal.

If you want something mouse proof -- petscreen.
 
I only changed your 180 degree bend in your example as you drawing showed a minor error in expansion at this point.
Djim; I just paralleled the new piece to the 14 3/8" board and so both dimensions came out to 5 1/2". This seamed fine on the unfolded hand drawing I did but it could be off. So you moved the new 7 5/16 board? What would the new upper dimension be? Andy
 
Rabbit fencing wire

I used rabbit fencing wire. Approximately 1 cm squares. Galvanised steel.
(Looks very ugly) On top of that I added a layer of speaker front foam, and that looks nice. So I have a strong, flexible front for my stadium horns - which are still in use for now. This provides no stiffening, only a little tension. But the wood is thicker, so none is needed.

I have a lot of people dance / jump on my stadium horns, and I am afraid that the 1/2 inch SS15 wood wouldn't like that!

Am following the thread eagerly, (hoping that) maybe the 3/4 inch version will be the right one for my party animals.

Regards, Ben
 
As in vinyl?

Pet Screen - Pet Proof Screening

Can the mice eat thru it?
Andy

Any of my installs where I thought mice, bugs, birds was an issue I used petscreen and have had no issues.

To your question, mice can eat through anything, even plywood in some cases. Your best bet for storage is to put the cabinets face to face and use a ratchet strap to strap them together in pairs.
 
Placement of tapped horns

Maybe I'm thinking about this too much - but anyway, here goes:


When laying tapped horns on their side (e.g in front of a stage),

is it best to have them:

(A) top touching bottom - to have a wider area with the same level (mouths are a few feet apart)

(B) or bottom to bottom to achieve a coupling effect and avoid any power alleys? (mouths essentially touching)

and with many small tapped horns, all standing up (i.e. driver end standing on floor?), or a small stack on their sides?

Regards, Ben
 
Maybe I'm thinking about this too much - but anyway, here goes:


When laying tapped horns on their side (e.g in front of a stage),

is it best to have them:

(A) top touching bottom - to have a wider area with the same level (mouths are a few feet apart)

(B) or bottom to bottom to achieve a coupling effect and avoid any power alleys? (mouths essentially touching)

and with many small tapped horns, all standing up (i.e. driver end standing on floor?), or a small stack on their sides?

Regards, Ben

Ben... it's like getting older... it depends... (sorry for the bad joke)

Due to the directionality, you have to in various rooms play with things to get the bass as even as possible. In general, I've found that on their sides has a wider pattern, and that makes on side better indoors. I have personally set up like your (B) description in gymnasiums with success. Scott runs 6 fury subs, 3 in a stack on their sides, with tops above with great success. Outdoor, where you want as much directionality as possible, I have stood them up side by side centered in front of the stage. Not saying this is the best or only way to do it, just what I've done in the past. In durability terms of the ss15 and people dancing on them. Just make the sides out of 3/4" and everything else out of 1/2" like flip did -- that seems to be the best durability upgrade.

Andy,
I use smaart, a reference mic, and a spl meter. However you can download test tones here RealTraps - Test Tone CD and then use any spl meter that is +- 1.5db and get reasonable results. Here is a link to a 'typical' meter. Tenma Digital Sound Level Meter | 72-942 (72942) | Tenma
60hz sine wave, typical dmm and 2.83v seems reasonable enough to me to set level.

There are calibration offset charts if you choose to go the radio shack spl meter route that also gets you pretty close. I will listen to a sub with sine waves every 1hz to know if there are problems I need to fix, and then record every 5hz -- just because that's how I started doing it, and I try to stay consistent one measurement/design to the next.

Yes 3015lf's should be broken in, the 20-30hz test tone from ethan is a good option, and there are many ideas on what level and how long you should break them in... (I personally like to loop the 20-30hz wave file, and then a 60 second silence file just because...)
 
Andy,
I use smaart, a reference mic, and a spl meter. However you can download test tones here RealTraps - Test Tone CD and then use any spl meter that is +- 1.5db and get reasonable results. Here is a link to a 'typical' meter. Tenma Digital Sound Level Meter | 72-942 (72942) | Tenma
60hz sine wave, typical dmm and 2.83v seems reasonable enough to me to set level.

There are calibration offset charts if you choose to go the radio shack spl meter route that also gets you pretty close. I will listen to a sub with sine waves every 1hz to know if there are problems I need to fix, and then record every 5hz -- just because that's how I started doing it, and I try to stay consistent one measurement/design to the next.

Yes 3015lf's should be broken in, the 20-30hz test tone from ethan is a good option, and there are many ideas on what level and how long you should break them in... (I personally like to loop the 20-30hz wave file, and then a 60 second silence file just because...)

Thanks Jim; I have a Phonic PAA2 SPL meter and a good Fluke RMS meter. I will down load the test files. I will break in for 20 hours with rock music, that should be good. Andy
 
Please, every time you are posting SPL charts provide it with following information:

1.) Temperature and humidity numbers if possible
2.) Information about surrounding like buildings and their distances
3.) Brands and model numbers of all your used equipment and software
4.) Detailed information about measuring distance (1meter, 10meter and 100meter if possible)
5.) Detailed information about mic position
6.) Detailed information about test tones and used voltage (2,83V or 28,3V – True RMS if possible)
7.) Driver model/brand and cab design

This will help people when they want to look back at your chart post and don’t have to search/discuss this information each time...
Remember it’s not a contest about who has the best gear but it’s all about being consistent and providing the necessary information.
 
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4pyros_SS15_mod

Hi 4pyros,

I entered your dimensions into Acad, and got the values for Hornresp from there. I would take jbell's advice in Post #524: "...test before you cut...". There seems to be no real improvement over the original SS15, and there is a larger dip @ 144Hz than in the SS15. There are also quite a few good size gaps in the drawing when inserting your dimensions, so again: measure twice, cut once.

When trying to get a feel for the SS15 I found that you have to double the volume to get any real improvement in the frequency response without giving up output level. The SS15 is one fine box. Another size that seems to work, and provides reasonably fitting dimensions for cutting wood is: 22W x 23.9375D x 31.9375H. It is actually quite a bit of work to get the layout to flow evenly around those corners.

I'll attach my drawings in pdf format, it was done late at night, let me know if you find any big errors..

Regards,
 

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Hi 4pyros ... Take a look at the impedance curve in Hornresp, it may help. Otherwise, maybe these threads by Don Snyder will be of use:

http://www.diyaudio.com/forums/subwoofers/179653-elements-tapped-horn.html

http://www.diyaudio.com/forums/subwoofers/135879-evolution-tapped-horn.html

Regards,

Thanks, Oliver. I wondered if anyone found these posts helpful. Tom D validated the "Evolution..." post.

Good call on the test files, guys. I used GoldWave to roll my own, but I thought that full-steps were fine enough detail (1/6 octave). I'm glad to hear
that RatShack meters are good enough at bass frequencies.

I tried to upload some DWG files, but the Forum doesn't allow it ...
 
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