AR55

You got my curiosity up, so I rechecked the 8" LMR in the three 98LS' that I've owned. My daughter has my original 98LS's that I purchased in January of 1983 and their 8" LMR's do not have a split seam. The same is true of a pair that I restored and sold to a friend. The 3rd pair, however, have US made 8" 200045 LMR's and their cones have a split seem. I also checked my AR-28B's. Their 8" woofers (model 200050), have a split seam. So, it appears that at some point during the initial production run of the Post Classic Series, AR modified the spec for the 8" midrange and woofer cones to have a split seams.

Although AR changed the cone spec for the 8" LMR between the AR9 (200027) and the AR9LS (200045), the 200045 cone still was specified with no split. I have had a number of AR98LS's in my possession over the years and all of them came with the American made AR 200045 LMR. None of those cones had the split. I presently own a pair of English made 98LSi's and a pair of American made 9LSi's. Both of them came with the Tongen made 2100450B LMR and all of them have the split cone. AR outsourced the manufacture of all their drivers to Tongen starting with the second generation of the Post Classic Series, which included the 9LSi & 98LSi. Interestingly, I haven't found an instance where Tongen ever used a split cone with any other driver, but the 2100450B, 8" midrange.

Midwest Speaker is selling a Chinese made tweeter that they say is a replacement for the 4X tweeter on eBay. See link below: Acoustic Research Replacement Tweeter for AR-4x Speaker - MT-4107-4 | eBay

You most likely have the original AR18. If you do, the tweeter will be offset from the woofer like my AR17 on the right. If it's the AR18B, it will look like my AR28B on the left. The original AR18 came with the AR 200001, 4.6 ohm, 8" woofer. Acceptable AR alternative 8" woofers include the following: 200037, 1210037, 200050 & 1210050. It looks like eBay has a couple of re-foamed 1210037 woofers for sale.

It's possible, based on the date of manufacture. At the same time, the notes to the A.23 tweeter do not indicate that the tweeter is cooled by ferrofluid, whereas the notes to the AR-11 tweeters (A.22 & A.24) do.

AR didn't introduce ferrofluid cooled tweeters until '77-78', when they introduced the improved AR11.

You just missed it. AR started using aluminum formers in their 12” woofers with the introduction of the AR9. The AR-11B was released about the same time as the AR9 and its woofer also had an aluminum former.

I purchased a pair of AR AV570’s over 30 years ago, and I can attest that they are quite musical. Leonard Feldman affirmed this in his review of the Powered Partners in the February 1987 edition of Audio magazine (see attached). If yours do not sound musical, then my guess is that there is something wrong with them. On the performance side, later Bose powered speakers may have compared favorably to the AV570’s, but not in 1987. From an appearance standpoint, a Polk M3 more closely resembles an AV570 then does a Bose. At the time, the biggest obstacle to owning a pair was their cost. Even with a J&R Music World’s discount, a pair still cost me a pricey $259. Powered Partners Review.pdf

A pair of AR338’s are currently for sale on eBay. The ad includes a series of photos that look pretty good until you get to the one showing the back of the speakers. Apparently someone decided to “improve” the bass response by adding a pair of ports. One can only imagine the ports’ contribution to the new “improved” bass distortion. Fortunately, it's reversable, but will the buyer realize it has been modified.

Per request, I have attached PDFs of the results of research studies that I assembled for the 1¼” tweeters, 8” woofers/midranges and 10” woofers used in AR speakers starting a few years before the ADD Series and continuing through the Post Classic Series. The studies were based almost entirely on information pulled from the AR archive drawings. I found that a few of the drivers were unique to just one speaker model; however, most were used in multiple speakers. Also, the differences between some of the driver models were minor. For instance, the model 200037 8” woofer appears to be almost identical to the original 200001 8” woofer. AR 1.25-inch Tweeter Research.pdfAR 8-inch Woofer-Midrange Research.pdfAR 10-inch Woofers 1973-1986.pdf

I have restored a number of AR speakers and there has only been a couple of times that the woofer’s voice coil and/or suspension was damaged due to the previous owner playing them with rotted surrounds. If the 8” midrange’s & woofer’s resistance measures between 8 & 9 ohms and the spider is still flat with its connection to the woofer cone intact, they may be fine. If you decide to replace the surrounds, make sure that they are appropriate for AR woofers. Most aftermarket surrounds are too stiff. I got mine from Rick Cobb Speaker Parts, LLC (eBay site - looneytune2001). The 1¼” cone tweeters look fine. If their resistance measures between 4.3 & 5.2 ohms, consider not replacing them until you have listened to them with the restored woofers installed. The specs for the AR93’s drivers (8” woofer – 200035, 8” midrange – 200036 & 1¼” cone tweeter – 200034/200038) are attached. Also attached is some research on AR 8” woofers/midranges & AR 1¼” tweeters. Lastly, if the grilles are in bad shape. Replace them. I have replaced the grille cloth/foam and refinished most of the speakers that I have restored. AR93 Driver Specs.pdfAR 8-inch Woofer-Midrange Research.pdfAR 1.25-inch Tweeter Research.pdf

There is a used pair of AR 300038, 1.25" tweeters for sale on eBay: eBay AR 200038 Tweeters. See attachment below for other tweeter options that should also work (you need to be logged in to see it): AR 1.25-inch Tweeter Research.pdf

These tweeters often show up on eBay. Presently, there is one from an AR-28s available from eBay for $28 + $7.95 shipping - AR-28s tweeter eBay This tweeter was also used on the AR-14 & Ar-48s.

One pair of my AR11s is a first generation. It came with 2 blown tweeters. One tweeter was a Tonegen replacement and the other was an original tan dome tweeter. I replaced both with 2nd generation AR11 tweeters. I no longer have the tan dome tweeter, but I remember it being stiffer than the 2nd generation tweeter. The fabric of the newer tweeter feels the same as those in the tweeters in my friends AR9 speakers and those in my AR9LSi, AR98LS & AR98LSi speakers. Also, I not sure about the original AR11 tweeters, but the newer tweeters have a domed wood button under the fabric dome that makes it difficult to push the dome in far enough to dent it. A case in point, recently while roughhousing, both of my grandsons smashed into one of my daughter’s AR98LS speakers. The 1½ dome UMR was flattened and the dust caps for both the 8” LMR and 12” woofer were pushed in. The tweeter, however, was fine. I haven’t tried to fix it yet. As far as which dome sounds better, I probably wouldn’t be the best judge. On a good day, I’m lucky to hear much beyond 8,000hz without a lot of help. I’m sure that I am not alone.

The AR11 first came out in 1976 without ferrofluid cooled tweeters. AR didn't introduce ferrofluid cooled tweeters until '77-78', when they introduced the improved AR11. See the AR11B ad below - note the black tweeter domes: