Greets!
OK, after delving into MathCad's more advanced tutorials, I see I mis-interpreted how to input 'kg/m^3', so now it calcs 60 kg/m^4 like the manual states, though I still haven't figured out how it calc'd all the other variations as when I try to do it long hand I don't get 60-anything, it's either 0.6 or 600.
Anyway, sorry for the confusion, I've had good luck using MathCad for simple calcs, so figured this one was a 'piece o' cake', but it was the first one I didn't have a clue what the answer should be in advance or would have kept picking at it until I had it right before posting.
GM
OK, after delving into MathCad's more advanced tutorials, I see I mis-interpreted how to input 'kg/m^3', so now it calcs 60 kg/m^4 like the manual states, though I still haven't figured out how it calc'd all the other variations as when I try to do it long hand I don't get 60-anything, it's either 0.6 or 600.
Anyway, sorry for the confusion, I've had good luck using MathCad for simple calcs, so figured this one was a 'piece o' cake', but it was the first one I didn't have a clue what the answer should be in advance or would have kept picking at it until I had it right before posting.
GM
Its easy to get lost in the Order of Operations.
My mistake was I didn't realize all of the m ratios canceled from the, Height differnce portion of the equation, and I divided the result from Height and depth by the 1.2Kg/m^3 constant, instead of multiplying.
In that case there would be a mass amsymptote becoming infinately massive until the ducts where equal height which would result in zero mass (which it should but not following and asymptote), so I had to re-evaluate my manual arithmatic.
It all makes sense now. I just haven't had to do any math in a while.
Its all fun and games until you reach and asymptote.
Antone-
My mistake was I didn't realize all of the m ratios canceled from the, Height differnce portion of the equation, and I divided the result from Height and depth by the 1.2Kg/m^3 constant, instead of multiplying.
In that case there would be a mass amsymptote becoming infinately massive until the ducts where equal height which would result in zero mass (which it should but not following and asymptote), so I had to re-evaluate my manual arithmatic.
It all makes sense now. I just haven't had to do any math in a while.
Its all fun and games until you reach and asymptote.
Antone-
Another thought
I belive the reason why the DTS-20 doesn't respond like Cowens horns Tapped at 1/4 cab height is that there is possibly another bend in the DTS-20 not simply dividing the box into 2 uneven (conical expansion) halves.
I have mine set at roughly 3:1 cross sectional area of the horn throat end tap, with relation to Sd of the Lab12
Here are some revised Kove woofer Ts parameters.
Meas_DiPole
dD=27cm |Piston
fs=47.95Hz
Mms=119.2g
Cms=0.0000924m/N
Rms=6.037Ns/m
Bl=20.61Tm
Qms=5.95
Qes=.563
Vas=.043m3
Re=6.667ohm
Le=2.012mH
ExpoLe=0.618
I belive the reason why the DTS-20 doesn't respond like Cowens horns Tapped at 1/4 cab height is that there is possibly another bend in the DTS-20 not simply dividing the box into 2 uneven (conical expansion) halves.
I have mine set at roughly 3:1 cross sectional area of the horn throat end tap, with relation to Sd of the Lab12
Here are some revised Kove woofer Ts parameters.
Meas_DiPole
dD=27cm |Piston
fs=47.95Hz
Mms=119.2g
Cms=0.0000924m/N
Rms=6.037Ns/m
Bl=20.61Tm
Qms=5.95
Qes=.563
Vas=.043m3
Re=6.667ohm
Le=2.012mH
ExpoLe=0.618
Hi GM
r57: how does boost sound vs the EQ bump being 'in' the alignment?
Post #205
> Depends of course, but basically you'll have a lot more linear dynamic headroom with acoustic gain and if the latter is damped enough, then it has much lower distortion on average to boot.
How is damping controlled in a reflex box or scoop?
Thanks again
r57: how does boost sound vs the EQ bump being 'in' the alignment?
Post #205
> Depends of course, but basically you'll have a lot more linear dynamic headroom with acoustic gain and if the latter is damped enough, then it has much lower distortion on average to boot.
How is damping controlled in a reflex box or scoop?
Thanks again
I was hoping to be able to take some measurements outside,but it's been raining,sleeting,and snowing several days now,with 30 mph gusts of wind...Hello...it's April.....it's supposed to be warm now....
Anyway,here's a measurement of the folded horn taken with the mic centered in the mouth,full range pink noise,as before. Third octave bands,5 db per div.
I don't have a convenient way to plot a curve with more than 1/3 band intervals.The behringer will put out 1/60 octave sine waves,but would have to plot them by hand...:-( Need to get something like the True audio RTA,but then I need to get a soundcard,preamp,move my computer into the living room(or get a laptop),learn how to use it,etc,etc....
Hopefully,this will be of some use in the meantime.
http://img182.imageshack.us/img182/3672/tappedresponse00751uz3.jpg
Anyway,here's a measurement of the folded horn taken with the mic centered in the mouth,full range pink noise,as before. Third octave bands,5 db per div.
I don't have a convenient way to plot a curve with more than 1/3 band intervals.The behringer will put out 1/60 octave sine waves,but would have to plot them by hand...:-( Need to get something like the True audio RTA,but then I need to get a soundcard,preamp,move my computer into the living room(or get a laptop),learn how to use it,etc,etc....
Hopefully,this will be of some use in the meantime.
http://img182.imageshack.us/img182/3672/tappedresponse00751uz3.jpg
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
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
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:
Here is a sweep of the Kove Driver in the TH at Mouth position:
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-
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:
Here is a sweep of the Kove Driver in the TH at Mouth position:
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-
Re: AkAbak
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
MaVo said:
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
sumsound said:
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/product_info.php?products_id=32
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-
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-
sumsound said:
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.
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?
How did you get it to model a tapped horn?
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}
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}