sub sticky question

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himhimself
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Location: Bloomington IN

sub sticky question

#1 Post by himhimself » Thu May 06, 2021 11:10 am

So in the sticky, it states "this shows a pair of coupled Tubas using wall loading. With two cabs the distance from the wall is 9 inches for T24s, 12 inches for T30s, 16 inches for T36s. For each additional layer of cabs add another 4 inches distance."
Would the width (which becomes height in this orientation) influence the optimum distance to the wall? How would that work? Is 12" for T30's at max width? mid-point in the range?
When I get my second pair finished, i am hoping to play around with various configurations and measure the outputs to get some real world numbers with my rig. Still have my arm in a sling... :x
2xT30 (20", 3012LF)
2xT30 (21", 3012LF)
4xOtop J-array (Beta12, melded/straight piezos)
Truck Tuba (MCM)
Next up: 2xJack12 or family of table tubas

himhimself
Posts: 513
Joined: Fri Nov 13, 2015 9:34 pm
Location: Bloomington IN

Re: sub sticky question

#2 Post by himhimself » Sat May 08, 2021 3:18 pm

Nobody willing to pontificate?? :noob:
2xT30 (20", 3012LF)
2xT30 (21", 3012LF)
4xOtop J-array (Beta12, melded/straight piezos)
Truck Tuba (MCM)
Next up: 2xJack12 or family of table tubas

Grant Bunter
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Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
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Re: sub sticky question

#3 Post by Grant Bunter » Sat May 08, 2021 4:30 pm

The statements re distance are pretty definitive.
I'm sure if cab width was an additional modifier it would be mentioned by Bill.

So, you're going to be setting up with the mouths 16" from the walls in the corner.

While it's great you're going to check it all out, I find the opportunity to corner load in all the venues I've worked in, to be less than a handfull.
Don't forget the prime directive either, mouths not between 2' and 8' of a boundary...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

himhimself
Posts: 513
Joined: Fri Nov 13, 2015 9:34 pm
Location: Bloomington IN

Re: sub sticky question

#4 Post by himhimself » Sat May 08, 2021 5:36 pm

Grant Bunter wrote:
Sat May 08, 2021 4:30 pm
I find the opportunity to corner load in all the venues I've worked in, to be less than a handfull.
Agree Grant, I've actually never had it work out to corner load. But wall load, yes. One spot lets me use the exterior wall of a building - 300' long x 40' high smooth concrete boundary!
It's actually the specificity of the distances in the sticky that got me thinking. I would think two slims stacked would work best at the same distance as one fat cab of the same overall mouth width. But cab width isn't mentioned, therefore the question. Maybe Bill will weigh in?
2xT30 (20", 3012LF)
2xT30 (21", 3012LF)
4xOtop J-array (Beta12, melded/straight piezos)
Truck Tuba (MCM)
Next up: 2xJack12 or family of table tubas

Seth
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Location: Sacramento, California, USA
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Re: sub sticky question

#5 Post by Seth » Sat May 08, 2021 5:54 pm

I was thinking along the same lines as Grant, but then considered some other angles.

A T30 with 12's can be built between 16" & 30" wide. A dual loaded cab can be built as narrow as 29"... A dual loaded cab being the equivalent to two single cabs of half the width.

The question arises for me too... Would the dual loaded cab of a slimmer width than a max width single loaded cab necessitate the additional 4 inches and the wider single loaded cab wouldn't? And a 5 foot tall stack of 4 single driver max width cabs would be the same additional 4" as 2 dual loaded slims of less than half the stack height?

Seems a reasonable line of questioning to me. But, I have no idea.
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

Grant Bunter
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Location: Ilfracombe Queensland Australia
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Re: sub sticky question

#6 Post by Grant Bunter » Sat May 08, 2021 6:41 pm

himhimself wrote:
Sat May 08, 2021 5:36 pm

It's actually the specificity of the distances in the sticky that got me thinking. I would think two slims stacked would work best at the same distance as one fat cab of the same overall mouth width. But cab width isn't mentioned, therefore the question. Maybe Bill will weigh in?
Sometimes the answers aren't exactly stated. Perhaps the answer has, in part, just been answered by Bill in your TT question.
Width affects sensitivity in the lows, but not extension or phase response...
Perhaps reinforcing that part of the answer is in the sticky itself, just not at the same spot as where the distances are stated.
in that (paraphrased) "boundary loading provides an extension of the horn mouth" (leading to increased sensitivity, +6dB for a wall, +12dB for a corner, but not extension).

Also remember that doubling cab count adds +6dB, and flattens response in the passband.

It's never easy working this stuff out lol, but I maintain that if width altered the value of the distances stated, it would be mentioned...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Bill Fitzmaurice
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Re: sub sticky question

#7 Post by Bill Fitzmaurice » Sat May 08, 2021 9:12 pm

The distance to the wall would be increased with a large enough stack, say eight cabs or more, but at that point you probably wouldn't gain much from aiming at the wall anyway.

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