Collaborative Tapped horn project - Page 26 - diyAudio
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Old 13th April 2007, 03:25 PM   #251
GM is offline GM  United States
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Location: Chamblee, Ga.
Greets!

Yeah, we got a 'taste' of this, the 'Ides of March' came a little late this year and I had to re-light the furnace for several days, but yesterday was sunny/73 F, so managed to get some spring cleaning done before my back called it a day.

I hear ya WRT to the hassle/cost of measuring and why I didn't do it even when I had a functioning system beyond copying the RTA's peak hold curve.

Anyway, thanks for the measurement! Without spending the time to sum the two driver position sims for best correlation and factoring in they're half space Vs only a semi-ground plane measurement, then I'm still seeing about what I expected if the L.H. vertical bar is 20 Hz.

GM
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Old 18th April 2007, 04:25 AM   #252
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Default Thoughts

Just wondering if anyone has any thoughts on what I've come up with in aKaBak So far??

I'm out of town now so I haven't been able to make any sawdust.

Seems like the TH colaborative has slowed down a little.

AAB-
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Old 25th April 2007, 08:34 PM   #253
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Default Tapped Horn Prototypes

Ok guys I've built my tapped horn proto type,

Mind you these test sweeps are most likely somewhat in acurrate as I left the pannel that I mount the driver to loosely jigged to stay in place and I clamp the side of the cab shut, so air leaks are a problem at the moment.

Here is a sweep of the Kove driver in the TH at Mid position:
Click the image to open in full size.

Here is a sweep of the Kove Driver in the TH at Mouth position:
Click the image to open in full size.

I'm not sure which position I should pick but I was thinking of going with Mid position as I think the Tunning will go down a bit once the gaps are sealed.

I will try and get some photos of the proto type up soon.

T-
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Old 25th April 2007, 08:41 PM   #254
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Oh by the way here are my aKaBak Predictions of this horn.

Click the image to open in full size.

I'm hoping that sealing the air leaks will help it acheive predicted response!!!

P.S.

Have a Taaka and Tilt morning!!!
Click the image to open in full size.

Blarf

T-
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Old 25th April 2007, 09:50 PM   #255
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Default Re: AkAbak

Quote:
Originally posted by MaVo
I just downloaded AkAbak.

Thanks for mentioning this program. It seems one can have serious fun modelling all kinds of loudspeakers, its like an acoustical playground. And its very complex. I am still reading the manual ;D

If someone besides me has looked into it, do you have a idea how to simulate a TH in it? Perhaps one could connect two horn structures to the same driver, one for the 1/2 wave and one for the 1/4 wave, since the sound travels both ways in the horn? Will the interaction of both be present in this simulation?
I had no idea it was for sale!

I heard Tom talk about it, I'd always assumed it was something he had written for him, and was strictly private.

How cool!

Here's a promising experiment:
http://www.akabak.de/Texte/aes102.pdf
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Old 26th April 2007, 02:43 AM   #256
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Quote:
Originally posted by sumsound


I'm not sure what you bass that statement on, I have done extensive modeling on many drivers.

I have found 12" drivers that are marginally more capable the Lab 12 bellow ~35Hz, and the only drivers that are possibly better sub 35Hz subwoofers cost twice as much or more.

<snip>
The statement that the driver doesn't have enough mass doesn't make sense to me either. It has enough mass that its Fs is around 21Hz. The More mass you add to the driver the Weaker the BL, or motor strength. So your caught chasing your tail. Think about it.

I don't think correctumundo is an accurate response to the posters assertion.

I still belive the Lab12 is one of the best subwoofers you can buy for the price weather or not its the best choice for a TH I can't say, but from what I understand the Driver in the DTS-20 is a slightly modified Lab 12 driver. But only Tom and a DSL representitive can verify that.

S-Master
I bought a pair of these a while back. If I build a tapped horn, I'm going to do it with the Diyma 12. It's Thiele-Small is comparable to the LAB 12, but it's superior in a few ways:
- it's cheaper
- it has more xmax
- it has a flatter BL curve

I'm not saying it's perfect, but it's definitely worth considering. Check it out:

http://www.diymobileaudio.com/shop/p...products_id=32
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Old 26th April 2007, 07:24 AM   #257
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Without seeing the klippel Data on the Lab 12, I'm not sure how you can make that dirrect comparison.

The Diyma looks like it uses the same basket as the lab 12, just a different magnet structure. Lab 12 has a slightly lower FS, but no where close to the same Xmax.

I wish the Diyma had a bit more of its TS parameters posted, so I could attempt to model it better.

Looks like a nice driver for the price though.

Otherwise The Lab 12 is pretty tough to beat for the price, and I have modeled a lot of drivers and only found a few in the same price range that come even close.

I wonder if the Diyma is anygood in a tapped horn, It appears the Lab 12 is not the greatest, its suspension is to loose, and doesn't have enought xmax to run full power bandwidth.

The interesting thing about a tapped horn is that you can use a driver with a much Higher Fs, mms and rms than you would use in vented Sealed or conventional horns.

I measured the Kove audio I'm using in my prototype at 49Hz Fs. I'm getting hefty output down to 24Hz so far!!!

T-
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Old 26th April 2007, 08:01 AM   #258
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Quote:
Originally posted by sumsound
Without seeing the klippel Data on the Lab 12, I'm not sure how you can make that dirrect comparison.

The Diyma looks like it uses the same basket as the lab 12, just a different magnet structure. Lab 12 has a slightly lower FS, but no where close to the same Xmax.

I wish the Diyma had a bit more of its TS parameters posted, so I could attempt to model it better.

Looks like a nice driver for the price though.

Otherwise The Lab 12 is pretty tough to beat for the price, and I have modeled a lot of drivers and only found a few in the same price range that come even close.

I wonder if the Diyma is anygood in a tapped horn, It appears the Lab 12 is not the greatest, its suspension is to loose, and doesn't have enought xmax to run full power bandwidth.

The interesting thing about a tapped horn is that you can use a driver with a much Higher Fs, mms and rms than you would use in vented Sealed or conventional horns.

I measured the Kove audio I'm using in my prototype at 49Hz Fs. I'm getting hefty output down to 24Hz so far!!!

T-
Believe it or not, the kid that sells these has access to a Dumax machine!
I don't think Danley or Wiggins even have that!
It's crazy, I don't know how he pulled that off.

But to make a long story short, he's posted Dumax results of the Diyma prototype on his forums. He's also done Dumax tests on Vifa, Dayton, Peerless, Adire, Seas, JBL, and Aura. Check out the forums, particulary the "review" forum. All the data you could ever want is over there.
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Old 26th April 2007, 08:18 AM   #259
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sumsound, that akabak program looks very interesting. I have downloaded it and had a bit of a play and a look at the manual. It's not the easiest program to pick up! I'd like to model the effect of making the line longer and see how low I can push the F3 of this thing.

How did you get it to model a tapped horn?
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Old 26th April 2007, 01:31 PM   #260
MaVo is offline MaVo  Germany
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I worked on a rough AkAbak simulation of the TH and just got something together that seems to work a bit. The skript uses variables, so one can compute the air mass and dimensional values in excel, then copy paste them into akabak.

I tried a sim of william cowans 30hz TH with the Peerless 830500 driver and i think it looks just about the measured plot on his homepage.

The skript follows below, if you find errors or know something to improve it please tell me. I dont know what to do with the air mass in the bend, so this is probably wrong. I cant attach the excel sheet to this post. so if someone needs it email/pm me.

Def_Const
{
m1 = 0.0192; m2 = 0.0164; m3 = 0.0142; m4 = 0.0124;
m5 = 0.0110; m6 = 0.0098; m7 = 0.0088; m8 = 0.0079;
m9 = 0.0072; m10 = 0.0065; m11 = 0.0060; m12 = 0.0055;
m13 = 0.0051; m14 = 0.0047; m15 = 0.0044; m16 = 0.0041;
m17 = 0.0038; m18 = 0.0036; m19 = 0.0033; m20 = 0.0031;

x0 = 10e-2; x1 = 11e-2; x2 = 12e-2; x3 = 13e-2; x4 = 14e-2;
x5 = 15e-2; x6 = 16e-2; x7 = 17e-2; x8 = 18e-2; x9 = 19e-2;
x10 = 20e-2; x11 = 21e-2; x12 = 22e-2; x13 = 23e-2;
x14 = 24e-2; x15 = 25e-2; x16 = 26e-2; x17 = 27e-2;
x18 = 28e-2; x19 = 29e-2; x20 = 30e-2;

L = 18.5e-2;
xT = 35e-2;

L5 = L/2;
}

Def_Driver '830500'
dD=26cm |Piston
fs=18.1Hz Mms=166.3g Qms=3.7
Bl=17.6Tm Re=3.5ohm Le=4.2mH ExpoLe=0.618

System 'S1'

Driver 'D1' Def='830500' Node=2=0=100=140

Duct 'D0' Node=100 HD={xT} Wd={x1} Len={L5}
Duct 'D1' Node=100=101 HD={xT} WD={x1} Len={L5}
AcouMass 'M1' Node=101=102 Ma={m1}
Duct 'D2' Node=102=103 HD={xT} WD={x2} Len={L}
AcouMass 'M2' Node=103=104 Ma={m2}
Duct 'D3' Node=104=105 HD={xT} WD={x3} Len={L}
AcouMass 'M3' Node=105=106 Ma={m3}
Duct 'D4' Node=106=107 HD={xT} WD={x4} Len={L}
AcouMass 'M4' Node=107=108 Ma={m4}
Duct 'D5' Node=108=109 HD={xT} WD={x5} Len={L}
AcouMass 'M5' Node=109=110 Ma={m5}
Duct 'D6' Node=110=111 HD={xT} WD={x6} Len={L}
AcouMass 'M6' Node=111=112 Ma={m6}
Duct 'D7' Node=112=113 HD={xT} WD={x7} Len={L}
AcouMass 'M7' Node=113=114 Ma={m7}
Duct 'D8' Node=114=115 HD={xT} WD={x8} Len={L}
AcouMass 'M8' Node=115=116 Ma={m8}
Duct 'D9' Node=116=117 HD={xT} WD={x9} Len={L}
AcouMass 'M9' Node=117=118 Ma={m9}
Duct 'D10' Node=118=119 HD={xT} WD={x10} Len={L}
AcouMass 'M10' Node=119=120 Ma={m10}

AcouMass 'MB1' Node=120=121 Ma={0.925/xT}
AcouMass 'MB2' Node=121=122 Ma={0.925/xT}

Duct 'D11' Node=122=123 HD={xT} WD={x11} Len={L}
AcouMass 'M11' Node=123=124 Ma={m11}
Duct 'D12' Node=124=125 HD={xT} WD={x12} Len={L}
AcouMass 'M12' Node=125=126 Ma={m12}
Duct 'D13' Node=126=127 HD={xT} WD={x13} Len={L}
AcouMass 'M13' Node=127=128 Ma={m13}
Duct 'D14' Node=128=129 HD={xT} WD={x14} Len={L}
AcouMass 'M14' Node=129=130 Ma={m14}
Duct 'D15' Node=130=131 HD={xT} WD={x15} Len={L}
AcouMass 'M15' Node=131=132 Ma={m15}
Duct 'D16' Node=132=133 HD={xT} WD={x16} Len={L}
AcouMass 'M16' Node=133=134 Ma={m16}
Duct 'D17' Node=134=135 HD={xT} WD={x17} Len={L}
AcouMass 'M17' Node=135=136 Ma={m17}
Duct 'D18' Node=136=137 HD={xT} WD={x18} Len={L}
AcouMass 'M18' Node=137=138 Ma={m18}
Duct 'D19' Node=138=139 HD={xT} WD={x19} Len={L}
AcouMass 'M19' Node=139=140 Ma={m19}
Duct 'D20' Node=140=141 HD={xT} WD={x20} Len={L}

Radiator 'Rad1' Def='D20' Node=140 HD={xT} WD={x20}
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