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Robthomp

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About Robthomp

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  1. Model Seventeens

    I bought a pair of Model Twenties a few months back. The Model Twenties are identical to the Seventeens except they are 4 ohm instead of 8 ohm. They sounded pretty good when I got them but then I recapped them and resealed the cloth surrounds on the woofers, and now they sound amazing. I used the caps from Parts Express that Kent suggested. Rob
  2. What is a good price for a pair of Ar3s?

    "Several" KLH Model Eight radios! That's several all right. Great photo. A lot to behold.
  3. What is a good price for a pair of Ar3s?

    I realized this is not a very good question, or at least not a question with an easy answer. All of these vintage speakers, and other vintage hifi equipment, have an intrinsic value based on the quality of the sound, the aesthetics, their place in history, and many other enjoyable factors. But there's no objective dollar value you can place on it, other than to simply observe that this person agreed to sell something for this amount, and this other person agreed to pay that amount. If one's goal is to flip something, then it's certainly possible to watch market trends and make a calculation. In my case that isn't my intention - I just got hooked on acquiring the stuff and I love fixing it up and listening to it. Now I have a problem - I only started this in March and I've managed to get 10 pairs of speakers, 5 receivers, and 4 turntables. I've filled a room in my house. My girlfriend is aghast and my kids think I've lost my mind. Oh, and my performance at work has suffered. Is there some sort of 12 step program that goes along with this hobby? Rob
  4. Hi, I've been following the discussion here about recent price trends for the AR3s. What is a reasonable price? I would love to get a pair and restore them. I'll be looking at a pair offered for $800. All original drivers, all drivers produce sound, never been opened. The cabs look fine, a little dry and scuffed but nothing a light restoration won't take care if of. Should I go for it? Rob
  5. Should I attempt to repair an AR3?

    Instead of spending time trying to test the tweeters directly, which carries some risk, why not just proceed and replace the caps and clean the pots? You're going to want to do that anyway, and the probability is high that it will restore function. Rob
  6. Thank you lakecat and ra.ra for the advice about grill cloth cleaning, and congrats larrybody on the AR4's. Ra.ra, that's a lot of great research on the grill cloth. Here are two pictures I took, one of the grill cloth on these 4's I just got, and one of Wichelt Lambswool linen from 123stitch. It looks like they have the same threadcount (~ 20 /inch) but the thread in the original cloth looks to be a smaller diameter than in the new stuff, so the amount of space between the threads appears to be greater. I assume that would affect the sound wave passing through the cloth, but what I don't know is if it's a difference that people can hear. I went ahead and removed the grill on the first speaker. I didn't have a dental pick, but I tried a variety of small screwdrivers, tweezers and needle nosed pliers. Unfortunately as you can see in my pictures, the cloth is not unscathed. In my defense, some of these marks, in particular the worst ones in the middle, were not due to my work, but simply are there because the staples were a little rusty and the thread was crushed under the staple, and so that's just the condition of the fabric with the staple removed. I'm not too concerned, I managed not to rip any holes, and those marks may be a little less noticeable after I clean them. A fifty year old object is bound to have some 'character'. The drivers appear to be in great shape. There's hardly any dust, and the surrounds have some suppleness.
  7. That's what I originally thought. I just second guessed myself when this seller, who is not a hifi person per se, seemed a little concerned that I would monkey with them. Thanks for the tip on getting the grills off - that seems like it will work. I guess patience is key. How did you clean yours? When I cleaned my 4x grills I used Woolite fabric cleaner and it left some slight streaks and didn't get them much cleaner. Rob
  8. Lakecat, congrats on the MC2205 + LSTs. I would love to hear that. Coincidentally, a friend of mine, a recording engineer, heard I was getting into 70s hifi, and so he loaned me his MC2205. We had to carry it to my car together, and I got my son to help me when I got home. I don't think I've got speakers big enough to handle it - the biggest I have are AR-2axs. Rob
  9. Hi, I found a pair of AR4s on CL for not too much money so I got them. I have read that the AR4 is less common than the AR4x. I do a see quite a few 4xs on CL and the auction site, but not too many 4s. These have low serial numbers 00204 and 00221. When I went to get them I assumed I would be restoring them, but now I wonder what's more important -- getting them to sound wonderful, or keeping them original and untouched? My 4xs, after restoration, sound incredible. This seller, who has a house full of amazing vintage items, seemed a little dismayed that I might tamper with these. They certainly don't look like they've ever been opened - the grills are firmly stapled with many tiny, old staples. They don't sound wonderful - there's nothing coming from the tweeters. I presume the caps may be bad and the pots corroded. The grills are in good shape but terribly stained (although they're not as dark as they look in my bad pictures). The cabs are pretty good, they would clean up nicely. Getting the grills off without destroying the fabric seems like a challenge. I wonder what your thoughts are on restoring good sound vs. keeping a 'collectable' unmolested. Rob
  10. 3/4" dome tweeter rebuilds

    I restored a pair of AR-2axs in the spring and I had Chris rebuild the tweeters. For no particular reason I had him do one, then do the other. So when the first one came back I was able to compare it to the second one before it was done. I didn't take a measurement with instrumentation, I just 'earballed' it, but the restored tweeter was significantly louder than the unrestored one. Rob
  11. Model 22 vs Model 22A

    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
  12. Model 26 crossovers and tweeters

    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.
  13. Model 22 vs Model 22A

    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
  14. KLH Model 20 questions

    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.
  15. KLH Model 20 questions

    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.
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