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Paducah Home Theater

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  1. An article worth checking out is below. Note that some parameters can wildly change over the course of 80 hours on some woofers, others not so much. Also worth noting is that this is a 40 hz sine wave which will be more aggressive than simply playing material at normal volumes. Also, these are just normal 5-6" woofers. If you get a large 18" or something with dual spiders and a very stiff suspension, that's going to be much worse. You can't break in a stiff 18" sub with normal music at normal listening levels in 15 minutes, doesn't work that way, those spiders needs to be spanked for quite awhile. https://www.gr-research.com/burn-in-myths.html
  2. I've had Forte III's sustaining 110 db with only a 45 watt half sized Marantz receiver, playing bass boosted Eminem. So yeah they thump. But the Eminem songs I was playing was pretty low, most of his stuff is low 30 hz, Killshot for example is 27 hz. The problem is that passive radiators work like ports, and if we consider what ports do, well they stop doing much of anything once you get to an octave above the tuning frequency. I suspect that by the time you get to about 70 hz they're just not doing much. That's not to say that they don't produce bass or that they can't thump but rock music in particularly with the kick drums is all about the punchy 60-80 hz area and I'm just saying that I don't think the radiator is doing quite as much as people think it is once you get up that high. Even without a rear firing radiator you still ideally need a wall behind you for it to sound punchy though. It's not ideal either way.
  3. There's a few thoughts of his that I don't always buy in to. For example never wanting nicer speaker cables than zip / lamp cord. He always used lamp cord or the equivalent it seems. Lamp cord nowadays is 18 gauge but I've done research on the subject and it seems that speaker wire in the 60's was often closer to 24 gauge, you could pay extra for the larger stuff and get more like 20 gauge. Even at 18 gauge, all it takes is 13 foot of the stuff for you to be into the danger zone of less than 20 on the effective damping factor when you're dealing with some of the impedance dips that Klipsch speakers have. I can't even use a calculator to enter a smaller gauge, at this point nobody seriously considers using smaller than 18 gauge but if you could use those figures obviously it would be significantly worse. I'm sorry but I'll stick with my 12-14 gauge flexible pure copper wire with a nice jacket, either CL2 in-wall rating or with a nice braid. PWK would probably label such things as total BS. Sorry but it is what it is.
  4. I wouldn't speculate on such a thing but REW has a way that you can generate frequencies even down to the 10th of a Hz, and I had four sealed 18's I was able to figure out exactly how low I can hear. Takes a lot of guess work and speculation out when you can step through it and not have to worry about whether the equipment can actually produce the frequencies in question. Like I said though, 15 hz is very faint. Personally I wouldn't call 18 hz an infrasonic frequency.
  5. You may not be able to hear 18 hz. I definitely can. 15 hz is more debatable. 16 not an issue. 15, I can make it out but it's very faint. 14, all bass is gone, it's just air moving or stuff in the room shaking if I hear anything. 18 hz is completely audible.
  6. Sorry but this just isn't correct. I've done plenty of tests and have even measured them outside. If multiple units are not doing anything below 30 hz then you've got something going on in your room Actually I've even done the Barbie Doll test. Played an 18 hz sine wave and it was moving so much air that I got my daughter's Barbie Dolls and lined them up for a hair trick video. Was epic.
  7. From what I hear, tube amps as a whole really weren't all that great during that time period. William Zane Johnson founded Audio Research and reintroduced tubes into the high end world in 1970 but it was mostly him against the world at first. The rest of the community didn't catch on until the 80's and there was somewhat of a tube revolution / renaissance at that point. On the flip side, the early solid state amps weren't all that great either, the early transistors being made of germanium, being unreliable, and producing a bunch of odd order harmonic distortion, which is why Johnson did what he did. Basically everything kinda sucked back then.
  8. I've taken four identical 18" Ultimax woofers, used two for six months, then built a new box that used four. I A/B'ed the old ones vs. the new ones in an identical box. Down low there wasn't really any perceivable difference, a 35 hz thud sounded about the same on either. Where I could tell the difference was in faint upper harmonics such as on bass guitar, just was not the same at all. The old ones were crystal clear with lots of micro-details. The new ones sounded like you threw a wet blanket over them comparatively.
  9. Cones shouldn't flex much. It's all about the spiders. The spider contributes to about 70% of a woofer's compliance according to the Loudspeaker Design Cookbook. It's often coated with a layer of epoxy. Basically as the cloth moves you create little micro-tears which loosens it up. Just as a visual, consider buying a new pair of jeans, what those feel like vs. ones that are 10 years old, and those aren't even really stiff like new spiders are, yet you can still tell a big difference.
  10. piston engines do break in, most new vehicles start getting better gas mileage like at 10,000 miles. Whether that applies to a jet engine or not, I have no idea, but I'm not sure what else could require break in on a plane.
  11. The general consensus is that about 80 maybe 100 hours of normal use will do it. If you want to speed it up, there's a few things that can be done. One Klipsch exec takes speakers, wires them out of phase, places them close and facing each other, then plays pink noise all night. Seaton Sound basically takes a woofer, plays a sine wave where it's approximately 1/2 full exertion, a few hz below Fs, for half an hour. In the Klipsch lab they do something similar as the latter but I forget the exact parameters, do it for 15-20 minutes.
  12. it would work but you're obviously not going to get the same lower bass from that radiator as you would with it being 8" from a wall. Most of your "feel it in the solar plexus" rock bass is higher than most people imagine though, I've heard it's centered at 63 hz which is what concert engineers boost. Not entirely sure the radiator is doing a heck of a lot in that region, pretty sure it's tuned to almost an octave lower.
  13. In a sealed box, polyfill dissipates the shockwave behind the cone which is why it acts like it's in a larger box in a smaller box, the cone is allowed to move more at lower frequencies. R-19 insulation has about the same effect but with the added benefit of absorbing the back wave more, which polyfill is poor at doing. The Seaton F18's use insulation and they're stuffed pretty good. In a ported box, polyfill does about the same thing but the effect is that it cuts down on the port velocity. That can keep you from chuffing but it also kills the backpressure from the port which could have negative effects. At the tuning frequency the cone will move more, raising the impedance, and possibly putting it at a higher risk of damage due to overexertion. Depending on how hard you stuff it, you're going to end up somewhere between a proper ported box and a sealed box.
  14. Without studying too much, my opinion is that it's because your box is tiny for four of those subs in a ported box. Your internal dimensions are basically 18 cubic feet at best after driver displacement, not counting bracing, assuming 3/4" wood. Doesn't count a thicker baffle either. That's small even for a sealed box, you really need 4 cubic feet each after displacement. And you're trying to port it? Those drivers need at least 8 cubic feet each, preferably 12, each. You're trying to cram four into an 18' cubic foot box. That doesn't count the port either though which is another foot and a half with these dimensions. Your box is basically the size that it needs to be for one ported one, it's undersized for two even at like 20 hz tuning. Parts Express did an 8 cubic foot build and they recommended stuffing it with poly-fill to reduce the port velocity to keep it from chuffing, really needs to be bigger. If somebody really wants a F18 build for cheaper, just come pick mine up, I even have the Seaton F18 amp, it's the 4,000 watt speakerpower that was programmed by Mark. Same size, same stuffing, same amp. It's as close as you're going to get.
  15. single um-18. Flat as a pancake 32 hz on up, even when being severely spanked. Intermodulation distortion is a different story but alas such things don't exactly have a standard for measuring. Ouch indeed.
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