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About Robthomp

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  1. Hi, I think I can ask a better question: I'm recapping these speakers. Should I replace the crossover in the 22 with the same one that's in the 22A? If the drivers are in fact identical, then presumably KLH decided the second crossover was an improvement, otherwise they wouldn't have put it in. On the other hand, if the drivers do not have the same electrical characteristics (even though they look the same to my untrained eye) or if the inductors have different values, then modifying the crossover in the 22 might be a bad idea. Rob
  2. The 22A I opened up has the 8 MFD and the 16 MFD, like this Model 26. The 22 is different and only has one 4 MFD. I posted schematics in the 22 vs 22A thread.
  3. Well, I opened the Model 22 and Model 22A. The crossovers are different: 1) The drivers appear to be identical. The Model 22 drivers are stamped with 1968. The Model 22A doesn't have a date stamped on the drivers, but there is a stamp on the baffle board which contains the line STY 5 21 70, which I am guessing is a 1970 date? 2) The Model 22 tweeter is housed in a cardboard enclosure, the 22A tweeter is housed in a plastic one. 3) The woofer on the 22 is sealed with the usual bead of white putty seal, but the woofer on the 22A is NOT sealed with that stuff. Under the rim of the aluminum frame there is just a thin ring of foam stripping. 4) The Crossovers: the Model 22 has a simple first order crossover - a 4 muF capacitor in series with the tweeter, and a coil in series with the Woofer ( I do not know the inductance of the coil, it doesn't appear to be printed on it.) The Model 22A on the other hand in addition to the coil, has a 16 muF capacitor in parallel with the woofer, and an 8 muF capacitor and a 3 Ohm resistor in series with the tweeter. I have attached drawings I made of the schematics. I am learning a little bit about crossover design and I'm very interested in knowing what the effects would be of this crossover upgrade and why KLH went to it. Is it possible to generate the frequency response plots for these two crossover designs, assuming identical drivers, and compare them? Is the modified crossover in the 22A related to the fact that the woofer didn't seem to be sealed as well? Or is the woofer on the 22A supposed to be sealed but KLH just cheaped out by using a flimsy foam strip instead of the airtight putty? How good would your hearing, or listening training, have to be to hear the difference between these two crossovers? Rob
  4. I do like the Kenwood KR-5030. I've got two of them! Replacing the resistors was probably not necessary. I think I read somewhere that as long you're in there you might as well, but maybe that was in a thread about a different model.
  5. I went ahead and purchased this pair of Model 20s. I put them in my living room alongside the newly restored AR-2axs and AR-4xs and did various listening comparisons. My girlfriend and I both agreed that the KLH speakers, while they sounded nice, noticeably lacked mid and high notes, and the bass sounded a little muddy. There was no comparison with the AR-4xs. Even though the AR-4x is smaller than the KLH Model 20, it had much richer bass. That was then, this is now. A couple of weeks ago I had time to do the refurb on the Model 20s. I replaced the caps with new Dayton Audio PMPC caps, replaced the resistors, resealed the woofer surround, and resoldered some joints that were causing intermittent connections to the RCA jacks in the back. In other words, the standard refurb. What a difference! The mids and highs are bright and nice (but not too bright!), and the bass sounds a little more responsive and richer. They compare favorably with the AR-4x. I wonder what others think about the KLH twenty vs the AR-4x.
  6. Recapping and redoping the Model 22's I just got (one is a 22 and the other is a 22a) is queued up to be my next project. I will probably get to it this weekend. I will be sure to post pics and descriptions of exactly what I find inside. Rob
  7. Also, the letter "A" on the back plate isn't part of the original lettering on the plate - it looks like it's stenciled on or something.
  8. Hi, Today I just bought a pair of Model 22's from a guy on CL. The cabinets are in beautiful condition and they sound great. When I got home I realized that one is a 22 and one is a 22A. He advertised them as 22A. Does anyone know what the A designation is for and is there any difference? I can find references online to both but no mention of the difference, if any. The tweeter on the 22 is mounted on a white cardboard ring, the tweeter on the 22a is mounted on a black plastic ring. The woofer cones are slightly different colors. The particle board backs have slightly different colors. The cabinets and grills are absolutely identical but I don't know if the grills are original or if the cabinets were ever refinished. The serial number on the 22 is 23519 and on the 22A its 45037. Rob
  9. To remove the grills on my 2ax's I had good success with the drywall-screw-in-the-badge-hole method (from the guide).
  10. The receiver is a Kenwood KR-5030 that I bought on CL and restored. I can see why you thought the SX-727 - I just looked at some pictures and from a distance they look pretty similar. The KR-5030 has 60 wpc but it feels like much more. I like it enough that when I saw another on CL for cheap I bought it, so now I have two. The TT is a Dual 1228 that I got at an estate sale, in great condition, for $35. I don't think I've heard EPIs. Are those from the same era? I recently fixed up a pair KLH model 20s and I'm comparing those to the ARs.
  11. Well, I finally got a chance to work on these AR-4x's (it's been a busy spring at work). Restored pots, recapped, sealed woofer surrounds, and cleaned up the cabs. They sounded great when I got them, they sound even better now, and the cabs look very nice. I have them next to my AR-2ax's. I don't really listen to the two pairs together. I find that I like to listen to the AR-2ax's when I want to listen to louder music and I'm not going to disturb the neighbors or my girlfriend if she's gone to bed. When I need to have the volume lower the 4x's deliver a rich sound, at a lower power level. The 4x's have less bass than the 2ax's of course, but they have a lot for their size. i have learned they're famous for that.
  12. Or cut a large hole in the back, as dxho suggested.
  13. Thank you for the links. These two threads really make it clear how to replace the crossover in these. Thanks for the suggestion about the resistors too. Now I just have to decide on a strategy for resealing the woofers. Based on what you are all saying, and what I've read in other threads, it sounds like the odds are very good that they will benefit from a resealing. My takeaway is that the original sealant degrades and just doesn't last 55 years. It also sounds like no one has attempted to reseal the woofers from the back through the small hole, so that may be impossible. Since the grills are in excellent condition, my initial impulse was not to touch them, for the sake of preservation and authenticity. On the other hand, having them sound as good as they are capable of sounding may be the higher priority (they are speakers after all, so that is their ultimate reason for existing). So maybe I will cut them out to reseal the woofers. I got sealant from Roy C for this pair of AR-4x's I'm finishing up, and it should be plenty for the KHL's. If I can't find replacement model 6 grills right away, maybe I'll make something out of the Wichelt linen ( which is such a close match to the original AR cloth!) and then keep looking for model 6 grills. The serial numbers on these are 64,996 and 65,531.
  14. Hi everyone, I just bought a pair of early model sixes this morning from a retired audio guy on CL. I've read a lot about these speakers in the last week. I had a lengthy discussion with the seller and I read up on the challenges of working on the early sealed versions before taking the plunge. I'm still fairly new at this hobby, but I like challenges and problem solving. The high range is not really present in the sound, and the seller and I both bet that a recap is needed to get the tweeters working. The bass sounds good, and the cabs are in great shape. My plan is to go in through the back plate, which seems to be the preferred method. I am wondering: 1) For initial diagnostic purposes, what would be the best way to test the tweeters, to determine if a recap is going to work, or if the tweeters themselves are bad? 2) Is there a detailed write up of this job, with pictures? Are all the capacitors near the switch and the back plate, or is there one buried further inside? I imagine reaching in with my arm and grabbing it, but how the heck would you actually replace it? 3) Is it possible they would benefit from resealing the woofer surround, and if so what's the best way to determine that - by listening? If they would benefit from that is it even possible to do it? I understand that the grills don't come off - in fact I read somewhere that there really is no grill, the speaker cloth is just wrapped around the baffle board, and epoxied, so the only way to access the drivers from the front involves destroying the cloth. Can you reseal woofer surrounds from the back? Thanks, Rob
  15. Good luck! Very exciting.