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About RoyC

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    Latham, NY

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  1. RoyC

    AR3 Mid Range Differences?

    Are you sure your 3's were not repaired along the way? Your crossovers may provide a clue. http://www.classicspeakerpages.net/library/acoustic_research/original_models_1954-1974/original_models_schematicss/thoughts_on_ar-3_schematics/ Roy
  2. RoyC

    AR3 Mid Range Differences?

    Welcome to CSP, Snow... The fiberglass pad showed up very early in the game, but the large magnet version of the AR-3 mid was used until the rounded magnet version was introduced around serial number 30,000. Only the earliest ones had no fiberglass pad. Most were equipped with the pad. Roy
  3. I do most of his repairs. Forum members can contact me directly through the forum. The 3a mid and tweeter have copper tinsel leads. When necessary, I usually extend them with 24ga or 26ga stranded, tinned wire, using ordinary electrical solder. AR-3 mids and tweeters have aluminum leads requiring special solder, and are more difficult to deal with. Roy
  4. RoyC

    Ar3 midrange

    I wouldn't hesitate to use the AR-11 mids, Ken. Roy
  5. RoyC

    Ar3 midrange

    That is easily your best bet. It is likely those overpriced AR-3 mids have the old caked material around the domes requiring work to remove it. There is no need to convert your 3's to 3a's. Simply use the last AR-3 crossover with the later mids. Roy
  6. RoyC

    Ar3 midrange

    arken, The AR-3 tweeter held up better than the first two versions of the AR-3 mid. It is also much more available, having been used in the popular AR-2ax (first version), so your tweeters shouldn't be a problem. On the other hand, finding decent non-3a type AR-3 mids anytime soon will be very difficult. You are likely in for a very long, and ultimately costly, wait. If I were you I would go with a pair of AR-3a or later mids and use AR's .4mh coil/30uf cap modified crossover as mentioned above. I have not done any careful listening comparisons with the earlier versions of the AR-3, but I have made this repair a number of times for other people and it sounds quite good...certainly much better than any AR-3 with a typically degraded/non-restored earlier mid. Bear in mind, use of the later AR dome mid simply converts your speakers to a later version of the 3. They would still be considered "AR-3". If by some miracle, you were to find a couple of worthy earlier mids down the line, it would not be difficult to convert your speakers back to original. I have a hunch, however, you would not find it necessary to do so. The LST is not without issues (four typically degraded tweeters in each cabinet). They often start at $2500+/- a pair, and shipping them is an absolute nightmare. The last two restored pairs sold by "Vintage AR" went for $4000/pr. It is probably best to stick with your AR-3 project for now. Roy
  7. RoyC

    Acoustic Research AR-5 rebuild service

    Pete, Earlier front-wired 3a mids measure below 3 ohms. Later back-wired mids through the AR-9 typically measure 3.2 to 3.5 ohms. (Your AR-11 mid seems to be a bit on the high side.). Two later back-wired AR-5 mids I recently measured were both 5.2 ohms. All the AR-5 mids I've measured in the past have been around 5 ohms, with earlier front-wired specimens, like the 3a mids, being on the lower end of the range. I estimated the series resistance on the high side primarily because the white dot/"normal" setting of the AR-5 mid pot is nearly 50% off maximum (around 6.5 ohms in series), so there is plenty of output to be had with the AR-5 mid. The prudent way to go would be to measure dcr and add enough series resistance to the intended low impedance mid to achieve 5 ohms. This would put it well within the desired spec. It should also be noted that the original "15 ohm" pots can vary by as much as .5 to 1 ohm one way or the other, and should be measured as well. Roy
  8. RoyC

    Acoustic Research AR-5 rebuild service

    Yes...and all of the LST-2 drivers are the same as the AR-5 drivers. Roy
  9. RoyC

    Acoustic Research AR-5 rebuild service

    Sure, a 2.5 ohm resistor in series with an AR-3a mid will bring it very close to an AR-5 mid. Roy
  10. RoyC

    Acoustic Research AR-5 rebuild service

    Yes, they are constructed very differently. The AR-3 mid is essentially a large version of the orange phenolic dome AR-3 tweeter (foam suspension blobs, aluminum voice coil wire, etc). The 3a and 5 mids have more modern construction with a cloth dome/rolled cloth suspension, among other differences. Roy
  11. RoyC

    Acoustic Research AR-5 rebuild service

    Hi guys, I've been repairing the AR-3 mid, not the AR-3a/5 style mid. Roy
  12. RoyC

    Cloth surrounds

    I experimented with lots of materials, including that family of adhesives, Pete. It dries to a stiff rubber-like state (much worse than the Permatex materiel discussed above), and it unacceptably changes compliance and mass. "Might have to thin it" would be an understatement if it were to work at all. :) Roy
  13. RoyC

    New AR3a find and restoration thread

    Agreed, Jeff....the pots shown in dtafil's photos began being used sometime in the mid 70's . They had reinforced wipers, metal shafts (as opposed to the previous red or black plastic), and seem to be a bit more resistant to corrosion. Roy
  14. RoyC

    KLH 17, variance in impedance, pair of tweeters

    It's the woofers themselves. They are otherwise identical. Roy
  15. Thanks, Jeff...but based on our past dealings in other matters, I have nothing on you in the "unselfish" department. I will, however, take you up on that beer. Roy