Collaborative Tapped horn project

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316a

316a

Member
Joined 2002
Hi ,
I just realised that I've had a pair of Celestion BX18-4085 sitting in the cupboard for years . Here's a model

| 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
Click to expand...

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
 
freddi

freddi

Member
Joined 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/img402/4195/bm15cxbibvscondn6.gif

cheers,
Freddy

ps anyone game to do a mustual load reflex box script?
 
316a

316a

Member
Joined 2002
Here's a good one . Precision devices 12" and it's a flapper with 7mm xmax

| 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
Click to expand...

Anyone else have any decent models going ?

cheers

316a
 

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V

vincentmolino

Member
Joined 2007
seh said:
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:

An externally hosted image should be here but it was not working when we last tested it.



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:

An externally hosted image should be here but it was not working when we last tested it.


I am not sure I have used the script correctly.
seh
Click to expand...


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

:cool:
 
freddi

freddi

Member
Joined 2005
Hi William --

re:Lab12 - how smooth of a model have you produced and what might one jiggle in the model?

since tapped (and other BLH) exhibit mass loading, is it a good idea to start with a driver whose fs is ~1/2 octave higher than the horn's 1/4 wave?

Best,
Freddy
 
freddi

freddi

Member
Joined 2005
guess it depends on goal - 2206 looks like a nice driver - maybe Walt and William will give comments as i don't yet know enough to make truly useful simulations. At some point one would have to decide whether TH is more useful for a situation than FLH and possibly consider a highpass filter.

btw- anyone here have nearfield measurements of their TH's cone? - does it exhibit two excursion dips? - or is one hidden? (IIRC Karlson make different F "near-cone" nulls as mic travels from top of driver to bottom of driver)

FWIW a 3M TH sim with 4 drivers - higher fs is smoothest
http://img70.imageshack.us/img70/2372/3m4drvrmx5.gif
 
316a

316a

Member
Joined 2002
2206H script , needs a little more work .

| JBL 2206H Tapped Horn

Def_Const |Horn Dimensions

{
a1 = 215e-4; |Area at throat (cm^2)
a2 = 220e-4; |Area at rear of driver (cm^2)
a3 = 1840e-4; |Area at front of driver (cm^2)
a4 = 1845e-4; |Area at mouth (cm^2)
l1 = 15e-2; |Distance from throat to rear of driver (cm)
l2 = 340e-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'

| JBL2206H 8max 8mm 12"

Sd=413cm2
fs=52Hz
Qes=0.34
Qms=4.5
Vas=62L
Re=6.9ohm
Le=1.5mH

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
Click to expand...

Looks like a good driver with xmax of 8mm .

cheers

316a
 
316a

316a

Member
Joined 2002
freddi said:
hi 316a - good start on 2206 - how are you esitmating throat, flare and mouth size vs TS parameters?
Click to expand...

I do what was suggested a few posts back as I don't really know what I'm doing . Just play around with the numbers until the thing models ok ;) Then do it again etc . Eventually I may understand what is really going on :D

cheers

316a
 
V

vincentmolino

Member
Joined 2007
i thought it might be a good driver...since it pretty much the same motor and magnet of the 2226H which is one of jbls best speakers....but the only differnece is is having only to push a 12 inch cone......i thought about this cus i think someone mentioned and it appeared that Mr. Danely uses car high end subs with large magnets for control.
 
V

vincentmolino

Member
Joined 2007
i really hope a TH works well for the JBL 2226J...i think its the best driver for (the money) on the market.

notice i said J....because used 2226H's and J's on ebay go for 150$.....new 400.

usually u buy crap on ebay as far as used PA equipment from roadies throwing cabs around, and other ways of wear and tear but the J's (the 16 ohm version) are used and sold by home cinema jbl fanatics (like in the jblaudio heritage forum) that keep this 4648-8 double 15 in their home theater, not to mention real theaters.....bottom line is they are all in pristine condition....i just bought 9 of ebay in the past 6 months. the G's (4 ohm versions) are also in horrible condition as they are often used in car systems.

anyway i have those 9 plus 4 - 2268H's (18 inch drivers) ready to throw them in a horn design as they should be.
 
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