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DS-21

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About DS-21

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  1. Honestly I'm surprised the relatively small single-layer coil held up as well as it did in your compression testing. The distortion readings...not a surprise. Nothing there makes me question what I've heard for the past decade or so.
  2. Looking forward to seeing how the NS18 handles your torture tests! Problem is the flange is a bit bigger than the open tool 18" baskets, so you might have to do a new baffle.
  3. Man, if only Jello put shorting rings in the motor (I suspect the flat FR is from EQ, like the Fathom) to extend the bandwidth up another octave or so....
  4. I agree with you. I recall reading an interview with Kevin Voecks where he mentioned the reason Revel went from sealed to PR in their then-flagship sub was that the PR variant was a lot more efficient in the range that actually matters. Not to mention that three cones looks more expensive than one cone...
  5. IME, an audible "bonk" sound. Here's a good thread on PETT with different drive-units and amps, but the same problem. Switching from those horrid old PE 240W plate amps to a very good multichannel amp (Boston Acoustics rebadge of the Sherwood A-965) fixed it for Brandon, even though on paper the A-965 is 1.5dBW less powerful. It's a smidge over $300 but I'd recommend the Crest ProLite 2.0, which is finally a real shipping product. (It was vaporware for quite a while.) It's basically Peavey's "adult" version of the IPR1600. Same basic amp, but (per its designer) a little more capacitance, and IMO more importantly the ProLite delete-options the IPR's hideous blue lasershow. I recently picked one up (eBay seller "audiosavings" regularly has them at $310-325 shipped) for my sister's forthcoming basement theater, and found it to feel considerably more solid than the IPR3000 I had for a time (steel vs. aluminum case), look an awful lot nicer, and is also quieter even with the stock fan. I think there's a DSP version too, but I've not played with it or looked into it at all. I'd rather use a miniDSP anyway.
  6. Probably the best reviewer in the business, Dr. David Rich, just gave Data-Bass a shout out: http://www.hometheaterhifi.com/technical-articles-and-editorials/technical-articles-and-editorials/subwoofers-a-brief-look-at-the-effectiveness-of-a-subwoofer-in-a-music-system/page-2-the-subwoofer-in-the-listening-room.html
  7. Thanks for the detailed explanation! Looks like it's off to the hobby store for me, because I don't want to waste any more time cleaning silly putty or duct seal residue off cones. Fortunately, I have a postal scale.
  8. Josh, I remember you posting somewhere (AVS perhaps) about using magnets on each side of the cone to measure Vas. Very elegant, as it allows adding mass without risk of greasy stains on the cone from putty or whatever. Alas, I can't find your post. So, any recommendations for magnet size/strength/quantity? Also, have there been any cone materials for which you method did not work?
  9. In my use, it was horrid. There was some interaction between it and the signal-sensing power strip I was using that led to awful noises. I cannot explain why, but no other gear has done that. When I plugged it into any other outlet, or indeed anywhere but in that strip, it was fine. But then I'd have to either leave it on or manually turn it off, and both options were unacceptable to me. Also, even with the Noctua fan it was borderline too loud for me. So I ended up reinstalling the factory fan and selling it locally. (I still have the Noctua fan.) But when I tried it in a different outlet, it sounded like nothing at all. Just power. The way an amp should. I don't know if it would interact the same way with other switching power strips; mine was a six-outlet unit by Monster that my fiancee had. Perhaps the IPR 3000 just didn't want to be associated with such a disgusting brand, and howled in protest. I wish it had worked out for me, because I like the technology and I loved the price. The one thing I don't like about the ElectroVoice amp is the price. True, it's 8 channels vs. 2 and more aggregate power, but the cost differential between the IPR 3000 (Black Friday sale) and the CPS 8.5 was roughly 10x...
  10. FWIW, I recently picked up an interesting amp that's driving my whole multisub system right now: ElectroVoice CPS-8.5 Class D, German-made, and rated 1kWx4/2 or 4Ω/all channels driven. EV claims it has no highpass filter down low, I don't know about that but it puts out plenty of power above 16Hz, and I don't care about stuff below that. It also will turn on with a consumer audio 12V trigger, and go into standby with same. That (and the space savings, compared to multiple mono amps) was the draw to me. Only downside of note is that all I/O are by Phoenix terminals, so one needs to slice of the ends of her/his signal cables if they're pre-terminated. And cost, though I don't know anything else that offers that much power and a 12V remote trigger input for less. Fan noise is much much much lower than a Peavey IPR 3000 modded with a Noctua fan. With the amp under my daybed, I can't hear it unless I put my ear to the ground.
  11. Obviously. My point is just that, in real life, the XLS12 as a direct radiator actually measures quite flat up to ~400Hz. No measured midbass hump. (As an aside, every time I've measured the Le of one on FuzzMeasure with my impedance jig, I've gotten a number about 1/3 the number Peerless specs.) I wonder if the VMP's might be too heavy for a BP, even with no mass added. The only reason I hadn't yet built this XLS12 design is because I hadn't seen a PR that was light enough and had decent throw. The VMP's, as well as the XLS12-PR's I have, are too heavy to effect the tuning I want in this design. And any other BP4 I've modeled, including a big one (~250L gross volume, F3's of ~16 and ~50Hz) with the Maelstrom-X Mk. I. The CSS APR12 looks like the only one that will work in that design. Geddes uses the flat-piston Dayton one for his, but he goes up to the 15 for a B&C 12TBX100, and a 15 won't work in the space I have. Now that I'm back in town - it's amazing how much one appreciates things like constant supply of electricity, when one hasn't had it for a while; Pakistan is doing this crazy "load shedding" thing that amounts to 10-14 hrs of electricity per day, with no rhyme or reason as to timing... - it's at the top of my recreation list. (Though since I do have 5 of the woofers and only one in current use, I'm also thinking of just doing a dual-opposed sealed with boatloads of EQ...) I'm not worried about mfg specs, because I can measure drivers. I'd fit the box to the driver in question.
  12. Considering that the xls12 is good to 400+ Hz as a direct radiator, why would Le be a factor up top? Does the bp loading interact with inductance differently that direct radiation?
  13. Not for a couple weeks. I'm in Lahore right now, and because air travel had gotten so annoying - Emirates now even has a one-bag-of-under-7kg carryon limit - I only took my iPhone. I expect, however, broadly similar passband efficiency at the cost of not being able to contribute to room pressurization below cutoff, unlike the bp4.
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