Collaborative Tapped horn project

[vincentmolino]

Re: Higher Frequencies?

Does it make sense to use a tapped horn for higher frequencies? I can simulate to get about 102dB (2.83V) out of a small horn in the range 90-300Hz.

Here's the script I used:

| Based on 30 Hz Tapped Horn (script adapted from William Cowan's Website, http://diy.cowanaudio.com/)

Def_Const |Horn Dimensions

{
a1 = 230e-4; |Area at throat (cm^2)
a2 = 240e-4; |Area at rear of driver (cm^2)
a3 = 800e-4; |Area at front of driver (cm^2)
a4 = 900e-4; |Area at mouth (cm^2)
l1 = 10e-2; |Distance from throat to rear of driver (cm)
l2 = 90e-2; |Line distance from rear of driver to front of driver (cm)
l3 = 10e-2; |Distance from front of driver to mouth (cm)
}

Def_Driver 'Dr1'

| 18sound 10MB400

Sd=350cm2
fs=70Hz
Qes=0.37
Qms=3.5
Vas=41L
Re=5.1ohm
Le=1.05mH

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




Any help appreciated! Cheers!

hey fella's....ive been helping Tommy with this tapped horn by drawing it in Cad.....we are both confused about sum things....

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

the areas in the green clouds dont pan out according to the s values.

thanks in advance and if any you need cad work for you tapped horn design....im a expert in Autodesk inventor and Autocad 2007

 

[JanFredholm]

Hi Vincent: since this driver has a weak motor BL =11,55 you need to have a large S1=500cm2.
and In my calculations i used S4=800-1000cm2.
It did not respond to any great lenght of the horn,L23=200cm
I also come to the conclusion that L12 and L34 should be about 15-20 cm. you get a pretty good curve ranging from 30hz(-6db) to 150hz(-6db)and after that alot of peaks but there is always peaks .Put in these values and you have a good start to begin with.I think it makes a box about 1,5meter high and about 170Litres big.

 

[JanFredholm]

Sorry vincent ...are you going to make a 90-300hz horn?

if that what you plan to do, make s1=400 s4=800 and L12=15,L23=50 and L34=15. then you use the tapped horn wizard and before you calculate try raising s4=1000.

there you have a start to continue with.

the horn is going to be about 55litres big.

 

[vincentmolino]

heres a bigger pic of what i have so far..

http://images30.fotki.com/v51/fileOCSm/50680/7/775094/4645766/WORKING.jpg



heres the spreadsheet....

Length (cm) Area (sq cm) Radius (cm) Angle (deg) Height (cm) Width (cm) Width Flare
0.000000 230.000000 8.556359 1.054288 40.000000 5.750000 Con
0.100000 230.098947 8.558199 1.054288 39.999817 5.752500 Con
0.200000 230.197915 8.560039 1.054288 39.999638 5.755000 Con
0.300000 230.296904 8.561880 1.054288 39.999462 5.757500 Con
0.400000 230.395914 8.563720 1.054288 39.999291 5.760000 Con
0.500000 230.494946 8.565560 1.054288 39.999123 5.762500 Con
0.600000 230.593999 8.567400 1.054288 39.998959 5.765000 Con
0.700000 230.693074 8.569241 1.054288 39.998799 5.767500 Con
0.800000 230.792169 8.571081 1.054288 39.998643 5.770000 Con
0.900000 230.891286 8.572921 1.054288 39.998490 5.772500 Con
1.000000 230.990424 8.574762 1.054288 39.998342 5.775000 Con
1.100000 231.089584 8.576602 1.054288 39.998197 5.777500 Con
1.200000 231.188765 8.578442 1.054288 39.998056 5.780000 Con
1.300000 231.287967 8.580282 1.054288 39.997919 5.782500 Con
1.400000 231.387190 8.582123 1.054288 39.997786 5.785000 Con
1.500000 231.486435 8.583963 1.054288 39.997656 5.787500 Con
1.600000 231.585701 8.585803 1.054288 39.997530 5.790000 Con
1.700000 231.684988 8.587644 1.054288 39.997408 5.792500 Con
1.800000 231.784296 8.589484 1.054288 39.997290 5.795000 Con
1.900000 231.883626 8.591324 1.054288 39.997176 5.797500 Con

9.700000 239.696904 8.734867 1.054288 39.999483 5.992500 Con
9.800000 239.797915 8.736707 1.054288 39.999652 5.995000 Con
9.900000 239.898947 8.738547 1.054288 39.999824 5.997500 Con
10.000000 240.000000 8.740387 1.054288 40.000000 6.000000 Con

Length (cm) Area (sq cm) Radius (cm) Angle (deg) Height (cm) Width (cm) Width Flare
0.000000 240.000000 8.740387 4.584867 40.000000 6.000000 Con
1.000000 244.424160 8.820580 4.584867 39.707896 6.155556 Con
2.000000 248.888725 8.900772 4.584867 39.436594 6.311111 Con
3.000000 253.393696 8.980964 4.584867 39.184592 6.466667 Con
4.000000 257.939074 9.061157 4.584867 38.950531 6.622222 Con
4.584867 38.793869 17.822222 Con
77.000000 698.887957 14.915192 4.584867 38.875103 17.977778 Con
78.000000 706.423371 14.995384 4.584867 38.957171 18.133333 Con
79.000000 713.999191 15.075576 4.584867 39.040053 18.288889 Con
80.000000 721.615416 15.155769 4.584867 39.123727 18.444444 Con
81.000000 729.272048 15.235961 4.584867 39.208175 18.600000 Con
82.000000 736.969086 15.316153 4.584867 39.293375 18.755556 Con
83.000000 744.706530 15.396345 4.584867 39.379311 18.911111 Con
84.000000 752.484379 15.476538 4.584867 39.465964 19.066667 Con
85.000000 760.302634 15.556730 4.584867 39.553316 19.222222 Con
86.000000 768.161296 15.636922 4.584867 39.641351 19.377778 Con
87.000000 776.060363 15.717114 4.584867 39.730053 19.533333 Con
88.000000 783.999836 15.797307 4.584867 39.819405 19.688889 Con
89.000000 791.979715 15.877499 4.584867 39.909392 19.844444 Con
90.000000 800.000000 15.957691 4.584867 40.000000 20.000000 Con

Length (cm) Area (sq cm) Radius (cm) Angle (deg) Height (cm) Width (cm) Width Flare
0.000000 800.000000 15.957691 5.528984 40.000000 20.000000 Con
0.100000 800.970857 15.967371 5.528984 39.998545 20.025000 Con
0.200000 801.942303 15.977051 5.528984 39.997122 20.050000 Con
0.300000 802.914338 15.986731 5.528984 39.995733 20.075000 Con
0.400000 803.886961 15.996411 5.528984 39.994376 20.100000 Con
0.500000 804.860173 16.006091 5.528984 39.993052 20.125000 Con
0.600000 805.833974 16.015771 5.528984 39.991760 20.150000 Con
0.700000 806.808363 16.025451 5.528984 39.990501 20.175000 Con
0.800000 807.783342 16.035131 5.528984 39.989274 20.200000 Con
0.900000 808.758909 16.044811 5.528984 39.988080 20.225000 Con
1.000000 809.735065 16.054491 5.528984 39.986917 20.250000 Con
1.100000 810.711809 16.064171 5.528984 39.985786 20.275000 Con
1.200000 811.689143 16.073851 5.528984 39.984687 20.300000 Con
1.300000 812.667065 16.083531 5.528984 39.983619 20.325000 Con
1.400000 813.645575 16.093211 5.528984 39.982584 20.350000 Con
1.500000 814.624675 16.102891 5.528984 39.981579 20.375000 Con
1.600000 815.604363 16.112571 5.528984 39.980606 20.400000 Con
1.700000 816.584640 16.122251 5.528984 39.979664 20.425000 Con
1.800000 817.565506 16.131931 5.528984 39.978753 20.450000 Con
1.900000 818.546961 16.141611 5.528984 39.977874 20.475000 Con
2.000000 819.529004 16.151290 5.528984 39.977025 20.500000 Con
2.100000 820.511636 16.160970 5.528984 39.976206 20.525000 Con
2.200000 821.494857 16.170650 5.528984 39.975419 20.550000 Con
2.300000 822.478666 16.180330 5.528984 39.974662 20.575000 Con
2.400000 823.463065 16.190010 5.528984 39.973935 20.600000 Con
2.500000 824.448052 16.199690 5.528984 39.973239 20.625000 Con
2.600000 825.433627 16.209370 5.528984 39.972573 20.650000 Con
2.700000 826.419792 16.219050 5.528984 39.971937 20.675000 Con
2.800000 827.406545 16.228730 5.528984 39.974079 21.850000 Con
7.500000 874.448052 16.683688 5.528984 39.974768 21.875000 Con
7.600000 875.463065 16.693368 5.528984 39.975482 21.900000 Con
7.700000 876.478666 16.703048 5.528984 39.976222 21.925000 Con
7.800000 877.494857 16.712728 5.528984 39.976987 21.950000 Con
7.900000 878.511636 16.722408 5.528984 39.977776 21.975000 Con
8.000000 879.529004 16.732088 5.528984 39.978591 22.000000 Con
8.100000 880.546961 16.741768 5.528984 39.979431 22.025000 Con
8.200000 881.565506 16.751448 5.528984 39.980295 22.050000 Con
8.300000 882.584640 16.761128 5.528984 39.981184 22.075000 Con
8.400000 883.604363 16.770808 5.528984 39.982098 22.100000 Con
8.500000 884.624675 16.780488 5.528984 39.983036 22.125000 Con
8.600000 885.645575 16.790168 5.528984 39.983999 22.150000 Con
8.700000 886.667065 16.799848 5.528984 39.984986 22.175000 Con
8.800000 887.689143 16.809528 5.528984 39.985997 22.200000 Con
8.900000 888.711809 16.819208 5.528984 39.987033 22.225000 Con
9.000000 889.735065 16.828888 5.528984 39.988093 22.250000 Con
9.100000 890.758909 16.838568 5.528984 39.989177 22.275000 Con
9.200000 891.783342 16.848248 5.528984 39.990284 22.300000 Con
9.300000 892.808363 16.857928 5.528984 39.991416 22.325000 Con
9.400000 893.833974 16.867608 5.528984 39.992572 22.350000 Con
9.500000 894.860173 16.877288 5.528984 39.993751 22.375000 Con
9.600000 895.886961 16.886968 5.528984 39.994954 22.400000 Con
9.700000 896.914338 16.896648 5.528984 39.996180 22.425000 Con
9.800000 897.942303 16.906328 5.528984 39.997430 22.450000 Con
9.900000 898.970857 16.916008 5.528984 39.998703 22.475000 Con
10.000000 900.000000 16.925688 5.528984 40.000000 22.500000 Con

 

[454Casull]

Has anybody come across or designed a good tapped horn for car audio? Obviously size is an issue, as well as moderately low extension.

 

[MaVo]

Has anybody come across or designed a good tapped horn for car audio? Obviously size is an issue, as well as moderately low extension.

i doubt you can make one small enough unless you have a really big car. additionally, with the small volume a car has, one should get enourmous room gain below quite a high frequency, a sub which is linear to a very low frequency like the tapped horn will in fact start to boom because of the room gain. so wouldnt a closed box with a f3 of around 40hz-60hz be better since it has a similar slope - both slopes cancel out and one gets a more or less flat frequency response?

 

[vincentmolino]

i getting really sick and tired of these pic links only working for 24 hours....

http://images30.fotki.com/v51/fileSOa9/e426f/7/775094/4645766/WORKING.jpg

 

[vincentmolino]

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

Hosted on Fotki

lol...Again??? ok clivk on the pic then click on "Get Original Uploaded Photo"

 

[Patrick Bateman]

i doubt you can make one small enough unless you have a really big car. additionally, with the small volume a car has, one should get enourmous room gain below quite a high frequency, a sub which is linear to a very low frequency like the tapped horn will in fact start to boom because of the room gain. so wouldnt a closed box with a f3 of around 40hz-60hz be better since it has a similar slope - both slopes cancel out and one gets a more or less flat frequency response?

I disagree. While everyone is publishing designs using relatively large woofers, there's nothing stopping you from making a TH with a 200mm driver or a 165mm driver and throwing it in a car. The tapped horn has a number of advantages over a sealed box in a car:
- better efficiency
- that deep notch would help create the "up front bass" illusion with a proper crossover
- a TH with a small woofer could potentially use a smaller box than a vented or bandpass.

Keep in mind, the size of the TH will depend on VAS and SD. So use a small woofer with high excursion. Too bad the Extremis is no longer for sale.

 

[454Casull]

Would the Dayton RS180 be a suitable driver?

EDIT: When modeling a tapped horn (or any horn, for that mattter) does one simply input random numbers? I have no idea how this program works.

 

[GM]

I disagree.

Keep in mind, the size of the TH will depend on VAS and SD.

Ditto.

Hmm, Sd has no bearing on regular horn design per se, so why does it matter for a TH?

How about a pair of these in a 'clamshell' dipolar layout on either side of the baffle cutout?: http://www.creativesound.ca/details.php?model=WR125S

 

[Patrick Bateman]

Ditto.

Hmm, Sd has no bearing on regular horn design per se, so why does it matter for a TH?

How about a pair of these in a 'clamshell' dipolar layout on either side of the baffle cutout?: http://www.creativesound.ca/details.php?model=WR125S

A lot of what I learned about horns was from King's work at quarter-wave, and his worksheets show that SD effects the horn size. I'd assumed it was due to the horn being an acoustic impedance transformer. Hence, a larger SD requires a larger horn. Would love to hear your input on that though.

 

[Sabbelbacke]

When we were dealing with front loaded horns, smaller SD mostly resulted in smaller horns. The problem was that a "regular horn" requires a certain mouth area to work properly. So the limitation was not SD but mouth area. Tapped hornes, not having the typical pressure-low of a quarter-wave horn at the mouth, seem to behave different on this account.
I played around with a tangband W8-745C trying to fit it in a TH which is smaller than Bill Fitzmaurices autotuba. I´ve come this far (It´s not perfect, just something I came up with a few nights ago...):

This is about 50 Liters. The goal was to create a small PA-Woofer for small jobsn ot home-usage. If a lower frequency cut-off is required, expanding the horn in length should do the trick.

 

[MaVo]

I disagree. While everyone is publishing designs using relatively large woofers, there's nothing stopping you from making a TH with a 200mm driver or a 165mm driver and throwing it in a car. The tapped horn has a number of advantages over a sealed box in a car:
- better efficiency
- that deep notch would help create the "up front bass" illusion with a proper crossover
- a TH with a small woofer could potentially use a smaller box than a vented or bandpass.

Keep in mind, the size of the TH will depend on VAS and SD. So use a small woofer with high excursion. Too bad the Extremis is no longer for sale.

i made a little th with a cheap 8 inch woofer from visaton for a friends home cinema. but even this box is quite big. about 90*40*40 cm.

but that are interesting points you make. i would like to see a working design!

 

[GM]

A lot of what I learned about horns was from King's work........

Not sure what he wrote and/or what you did with sims to arrive at this, but look at Leach's math, Sd isn't a design criteria. For that matter, look at T/S alignments, Sd only comes into play in power response calcs: http://www.diysubwoofers.org/sld/sealed1.htm

Sd only affects the compression ratio (CR), which has its own set of design considerations that can dictate max acceptable Sd in high power and/or wide BW alignments.

Anyway, for the type of simple pipe horns we can sim with Hornresp, you're right in that since we can only use a 1:1 CR and no filter chamber, Sd dictates the throat area, ergo for a small horn we'll need a small Sd and Vas.

 

[Patrick Bateman]

i made a little th with a cheap 8 inch woofer from visaton for a friends home cinema. but even this box is quite big. about 90*40*40 cm.

but that are interesting points you make. i would like to see a working design!

According to my calculator, that's five cubic feet. Last night I threw together a tapped horn for an MCM 55-2421 8inch woofer that's 80% smaller.


Here's a pdf of the response

Due to cabin gain, the ideal response for a subwoofer in car peaks around 80hz, then droops at about 6db per octave down to 10hz. For instance, if our reference was 93db at 80z, we'd need about 87db at 40hz, and 81db at 20hz. Right?

If you look at the graph I just posted, we have 93db at 80hz, 90db at 40hz, and 74db at 20hz. What I would recommend is building this small tapped horn, throwing it in a car, then applying a 3db CUT using your amplifier at 40hz. This is actually a great way to flatten the response AND double your power handling! (Since most subs are excursion limited at low frequencies, not power limited.)

What do you guys think?

If you want to build it, I'll have to throw together some diagrams. Like most of my subs, it's in a sonotube. It's basically FOUR cylinders nested together. It's almost twelve feet of horn crammed into a tube that's 3 feet tall. Picture a 10" sonotube, with an 8" sonotube inside, then a six inch tube, and finally a 3" tube. The 3" tube is the throat, the 10" tube is the mouth. But only 25" of the 10" tube is usable, because the other three tubes are INSIDE of the 10" tube.

Confusing, I admit. Take a look at my sub designs over on audiogroupforum to get an idea what it looks like.

:: PB ::

P.S. : Here are the notes I made last night, showing the volumes at each point:

segment one: 3" PVC, 2.5ft long (area = 45.6cm)
segment two: 6" sonotube, 2.5ft long (area = 182.4cm (subtract 53.52 for the nested PVC pipe to get 128.88))
segment three: 8" sonotube, 2.5ft long (area = 324.29cm (subtract 182.4cm for the nexted sonotube to get 141.89))
segment four: 10" sonotube, 3ft long (area = 506.7 (subtract 324.29cm for the nested sonotube to get 182.41cm ))

 

[GM]

Would the Dayton RS180 be a suitable driver?

EDIT: When modeling a tapped horn (or any horn, for that mattter) does one simply input random numbers? I have no idea how this program works.

Just based on its specs, it looks OK to me for a low tuned end loaded one.

Not me, I do a design, then sim it now that I can. Anyway, once you learn how the program works you could probably design this way, but it seems to me that not understanding either is a recipe for frustration and not getting the expected results unless you're sure you're building what the program simmed.

 

[Patrick Bateman]

Just based on its specs, it looks OK to me for a low tuned end loaded one.

Not me, I do a design, then sim it now that I can. Anyway, once you learn how the program works you could probably design this way, but it seems to me that not understanding either is a recipe for frustration and not getting the expected results unless you're sure you're building what the program simmed.

Here's a quick way to make a tapped horn, or a transmission line:

1: Make the length equal to the 1/4 the FS of the driver. A "quarter wave."
2: Pick an arbitrary size for the volume of the enclosure, then reduce or expand it to get the response you are looking for.
3: The taper of the horn is dependent on how efficient you want it. Low tapers play lower, high tapers are more efficient.

 

[DrWoofer.com]

Has anybody come across or designed a good tapped horn for car audio? Obviously size is an issue, as well as moderately low extension.

Check my post in Speakerplans.

http://www.speakerplans.com/forum/forum_posts.asp?TID=12173


Do you post there?If so,what's your nickname?

 

[winslow]

Almost finished up my 30 hertz TH today...have to glue 2 more panels and she's good to go.