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RoyC

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  1. Larry, The AR-3a/AR-11 mids' cloth dome suspension is a cloth roll, like a modern tweeter, and does not degrade or require maintenance. Other than front vs back-wiring there is not much difference between your mids. They will all work well with the crossover change mentioned above. Roy
  2. Hey Chris, I'm not sure it is worth the conversion effort without a properly functioning pair of original type AR-3 mids with which to compare. Using the 3a mid with the appropriate crossover modification (addition of a .4mh parallel coil, and removal of the .06mh series coil found in some iterations of the 3), can result in a significant improvement over a typical pair of AR-3's with degraded original mid drivers, but although the outcome sounds quite satisfactory in terms of being in AR-3 territory, it is not exactly the same as a pair of 3's with properly functioning original mids. AR adapted the later 3a type mid to the AR-3 in the same way as we have implemented the more modern HiVi tweeter in early AR models; using a parallel coil to bring it into the overall sonic ballpark of the original. As you well know, however, using a rebuilt original tweeter allows the use of the original simple crossover, which results in somewhat different sonic characteristics and system interactions. While both tweeters are quite satisfactory for most people, there are some sonic differences which may be of consequence in a discussion of this nature. I believe it is the same for the AR-3a mid as used in the AR-3. Roy
  3. Hi Glenn, These mutations are not common. There was a photo of a pair posted in the forum awhile back. Roy
  4. Great response, Kent. I agree completely. "Rated" impedance and/or dcr are not necessarily at the top of the list of considerations in this case. Mechanical properties and unique response characteristics often supersede impedance when substituting drivers in pre-existing designs. Other variables pertain to crossover slopes and level control characteristics. It certainly won't hurt anything to experiment, though the original driver is almost always the best replacement choice in a proven design. Roy
  5. zelgy1, As time went on the AR-3 shared a number of components with the 3a, including cabinets. Later 3's were equipped with the AR-3a mid, and, later still, the 3a foam surround/ferrite magnet woofer (just before the end of AR-3 production). It is also not unusual to find complete 3a's housed in AR-3 cabinets, as AR offered a 3 to 3a factory conversion. The 3 and 3a never shared the same crossover. Roy
  6. The only difference between the back-wired mids original to your cabinets and your AR-11 replacement mids is cosmetic. Bass response of the 3a Improved is technically the same as other iterations of the 3a, as well as the AR-11. The tweeter/mid response is complicating matters. There is no simple way to subjectively compare models until you eliminate those replacement tweeters and stop the tweeter/mid combo from shouting at you. If you end up disliking the sound of the 3a Improved an interesting project would be to change the crossovers/controls to that of the original 3a. The cabinets and drivers (including your mids) are functionally the same. Roy
  7. budney, You won't be able to compare them to the AR-7 or any other model in any meaningful way until you correct the tweeter situation. The level controls cannot compensate for the new crossover point and frequency response changes caused by these tweeters. I assisted another 3a Improved owner regarding replacement tweeter options, and after much experimentation he settled on AR-11 type replacement tweeters (https://www.midwestspeakerrepair.com/shop/home-audio/tweeters/dome/mw-audio-mt-4121-75-inch-dome-tweeter/), and retained the original .1mh coil in the crossover. He did not prefer the HiVi tweeter...and I don't know anyone else who has tried the HiVi in this model. (Of course the best option would be rebuilt original tweeters.) To use any other inductor coil you will need to remove the existing .1mh parallel tweeter coil or place another coil in parallel to achieve a desired value (ie you would place another .1mh coil in parallel for a resulting .05mh value). Just keep in mind any additional coil will interact with the existing one. The 3a Improved is different than the 3a. It was a short-lived transitional model, apparently marketed primarily outside the US about the time the AR-11 was introduced here in the States (note the European AR-3a and the 3a Improved cabinets are the same.) The mid and tweeter crossover circuits are actually significantly different than the original 3a, and the switches do not provide the flexibility of the variable controls of the original 3a. Like the AR-11 it has a more forward midrange character, so you can expect a different outcome compared to your earlier 3a project...regardless of the tweeters you use. Your replacement mids, woofers, and woofer surrounds all look very good, and will work just fine. If that really is a hole in the woofer surround mounting ring it must be repaired, and can be filled with epoxy putty. It is not, however, likely to be the primary cause of the differences you are hearing compared to the AR-7 or your earlier 3a project. Btw, it is much more likely you are becoming somewhat accustomed to the sound of your beasts rather than "caps breaking in". They are breaking you in. Roy
  8. Wow, memory lane, indeed! We were just getting to know each other. John later purchased level controls from AB Tech (based on a misleading website description) and ended up with overpriced 15 watt L-pads. This in turn lead to my playing around with resistors to compensate for the L-pad's higher parallel resistance, and the eventual use of a parallel 25 ohm resistor for this purpose. I really didn't know Larry at all at that time. When we later became acquainted we had some interesting debates on this issue. About the time of this thread John and I began spending many email hours comparing notes, and discussing other AR repair/restoration topics. Tom Tyson joined in early on, which ultimately resulted in the idea to put together the 3a restoration guide. Roy
  9. The 12 inch AR woofer, cloth dome mid, and Large Advent replacement woofers are replicas wholesaled by AB Tech. Although the woofers look fairly authentic, the cones are lighter and compliance is much lower than original. The AR replacement mid will probably do in a pinch, with a slight cabinet hole modification for the terminals, but it is less sensitive (smaller magnet) and does not have the same response as the AR dome mids it is intended to replace. As AR's primary service center, AB Tech continued to provide oem replacement parts after AR went out of business. Other than some older AR stock, most of the remaining drivers were initially manufactured by Tonegen in Japan for AR, and served as high quality replacements for a decade or so. When these were no longer available, AB Tech began sourcing various replacements/replicas elsewhere in Asia. Unfortunately many of these drivers fit the cabinet holes better than match the performance of the originals. The original owner of AB Tech closed the business a few years ago, selling a small inventory of remaining old stock (mostly some used cabinets, old drivers, and a few NOS AR-9 tweeters) to Vintage AR/Larry Lagace. Some of the later ABT replica drivers are still being sold by Simply Speakers and others. Roy
  10. The tweeter sold by SImply Speakers was sourced and sold by AB Tech as an AR replacement long after AR went out of business. It is rather cheaply made and has no damping material under the dome. Performance is different from the tweeters it is intended to replace, and its best attributes are cosmetic. The Midwest tweeter is much closer in construction and performance to all iterations of the cloth dome tweeter used in the AR-11 and 9 models, regardless of (AR) faceplate differences. Roy
  11. Agreed, David... Villchur's reputation and credentials are established. In the end the truly questionable credentials are usually that of the authors. Roy
  12. It somewhat depends at what frequency the capacitance measurements were done. Did you have the 72uf and 4uf caps tested as well? Was ESR measured?
  13. The amount of fiberglass typically found in the AR-5 is 23 to 25 ounces, with very early iterations (with the non-AR-2ax woofer) having more. The amount of fiberglass placed in the AR-5 cabinet decreased with time, just as it did with all of the early AR models. Something unique to most original AR-5's I have seen is a small piece of fiberglass placed over the Kempac just behind the woofer. We performed many measurements with varying amounts and types of fiberglass when putting the 3a restoration guide together, and did not find significant differences in Fc or listening impressions with variations of a few ounces. Given the changes made by AR along the way, I wouldn't be concerned with the precise amount of fiberglass, just consistency between the cabinets. Roy
  14. The "skiver" is another name for the spider, the fabric suspension at the base of the cone. It is not the surround's mounting ring. Your woofers most likely need only the correct surrounds. Don't mess around with anything else. The Parts Express foam replacement is acceptable. Roy
  15. The unique woofer magnets (note the indentations), the woofer cone, and missing surround mounting ring place the woofers firmly in the 1970-1971 era. I don't know anything about Simply Speakers replacement. This woofer requires the same surround used on later iterations, though I seem to recall the outer edge barely making it to the basket with this version of the woofer. The ring on the cone is foam, and will be fine as is. Don't mess with it. Roy
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