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Hey, thanks, you guys are great - - this is all helpful and interesting. Kent, this is yet another terrific re-build and I enjoy the way you take us through the various steps and decisions. I've seen pics of your work space and sort of imagined that your audition occurred there, which would certainly confirm the increased settings. Nonetheless, sometimes I almost cringe when I see unadorned rooms with smooth, hard walls and ceilings, tile floors, and large glass patio doors adjacent to speaker locations with virtually no absorptive materials to be seen - - - so I am reminded to bring up the issue of room acoustics when the topic of these variable controls comes up. Sorry if I diverged too far off course here. But Roy raises some other interesting points....... Yes, Roy, I do currently own one pair of speakers (2ax) with this 3/4" tweeter and this is largely why I was asking specifically about diagnostic techniques. Mine are old yet functional and probably much like Kent's recent pair. They're capable of making a little noise but nothing very impressive is coming out of them - even with fresh caps and pots at max setting. Like many members here, I've been very pleased to see at last two more good options (in addition to the Hi-Vi solution) for these tweeters crop up in recent years: this re-build of the originals (by yourself and Chris), and the new replacement driver from Midwest Speakers. With several suitable paths available, I'm beginning to feel guilty for not having remedied my own speakers yet - - I convince myself I'm still in the data-gathering stage, otherwise known as procrastination . Roy, your remarks about the questionable "proper" response, difficulty with performance consistency, and variable sensitivity of the suspension material are all very revealing and make it easier to understand the factory rejection rate - - also, they suggest the uncertainty in defining the target objectives during a re-build. If you have more to share on this, eager ears await. The comments regarding near universal agreement on the max setting for these controls makes me think my statements about "hard" rooms do not apply to this situation, but it also makes me wonder why a different fixed circuitry - - with no L-pad, since no adjustment is ever required - - has not become a more favorable solution for contemporary re-build projects with this tweeter. Perhaps the words 'restoration' or 'collectible' or 'vintage' get in the way, I dunno. In any case, this thread has been another successful example of giving two old walnut boxes a new lease on life, and this latest discussion has given me greater admiration for the skills and knowledge that are required for these delicate re-builds of these old drivers. Thanks to all who contribute and share here.

Hi Kent, this is another beautiful restoration you've completed and a great discussion about the many factors and components that are involved in such a project. However, I remain a bit confused about certain parts of this tweeter discussion so I'm pretty sure I'm missing something here - - please clarify further if you can. These speakers belong to original owner, never opened. I went back and re-read the brief statement where you said the mids were fine but tweeters were weak, hence requiring the re-build effort. Still having original caps and crunchy pots in the circuit, I'm curious about how this decision on the tweeters was determined. Basically, I'd like to learn more about proper diagnosis techniques. Was this a subjective evaluation while all drivers are in operation? If so, did tweeter pot offer a 'sweet spot' near max output? Or, was the tweeter played by itself out of the box?... or, are there certain measurements that can be made without lab equipment to confirm weak output? I always appreciate your opinions and subjective evaluations and comparisons, but your most recent post surprised me a little bit because there has been no mention of room acoustics or interior environment. Having newly re-built tweeters, fresh film caps, and brand new L-pads, I would expect that the max setting on the tweeter L-pads would be a recommendation for only the plushest of listening spaces - - by this I mean "soft" - - carpet and rugs, upholstered furniture, drapery, and/or perhaps even absorptive ceiling treatment. Specific musical selection is somewhat of a factor, I suppose, but my inherent sense is that the "all the way" setting in a more austere or "live" room would result in an unpleasant or even overwhelming HF experience. My rooms tend to lean heavily toward a "soft" acoustic environment, so I typically have these rotary controls (or switches) on my speakers set to an increased HF output setting. However, based on many room interior pics I see displayed in this forum, this is definitely not the case for many vintage speaker lovers, and I suspect that there is no universal "one-size-fits-all" prescription for these controls that will satisfy every installation. Great project, great discussion, thx for sharing.

Really....is this a common occurrence? The OP has already noted that the LMR was lacking the sealing gasket. Sounds like you have an interesting project. I don't think these 035 drivers showed up in any other speaker models, and I can't begin to understand the particular engineering objectives behind this woofer. I'll be happy to reach out to you after the OP chimes in.

Hey, John. I have no idea if these 8-inch drivers might be a suitable substitute for the 027 driver, but I have this pair of ready-to-go orphans that I don't know what to do with. These are part number 200035, which is the 8-inch woofer (not LMR) used in the AR-93. Drawing and specs or performance curve for this driver are available in the Library - - DCR is spec'd as 8-ohm ±10%, and these measure at 8.4 and 8.5 ohms. Originally, these had the unusual stiff white domed dust cap, but when re-foaming, I mistakenly replaced the original caps with new black ones of similar diameter. These days, I typically try to preserve the original caps. (Edit: I found this pic with original dust caps.)

That's a really good point - - so often this internal wiring has very little extra length available. As I recall, the original wires in my AR-6 tweeter replacement were long enough, but not by much. Splicing extra length is always an option, but hopefully not necessary. Glad to see you add your two cents here - - - I know we've discussed the merits of these tweeters before, and I would tend to agree with this assessment. You have such an admirable collection of so many AR models that I would encourage you to simply restore these 8b's as complete two-ways instead of scavenging parts. Despite my personal disaffection for the cabinet styling and budget slashing that haunts the "B" lineup, all of the models in this series that I have heard are terrific performers (I personally have 18b and 28b models). IMO, the nearly identical speaker had a far better look in the Euro market - - this appears to be the model (AR-8s) where AL78 might be getting his tweeter.

It is really of no benefit to remove the oval-shaped terminal plug - - it is loaded with staples and is made from 1/4" Masonite. If my memory serves me correctly, I snipped the original green and yellow tweeter wires right behind these terminals, stripped off the colored insulation, and then soldered or crimped new push-on female terminals to fit the male tabs on the tweeters as shown. And yes - - - in order to snip these wires, the woofer must be removed. Let us know how this works out if you end up going this route. I have a couple pairs of AR-7's, but they both have very good original front-wired tweeters. If they were to ever fail or become damaged, I would have no hesitation about pursuing this solution to use substitute 038 tweeters with rear wiring.

I think this tweeter should work well as a replacement, but I would say that it seems to be the general agreement among members that these newer tweeters might contribute a bit more HF output than the older originals. They are excellent tweeters - - - all in the same family - - - and this 038 tweeter worked very well for me in an AR-6 project (see image) where the front-wire terminals were abandoned. However, this pair of AR-6's have fully functional rotary pot controls for HF adjustment, whereas your AR-7's just have the two-position switch for attenuation. Not sure if this an option for you, but normally I like to make identical changes to both speakers at the same time when working on paired (stereo) speakers. On magnet sizes, the original should be 2-1/8" diameter (54 mm), and the 038 should be 2-3/8" (60 mm). My AR-6's did not require enlargement of the magnet hole, but did require some wood removal to allow for the tweeter tabs to fit.

Hi AL78 - - - I'm not quite sure exactly what the problem is that you are describing here. Nonetheless, that tweeter part number 038 from the AR-8s should probably be a suitable replacement driver - - it is a rear-wired later version of the original front-wired 1-1/4" tweeter used in the AR-7. It is constructed a bit differently from the original, and it may have slightly increased sensitivity. The newer 038 tweeter employs ferrofluid and has a larger diameter magnet, and in fact might be the same tweeter mentioned in a Euro version of this speaker called the AR-7x, as noted in this thread started by you six years ago. http://www.classicspeakerpages.net/IP.Board/index.php?/topic/7668-ar-7x/ I suspect making this substitution might require two alterations. The first is that the cabinet cutout for the tweeter may need to be slightly enlarged in order to fit the larger magnet diameter of the newer tweeter. Secondly, I think you might want to disconnect the internal wires leading to the backside of the front terminals, and then add female disconnect terminals to snap on to the rear tabs on the 038 tweeter. First pic shows smaller magnets from AR-7 tweeters. Second pic shows 034 (left) and 038 (right) tweeters with larger diameter magnets.

Nice to see this detail - - and I agree with Larry - - a solid wire nut connection works fine for this purpose, and I've been re-building my speakers with this technique for the exact reason that JKent has already stated (future removal and access). Just be sure you put the Kimpac in before you connect the wire nuts. This 3a restoration project looks really good. Don't think I recall seeing you use Audyn caps before, but I know a speaker manufacturer in these parts that strongly advocates for this line of (red) Audyn caps. His opinion is that they offer excellent performance vs. cost value, and I'll probably be using this brand soon in some upcoming projects. Thanks for the meter info. That B&K meter looks pretty nice, and I've been thinking about trying one of those little cheapies, too, but I'm trying to find one that has a provision for wire leads with alligator clip. Thx Roy, I'll keep this in mind next time I poke my head into the pair I'll be working on.

I usually make every attempt to re-use the original material unless it is substantially tattered, but regular kitchen cheesecloth will even work in a pinch and it is very flexible and form-fitting. If you plan to replace the original stuffing with new long-strand FG, this issue may be somewhat less relevant if your woofers have screen segments covering the voids in the woofer basket.

Hi Meerkat, These speakers are from the mid-to-late 80's, so it is perfectly normal for the foams to have deteriorated. Nonetheless, having rotted foams is usually not sufficient reason to "toss" the original woofers and begin a search for new replacement drivers. This is a mistake that many people have made and lived to regret. Your TNG drivers might be factory replacements, or perhaps Tonegen was providing original drivers to AR in these years. The 072 part is the important part to identify that particular woofer, but I would discourage you at this time from conducting a search to find similar part number replacements since it is quite possible that even those might require new foams. Instead, I think JKent offers sound advice to attempt to re-foam these yourself or with assistance from a local audio shop. I believe these are 8-inch woofers, and replacement foams should be available regardless of which continent you are living in. Regarding re-foam, the thing to be aware of is these woofers have polypropylene cones, so you want to be certain that you use an appropriate glue that will bond with this material. Also, because of age, it might be prudent to consider replacing original capacitors. Schematic diagram is attached.

Velcro is indeed a multi-use miracle invention, and it works very well for holding grilles in place, yet I think only one pair of my modest collection of AR's still uses (original) Velcro strips for this purpose. First used as a temporary 'fix' but now a more long-lasting solution, I have resorted to making various type of thin, small shims to wedge in the gap between the grille frame and the cabinet perimeter to hold the grille firmly in place. When they are dark in color and properly sized and wedged into place, they are virtually invisible. These shims are cut from material scrap, sometimes thin cardboard and sometimes craft felt - - I think I even used flexible roll cork at least once.

Sounds like a really good project and I'll be interested to follow your efforts. Similarly, I'll be working on a pair of 3a's in the coming months with a friend of mine. This pair has great cabinets, grilles and badges. Have only conducted a brief cursory test/inspection, but all drivers are functional and pots are very crunchy and intermittent. These are consecutive serial numbers in the 461XX range and have the first generation ferrite-foam woofer (Fig A.2 in 3a restoration guide) and the brick-size double 50/150 cap. Probably next month we'll dig into these for a closer inspection, put together a parts list, and get to work. I'd be curious to know about the type of meter you're using for cap measurements, since I've never been fully comfortable with my meter for this application. Also, didn't the change in coil coincide with the change from alnico/cloth to ferrite/foam woofer?

Beautiful speakers. Cards show no zip codes.......pre 1963 date?

Ditto to everything stated thus far. Roy's contributions here have taught me a great deal. They are always offered with specific detail, good humor, and humility, but mostly, it is his enthusiasm and generosity that truly sets him apart.

Just wanted to post this comment found on the AK forum regarding DA PS-10's. Unfortch, there were no pics to show how he achieved the re-cap. "BTW- I did a recap on a pair of PS-10 crossovers. Just for S's&G's I measured the capacitance and ESR values on the original caps. All the original caps measured within tolerance for capacitance and the ESR was well under .5 ohms also. The crossover capacitors may be the last place to do your troubleshooting based on my experience. Just FYI." Also, starting on page 4 of this thread, you can see the stands that Glenn built for his PS-10's. https://www.audiokarma.org/forums/index.php?threads/lets-see-your-home-made-speaker-stands-im-going-to-build-some.457303/page-4

Re: "A" designation, I suspected there was something you had discovered that we were unable to see, and I would tend to agree with your interpretation of the serial numbers. And yes, I think I recall reading a reasonably positive review from Glenn regarding the PS-10. Even before I provided any supplemental pics, my well-informed DA source (located in CA) was able to describe and/or confirm that all of my D-4 drivers are indeed original. I have read the same overall diagnosis about DA after AT purchased the company, but the general decline may have begun even earlier, as described in the D-4 to D-4a transition. About the caps, I'm not quite sure what to report, but like yourself, I would be real hesitant to dig into that tight mass of crossover assembly in the PS-10's. In my case, both pairs of D-4's have two caps per cabinet: a cheap tiny 4uF tweeter cap attached to the terminal panel, and a larger midrange cap (20uF in one pair; 33uF in the other) located deep inside the cabinet next to its driver. None have yet been removed and/or measured. The tweeter caps will be replaced without question because these panels need to be fully rebuilt due to broken switches and weak binding posts. The different values found in the mid caps are a bit of a mystery, but after some exchanges with my "source" regarding the particular drivers and the designer's basic philosophy, we've agreed that the 20uF with its higher x-o frequency is probably preferable. Nonetheless, due to their location in these cabinets, these will be a challenge to replace, as I'll be doing all of this without removing the iron-clad front grilles.

Thanks for providing this write-up, Kent, but I could not see in your pics any designation of the "A" in the model number. It is often interesting to see a product (speaker or otherwise) go through these revisions and iterations (A, B, C, etc.) during its market run and then identify the specific changes and/or market strategies or justifications. In the case of the DA speakers I am currently working on, the later D-4a was a very different and far inferior speaker design than the original D-4 - - - it shared some similar proportions and vague visual identity, but had a different number of drivers which were all different from the original parts. A couple curious thoughts. That first sentence in the review in the Lab Measurements section: Isn't that sort of a redundant statement? Yet there appears to be no mention of a separate enclosure for the cone mid, as was found in your speakers. The oddest thing, however, IMO, about this speaker is its proportions, and the review does address this - - - the PS-10 clearly "looks" like it's meant to sit on the floor, but of course this puts all the HF delivery in the wrong place. Too deep for a bookshelf, and yet it's hard to imagine these fitting and looking good on a pedestal base. Now I'm getting a little curious to see what the rest of the PS line was all about.

. Stoopid me...... Ugh.... I really despise working on hot melt glue schmoo assemblies.

Those are stubby little fellas, ain't they? Almost cubic in dimensions. The drivers appear well constructed - - yes? - - but it took me a minute to realize that the tube is a separate enclosed chamber for the cone midrange. Crossover looks fairly robust, but a cap replacement could be a bit of a challenge unless that board is easily removable. I would guess there is at least one more cap we cannot yet see. Interesting to see the little response curves which illustrate the crossover frequencies, and that Da logo does not show up anywhere on my D-4's, but yours do have nice binding posts. Two questions: What's going on with that black top grille that is held away from the vinyl top panel? And, did these woofers have a gasket between metal frame and bottom cabinet panel?

This is a great point about the human voice range and midrange frequencies. While my AR-4's do not quite match the 4x or 4xa (nor the AR-6!) in LF extension, there are times when the AR-4 is the preferred speaker - - - like when playing female vocals or jazz (vocals, strings, brass) at moderate volume levels.

Hey, thanks for adding that little blurb from the buying guide. These speakers were partially disassembled for inspection, and then the project was slowed down as I was seeking additional information. Now that I've found my lodestar, I'll probably be tackling these next month. Before any disassembly, I did wire up the speakers (in pairs) for an initial listen and to confirm that the drivers are all functional. This was by no means any type of serious test run. The sound provided a nice blend amongst the many drivers, but first impressions suggested that top-most and bottom-most frequencies were muddy and lacking. Until any post re-build demonstrations occur, my guess is that the lack of high sparkle might be due to several broken switches and/or cheap, tiny, aged capacitors. Regarding bass output, the cone mass/stiffness needs to be addressed, and I think the placement is probably critical with rear-firing woofers. Also, considering this is a non-ported speaker, I was surprised to find no gaskets sealing the woofer frame to the cabinet. (Edit: I forgot to mention that in the original DA series (D-2, D-4, D-6, D-8, D-12), the notion was that the model number referred to the number of planes that contained a driver - - - I've been able to confirm this for all but the rare D-8.)

Hi Kent. Before you wrap up this thread, please show us some additional pics and info about this speaker model. Also, exactly what are the SW recommendations for VC centering? Your re-foam looks very good done the "correct" way. Have never seen a spitwad cap that was not a Smaller Advent, and that woofer also has inner foam placed under the cone. And, is that a radial seam in the paper cone at 9 o'clock? The DA speakers I'm working on (two pairs of D-4's) are from the early original series (D-2, D-4, D-6, D-8, D-12), when the company was located on Oregon Court in Torrance, CA. At that time, all speaker design (and marketing and purchasing.....) decisions were controlled by founder George Sioles, but I am not at all familiar with the PS series.

Greetings bluelick, and I'm pleased to hear that you have discovered the problem for yourself. As I was reading your thread, I spotted that as soon as I saw your little wiring sketch ("Never trust a schematic that says wooger." - Rutherford B. Hayes). NPE caps are just fine and yes, it will be a PITA to dig in and make the switcheroo - - - but you may want to also use this opportunity to confirm the wiring on the woofers to see that they are both connected properly. (as a side note, the crossover pic shown in Aadams post is the re-cap of my 2ax's from 2012.)

Whoa!.......the level of interest in this thread has been so fast and furious that I've barely been able to keep up. In any case - - - just a few more pics for posterity here. Both the woofer and the (3) tweeters have two-position switches for varied output, while the midrange runs full-tilt all the time. The 10-inch woofers were manufactured by ROLA (also used in ADC speakers), and I've never seen anything like these amendments added to the cone surface. Apparently, these three little strips of balsa wood have been added to the OEM driver in order to provide a slight increase in mass and/or stiffness. Most of this information - - and much more - - comes to me courtesy of a very kind and generous fellow I've contacted who used to work in the company's wood shop in CA in the mid-70's when these speakers were first produced. He has been a trove of information and immense help, and his comments often refer to the ideas and practices of the founder and lead designer for Design Acoustics, George Sioles.