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New Klipsch horn subwoofer


jason str

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There isn't a seperate vent if I understand what some here are thinking.

KD-1802 is the drone and it's use is what tunes and makes the system a "vented system" and the loading of both the driver and drone by a shared horn makes it a "Horn-Loaded Vented System".

post-12368-0-20480000-1388163236_thumb.j

Edited by mikebse2a3
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I read through the patent, and the vent discussed is either the passive, tube, or hole. In my drawing above, the vent is represented by the passive on the right.

I now get what this design does. The sub is a tuned port or radiator tuned sub enclosure with a horn to amplify and further tune the frequency. If the box without the horn is tuned for say 25Hz, then perhaps the horn further reduces that tuning to 21Hz for the whole speaker.

That is cool, and opens up a whole new strategy for horn loading. The benefit I can see is the wattage this thing can handle. In a THT for instance, about 300 watts is the limit. In this new sub, the limit is 1100. I recall BFM telling folks about the limits of the wattage for this or that reason.

I'm not sure what the actual efficiency of the THT is in freespace. Most of its more impressive numbers require corner loading. Here is a chart of the THT

Pi12.gif

I don't know how to calculate overall efficiency. Any ideas?

Edited by mustang guy
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If it helps any the Klipschorn and Jubilee are "Horn-Loaded Sealed Systems".

By the way note the -3db at 26Hz for this system is for 1/2 space loading and if placed at a floor/wall or corner area of a room the increased loading could be expected to lower the -3db point even lower in frequency.

miketn

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If it helps any the Klipschorn and Jubilee are "Horn-Loaded Sealed Systems".

By the way note the -3db at 26Hz for this system is for 1/2 space loading and if placed at a floor/wall or corner area of a room the increased loading could be expected to lower the -3db point even lower in frequency.

miketn

My understanding of the math says that a larger mouth just improves the impedance matching, and that the dominant factor for Fc is the length of the horn. The Fc is usually a resonant point in the system, which means 1/8 space loading doesn't end up lowering the F3; it just reduces the dip above the F3. Now if the horn was designed to be a flat passband in 1/2 space, then going to 1/8 space doesn't change the frequency response: it just increases the output at all frequencies equally.

Now if we want to talk pressure vessel gain (or room gain), then that's a totally different matter. However, this system is rolling off at ~24dB per octave....we might see around 9dB/octave in our rooms of pressure gain, which at best, reduces the rolloff to somewhere around 12dB/octave. You might see an extra 2dB at 20Hz from putting this system into an acoustically small room.

If you think about it, this almost has to be the case because a sealed box horn typically rolls off at 18dB/octave. Going to a vented system adds another "pole" which increases the rolloff another 6dB/octave. The "vent" is just another reactive system being fed into the reactive system of the horn, so you're creating a higher-order highpass filter - and that's tricky to do electrically, let alone acoustically....which probably explains why Roy says it's a crazy balancing act.

I think the real advantage of this bass horn is the fact that it is usable to 250Hz (maybe even higher with EQ). You could go to a straight up 3-way system that covers the entire 20Hz - 20kHz bandwidth. If you want to go all Klipsch, then I'd run a stack as follows:

K402 or K510

KPT-305-MB

KPT1802-HLS

After thinking about it some, I think I personally would do the following:

QSC HPR125 1" horn with BMS 4550 Driver

K402 horn with B&C 8PE21

Othorn

I think a 1" throat for the tweeter makes way more sense than a 2" - especially if you can get the xover up to around 1.5kHz. The smaller horn also helps with the overall height of the system. The KPT-305-MB is only rated for 900Hz up top. The 8PE21 should be good up to 3kHz or so and wouldn't break the bank. Not sure if it's a drop-in replacement for the 305-MB design, or it is quite possible the 305-MB is good to 1.5kHz with a little EQ. I bet the Klipsch 8" driver doesn't have a shorting ring in it though, which should reduce the distortion quite a bit for a higher frequency xover point. And then the Othorn is 1/3 the size with the same output and crazy low distortion. It'll also be cheaper than buying the Klipsch system. That said, I would still love to hear the two subs in a shootout because I don't have a 4000W amplifier so the KPT1802-HLS would go louder with the amplifiers that I have. Also, I'd be curious to compare the "HF" performance of the 1802 to the Othorn. I've already heard the Othorn up to a 180Hz xover and it was comparable to a quad 18" cabinet, but I have a feeling the 1802 could be a bit cleaner and make things easier on the midbass unit.

Anyone interested in some shootouts? I've already got the Othorn and QSC tweeter. I think a few guys have mentioned they have the KPT-305-MB, which I'd love to hear and measure.

Oh, and a port and a drone are the same thing....except a drone can give you an extra degree of freedom in its tuning (since you have the suspension compliance to play with). Ports will distort when air moves through them which creates a chuffing sound. A drone will sound like a bottoming driver when it runs out of excursion. Generally ports distort nicer, but it's possible the crazy alignment needs the degree of freedom the drone offers...

Edited by DrWho
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Yep, built an othorn and will be building more. The Gjallerhorn doesn't measure nearly as good so I haven't been interested in it.

I really want to hear this klipsch sub though. I won't be able to afford it, but I could see it having lower distortion at the upper octaves, which arguably matters more.

Maybe Ricci might pick one up? Now that'd be fun to get it on data-bass.com.

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Have to say, this would go really well with my Jubilee's. My door happens to be 33 inches. Wondering if a crown xti1000 will work? That pushes my KPT684 no problem.

Remember when they started collecting idea's? I mentioned a horn loaded subwoofer as I'm sure others did as well.

72*48*31 is quite large.

The MWM is 67 inches wide, about 34 tall and 45 deep. Not really much larger for the 1802.

Pretty cool.

Bruce

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