RoyC

That would be a waste of what appears to be a nice "artist" brush, Steve. The included brush is a common "flux brush", and will do an excellent job of applying the sealant. Roy

Most meters will not measure capacitance when they are inline with resistors. Whatever the case may be, I would wire them in accordance with the schematic showing the 2uf caps. Roy

Not sure I understand your post, Brad. I've never seen a KLH 6 without caps in the tweeter circuit. There is no quicker way to burn out a tweeter than to omit the capacitor(s) from its circuit.

There is absolutely no problem with mixing those manufacturers and tolerances, and as Kent mentioned, you can always parallel capacitors to make the desired value. You could also use non-polar electrolytic (NPE) caps for the larger values. It is isn't easy to fit larger caps on the KLH 5 crossover board. Roy

Any work you may be inclined to have done by Vintage_AR can be sent directly to me. Turn around time will be much quicker and you can save a few dollars along the way. This forum's personal message system is your friend. Roy

The serial numbers and dates on the woofers show these to be early specimens constructed in the first year of manufacture. Approximately 50,000 were manufactured. Roy

Hey Kent, I learned some of this along the way as well. I suspect the KLH material was too soft to be made into a roll, making the inverted installation necessary. Roy

The AR woofer's surround always looks like that, and is different than the KLH surround. The original sealant does not flake off or disappear from either of them. Many KLH woofers were simply insufficiently treated at time of manufacture, prompting the KLH technical service bulletin recommending additional sealant. AR woofers were usually pretty well treated at the time of manufacture, especially the 12 inch AR woofer. Accordingly, my sealant is is deliberately thin and intended to only be supplemental to the original treatment. When my sealant is used on cloth surrounds of AR woofers, I recommend a very light application. The toluene in the sealant softens the original sealant, which may be somewhat beneficial, but if it is applied too heavily it can collapse the roll of the AR canvas-like material. For this reason I don't recommend using it at all if an AR woofer passes the "push test". On the other hand, the inverted cloth roll of KLH woofers is made of a different (more porous) material and is not prone to this potential issue. KLH woofers almost always require a couple of additional applications. Roy

1.5 ohms in series will reduce the mids' output by about 1.5db...as well as lower the crossover point slightly. It just doesn't seem to equate to adjusting your mid settings "almost all the way down on my stereo for them to sound right"....which would imply significantly more attenuation than that. There is no doubt new caps (of any type) would have less ESR than the nasty old KLH caps, so any added series resistance will make a difference. In the end, it is only your ears that matter. Hopefully you have resolved whatever the issue was. Roy

Brad, The (2) 3 way switches of the KLH 5 affects only the tweeter's response, not the mids, so turning those all the way down will reduce higher frequencies much more than the middle frequencies. There is also no way the type of capacitors you used could have caused such a dramatic difference in the mids' response. Based on your description, an additional ohm or so of series resistance to replace some capacitor ESR would not be enough to make a significant difference. Frankly, I have never heard of this being an issue with the KLH 5, regardless of the type of capacitors used to replace the originals. Are you sure the crossovers are wired correctly? I know a person who connected his KLH 5 crossovers' woofer leads to the mids and mids' leads to the woofers....with obvious consequences. Roy

This pair was obviously extensively refurbished at some point. -I am not aware of any AR model of that era being sold with special paint (or that type of grill cloth). It is much more likely that these were "unfinished pine" cabinets which were nicely painted. Unfinished pine cabinets were sold for that purpose. -I believe the 4xa was discontinued before the ferrite/ceramic magnet woofer became available...and the one in Luxman's photo has a manufacture date stamp of 1978, which is quite some time after the 4xa was discontinued. The response is somewhat different than the alnico magnet version seen in the other cabinet. -I do most of the technical work for Larry/Vintage AR. Unfortunately the foam he is providing for the 8 inch woofer is no longer unique, as his original replacement is no longer available. (It is now generic in nature, and is sold primarily as a Bose and JBL part.) Currently, the best surround for the "universal" AR 8 inch woofer is the Boston Acoustic 8 inch replacement. It is more compliant, unique, and available from many sellers. Roy

The soft cone is normal... Roy

Hi Abel, The 10 ohm resistor is not an original AR part. Based on the appearance of the corroded rivets, there is a very good chance the pot is not functional. Consequently, the entire signal is shunting through the resistor resulting in very little high frequency response. One way to test the tweeters is, as you suggested, to simply replace the resistor with a piece of wire. This should result in strong tweeter output. If the tweeters are OK, replace or refurbish the pot to restore the original tonal balance and crossover point. If the green crusty corrosion is present on the pot's wiper and disk I recommend replacing it. While you are doing this work, take the opportunity to replace the 10uf capacitor. The above recommendations are made with the assumption the tweeters and woofers are original, and functioning properly. Roy

100k? What industry standard are you referring to? Most non-adjustable LCR meters are measuring well below 100hz (not k), with some as low as 8hz. The labels on the capacitors we are using for crossovers show the rated value at 1000hz (1k or 1khz). Frankly, your Mundorf caps do not appear to measure nearly as well as the Madisound (MDL) or Parts Express electrolytics I've been using. Roy

jessi, Does your capacitor meter have a frequency setting? If these were measured at the rated 1000hz, I agree with Kent. I have a feeling, however, your meter is measuring at a much lower frequency. Electrolytic crossover capacitors behave differently than film caps at higher and lower frequencies, which is the primary reason for any sonic differences. Roy

Thanks, Mot! It appears your dual 3/4 cap was either installed incorrectly at the factory, or the "follow the label" theory may not be correct. The KLH 5 schematic confirms the diagram posted by Kent to be correct, so your 4uf cap and 3uf cap should be reversed relative to your photo(s). If there is one constant when it comes to KLH speakers, it is the awful red and black capacitors. I have worked on 3 pairs of KLH 5's, a pair of KLH 17's and a pair of KLH 23's in the past 2 months, and only 6 out of the 44 capacitors measured anywhere near their proper values...and when they did, ESR was crazy high. I often wonder if some of these caps were within spec when they were new. jessi...I don't subscribe to the pricey Mundorf world, but Madisound is another good source for those: https://www.madisoundspeakerstore.com/index.php?p=home Madisound has an excellent variety of other brands as well, with their electrolytic and film MDL brand caps being a particularly good/high quality value. Roy

As I've read Kent's resistor replacement recommendations over the past few years I realized I have not actually seen many bad resistors on KLH 5 boards, so I have not been replacing them if they measure satisfactorily. Upon recently finding a burned out 5 ohm/5 watt specimen I contacted Kent to compare notes. He concurred that the crispy resistors he had seen before was the 5 ohm/5 watt one. I decided to take a close look at the schematic, and It turns out that this is the only KLH 5 resistor in the woofer circuit. With a power rating of only 5 watts it is really quite small to be in this location. A replacement with a 15 to 20 watt rating would not be unreasonable if the speakers are going to see any kind of hard use. On the other hand, given the type of use most of them are seeing these days, I'm sure the 10 and 12 watt replacements Kent has used in the past are holding up just fine. The 15 ohm resistors in the mid and tweeter circuits respectively are 7 watters, and the others (5 watts) are in the tweeter circuit. I don't have a problem with them unless the speakers are going to frequently be used at high volume levels, at which point a prudent upgrade could be made to the mid's 15 ohm resistor (as Kent mentioned above). EDIT: It appears the 15 ohm resistors were reduced to 5 watts for the later PCB board. The earlier point to point wired boards (6 of which I have worked on in the past month or so) had the 7 watt version. Either way, I still would not be too concerned about it. Coincidentally, as Kent and I were discussing the above, I found a crumbling "Rockwood" 10 watt resistor in a KLH 23. It was identical to malfunctioning 10 watt Rockwood resistors I have found a number of times in Kloss era Advent Loudspeakers. Interestingly, other brands such as Colber, also found in Advents, seem to have held up very well. When poking around inside KLH speakers, it would be prudent to look for these as well. They often do not appear to be burned, despite being nonfunctional and/or falling apart. It bears mentioning once again...Whether it be pertaining to resistors or capacitors, anyone planning to work on old speakers should invest in a basic LCR meter. Mot's dual cap question could potentially be answered by simply measuring it with an inexpensive meter. (On the other hand, KLH caps are typically so crappy, who knows...) Roy

If the 3uf and 4uf leads are marked as such, Mot's photo shows them to be labeled differently than those in Kent's photo. Mot, if you can show us the reverse side of the board and circle the solder points of the cap leads we are discussing, along with those of the 15 and 10 ohm ohm resistors, I can probably tell you for sure. Switching the caps will make a relatively small difference at the level control settings. Roy

Hi Kent, I don't have a reference board to look at, but it appears you have the separate 3uf and 4uf leads reversed relative to Mot's photo. Roy

It is ok. It looks to be well done, based on your photo.

Scottie, Attached are a couple photos showing how the rings are used. I acquired them specifically for the purpose of rebuilding the old 3a style tweeters for "Vintage_AR" and others, but can sell some to forum members on a case by case basis. There are no messages from you... Roy

The 4 and 6uf caps were just a way for AR to use up old capacitors. They were wired in parallel with the 30uf silver capacitor in your photo to make the required 40uf capacitor. You can see the 4/6uf leads converge to the 30uf cap. Eliminate the 4/6/30 combination and replace the whole arrangement with a single 40...and replace the single 6uf block cap with a new 6uf cap per usual. Attached is a photo of a slightly later LST board showing a single 40uf cap in the same location as your silver 30uf cap. This is what your board should look like when you finish your work.

Of course not...and nobody is saying the 3a wasn't intended to be a technical upgrade, regardless of marketing jargon and magazine opinions. My sentence was "...an early Consumer Reports review back in the day actually found the early AR-2ax and the AR-3 (subjectively) preferable to the 3a ..." These days I know people who prefer one or the other, and at least two dedicated AR fans who prefer the early 2ax over both. My own experience has more to do with "restored" condition of these models, and the 3a has an advantage in that regard for the reasons I mentioned above. There were many speakers marketed with legitimate technical enhancements, which did not translate to a definite "subjective" improvement. Apparently the difference between the 3 and the 3a was/is not all that clear to many people. On the other hand, frankmarsi, we both know the LST technically and subjectively sucks, so get outta here. Roy

Ouch, Glenn...You just had to remind me of that bad advice (though I think I may have actually called them really big refrigerator magnets at the time 😒)You are certainly not alone. I try not to think about the number of those old tweeters I disposed of over the years. On the other hand, the 3a/5/LST/LST-2 type were flimsy and inconsistent, often suffering from bent and broken face plates and response anomalies. It was easy to believe there would be no further use for them in the absence of anything resembling the original construction materials. When AR was taken over by International Jensen in 1994, AB Tech Services became the only game in town, selling their remaining supply of Tonegen-made AR-11 type tweeters as a "universal" replacement. The supply lasted until the late 90's, after which ABT sold nothing worth mentioning. It wasn't until much later that the HiVi tweeter replacement became available as a way to bring 3a's back to life. Today, of course, we have a couple of different ways to rebuild the old timers. Very recently, I was even able to acquire a good supply of face plate repair rings through the magic of 3D printing (photo below). Who knew.... Regarding the AR-3 vs 3a...According to Tom Tyson, the AR-3a was less costly to manufacture than the 3, so if nothing else, the 3a was a way to increase profits by selling an "upgrade" to the popular 3. Roy

The AR-3 was the first of its kind, and there were fewer manufactured, so if nothing else, the 3 fetches a higher price because it is more collectible. There is also a preference for the AR-3 by many AR enthusiasts, and an early Consumer Reports review back in the day actually found the early AR-2ax and the AR-3 (subjectively) preferable to the 3a (see attachment below). Today, however, it is easier to bring a pair of 3a's closer to original sonic condition than a pair of 3's, primarily because there are more decent used (and rebuilt) drivers available for the 3a. This usually makes the 3a a better bet at a lower cost when navigating the minefields of Craigslist and Ebay listings.. Despite being marketed as an upgrade, AR sold them side by side for a few a years before the 3 was finally discontinued.