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About Nordfinn

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  1. KLH 17, variance in impedance, pair of tweeters

    Thanks much, to both you and Roy. Much appreciated. I've already done the first, will proceed with the rest. One question: Is it possible to run with the woofer disconnected and the xo still in the circuit, or do you mean connect the tweeter direct to a source? If I can't solve the buzz, I may get them off to a professional. Anybody have experience with Audioproz in the Boston area? N.
  2. KLH 17, variance in impedance, pair of tweeters

    Below link is very helpful regarding equivalent drivers. According to it, same tweeter is used in models six (later version), seventeen, twenty, thirty, and thirty-three. http://centerforawareness.com/misc/electronics/speakers/klh/all_klh.htm
  3. KLH 17, variance in impedance, pair of tweeters

    I just talked to someone at the Speaker Shop in Ohio (lucky to get him, because he's basically retired, and the shop is just taking on occasional jobs at his discretion, it appears). He worked on some old EV 12-in Wolverines for me a decade ago. Very knowledgeable. I didn't completely understand, but the first thing he recommended was to bring to a shop with a frequesncy generator to isolate the frequency of the ringing (I think, though, that I can do myself, with a desktop frequency generator). He said that if these were much overdriven (which might be indicated by the (apparently) blown original capacitors, they can have a partial unwinding of the voice coil that could account for what I am hearing. In other words, a problem short of outright failure. Possibly addressable by adjusting the crossover, but otherwise not repairable, even by him (which I would think means neither by anyone else). Anyone here have a couple of good tweeters to sell? I'm seeing a little bit of conflicting info, but it looks like models six, twenty, twenty-two, and thirty all used the same tweeter. That sound right? I'll be looking to find on auction. I assume there's no good modern replacement, or I would have heard of such here. Worth waiting for, I suppose, because these otherwise sound so wonderful, and they are in such unusually fine shape physically. N
  4. KLH 17, variance in impedance, pair of tweeters

    Thanks, Kent. I had the original foam gaskets in. Yesterday I replaced them with Mortite. Maybe it made a small difference, but the ringing is still there. If I can't tame it, it will be a deal-breaker for these speakers. I suppose I could try original replacement tweeters, if I can find. (the only source is the auction site, I assume) I'll try redistributing the damping material, but otherwise I'm stumped. The cabinets are very tight and solid. Seems like the back panel, the metal binding post panel, could resonate? That's a beautiful amp. I talked to Bristol electronics some time ago, about a 350 tuner. I trust that he is indeed good, but the turnaround time! I'm the second owner of a 299b amp restored by Craig Otsby, in Michigan, so it's going back to him. N.
  5. KLH 17, variance in impedance, pair of tweeters

    Have a problem, noticed today after further listening. I think it's new, but it's possible something I hadn't noticed previously. Speakers still sound overall very good and open, but I have a buzz at certain frequencies. Especially noticable with piano, upper middle register. Sounds sometimes congested, other times outright distorted or buzzing (for signals that through headphones sound clean). It's defenitely in the tweeter range, but it's hard to tell if it's the tweeters themselves or something mechanical, something resonating. Opened them up to makes sure everything was tight and solid. The sides of the cabinet do vibrate considerably--the tops especially. There would seem be a lot of variability as to how the fiberglass is distributed when you restuff them. I tried to get it all in evenly. Any thoughts? It's frustrating, because they were sounding so fantastic. The problem is not ignorable, once you hear it. I've been checking it out all day, and starting to think it's the tweeters themselves. And they are not so easy to come by, I guess. If anyone is curious, the piece of music that I've been using to test this (and on which the buzz becomes unlistenable), is George Cables Trio, "Farewell Mulgrew," from "Icons and Influences."
  6. KLH 17, variance in impedance, pair of tweeters

    Got the xo's finished and everything hooked up over weekend. First impressions: They sound unbelievably good, fantastic, hooked up to my restored Scott 299b amp. I think I'm gonna be selling my modern speakers. I had certain preconceptions about acoustic suspension designs: that the bass could be muddy, that the design was inherently inefficient. These are obviously very efficient, very dynamic, and the bass is very articulate, as well as very much there. The sound is so open that it's taking a little getting used to. Perhaps it's the simple xo's, combined with the decent new capacitors, but everything must be accurately in phase, because I'm getting very vivid stereo imaging, which I also did not expect. The tweeter control differences are quite noticeable, especially with certain material (e.g., ride cymbal). I'm very inexperienced soldering, but managed it ok. The two circuits are were put together just a little bit differently, mechanically (pics below), but I expect it makes no difference. I only soldered in the new caps, used the wire nuts where they had been originally (unlike the thread above). I had a sheet sorbothane lying around, so put that under all the new caps, and used the original harness for the large cap. One small mistake was not tightening enough the machine screw binding post on the inside against the nut on the outside, so that everything was rotating when I hooked them up to a source. There isn't much insulating material there, and it's of course old, so you hesitate to put a lot of pressure. But I had to open them back up and tighten up the binding posts. I mounted the woofers 180 degrees from the original orientation, on the theory that the next 50 years of gravity will counteract the effects of the first 50+, on these stamped-metal frames. Who knows. I used Mortite for the woofer gaskets; it's just a little more expensive than the duct sealer stuff some here recommend, and it comes already in ropes of about the right thickness. Very easy. I used three coats of the Roy C dope for the woofer surrounds, more than one jar. Seems like enough (see pic), but I get nothing like the delay with the three-finger test that some here say is optimal. Used the original foam gaskets with the tweeters. When I opened them back up to tighten the binding posts, I was dismayed to see quite a bit of sawdust and detritus inside the shroud, from remounting the woofers Took the opportunity to use some wood filler on a couple of holes that weren't holding a screw well. Not sure what to do about the sawdust. It's hard to know how to fit the shroud. I guess it just lays in there. You can't tuck it into the lip of the mounting hole, so that nothing could get at the driver, so far as I can tell. Also, I was a little afraid of it getting too close to the tacky underside of the surround. Long time ago, the guy at the Speaker Shop in Ohio (he was restoring some old Electro-Voice triaxials for me) warned me of the hazards, for drivers, of pink fiberglass. Seems like these tweeters could use a shroud also. Anyone done that? The grille cloth cleaned up nicely with Scotchgard foam fabric cleaner. It's very hard to get the grilles on and off without a very slight dent to the veneer. Keep them off until you're sure you're done. Watco Rejuvenating Oil and then Butcher's Wax for the cabinets--they look great. I'll post some beauty shots everything is properly set up. A few process shots below. Alas, the tube amp has to go into the shop, and now the speakers are hooked up to a little desktop T-amp, which drives them just fine, but they don't sound as good. I hope, and expect, it's just that, and not something having gone awry, with the drivers getting a signal for the first time in who knows how many decades. The first day of listening with the tube amp was a revelation. Thanks for all the info on this site. N.
  7. KLH 17, variance in impedance, pair of tweeters

    Thanks much, Ra. I'm just gonna go ahead, then. Will report back next when done, unless I run into problems. This site is great. N.
  8. KLH 17, variance in impedance, pair of tweeters

    Proceeding slowly with these: gathering the crossover parts, doping the woofers, refurbishing the cabinets. Since the finish was in such fine shape, I used Watco Rejuvenating Oil, followed by some paste wax, which worked very well. I'll probably finish up this weekend. One question: I got two 8.2 uF (with 1% tolerances) caps for the crossovers, in place of the four 4.0 uF caps specified in the thread mentioned above, just because I thought they would be easier replacement for the two 2 x 4 (into a common lead) originals, and also would fit well into the original plastic harnesses. So I'm just a little off spec, which I assumed was not a problem. But then I just saw the below (italics), from the extensive guide to AR restoration on the AR forum. Is this something to be concerned about? Have y'all been compensating this way? Thanks, N. If you install PP capacitors, you may wish to add a small amount of series resistance to compensate for their reduced ESR and maintain the authenticity of the AR crossover. A 0.27-to-0.33-Ω, 10-W non-inductive resistor is best added in series with the 6-μF hi-range capacitor. One-hundred-fifty- and 50-μF capacitors should each have ~0.27-Ω, 20-W resistors added in series. Solder each series [C+ R] in the same location as the original C.
  9. KLH 17, variance in impedance, pair of tweeters

    The wire nut connections were quite tight (not easy to disassemble), so I don't think it was that. I didn't think to check the back switch, however, as someone suggested, before taking out the tweeters Since I've already partly disassembled and the parts are on order, I'll go ahead and replace the capacitors anyway. Thanks much. Lots of info and back-and-forth on finishes! I'm not eager to work with BLO in my little Brooklyn joint, but probably I will, since the speakers are about as near to original as one could hope.
  10. KLH 17, variance in impedance, pair of tweeters

    Yes, I'm pleased with them. A Craigslist score, and reasonably priced, although I was of course disappointed to get them home and find that they weren't fully functional. No, those leads from the tweeters were attached with wire nuts. Note the knot in the lead on the positive side (is this common?). The RoyC dope arrived today. I will apply as directed, although I confess I don't fully understanding the physics. If properly sealed, the cone should slowly return to rest if pushed in? I would think that, as the whole system gets more airtight, and so behind the cone the volume is being compressed, the cone would spring back that much faster. Also, seems strange--that slowing down, inhibiting, the cone would be a desirable thing. But I trust the collective knowledge here, and I'm very appreciative of all the help I got even before I asked a question. To freshen up the finish on the veneer: What would be closest to what was originally used? Linseed oil? I'll probably have them functional in a week or so. Will report back. Thanks, N.
  11. KLH 17, variance in impedance, pair of tweeters

    Photos, as requested. All the veneered surfaces are as nice as those pictured, even the bottoms. The finish is a little dull, though, after all these years. Anyone know: Am I right in assuming the the original finish was linseed oil?
  12. KLH 17, variance in impedance, pair of tweeters

    Thanks much. I caught that, and have already ordered the RoyC elixir.
  13. KLH 17, variance in impedance, pair of tweeters

    Thanks very much everyone. Somehow I hadn't thought of connecting the tweeters to a source directly. Just did, and they are both functioning. My question about differing impedances was more a matter of whether it meant that they would have markedly different responses. I'll post photos soon. Don't know where these have been for fifty years. By all appearances they've been in their original shipping boxes. Thanks much for the schematic. I was gonna replace caps according to the below thread. Already ordered parts from PE. This is all pretty new to me (not much experience soldering), but it looks pretty doable. One more detail that might be of interest, to someone, sometime: The hot leads on the tweeters were distinguished, apparently, by putting a knot in the lead. (The wires are the same color, and there aren't any markings on the tweeter itself, that I can find.) Oh, and: No, not red and black wire nuts, on the tweeter leads; all black. http://audiokarma.org/forums/index.php?threads/renovation-of-my-klh-17s-is-complete-long.102176/
  14. All-- New here. What prompted joining was the recent acquisition of what appeared to be an absolutely pristine pair of KLH Model Seventeens, in their original shipping boxes. The cabinets and everything appear so untouched that I might have thought they were never used. Alas, getting nothing from the tweeters. So I will be rebuilding the crossovers, according to a couple very helpful threads here. My question: I do get an impedance reading from the tweeters (which, I take it, indicates that they are not completely blown); however, one measures 3.7 to 3.8 ohms, and the other 4.4 to 4.5 ohms. Is the difference significant, something to be concerned about? Indicate damage? Serial numbers are 032803 and 032816. There are no date indications (or any script) on the tweeters. One surprise: the tweeter leads were not soldered to the leads from the crossover, but only (well) mechanically connected with the screwcaps. Would this indicated that they are replacements? I am certain, in any case, from comparison with various photos on this forum, that they are the correct KLH period-specific tweeters. Thanks much, Nordfinn