DrWho

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  1. Do you have a plot of the frequency response for each driver overlayed with the full speaker response? It would look a lot like the screenshots of your filter settings. This will give a good indication for how much summing you're getting at the xover frequency. One thing about phase is that it will change dramatically if you move the microphone around. Are you driving all three woofers in parallel? Didn't they do a tapered array in the passive xover? Are you sure you're not seeing polar lobing at 250Hz? Or is the mic within 14 inches of a reflective boundary? That could also be true of the speakers too. Is there a 28" path-length difference between the bottom and top woofer?
  2. Btw, have you seen this website? http://www.data-bass.com/data?page=systems&col=2&type=1&sort=desc&mfr=-1 That's a direct link to sorting by CEA2010 distortion numbers over a 10-63Hz bandwidth.
  3. There is an assumption that "horn loaded systems" have less driver excursion than direct radiator systems. It's a nice thought, but that simple remedy is simply not true across the board. You see this in both simulation and measurement world. This becomes the reality when the horns are undersized, which is the case for very low frequency devices. Also, if we're talking about "impedance matching" - which is one way to talk about horns, then you can't talk about "impedance matching" without first understanding the load you're trying to drive. The load in this case is the listening room - and specifically the wavefront that arrives at the listening position. The source in both cases is the driver. If you crank through the math, then you will find that a "classic horn" is not the best way to couple the wavefront to the listener at the listening position for a "typical" home environment, especially if you're dealing with an "undersized horn" in an acoustically "small room". A "classic horn" assumes radiation into free space. You get more power per displacement using other methods in a "small room". Not that this is an example of quality reproduction, but there's a reason you don't see horns in the car audio subwoofer SPL drag races. It's the same physics at play - just that the room is even smaller. I'm putting quotes around these terms because they are loosely defined concepts that can have an effect on these conclusions depending on the specific situation. Anyone claiming that a horn automatically has less modulation distortion is drinking kool-aid. Can it have less? Yes. Can it have more? Also yes. It depends on the design and implementation. The thing is - you're going to get more bang for the buck avoiding the classical horn route for very low frequencies. It's just how the physics play out. Anytime you make the horn bigger to give it more advantage, then you can always add more drivers and end up with a smaller total footprint that meets the same SPL requirements. And even if you make the horn bigger, it's the compression ratio that determines your best-case excursion reduction. Make the compression ratio higher and the horn has to get much much longer for the same pass-band ripple. It's more volume-efficient to use multiple drivers to achieve the same excursion per SPL at the lower frequencies (and you have a perfectly flat passband). This is why pro-sound touring companies use direct radiators for their subwoofers. At high frequencies, horns are always better. Our rooms are acoustically large at high frequencies (so the free space assumptions are valid) and we're getting very large compression ratios because there is enough space for the horn to be appropriately sized and couple well. At low frequencies, we have small rooms and the horn isn't big enough to get the energy out of the horn. The frequency response ripple in an undersized horn is the result of "room modes" inside the horn. Designs that are undersized but appear to have less ripple are converting energy to heat inside the horn (which is still energy not getting out). On top of that principal, inside a small room, the direct radiator gets coupling benefits from the room itself. That "room gain" provides more gain to the direct radiator than the horn firing into the same location. A lot of that impedance matching work of the horn is duplicated by the room - the thing is, you can't get a double benefit from impedance matching. Anyways, that's not to say that you can't get a good sounding horn loaded subwoofer. It's simply going to be a larger cabinet than a comparably performing direct radiating setup. And by comparable, I mean same bandwidth, spl, and excursion requirements.
  4. Just to clarify, I was recommending to purchase the IB drivers, but don't install them in the walls or ceiling. You can put them in a classic speaker cabinet of your choice. Start with the drivers and then figure out which cabinet alignment meets your current needs best.
  5. There is no science in the world backing up this aversion to direct radiating bass...especially for a narrow bandwidth subwoofer. There are measurements however that disagree with the claims presented thus far, which also lines up with the science. I'm not going to debate it though because these guys have drunk too much kool-aid. I have always been a proponent of audio purchases aligning with long-term goals. If you want to go the IB route in the future, then perhaps you might consider investing in the IB drivers now, and installing them in a slightly different cabinet alignment. That can be hard with the IB drivers, but would be something worth investigating I think. Plenty of guys on the AVS forum to help hash out the details. What kind of amplifier will you be running for the sub?
  6. LTSpice is free btw - and also my simulator of choice: http://www.linear.com/designtools/software/#LTspice The tool is fairly straightforward, but adding parts is a major pain.
  7. ces

    Interesting - where are they located? Hidden behind that grill going down the sides?
  8. ces

    The JBL 2226H uses a 4" voice coil and extends beyond 1kHz... https://www.jblpro.com/pages/pub/components/2226.pdf That's what, a 25 year old design? I'm sure there are plenty more examples - I hope it's not poor form to mention a JBL driver here. Do they count as "low mass" drivers?
  9. ces

    I was just thinking - if we're really using different words to describe the same thing, then perhaps we can throw some numbers on the table? When I hear low mass 15" driver in a sealed cabinet of that size, then I'm expecting an acoustic F3 somewhere between 50Hz and 70Hz, which is basically lascala territory. It's interesting that PWK noted 50Hz in that article @dwilawyer posted, so I'm probably not too far off. Is it too early to release numbers like that? Is it possible you've achieved better THD numbers at the expense of increased frequency modulation distortion? PWK had a lot to say on that subject...
  10. ces

    " I am talking about the speed in which a driver can go from rest to excursion and back to rest. " *sigh* That's also called frequency response. Honest.
  11. ces

    Perhaps the physics are different over there in Indy?
  12. ces

    Speed and frequency response are the same thing. Why can't we just use normal terms? I could be shortsighted here, but you can't talk about mass outside motive force and cone stiffness. High excursion designs exist with high frequency extension and equally stiff diaphragms. And physics dictates that low displacement = no bass. Voicecoil magazine is often publishing exciting Klippel results. The legacy of PWK was engineering driven designs. We don't want a speaker designed for a specific application, or based on some weird philosophy about the limitations of drivers from the past. Nor does it matter what the competition is doing, or what marketing label gets placed on a product. The physics are a constant. Yes, by all means keep the cool marketing stories and emphasis on heritage, but at least be authentic about it. Btw, there's a reason the "evil" consumer stuff focuses on what they do today. Achieving those goals with greater fidelity is what high-fi is all about - not arrogantly dismissing it. Btw, my intentions here are to provide some honest feedback. Not trying to dig anything through the mud. Quite frankly, I've realized the design targets here aren't going to emulate the performance of the K48 in a similar application. I bring it up because it will disappoint a lot of my peers that I think fall into this target market. Not everyone listens to old jazz on vinyl. Klipsch hasn't released it yet so there's still time. The thing is, my peers haven't drunk the Klipsch koolaid...
  13. The closed backs aren't the same thing as false corners. The flare needs to extend beyond the front of the speaker. Not just that rear corner.
  14. ces

    Hah! I've heard those already. I really want a 15" 2-way with hypex amps and active xover. I've been hunting this down for many years now - that might be a fun forum search to find my first mention of it. I never thought Klipsch would ever come out with something like the Fifteens, but here they just announced it. No way! The thing is, I want it to be voiced like the ki396. None of this "no bass, SET like, tone" nonsense. Those are words I hear at the local audiophile boutiques when they're trying to overcharge for crap sound. I'm not saying that's the case here, but it's made me want to demo it first. On the topic of mumps....Why isn't this just standard approach on all the horns now? It's not like it costs more to add that shape to the molds. Yes, I'm totally being an annoying audiophile here, hah! This thing is so close to my ideal setup that any shortcoming would be so disappointing. I've wanted something like this so bad I've set out to build my own, but I could never bring myself to shell out for all the tooling costs. Plus, you guys are better at this stuff. This is a product niche that's been seriously lacking, but if it requires a subwoofer then it totally ruins the simplicity story.
  15. You can always add "false walls" to the khorn....or basically build a room corner for them to sit in so that the flare of the bass bin is finished without using your room's corners. And then you can place them anywhere in the room. If you're going to pull the khorn out without the false corner thing, then you should just get the lascala since it sounds better in that configuration. Just make sure you get a potent subwoofer to make up for that bottom 1.5 octaves you're missing. Or just get the Jubilee - getting a passive xover made for you is easy if you don't wanna deal with the active route.