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char355 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote char355 Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2010 at 7:24am
Good, like i said, never seen the inside I'm just guessing. I was impressed with the ones I've heard so thought i would see if i could come up with something similar. its a series-tunes bandpass / horn hybrid. The bandpass part is easy enough to design and so is the horn but i have no idea how they would work together. hopefully someone could point me in the right direction?

something nice and complicated for when i cant sleep at 7 in the morning!
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mobiele eenheid View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mobiele eenheid Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2010 at 8:03am
Look at it as a overall band pass enclosure: The series tuned bandpass giving output centered around 30-40 Hz (much like an ordinary reflex) and the horn part coming in around 50-80 Hz. The more so as frequency increases from that point.
 
Off course making an AkAbak-script will make it even easier. I can look one up for you, or can you do it yourself?
 
Best regards Johan


Edited by mobiele eenheid - 05 February 2010 at 8:04am
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char355 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote char355 Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2010 at 8:38am
Thanks Johan. i've never used Akabak though, everything i've done so far has been with winisd, bassbox pro and hornresp (still trying to get my head around hornresp tbh). maybe its something i should look at before attempting this. still relatively new to speaker design in general too but i think im picking it up quite quickly.

this is what i have so far, different internal ports though.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote mobiele eenheid Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2010 at 9:39am
Looks good!
 
Hornresp is easier and quicker to work with then AkAbak. Ussually the order is WinISD Pro/Bass Box Pro, Hornresp, AkAbak. Hornresp allows you to make a port assisted horn, the change of horn/reflex parameters can be compared to previous results in the blink of an eye. AkAbak is the only program (that I know about) that will make you use parameters for the second chamber and port that make any sense. It's kinda slow to work with though but the possibilities are endless.
 
Hornresp allows you to make a port assisted horn and export it as an AkAbak script. The only thing you have to do then is to put a second chamber and port between the radiator asigned to the original (= first) port and the rear chamber.
 
Personally I got better results with a large rear chamber (say 150 liter plus for an 18") and the secundairy port shorter then the first.
 
See my next post for a script ;)
 
Best regards Johan
 
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mobiele eenheid Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2010 at 9:41am

Def_Const
{
S1  =      555e-4; 
S2  =     4200e-4; 

L12 =       90e-2; 

Vtc =    40000e-6;
Atc =     2550e-4;

Vrc =      165e-3;
Lrc =       30e-2; 

Lpt =       15e-2;
Ap  =      555e-4; 

Vpc =       55e-3;
Lpc =       12e-2;

Lpt2 =      25e-2;
Ap2  =     555e-4; 

|Parameter Conversions:

Sd  = 1225.00e-4; 

Arc = Vrc / Lrc;

Apc = Vpc / Lpc;

Ltc = Vtc / Atc;
}
|=====================================================================================

|Network node numbers for this horn-loaded vented-box system:

|                                                                     0-Voltage-1
|                                                                                      |
|Radiator(1)-99-Port-2-Chamber-3-Port-4-Chamber-5-Driver-6-Chamber-7-Segment-8-Radiator(2)

|=====================================================================================

Def_Driver 'Driver'
  Sd=1225.00cm2
  Bl=24.73Tm
  Cms=1.39E-04m/N
  Rms=4.89Ns/m
  fs=31Hz 
  Le=2.30mH
  Re=5.00ohm
  ExpoLe=1

System 'System'
  Driver Def='Driver''Driver'
    Node=1=0=6=5
  Radiator 'Port outlet'
    Node=99
    SD={Ap2}
    Label=1
  Duct 'Port tube 1'
    Node=3=4
    SD={Ap}
    Len={Lpt}
    Visc=0
  Duct 'Rear chamber 1'
    Node=4=5
    SD={Arc}
    Len={Lrc}
    Visc=0
  Duct 'Throat chamber'
    Node=6=7
    SD={Atc}
    Len={Ltc}
    Visc=0
  Waveguide 'Horn segment 1'
    Node=7=8
    STh={S1}
    SMo={S2}
    Len={L12}
    Conical
  Radiator 'Horn mouth'
    Node=8
    SD={S2}
    Label=2
 Duct 'Port Chamber'
    Node=2=3
    SD={Apc}
    Len={Lpc}
    Visc=0
  Duct 'Port tube 2'
    Node=99=2
    SD={Ap2}
    Len={Lpt2}
    Visc=0

 
With the script highlighted: Sum: Acoustic Pressure: In these tabs, voltage 2,83 V for 1W/1m, showing phase gives a good idea of the final tuning.
 
With the script highlighted: Inspect: Excursion: In these tabs, select driver (diaph) driver, range ordinate say 0 - 2,5 cm and 90 V input voltage roughly equals 1000 W (into 8 ohm, see Hornresp guide in the newby-section for details).
 
Best regards Johan


Edited by mobiele eenheid - 05 February 2010 at 9:51am
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char355 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote char355 Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2010 at 9:58am
Thanks. I'm playing around with making the rear chamber larger but don't want to make the horn shorter or the overall size larger. think I'm in over my head with this design though, I'm still learning a lot of the basics. maybe someone else might be interested in the design and do some work for me! Wink
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Post Options Post Options   Thanks (0) Thanks(0)   Quote staiper Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2010 at 10:46am
Looks very "X" Smile
I have tested one with similar system but a bit different folding schema  (but single driver version, chipboard - for test only)
Works like charm, SPL+ depth + rapid kick .
Thought that cabinet is pretty messy for DIY-ing.
Planned to test double version (all panels already cut prepared out of 15mm ply .. but unfortunately no more adequate 18" drivers for test .. so to will wait some better times as pile of panels :)

In my opinion those are nice hybrid of FLH and DTBR-s ...gives excellent "one compact bass box for all" solution.  However if space/stacking is not problem big stack of standard horns will give you ~ same extension and higher SPL .. but than tradeoff is size.

Those hybrids seems to give nice LF extension and superb kick even from single pretty compact cabinet. Ofcourse , stacking in multiples will improve thing even more (but not as much as standard horns benefit in big stack)


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Post Options Post Options   Thanks (0) Thanks(0)   Quote mykey Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2010 at 10:53am
did you do the cabinet like a schematic layout staiper?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote staiper Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2010 at 11:11am
Originally posted by mykey mykey wrote:

did you do the cabinet like a schematic layout staiper?


Not .. same system (front horn + two chambers - serial tuned , like on that schematic) but different internal folding / chamber volumes.  .. not big philosophy , theory is same Big smile
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char355 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote char355 Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2010 at 11:14am
was just thinking about going to get some chipboard to mess around with, but oh yea, i need some drivers too! might see what i can do with some 15s without changing it too much.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mykey Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2010 at 11:25am
Originally posted by staiper staiper wrote:

Originally posted by mykey mykey wrote:

did you do the cabinet like a schematic layout staiper?


Not .. same system (front horn + two chambers - serial tuned , like on that schematic) but different internal folding / chamber volumes.  .. not big philosophy , theory is same Big smile
No, I meant build it on a bench with a schematic layout like this

....easier? harder? more fun?

then the best part is fitting it in to the space required, IE: cabinet


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Post Options Post Options   Thanks (0) Thanks(0)   Quote darkmatter Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2010 at 1:10pm
Mykey - I think that'd be a great way to do it and would allow you to tweak the tuning as required. However, the difficulty is working out a way to do it that's tweakable while still keeping the port output aligned with the horn mouth, as it seems the crucial bit in this sort of design is the phase alignment between port output and horn output.
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