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D-MAN

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Everything posted by D-MAN

  1. JC, that is a good question! The tubes are each 8" long, the Vb is approx. 4.5 cu. ft, I would guess. The volume is a bit tricky with this stuffing. Might go with longer tubes; I went with the tube size that Chris Munson (popbumper) used as most of the ported La Scala dudes reported that they preferred the shorter tubes. There is a noticable fall-off below the resonance of the tubes, not like a bass horn. It is a very steep cliff - you really notice it, unlike the gentler roll off of the corner horns. This could be from the Fr being too high (too small of a Vb) for the K33E to resonate at the expected tuned frequency, that's my suspicion, but its still quite smooth and entirely listenable. At this point, because I tried the KAPPA-C's which really "fit" the Vb volume, I won't know until I get the Crites in them. I didn't think that they would go well with the crossovers that I have, so I sent them home with my buddy as they were just taking up space. But they are a definite candidate for use in these. I used the 6" wide slot on those, as I would all drivers except the K33E and Crites drivers. I know that the K33E's are not resonating anywhere near the Kappa-C's in the volume that I currently have (but within a couple of Hz of the V2's (34 Hz Fc), I'd say). I used the commercial "Acousti-Stuff" in these instead of fiberglass, as they have open ports and I didn't want fiberglass being puffed out the ports. About 1-1/4 lbs in each cabinet. I'm not sure about whether its the equiv. of fiberglass or not. The K33E's could use more stuffing (4.8 cu. ft if I remember correctly), the Crites should be close as they currently sit. I'm also using the narrow slot for the K33E's. I will get around to checking wider slot variants too. But I have to say, MAYBE, or even PROBABLY, when properly tuned, the corner horn has met its match. These are very promising - I didn't expect them to compete effectively with the corner horns (I intended them as rear-channels). Test-wise, currently I don't have any test gear. It would help, certainly. Dana
  2. I think PWK was right, the measured K33(x) T/S parameters put it outside of the accepted workable horn formulas, so I would agree that it cannot be accurately modelled by most horn programs that I know of. It remains a matter for empirical testing. The Keele formulas, for instance, would predict the optimum efficiency of the K33E at a throat size (St) of 115 sq. in. and a Vb of rather large volume at 9343 cu.in. Not practical, in other words. This all changes when under pressure as in the Khorn and equivalents. I think that he's used to dealing with John Q. Public on the whole, so what he says may be watered-down quite a bit (for public consumption, as it were), but the gist of what he said is entirely correct IMO. DM
  3. Got a pair in the house, nasty-looking, but suprizingly sweet sounding. These pups can ROCK! Painted black with that spray epoxy with lumps in it. This will take some practice. Phenolic midrange diaphragm, K33E and a stock ALK crossover. JBL tweets are not going in these, I ordered some Crites tweets for these (hence the offset mid horn). Compared to the V2's (the corner horns), these don't go quite as low, but ran out of that nylon stuffing, so resonance isn't quite where it should be. I ordered CW1526C's from Bob Crites. We'll see how they do as they can resonate in a slightly smaller volume than the K33E. My buddy who built these is a bass player, and he was suitably impressed enough that he went back home and immediately started building himself a pair. We tried one cab with the Eminence Kappa 15C (4 Ohm) which I had sitting around and only one cabinet totally kicked tail. 30 watts was flabbergasting. These not only blow out matches, they blow the extinguished matchstick out of your hand! Real pant-flappers. I was amazed at how much air these can move. He also couln't believe how loud they were at 1/3 watt. The next day I got to messing around and discovered that I had wired one woofer out of phase. I was thinking that the K33E sounded a little weak. Now that they are both wired in correct phase, I no longer think that at all. Doh! These bass bins are on casters so they can roll around easily. I thought that raising the cab up off the floor would hamper the bass, but it is more than satisfactory, another suprize. The 400Hz 1rst order crossover may not be the best - seems that the bass horn goes higher. I had the same problem with the V2 so I was sort of expecting this, and on the V2, I had to go with a steeper slope crossover to compensate. Probably the same thing here. There isn't enough room in the back chamber to allow for a front chamber to be employed, so I'm probably stuck with the crossover solution. Too bad its the most expensive! My overall impression is that these will definitely give the corner horns a run for their money. They are just as efficient, and I think when properly tuned, these will perform just as well. They image better because they are not in a corner (apparently). Their ability to image and throw a very stable soundstage is better, and the fact that they are free-standing is a real bonus. Now to get a nice veneered set. These are butt-ugly. But in the dark... Dana
  4. Looks like 1985... (!) However, PWK is absolutely correct in his response, the T/S params of the K33(x) put it way out there into unpredicable territory when under compression such as in a Khorn. DM
  5. Interesting comments above. Let me think about those for awhile... Personally, I think the dynamic range of digital media and low noise level is far better than vinyl, but that's just me. See this letter from PWK posted by Freddyi on the audioasylum forum referring in part to digital technologies. DM
  6. I think the curves are quite useful. They also seem entirely consistant enough for our purposes. The reason I keep coming back to the Jubilee as a comparison is that I think that it acts as a reference, overall size, shape, freq. response, and mouth size, etc., are closer than anything else we could compare it to. It serves to give an ability to determine what portion/element(s) in the curve is likely result of the testing methodology. I think there are 3 portions that are consistant between the Jamb and Jub and do not seem to change. I attribute these to being anomolies that are the result of the "particulars" of the testing methodologies. JC has also done the impedance testing as he went, so we have other information available. But I'm still trying to decide which configuration is "best" overall, since I have to tell Al K. which one to do. That's what the thought behind the above curves is, anyway. JC knows I have wanted to go with a series config from the start for reasons of power handling ability. However, I'm still not quite sure. Dana
  7. ...and the 8 Ohm series curve over the Jubilee clone curve... I really am suprized at the differences in the curves based on impedance alone. DM
  8. Another set of overlays - comparing to the Jubilee clone... Dana
  9. I guess I'll do the series version crossover, then. Between us, we'll get it covered. Is there any T/S difference between the stamped-frame Crites driver and the cast one? Dana
  10. Yes, I'd go with series, too. Perhaps listening would be the best determiner between 4 or 8 Ohm. I really thought that there would be a drop in SPL in series at 8 Ohms, but motors are very strange animals compared to plain old resistance. I wonder what the overall impact is once the mids and tweets/network is also in the loop - could have an influence, too. Dana
  11. Looks like the McIntosh folks are right! Seems to me to be like a difference in "flavor" more than anything else... Dana
  12. Added 4 Ohm PARALLEL to the previous overlay... DM
  13. Here is an overlay of the 4 Ohm vs. 8 Ohm SERIES lashup... 3" slot. Dana
  14. JC wait - before changing out the motor boards, try the 8 Ohm taps first on the narrow slots and take a curve of that - it will be informative, that's for sure. Should clear things up once and for all, anyway. My guess is that it will "flatten out" the curve as it looses some efficiency. Dana
  15. Overall impedance has changed - series is at least 8 Ohms. Change the output taps on the amp to 8 Ohms and we should see a drastic change (drop) in efficiency, too. The current flow is higher in 4 Ohms than 8 Ohms, which is why wattage ratings always are higher at lower impedances than higher (voltage is the same for both settings). The benefit of series wiring is that the overall power handling doubles in the case of the Crites drivers from 150 to 300 Watts. The drawback is that it is only as loud as a single driver. I figure that's OK, because it puts the Heritage series components back into the game. Dana
  16. I didn't expect THAT! Hmmmmmm... JC, are you up for the SERIES configuration using the 13x6" wide slot motor boards? (I'm cringing as I ask this)... I'll do an overlay when I get home tonight. Thanks, JC! P.S. wired in series we are 8 Ohms instead of 2 (parallel) - did you change the output impedance to compensate? Dana
  17. Maron, well, I did say it was a viable alternative! For $200, I'd say hell yes! $750? - that would be a hell no! But that's just my opinion. You NEED to write this stuff down for posterity! Who is going to set us straight after you're gone?! Dana
  18. JC, yes - another front-loaded mod, sorry I didn't think of it before. Up to you whether you want to check it out or not. I don't know whether it is worth doing or not. Anyway, before you move away completely from the front-loaded configuration, could you please get me the impedance for the Crites drivers (front-loaded) wired in series on the small slot and I'll have Al K. make me a crossover for them, too. Looks like a pretty good setup at a reasonable price to me. Thanks, Dana
  19. Well, that seems like asking for an opinion - and I just happen to have one available! In my opinion, due to the relatively narrow bandwidth involved (Khorn -6db @ 400Hz), I'd say no, it's NOT worth that kind of money for what you are going to get out of it (6 times the money as compared to a K33E). Do you REALLY think that you are going to get 6 times an improvement out of a TAD? Not likely, so it doesn't make economic audio sense (now that's a real misnomer!). The TAD is a stronger motor than a K33E, but it doesn't give any increase in power handling or excursion. Improvement - possibly, but more likely a change in "flavor". However, it looks good for a larger slot size, too, although it would probably be fine in the standard 3" wide Khorn slot. Is it a viable alternative driver for a Khorn - yes. Would you have to change the inductor on the crossover? yes. But as to whether it is worth the money... Throwing that kind of dough into a Jub would make more sense to me because it has an extended bandwidth capability that could make some use of it, seems to me... DM
  20. JC, if it were me, and I was going to build a pair, I'd go with the 218 version which is probably going to be a good bet being that it can more easily accept 18" drivers. The horn is very much the same, except the 218 would have a slightly smaller horn mouth. Still within specs, of course, and still inside the same footprint. As another "mod" to the current Jamboree test bed: I also thought of another "mod" to the motor board (current)... It consists of a 6 x 6.5" slot, the 6 being the horizontal width, and the 6.5" being the vertical dimension. The reasoning behind this is that the horn throat channel expands vertically, and our previous motor board slot is 13 x 3", that is, the narrow portion allows for diffraction to the sides of the channels, which don't expand. Both slots afford the same cross-section of 39 sq. in., of course. Therefore, I wonder what effect the diffraction to the expanding top and bottom of the channels would have? Might be a good thing... Dana
  21. Getting closer... but I can't figure why the horn isn't noticably more efficient?! Oh, well.... Dana
  22. Here is a comparison of the DBB outdoor curve and the Jamb w/Crites driver in parallel at 3 meters. The DBB are also Crites drivers in parallel, too, JC? Dana
  23. Ok. Will do. I'll email them. The 14" above refers to a 14" square panel raised 1" (air space) from the motor board with the 6" wide slot in it. It would be open on all 4 sides, in other words. Not like what is shown in the drawings, but sort of the same idea. This approach uses a "fold". Another adaptation for the V2 is an entirely enclosed 14x14x1" chamber attached to the 17x17 motor board with a 6" slot on both panels, facing each other with the slots lining up. Essentially, its a straight-through expansion chamber with no folds. This may only give -3db down at the chosen frequency, the other -3db coming from the mass rolloff of the driver, but in this case, I wouldn't count on it, judging from the curves - pretty usable to 1k! So the actual crossover point would be determined by the drivers impedance at a chosen frequency to stay within an appropriate phase angle when crossed over. This would apply to all of the possible configurations. The calculations on the fiberglass/equivalent is that any space of known volume when completely filled can be effectively increased up to 25% of the original untreated volume. This assumes an appropriate density of fill material, and no air spaces in the volume. The actual value of density is a variable that is only guessed at, so if the space is "naturally" filled (not "overstuffed") and contains no air spaces, it can be estimated that the value of increased volume is assumed to be 25% based on the known characteristics of fiberglass. Other insulative materials all have other densities and absorption characteristics. We are only talking fiberglass at this point. I read somewhere that the Khorn Vb was approx. 3800 cu. in. Dana
  24. Maybe a restricted Vb with the 3" slot might pick up a tad at 80 Hz. If the other drivers do it, so should these... Dana
  25. Finally, a comparison of the Crites in 6" slots compared to the 3" slot. Dana
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