I had a few free minutes so I played with this a bit more. As expected, since you don't care about wide bandwidth you can get basically the same results from a much simpler enclosure. Here is a simple tl, quite a bit smaller (about 1/3 smaller) and very close to the tapped horn response from 20 - 60 hz. A bit of light stuffing in the first half of the line would calm the resonant spikes right down too if that's what you want, but for high power spl competition you probably won't want that.
Shown at 3000 watts, it exceeds xmax by about 1 mm at 28 hz but none of your test tones exceed xmax (20, 25, 33, 40 hz). Velocity is right around 27 m/s with no stuffing, it will be lower if stuffing is added.
This is just one more thing to think about. This design trades the tapped horn's bandwidth for something that's much easier to fold and maybe a bit easier to build.
To be clear, this design takes more power to reach xmax (and equivalent spl) compared to the tapped horn but that's just because it's significantly smaller. Reducing the size of the tapped horn (which can be done easily) would do the same thing, the smaller tapped horn would require more power to reach xmax and equivalent spl compared to the larger tapped horn.
Shown at 3000 watts, it exceeds xmax by about 1 mm at 28 hz but none of your test tones exceed xmax (20, 25, 33, 40 hz). Velocity is right around 27 m/s with no stuffing, it will be lower if stuffing is added.
This is just one more thing to think about. This design trades the tapped horn's bandwidth for something that's much easier to fold and maybe a bit easier to build.
To be clear, this design takes more power to reach xmax (and equivalent spl) compared to the tapped horn but that's just because it's significantly smaller. Reducing the size of the tapped horn (which can be done easily) would do the same thing, the smaller tapped horn would require more power to reach xmax and equivalent spl compared to the larger tapped horn.
An externally hosted image should be here but it was not working when we last tested it.
I already said this very clearly in post #30. OP does NOT have money to buy more drivers and amps.
This has been well known since about 2 months after the tapped horn patent application was released. I'm not sure why you didn't know about it, but ported boxes give the most output per cubic foot and always have.
There was a lot of hype when the tapped horn was released but it was dispelled very quickly. Horns (even tapped horns) are for when you don't have a lot of money, drivers and amp power but you have a lot of room. Ported boxes are for people that don't have a lot of room but have lots of drivers and amp power. I thought this was common knowledge by now. It's been years since the "magic" (marketing) wore off the tapped horn hype.
The loudest cars in the uk at the moment are all using 6 subs and close to 20kw in ported boxes thats getting them 160db. There's no way you could do that with a sealed box, there wouldn't be enough air movement to keep the coils cool for one thing. If you could feasibly make a sealed box loud in a car someone would've done it by now. I've been attending car audio competitions for a few years and I've not seen a sealed box louder than mid 130s. It may be possible to get louder sub 20hz with a sealed box compared to playing a ported box under tuning. But I'm only interested in about an octave, lower output above 60hz is desirable because I don't want to muddy up my midbass.
I do see what you're saying though, 4 sealed subs may well be louder than one or two in a less than optimal horn but I've only got two.
I do see what you're saying though, 4 sealed subs may well be louder than one or two in a less than optimal horn but I've only got two.
You are confusing two separate issues here. Both a sealed box and a tapped horn will benefit from the "free" gain afforded by cabin gain so this statement is incorrect. Cabin gain has nothing to do with the fact that multiples of sealed or ported boxes will beat a single tapped horn.
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Thanks for modeling that Just a Guy, the response looks similar to a 6th order bandpass I designed for these subs although I dismissed it for being too peaky, that does look a bit smoother and a lot smaller though. Would a taper reduce output? I'd not considered a transmission line, I always thought they have a fairly low sensitivity
Since you are using the same driver and a vented resonant enclosure in all the sims, your sensitivity is going to be mainly dictated by enclosure size (vs tuning). None of the enclosure types are magic and there is no free lunch. A tapped horn is only a transmission line with a clever driver placement to gain more effective bandwidth without stuffing.
This means that a ported box, a transmission line, a tapped horn, a front loaded horn, etc, will all have roughly the same output for a given enclosure size and tuning.
You can change enclosure size and shape to better fit a given situation or goal but you can't trick physics, the statement above will always be true. To answer your question, adding a negative taper to a tl would reduce the enclosure size, lower tuning and reduce spl level. Adding a positive taper to a tl would increase enclosure size, raise tuning and increase spl. Spend a bit of time with Hornresp playing with enclosure shapes and sizes and this will all make sense.
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I think I have a good grasp of the situation.
If I'm not mistaken, there is only one person in the world who's put more tapped horns in cars than me. (I may be wrong, but I haven't stumbled across any data to dispute that.)
The sealed box and vented box have a very simple advantage : displacement.
That's the critical difference in the car. The tapped horn may be more efficient for a single unit, but if space is a factor, the sealed and vented boxes win.
All of these statements assume you have unlimited power on tap. In a car, we don't, so exotic enclosures have an advantage if you're limited in power or money.
If you have unlimited power, unlimited money, and a fixed amount of space for loudspeakers in a car, sealed and vented win.
I said exactly the same thing in post 30 and then again in post 42. I agree with everything here. Multiple drivers will beat a single tapped horn.
The problem is that you have said twice now in previous posts that sealed will win due to cabin gain. (You didn't mention cabin gain in this last post and that's why I agree with it completely.)
Cabin gain has nothing to do with this. This issue is all about using multiple sealed boxes vs a single tapped horn. Put a tapped horn in a car and it will benefit from cabin gain just as much as a sealed box. Compare 6 sealed boxes vs 1 tapped horn and the sealed boxes will win because there are 6 of them, not because of cabin gain.
Yeah, I can unless you plan to build a ~38 ft^3 net [est. ~47.5 ft^3 gross] cab. Once shrunk down to your ~10 ft^3 gross size limit, even a theoretically ideal 12 dB/octave cabin gain curve won't be enough to make up the difference of HR's 9 dB/octave [0.5pi] gain [referenced to 2pi] + the cab's reduced acoustic efficiency.
Factor in that most [all?] vehicles don't have an ideal gain curve and TH's don't protect the driver all that well unless it's ~reactance annulled, which yours won't be due to space limitations, this normally makes the HR 0.5pi sim a pretty accurate one.
Then there's the limitation that you can't safely use a > ~3:1 CR with these types drivers at high power, so can't take advantage of any specs changes that otherwise might allow 'squeezing out' anymore dB/w out of them.
Typically, the measured specs will dictate an even larger cab, so likely its acoustic efficiency will be even further reduced than what's been simmed so far.
GM
If the only variable in the equation is output vs space then this is the most efficient to least.
Passive radiator>Ported Box>Tapped Horn>Sealed.
I don't know if I have as much experience as Patrick in putting tapped horns in cars but I have tried several times and a well designed ported box beat my horns in output every time. I believe this has something to do with boundary loading and the cars cabin. I have done a lot of searching on these forums and others including reading all of Patrick's threads and others, and we have all run into the same problem. In a very small area a horn does not pressurize as well as a ported enclosure does. I've heard a few different theories, some say its boundary gain, some say its the way a horn gains efficiency by directing the sound in a more specific direction and the very long wave lengths at these frequencies...
Either way a well built ported or passive radiator box destroys a horn in a car every time. Assuming same size box and 1000's of watts available.
Passive radiator>Ported Box>Tapped Horn>Sealed.
I don't know if I have as much experience as Patrick in putting tapped horns in cars but I have tried several times and a well designed ported box beat my horns in output every time. I believe this has something to do with boundary loading and the cars cabin. I have done a lot of searching on these forums and others including reading all of Patrick's threads and others, and we have all run into the same problem. In a very small area a horn does not pressurize as well as a ported enclosure does. I've heard a few different theories, some say its boundary gain, some say its the way a horn gains efficiency by directing the sound in a more specific direction and the very long wave lengths at these frequencies...
Either way a well built ported or passive radiator box destroys a horn in a car every time. Assuming same size box and 1000's of watts available.
I've asked my recone guy about how much it'd be to get just a pair of cones and baskets to make a passive radiator enclosure. I'll do my best at measuring ts parameters tomorrow, didn't have time today. But it looks fairly straightforward, I've got resistors, an oscilloscope, voltmeter and a tone generator.
I'm happy with making my box significantly bigger but that means I could also make a ported, passive radiator or bandpass box of a bigger size.
Is there a way of modeling passive radiators?
I'm happy with making my box significantly bigger but that means I could also make a ported, passive radiator or bandpass box of a bigger size.
Is there a way of modeling passive radiators?
Yep.
And for a while I continued to build tapped horns and back loaded horns for the car. But then when I saw one of Danley's ported boxes that's at danleysoundlabs.com, it occurred to me that you can improve the phase response of a ported box with a carefully designed port. And that was a real eye-opener, it never occurred to me that the phase response of a ported box isn't just based on the frequency that it's ported at, the location and shape of the port matters too.
Patrick,
DSL's CS 30 has the same phase response as any other phase inversion (bass reflex) box with the same Fb.
It is not "improved" in regard to phase.
The CS 30 has an Fb around 30 Hz, below it is a single Lab 12 with around 36 Fb, both boxes have the same 180 degree phase rotation from around 70 Hz to Fb.
Art
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Right! I have finished measuring the ts parameters, although the results are odd, possibly due to them being reconed once or twice in their lives. There is a resonance peak at 37hz, which is to be expected, then a dip and a plateau to mid 40s on one side of that peak, but before the 37hz peak the impedance rises as expected. Possibly this is due to a difference in the spider and surround? But nevermind, the rest of the specs are pretty close to the manufacturers.
I think a passive radiator will be a better route to take for low tuning in a small volume. A matching radiator to my drivers will be about £120 according to the distributor, not too bad as I could probably make do with 1 18". Europe-Audio have Dayton 12" PRs for £35 but they have half the xmax of my subs so presumably I'd need at least 4 which makes them more expensive.
I may ask a moderator to adjust the title
I think a passive radiator will be a better route to take for low tuning in a small volume. A matching radiator to my drivers will be about £120 according to the distributor, not too bad as I could probably make do with 1 18". Europe-Audio have Dayton 12" PRs for £35 but they have half the xmax of my subs so presumably I'd need at least 4 which makes them more expensive.
I may ask a moderator to adjust the title
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