Collaborative Tapped horn project
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316a
diyAudio Member

Join Date: Dec 2002
Location: West London
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

 16th May 2007, 10:40 PM #402 freddi   diyAudio Member     Join Date: Aug 2005 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?
316a
diyAudio Member

Join Date: Dec 2002
Location: West London
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
 pd12.jpg (58.3 KB, 1205 views)

 17th May 2007, 01:12 PM #404 freddi   diyAudio Member     Join Date: Aug 2005 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
 17th May 2007, 06:28 PM #405 freddi   diyAudio Member     Join Date: Aug 2005 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
 17th May 2007, 10:23 PM #406 cowanaudio   diyAudio Member     Join Date: Jul 2004 Location: Canberra 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
 18th May 2007, 01:09 AM #407 freddi   diyAudio Member     Join Date: Aug 2005 hi William - just like to see what it does - maybe not enough to squint on-screen for hours :^) Freddy
 19th May 2007, 07:26 AM #408 vincentmolino   diyAudio Member   Join Date: May 2007 this is a beautiful thread...thanks to all
vincentmolino
diyAudio Member

Join Date: May 2007
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: 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: I am not sure I have used the script correctly. seh

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

 19th May 2007, 02:03 PM #410 freddi   diyAudio Member     Join Date: Aug 2005 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

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