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Old 16th May 2007, 10:30 PM   #401
316a is offline 316a  England
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Hi ,
I just realised that I've had a pair of Celestion BX18-4085 sitting in the cupboard for years . Here's a model

Quote:
| Large Tapped Horn for 18"

Def_Const |Horn Dimensions

{
a1 = 644e-4; |Area at throat (cm^2)
a2 = 650e-4; |Area at rear of driver (cm^2)
a3 = 1950e-4; |Area at front of driver (cm^2)
a4 = 1955e-4; |Area at mouth (cm^2)
l1 = 25e-2; |distance from throat to rear of driver(cm)
l2 = 400e-2;| distance of horn path
l3 = 40e-2; |Distance from front of driver to mouth (cm)
}

Def_Driver 'Dr1'

| Celestion bx18-4085

Sd=1129.6cm2
fs=30Hz
Qes=0.206
Qms=6.635
Vas=337.8L
Re=5.85ohm

system 'S1'

Driver Def='Dr1' Node=1=0=3=4
Waveguide 'W1' Node=2=3 STh={a1} SMo={a2} Len={l1} Conical
Waveguide 'W2' Node=3=4 STh={a2} SMo={a3} Len={l2} Conical
Horn 'H1' Node=4 STh={a3} SMo={a4} Len={l3} Conical
Flat-ish to around 22Hz . Makes a very large sub approx 46x60x200cm internal , so the wife will love it and I'll have to build a pair Driver will have to be mounted magnet outwards . As I've got the drivers it makes a cheap project . What do you lot think ?

cheers

316a
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Old 16th May 2007, 11:40 PM   #402
freddi is offline freddi  United States
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if one can afford the wood and possible WAF consequences then might not be too shabby! - it modesl nice - (how does one get past the typcial 6dB hole?)

316a's 18" tapped horn
http://img522.imageshack.us/img522/9056/18thjx4.gif

the large size of yyour horn plus good driver buys pretty good sensitivity and relatively hiah input Z

316a horn again
http://img522.imageshack.us/img522/4959/th18zaw1.gif

I wanted ot look at a tapped horn's excursion vs reflex but AJ-Horn seemed to be giving more edge to the reflex than what seems right. Are there any accurate freeware reflex modelers to handle excursion besides WinISD which locks up on my pc?

guess TH typically have double excursion notch areas- BIB BLH may show this too (I think)

BIB vs conical - all huge
http://img402.imageshack.us/img402/4...ibvscondn6.gif

cheers,
Freddy

ps anyone game to do a mustual load reflex box script?
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Old 17th May 2007, 09:53 AM   #403
316a is offline 316a  England
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Here's a good one . Precision devices 12" and it's a flapper with 7mm xmax

Quote:
| PD Tapped Horn

Def_Const |Horn Dimensions

{
a1 = 185e-4; |Area at throat (cm^2)
a2 = 190e-4; |Area at rear of driver (cm^2)
a3 = 1060e-4; |Area at front of driver (cm^2)
a4 = 1065e-4; |Area at mouth (cm^2)
l1 = 15e-2; |Distance from throat to rear of driver (cm)
l2 = 320e-2; |Line distance from rear of driver to front of driver (cm)
l3 = 30e-2; |Distance from front of driver to mouth (cm)
}

Def_Driver 'Dr1'

| PD 12SB30 xmax7mm

Sd=530.93cm2
fs=50.238Hz
Qes=0.316
Qms=5.024
Vas=58.94L
Re=5.493ohm
Le=1.773mH

system 'S1'

Driver Def='Dr1' Node=1=0=3=4
Waveguide 'W1' Node=2=3 STh={a1} SMo={a2} Len={l1} Conical
Waveguide 'W2' Node=3=4 STh={a2} SMo={a3} Len={l2} Conical
Horn 'H1' Node=4 STh={a3} SMo={a4} Len={l3} Conical
Anyone else have any decent models going ?

cheers

316a
Attached Images
File Type: jpg pd12.jpg (58.3 KB, 1179 views)
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Old 17th May 2007, 02:12 PM   #404
freddi is offline freddi  United States
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that PD12 does look noisy and climbing in the hit region.

here's sim on AJ as 3.2M "BIB" with driver offset 0.2* path length - might be a bit smaller (?) - look at power dip AJ predicts around 50Hz

PD12 BIB
http://img153.imageshack.us/img153/2325/pd12bibdr4.gif

PD12 180 sq.cm throat, driver at 0
http://img87.imageshack.us/img87/265...s180sthdp1.gif

the Z curves must tell some story
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Old 17th May 2007, 07:28 PM   #405
freddi is offline freddi  United States
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hey 316A - forgot to ask - what general script would you use for the following box? - will the regular model of areas adapt??

http://img526.imageshack.us/img526/3801/ml1blkvo4.gif
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Old 17th May 2007, 11:23 PM   #406
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G'day Freddi

You'd have to spend some quality time with the AkAbak manual to work that one out. I think the tapped horn concept shows much more promise.

Cheers

William Cowan
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Old 18th May 2007, 02:09 AM   #407
freddi is offline freddi  United States
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hi William - just like to see what it does - maybe not enough to squint on-screen for hours :^)

Freddy
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Old 19th May 2007, 08:26 AM   #408
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this is a beautiful thread...thanks to all
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Old 19th May 2007, 01:52 PM   #409
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Quote:
Originally posted by seh
I just came across this thread. I buildt some tapped horns this winter. I started with a small 8" for prototyping. Did some modelling in Hornresp. Then I have made two 30 Hz horns for 15". I did some measurements that I believe may be of interest to you. I tried an Altec 515B and a Jensen F15LL. Here are the curves:

Click the image to open in full size.


The red is the 515B and the blue is the F15LL. The horn is the same for both drivers. The measurements are done in the mouth. Measurements at 1m are similar and between 90 and 100dB.

I also had to try the Akabak script and did a quick test this evening. I only have TS data for the 515B as my computer with all my data on crashed last week and have not gotten to the data yet. Here is the modelled results for the 515B:

Click the image to open in full size.

I am not sure I have used the script correctly.
seh

wow thats a beautiful response for a sub in a 4 way system!!!

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Old 19th May 2007, 03:03 PM   #410
freddi is offline freddi  United States
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I'd like to see how folks are interpreting areas a2,a3, & a4 plus interpretation of l2. maybe FAQ plus a few labled diagrams would help

Click the image to open in full size.
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