C/E/X PA Flat to 30 (FT30) PA TH Awesomeness - diyAudio
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Old 27th November 2010, 09:07 PM   #1
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Default C/E/X PA Flat to 30 (FT30) PA TH Awesomeness

This thread is a continuation of woody1's thread (flat to 40Hz) which can be found here: 15" tapped horn with RCF

Epa, Xoc1 and others have been contributing their time and effort in attempt to help me reach my goal: Flat to 30Hz with as much clean output as possible - XTRA points for breaking physics and keeping it small. Heh.

We have found 15" drivers are limited by xmax far before maximum power is reached.

Here's where we left off:

Quote:
Originally Posted by Xoc1 View Post
Post 73 (Epa) @ 2.83V
30Hz = 95.28 dB
40Hz = 98.58 dB
3.3 dB difference
Click the image to open in full size.



Quote:
Originally Posted by Xoc1 View Post
Post 98 (Xoc1) @ 2.83V
30Hz = 96.17 dB
40Hz = 100.74dB
4.57 dB difference, so step from 30 to 40 Hz is 1.27 dB more...
Click the image to open in full size.
Click the image to open in full size.



My REAL 6 Fold mod (I meant to post) @ 2.83V
30Hz = 98.29
40Hz = 98.48
0.19 dB difference, so step from 30 to 40Hz is 4.38 dB less AND 2.12 dB more output at 30Hz

Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

What's your take on this version?


Quote:
Originally Posted by Xoc1 View Post
Post 98 is more efficient at both frequencies as would be expected as it is bigger. External is 600 litres compared to 397 for post 73.
Biggest misgiving I have about the post 73 design is the small S3 dimension.
At 1236 this is about the same size as SD. You can see how tight the mouth is positioned to the rear of the driver. This would require care and adjustment to make it work due to the driver seriously restricting the mouth. I suppose an access panel would be needed to actually get the driver in the box!
Quote:
Originally Posted by epa View Post
restriction is not to bad because of the neodinium magnet.
Click the image to open in full size.
Quote:
Originally Posted by epa View Post
i designed the post 73 th for the use in a cardroid sub aray.
this is why its symetric.
i like xco1 model 2,its a easier bild but for me a little to big.

i wil work this weekend on it to give you al the details
meanwile here are some designs,most of them are posted here.to make your choice more diffecultClick the image to open in full size.
Must they (post 73) be used in a cardioid sub array? Will I/we loose any performance if they're not?


Quote:
Originally Posted by epa View Post
yes the idea was to make the front parts removeble
(Referring to post 73)

Quote:
Originally Posted by epa View Post
ok lets make it 15mm.i think 18 is a bit over the top.
horizontal there are only small spaces ,and vertical wil do some bracing in the middle.
front wil be removeble in one piece.
it might be a good idee to send you the dwg,dxf file when im finnished.
then you can make a 1 on 1 print on A0 paper(it fits)in the copy store.
cost about 4 euro here on this side of the pond
Quote:
Originally Posted by epa View Post
justin ,we need to make a new topic,because this has no longer anything to do with woodys design ,
Welcome


Any others: feel free to post your design if you believe it betters any of these and fits the goal posted above. Many thanks!

Justin

Last edited by CRESCENDO; 27th November 2010 at 09:29 PM. Reason: Adding more info
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Old 27th November 2010, 11:21 PM   #2
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Note: I will be crossing over at 80 or 100Hz, so designs need only be flat up to that point.

Note: I would rather the low end freq response drop off after 30Hz than drop off after 40Hz. A lot of material played has 25-30Hz focus.

So far, I'm debating between Xoc1's modded 6 fold (Xoc1.m) also referred to as 'post 98', my 2nd modded 6 fold (Xoc1.cm) and epa's small (392L) symetrical fold (epa.sm) also referred to as 'post 73'. The following table will show each of these designs maximum output (all xmax limited) and coincidentally use the same driver (BMS 18N850v2). The mathematical xmax of 16mm one-way, is used for these calculations:

Box
Freq ______30_____ 35_____ 40_____ 55_____ 65_____ 80_____ Hz

Xoc1.cm: _126.5___ 127___ 126.5__ 126.5___ 127____ 127_____ dB
Xoc1.m: __125.8___ 129.2__ 130.1__ 130.1___ 130____ 130
eps.sm: __124.7___ 127.2__ 127.7__ 127.6___ 127.6___ 127.8

Below is a .txt file if you would like to update this info for your own use or to add and re-post for further comparisons.
Attached Files
File Type: txt DIY Sub Comparisons.txt (262 Bytes, 99 views)
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Old 27th November 2010, 11:38 PM   #3
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Updated .txt file
Attached Files
File Type: txt DIY Sub Comparisons.txt (408 Bytes, 131 views)
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Old 28th November 2010, 08:32 AM   #4
epa is offline epa  Netherlands
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verry nice justin.
i,m almost finnished wit the drawings.i wil post them shortly.
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Old 28th November 2010, 09:27 AM   #5
epa is offline epa  Netherlands
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here we goClick the image to open in full size.Click the image to open in full size.Click the image to open in full size.Click the image to open in full size.Click the image to open in full size.Click the image to open in full size.Click the image to open in full size.Click the image to open in full size.
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Old 28th November 2010, 09:33 AM   #6
epa is offline epa  Netherlands
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Quote:
Must they (post 73) be used in a cardioid sub array? Will I/we loose any performance if they're not?
no ,its just easy'er to use in csa stacks if they are symetrical.
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Old 28th November 2010, 10:04 AM   #7
epa is offline epa  Netherlands
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Xoc1.m moddel is 601 ltrs,minus the cutoff bit at the bottem where you can nicely fit 2 casters for easy transport.
i can't find the drawing of the Xoc1.cm ?
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Old 28th November 2010, 11:15 AM   #8
epa is offline epa  Netherlands
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aprox same volume /same output,but easyer bild , actualy 400 ltrs (not 440)

Click the image to open in full size.
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Old 28th November 2010, 03:53 PM   #9
Xoc1 is offline Xoc1  United Kingdom
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Quote:
aprox same volume /same output,but easyer bild , actualy 400 ltrs (not 440)
oops
Been out and about this weekend
Saw Leftfield in concert
18 off TSW218 turbosound bass cabs so 36 x 18" 104dB/W hornloaded drivers and Turbosound Aspect point source PA very nice.
As it is not possible to break the laws of physics a choice has to be made. Basically size can be traded against efficiency.
Crescendo you will need to make a choice, based on what you are prepared to carry and what amplification you have available.
The bandwith of the cab is 30 to at least 100hz I would be wary about introducing a dip in the response above 100hz especially if the real cab response does not match the sim exactly.
My personal choice would be for efficiency, its easier to turn the bass down rather than up!
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Old 29th November 2010, 04:25 AM   #10
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Quote:
Originally Posted by epa View Post
no ,its just easy'er to use in csa stacks if they are symetrical.
Got it

Quote:
Originally Posted by epa View Post
Xoc1.m moddel is 601 ltrs,minus the cutoff bit at the bottem where you can nicely fit 2 casters for easy transport.
i can't find the drawing of the Xoc1.cm ?
There are only hornresp jpegs - the 3rd on this page (1st is your small TH aka epa.sm, then Xoc1's modded TH aka Xoc1.m, and finally my modded TH aka Xoc1.cm

Quote:
Originally Posted by epa View Post
aprox same volume /same output,but easyer bild , actualy 400 ltrs (not 440)

Click the image to open in full size.
Lookin this one over now - looks nice. I'd definitely appreciate a simpler build and easy transportability. I'll be lookin over these closely.

Quote:
Originally Posted by Xoc1 View Post
oops
Been out and about this weekend
Saw Leftfield in concert
18 off TSW218 turbosound bass cabs so 36 x 18" 104dB/W hornloaded drivers and Turbosound Aspect point source PA very nice.
As it is not possible to break the laws of physics a choice has to be made. Basically size can be traded against efficiency.
Crescendo you will need to make a choice, based on what you are prepared to carry and what amplification you have available.
The bandwith of the cab is 30 to at least 100hz I would be wary about introducing a dip in the response above 100hz especially if the real cab response does not match the sim exactly.
My personal choice would be for efficiency, its easier to turn the bass down rather than up!
Oh nice! Those Turbosound TSW-218s are monsters! I heard 8 inside a warehouse - SPL levels were ridiculously high. I loved it

I was half joking about breaking physics. Epa's small design plays about as loud as the one I modded, but the one I modded has 2.3 more dB at 30Hz. That's what I was referring to as breaking physics - his was smaller and AS loud, for the most part. I know I won't get em ALL

Again, I want the focus to be 30Hz and flat from there. That's where I would need to turn it up, so like you said, start with something that's loud at 30Hz to begin with.

Xoc1, you are excellent at bringing more efficiency to designs - props to you! I'm wondering if you or epa could bring more efficiency (from 30Hz) to the Xoc1.cm hornresp design I posted above

These will be used for mobile apps, so wheels/casters are sought after.
Power? I'm sure a QSC PLX3402 will fit the bill nicely and can be found online for nice prices. I've got an RMX2450 atm - so, I'll be able to do shows with that in the meantime.

Once again, many thanks,
Justin
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