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Hi ChrisM, if you have observed some subtle difference in the cloth surrounds from various drivers, the very best way to receive specific feedback to your questions would be to post a few well-focused good quality pics (± 100KB is fine) for readers to see the situation you are trying to describe. This is very easy to do, and it is always helpful.

If you post some pics of your crossovers, members might be able to give more specific advice about the potential re-cap ideas. Generally, I agree with others that these would most likely benefit from full cap replacement. Kent raises a very good point here which should be researched and confirmed. While I find it difficult to think that a serious 70's receiver could not be adequate for a single pair of 4-ohm speakers, the Marantz literature is indeed very non-specific on this topic. The user's manual makes only this one mention of 4-ohm speakers, and even this statement can be read with two interpretations.

Without looking this up to confirm, I believe the primary difference between the AR-7x and the AR-7 is that the 7x uses a tweeter with ferrofluid for somewhat increased power handling. Also, I think the 7x was offered only in Europe, uses a multi-color cabinet stuffing, and often had the lovely teak veneer found on many Euro cabinets. The 6uF cap (and switch and resistor) found in the AR-7 is dedicated to the tweeter circuit only, and the woofer has no crossover components - - I'm pretty sure the 7x circuitry is essentially identical. Regarding the bass performance, I think you'll need to closely inspect the problematic woofer. Be certain that the cone seems to have adequate movement potential, but also, I can imagine bass performance suffering in a small sealed cabinet if the woofer foam has developed any cracks or deterioration.

Aadams, Glenn is much more active on the AK site than he is here, so I'm just helping out by providing a link to his other thread for others to read-listen about the recent gathering - - - a whole lot of very nice gear and music. https://audiokarma.org/forums/index.php?threads/peekskill-ny-blue-mountain-lodge-audio-fest-saturday-september-14th-2019.851987/page-9

Not sure where you are located, but there was a pair of these being demo'd today at Glen's get-together. http://www.classicspeakerpages.net/IP.Board/index.php?/topic/10476-peekskill-ny-blue-mountain-lodge-audio-fest-saturday-may-18th-september-14th-2019851987/&tab=comments#comment-126463

You should be able to find this in quart container - - - not sure about your state, but it's legal here and available in many good hardware stores.

Yeah, you may be right, Pete, but that data sheet does not describe the chemistry of the solid components, so we just don't know. Always a good idea, particularly in a "test case" scenario. I have some AR-4 woofers that had never been touched in fifty years but the surrounds were dry, and a little bit stiff and delicate. Carefully, I brushed on some solvent a few times and let that fully evaporate, then followed up with a light coat of Roy's butyl and this really did improve their texture and flexibility.

There have been many hypotheses applying and guessing at suitable re-sealing materials which have resulted in damaged or ruined drivers, and unless/until these materials are documented with results measured over time, my own attempts to re-seal cloth surrounds will remain confidently loyal to the liquid butyl goop that Roy has cooked up and generously shared with this community. It works very well on AR and KLH drivers, and I see no reason why it shouldn't perform the same on these Phillips drivers or similar. BTW, where does this "12.5" nomenclature come from?

Yes, this is correct. There is a similar marking on the backside of the woofer baskets for the identical purpose.

Both the KLH 12.5 and the Phillips 5060 are open-backed with cloth surrounds. In the KLH Five and Twelve (used in pairs), they are installed in their own separate sealed cabinet chamber. My familiarity with the Phillips driver (with whizzer cone) is from its use in several of the best Rectilinear speaker models, where it is installed in an isolated cup chamber. Attached images are: KLH 12.5; Phillips 5060; Phillips 5061; and 5061 tech sheet. If you look closely at the Phillips cones, there appears to be traces of a liquid sealer probably used on the cloth surrounds.

I plucked these pics from stever's attachment so that other readers won't have to open up a 21MB document. I agree with Kent - - no need to switch binding posts - - those look perfectly fine to me. These speakers do appear to be in very nice condition. However, the rust on the driver screws suggests that these may have been stored in a humid environment, and it would be worth taking a look inside at all components for any further signs of corrosion.

Hi, Marc, and welcome aboard. With your collection, you know more about BA products than I do, but it appears to me that everything shown is most likely original - - am curious, what makes you think otherwise? Quite possibly, what you heard moving was the black 16uF Bennic cap, which has become dislodged from its original position with hot glue adhesive. Edit: Oh, now I see - - - it appears that the upper left coil and resistor have also become dislodged - - it should be very simple to re-attach everything in original positions with a few dabs of hot glue.

Hi stever, I think what Larry means is that there are many threads on this site about the AR-91 that will tell you everything you need to know. Some people regard the 91 as among the very best three-way speaker models ever conceived by AR, so you should read up a bit before you do anything. For an intro to this topic, just copy the line below and plug it into your favorite web browser for a number of excellent online threads. site:classicspeakerpages.net "AR-91"

Off topic, but......I just re-read that thread of your AR-91 restoration, and I see in an edited comment that you have soured on Erse caps - - what happened here?

Most likely, the backside of the drivers will have an ID sticker label, and these should have info that satisfies this question of roughly dating the speakers.

No picture of the earlier AR-1 crossover assembly to share, but nonetheless am providing this schematic and rear views FYI. I find it interesting that the earlier speaker label shown carries the Mt. Auburn address (Henry Kloss' loft), while the later speaker label shows a Thorndike St. address across the street from the well-known 24 Thorndike found on most early AR's. With your rare specimens in such excellent condition, you'd be be well-advised to not consider any attempt to adapt to the multi-strap configuration. Yours most likely do have early robust pot controls, but even if the rotary controls are unserviceable, this project would be well worth the cost of some new heavy-duty Ohmite controls.

Yeah, my WAG is simply based on proportions of frame width to cabinet width. Not much to go on with the OP's pics, but we definitely gotta find a source for more of that grille cloth! Really nice looking 4x's, Kent.

As stated in your other audio forum, you will need more than one misplaced AR badge to confirm that these are indeed an AR speaker model at all. The confounding thing is not being able to view their entire cabinet height, so the relative scale in these pics is deceiving. But assuming that they are AR's, I'm inclined to see something different than what JKent is seeing, and my thought would be to guess they are some model from the AR-4 series.

I think those are from something called the Hi-Res series, but even this site's Library has no info on them. That's a really bad idea to recycle a product model name or number several decades later, but I guess they kinda did it with the VW Bug, too. http://techtalk.parts-express.com/forum/tech-talk-forum/56697-acoustic-research-ar17-black-bookshelf-speaker

Thinking about this discussion, I just had to chuckle when I saw this online sale listing the other day - - - all of those a's and x's can indeed be a bit confusing, but these type of nomenclature designations can be confounding with many products, not just AR speakers. In any case, this seller has apparently located the never-before-seen AR-4ax speaker model.

Hey Skinni, glad to hear your project was such a success. While I have absolutely no knowledge of that speaker model, I do know Brian a little bit from our local audio gatherings, and I know he tackles every project with great enthusiasm and buckets of knowledge and experience. Nice looking set-up you've got there. Re: wall poster - - - I've probably never given Rush enough serious musical attention, but my favorite power trios are always Cream and both of Hendrix's groups, the Experience and Band of Gypsies.

I believe that many LST/2 crossovers used the colorful Sprague Compulytic can-type caps, and those are known to often retain their value quite well. However, the small tweeter cap may be the type in the wax box - - if so, this should probably be replaced. You'll have to take a look inside and report back. And maybe this will be helpful: I found the pic of my 10-inch 2ax woofer where I used the "filled fillet" type foam surround and also preserved the original cap after shimming. If you do try this method to preserve original cap, be sure to use a fresh #11 blade on your X-acto knife when cutting the cap.

Whoa.......not so fast..... Well, I feel a little sheepish offering this info 'cuz there's not a whole lot known about them, but somewhere out there in the wild there is this rare beast roaming around. This pair shown was for sale in AZ or FL several years ago, and this CSP thread seems to suggest they are essentially Euro AR-2ax's with switches instead of pots. http://www.classicspeakerpages.net/IP.Board/index.php?/topic/1287-ar-2xa/

I totally agree about the use of shims, and the water-based glue, but when the dust cap is a unique part of the visual identity of the woofer, my preference is to hinge and re-use the original cap. The flat caps AR used on some 8 and 10-inch woofers are a perfect example, and it is fairly easy to retain the original "look". Shown is AR-7 woofer with flat cap.

Re-foaming that 10-inch woofer is not all that difficult and that driver is relatively forgiving. Everyone's anticipation of their first re-foam feels like it will be a nail-biting summit of Mt. Everest, but you are correct that it is actually no more than a fussy arts-n-craft project. Once you have the proper foam surround and a slow-setting glue, the process is mostly a focused meditation, and successful results can be very satisfying. Other members will chime in about their favorite source for surrounds, and with the LST-2, you should seek the highest quality foams if they fall within your budget.