There is a little more action in the Tapped Horn for Dummies thread:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=114340
http://www.diyaudio.com/forums/showthread.php?s=&threadid=114340
Thanks for posting this info, since building the non-folding version of this I've found the main downside is that it will not fit in my car, which is a shame.Don Snyder said:
Anyway, as I have a few of these 4012's I'm gonna give the folded one a whirl, but out of 1/2" ply to save weight. I'll add some bracing tho to compensate.
Anyway, a quick question, shouldn't the hole in the baffle (j) be a little smaller as S2 is 207 cm(squared)?
If I understand the theory, the hole for the driver should match s2, but anything close is good enough. Not necking down the opening just makes the space between the cone and s2 into a mini front chamber, dropping out some (very little) of the highs above bandpass. Just be sure the rolled edge of the cone doesn't touch the baffle!
Volvotreeter's Eminence horn matches s2 and the baffle but I don't think it matters. The geometry between the driver and the throat is never ideal, that's one reason that the sims never quite match the real world. All of William Cowan's horns used full sized holes in the baffle, and my KappaLite 3015 LF seems to work fine with the large hole.
The 1/2 inch ply shouldn't be too bad if you x/o at 100Hz or below. All the TUBA's use light ply.
Good luck,
Don
Volvotreeter's Eminence horn matches s2 and the baffle but I don't think it matters. The geometry between the driver and the throat is never ideal, that's one reason that the sims never quite match the real world. All of William Cowan's horns used full sized holes in the baffle, and my KappaLite 3015 LF seems to work fine with the large hole.
The 1/2 inch ply shouldn't be too bad if you x/o at 100Hz or below. All the TUBA's use light ply.
Good luck,
Don
Hmm, my understanding of the theory is that unless the driver is truly end loaded, the sims are based on the driver's acoustic impedance (i.e. a 1:1 CR) at whatever point it is along the line, so should get a standard full size cutout, but DB needs to confirm which is correct.
That said, if you worked up the specs for a compression driver with a reduced exit I assume it would take its front chamber's acoustic effect into account regardless of throat size.
GM
That said, if you worked up the specs for a compression driver with a reduced exit I assume it would take its front chamber's acoustic effect into account regardless of throat size.
GM
I still don't understand it, but I think the answer to this dilema is in Danley's Unity Summation Patent (US 6,411,718 B1).
It talks about the horn area at the tap and the restriction required for the driver, that these should be equal (see 6-50 for more info).
At 7-30 "In this case, the throat area for the high frequency section is 0.78 sq in while the lower portion drivers have a throat area of 10 sq in and enter the horn where the horn area is 10 sq in."
Can anyone shed some light on this issue?
Don
It talks about the horn area at the tap and the restriction required for the driver, that these should be equal (see 6-50 for more info).
At 7-30 "In this case, the throat area for the high frequency section is 0.78 sq in while the lower portion drivers have a throat area of 10 sq in and enter the horn where the horn area is 10 sq in."
Can anyone shed some light on this issue?
Don
Funny you should mention the tuba, my first speaker build was the autotuba, that's what converted me to DIY (and horns). Hopefully I should be able to build the folded TH without too much trouble, the main challenge is keeping it airtight I've found.
I think I understand about the baffle hole, I ended up building my non-folded version with the baffle hole a little smaller than the driver cone... and it appears to work fine. Unfortunately I don't have any good measuring equipment (apart from a ratshack SPL meter) so I'm not 100% sure how close it is to the hornresp model. Regardless, I'm more than happy with the performance.
It wasn't until I finished building it I read on here that S2 should be the size of the hole in the baffle for the driver, but I couldn't really see an easy way of doing this even if I was to start over. Anyway, I'll have to have another look at the patent, I must admit a lot of it went over my head the first time I saw it...
I think I understand about the baffle hole, I ended up building my non-folded version with the baffle hole a little smaller than the driver cone... and it appears to work fine. Unfortunately I don't have any good measuring equipment (apart from a ratshack SPL meter) so I'm not 100% sure how close it is to the hornresp model. Regardless, I'm more than happy with the performance.
It wasn't until I finished building it I read on here that S2 should be the size of the hole in the baffle for the driver, but I couldn't really see an easy way of doing this even if I was to start over. Anyway, I'll have to have another look at the patent, I must admit a lot of it went over my head the first time I saw it...
Hello Tako,
Here a responscurve of the (above) tapped horn
vs. a vented box 18". Of course the lower is the vented box.
The vented box has a beyma loudspeaker, type: 18P1000ND.
I think you could say the vented box has a sensivity of 97dB, you can figure out what the sensivity is of the tapped. Between 40-60Hz 103db, toward the 125Hz somewhere by the 110db. The dip at 63Hz is a strong reflection.
I build myself 2 tapped horns and they have a lot off horsepower.
After the holidays i am going to make some more measurents, also some impedance charts.
Cheers,
Marcel
Here a responscurve of the (above) tapped horn
vs. a vented box 18". Of course the lower is the vented box.
The vented box has a beyma loudspeaker, type: 18P1000ND.
I think you could say the vented box has a sensivity of 97dB, you can figure out what the sensivity is of the tapped. Between 40-60Hz 103db, toward the 125Hz somewhere by the 110db. The dip at 63Hz is a strong reflection.
I build myself 2 tapped horns and they have a lot off horsepower.
After the holidays i am going to make some more measurents, also some impedance charts.
Cheers,
Marcel
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Hi Marcello,
Especially the measured Vs simulated response of that Tapped horn would be of interest for me.
I was tinkering on a model for a midrange/broadrange TH and gave it up (mostly for size reasons in where I wanted to put it), but the relatively smooth high frequency response of your measured TH has sparked my interest again.
Is the driver mounted so it has a clear path of view trough the mouth? And at what place did you actually measure that curve?
Especially the measured Vs simulated response of that Tapped horn would be of interest for me.
I was tinkering on a model for a midrange/broadrange TH and gave it up (mostly for size reasons in where I wanted to put it), but the relatively smooth high frequency response of your measured TH has sparked my interest again.
Is the driver mounted so it has a clear path of view trough the mouth? And at what place did you actually measure that curve?
Over on the Hornresp thread, I asked David McBean "Does Hornresp expect the hole in the baffle of a tapped horn to be equal to the area at S2? "
He replied "No, not at all. The Hornresp tapped horn simulation model is quite flexible in this regard. Note that as from Version 18.10 a throat chamber can now also be included in the design, if required."
Also, AkAbak models posted on this forum have no parameters to account for a reduced driver baffle.
Is L12 really just a stub? Does S2 form the true horn throat? Should the driver throat be at least as big as S2? And how does all this affect the compression ratio?
Hell if I know!
~Don
He replied "No, not at all. The Hornresp tapped horn simulation model is quite flexible in this regard. Note that as from Version 18.10 a throat chamber can now also be included in the design, if required."
Also, AkAbak models posted on this forum have no parameters to account for a reduced driver baffle.
Is L12 really just a stub? Does S2 form the true horn throat? Should the driver throat be at least as big as S2? And how does all this affect the compression ratio?
Hell if I know!
~Don
"Also, AkAbak models posted on this forum have no parameters to account for a reduced driver baffle."
I posted one of these way, way back in the beginning of this thread. It has a reduced driver opening and a front cavity model.
"Hell if I know!"
That's why I use AkAbak. I find it easier to do design changes quickly, and see them. The compression ratio does eaffect things. In general, I find the lower the Qts of the driver, the higher the compression ratio can be, and the closer to the mouth it ends up being.
Def_Driver '3015LF'
Sd=881cm2
fs=42Hz
Qes=0.41
Qms=6.82
Vas=160L
Re=5.31ohm
Le=0.92mH
Def_Reflector Wall=25cm
HAngle=0 VAngle=-90
System 'S1'
Driver 'D1' Def='3015LF' Node=1=0=20=21
Waveguide 'W1' Node=20=21
STh=500cm2 SMo=2400cm2
Vf=10L Len=2.55m T=0.9
Horn 'W2' Node=21
STh=2400cm2 SMo=2650cm2
Len=25cm Conical
x=0 y=0 z=0 HAngle=0 VAngle=0
WEdge=55cm HEdge=1.14m reflection
With AkAbak I can easily do things like this (compare different drivers):
I posted one of these way, way back in the beginning of this thread. It has a reduced driver opening and a front cavity model.
"Hell if I know!"
That's why I use AkAbak. I find it easier to do design changes quickly, and see them. The compression ratio does eaffect things. In general, I find the lower the Qts of the driver, the higher the compression ratio can be, and the closer to the mouth it ends up being.
Def_Driver '3015LF'
Sd=881cm2
fs=42Hz
Qes=0.41
Qms=6.82
Vas=160L
Re=5.31ohm
Le=0.92mH
Def_Reflector Wall=25cm
HAngle=0 VAngle=-90
System 'S1'
Driver 'D1' Def='3015LF' Node=1=0=20=21
Waveguide 'W1' Node=20=21
STh=500cm2 SMo=2400cm2
Vf=10L Len=2.55m T=0.9
Horn 'W2' Node=21
STh=2400cm2 SMo=2650cm2
Len=25cm Conical
x=0 y=0 z=0 HAngle=0 VAngle=0
WEdge=55cm HEdge=1.14m reflection
With AkAbak I can easily do things like this (compare different drivers):
Don Snyder said:
Patents are often as much about obfuscation as enlightenment, so look at a real Unity or Synergy horn and you'll see that excepting the end loaded HF driver the sum total of all the orifice areas for each segment are but a fraction of the CSA of the horn where they tap in. On the three way there wouldn't be much horn wall left if this criteria were followed, not to mention the havoc these large cavities would create with the HF and mids driver's responses (been there, done that long before I read the patent), ergo this particular version of the patent just describes a concept, not an actual excellently performing product.
GM
