tysontom

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  1. Wow, we've seen it all! Those "tweeters," more than twice the diameter of the 3.5-inch mid-range drivers, are old WWII University Sound field PM speakers used in jeeps and so forth. They were mil-spec and environmentally sturdy, but there is scarcely any semblance of "high-fidelity" sound emanating from those phenolic cones. Those woofers look like Pioneer or Sansui models with probably a very high fs, resulting in no deep bass but lots and lots of boom. These are the pre-1970 AR-2ax versions that had the 1-3/8-inch tweeter and the six-bolt alnico woofer, but it looks as though a larger hole or recess has been put into play. Nevertheless, if free,what could you lose? These could still be rebuilt back to original specs with a lot of work!
  2. AR-LSTs

    The cabinet on one AR-LST has been seriously damaged (obviously dropped), causing huge damage to the speaker enclosure. There also are no pictures of the woofers. Hard to say what they are worth. The person listing them bragged about a "matched set" when, if fact, there was no such thing as a "matched set."
  3. Lovely set of LST's

    This early AR-LST, #00081, was built in 1971. It is remarkable (to me, at least) that one of the urethane surrounds is original if barely barely intact, even though the other speaker's surround has begun to collapse in on itself! AR coated all of these early (until 1975) 12-inch woofer surrounds with a clear butyl-latex coating, and this one has been a survivor after 45 years, defying the odds. My LST woofer surrounds lasted this way until around 2013. Most of these surrounds were beginning to go south after 17-20 years, so to see them last for this many years is great. This pair of LSTs has great original grills -- and the cabinets look great -- but sadly there appear to be problems with some of the tweeters and/or the crossover network. Still they should do well considering their overall excellent condition. My pair of LSTs are packed away, but they are in similar condition and have no electrical issues. I stored the original beige-linen grills and ordered replacement grills from AR in Norwood, which were the later "white linen" versions, so the original grills are still in nearly new condition. Norwood "white-linen" grills AR-LST No 636, 1972 AR-LST No. 636 Norwood "white-linen" grill in center vs. "beige-linen" original grills behind. The black outline is a result of a black sticky substance the AR Norwood people put on the grill frame before mounting the grill itself, supposedly to keep the grill material from "migrating" or sagging. Instead, the black mastic leached through the grill. This was later corrected, but some grills have the black showing through the grill itself. --Tom Tyson
  4. Is this 3a woofer toast?

    WTF! Never, ever put anything like that on the inside of the voice coil! To add grease to that woofer (one not designed for anything like this) would seriously degrade the performance of the woofer and cause it to be very over-damped. The grease will always be somewhat in contact with the pole piece and coil, and it will drag it down a small amount, just enough to ruin the normally ruler-flat bass response of this woofer. Bass response would seriously suffer and the roll-off in deep bass would be very audible. Someone had the erroneous notion that putting grease in between the voice coil and the pole piece would create a path for heat dissipation and give the woofer greater power-handling capability, much like the addition of Ferrofluid to a tweeter voice coil. It won't work this way with a woofer with such great excursion (greater than one-half inch, peak-to-peak, or more). --Tom Tyson
  5. Probably not many people actually mount their "classic" AR speakers horizontally on shelves anymore, but the speakers definitely sound better mounted that way. For one thing, it eliminates the fairly audible "notch" in the mid-bass response caused by cancellation reflections of bass frequencies bouncing off the wall behind the speaker and joining, out-of-phase, the forward-firing bass frequencies. This causes a "notch," or "suck out" of frequencies in the 200-300 Hz range. If you have one of the tower speakers such as the AR9 or AR90, AR9Ls, etc., the woofer is mounted close to the floor-wall intersection, and the notch is pretty much eliminated. If the woofer in a bookshelf speaker has a low-enough crossover, say below 200 Hz, then the notch is a non-issue, but few bookshelf speakers have such a low crossover. You can also plunk the speaker directly on the floor, but the sound gets pretty boomy and heavy when you do that. Here is the way I had mine mounted at one time. The sound was great.
  6. Are these AR3's?

    Good! First thing to do is to take a knife and scratch off the paint on the three terminals on the tweeter-terminal strip. The "TTS" is the oblong terminal plate located between the midrange and tweeter. Then, take a 1.5 VDC flashlight battery with a wire connected (preferably soldered) to the negative and another wire connected to the positive terminals, and "touch" the wire to first the center terminal and the other wire to each outside terminal and listen for any "crackling" noises from the drivers. Never attempt to directly check voice-coil's continuity of the exposed aluminum lead-in wires. Also, do not hold the battery connections for more than a brief second; this will needlessly heat the aluminum voice coils. In fact, it's best to simply touch the wire on and off to listen for any sound, thus establishing continuity of the midrange and tweeter voice coils. This is just a quick, simple test to be sure you don't have any voice coils that have been burned out by someone over-driving the speakers. By touching these terminals, you are bypassing the crossover by putting small voltage directly to each driver. Do it sparingly. Be very careful when you work around the tweeter's lead-in wires. These wires are aluminum and are fragile; avoid touching them if possible unless you are very careful. That tweeter looks to be in excellent condition, by the way, and the suspension has not "popped" in any way, meaning that it is clearly within the original spec as far as alignment is concerned, and the dome hasn't migrated away from the top plate. The woofers, though ugly looking here, are probably fine. They are very durable and don't often give trouble. You should put all of your fingers around the outside of the center dust cap and gently push the cone "inward" about 1/4 to 1/2-inch, and then immediately release the cone. It should return to the "center" position slowly within 1-3 seconds or so. It should feel like you are pushing the cone through a viscous fluid when you depress the cone. If you don't feel this resistance and the cone bounces back immediately when you depress it, the surround might be leaking air; but frankly, only a few of the 3700-series woofers suffer from this problem. Do not apply any butyl-rubber or other compound to the cloth surround unless you are positive the cone is leaking air through the cloth. Applying anything to the surround can do more damage than good if the surround is not leaking, despite what anyone says. The free-air resonance can be affected by applying substance to the surround, and this is not good. Take a clean paint brush and lightly "dust" the dirt and grime from the cone and surround. It has collected a lot of dust over time. This AR-3 definitely has an AR-3a cabinet, but the drivers are the original-type Alnico #3700 woofer and #4500 2-inch midrange and the #375 1-3/8-inch super tweeter. This was definitely getting to the end of the line for these drivers, so you are fortunate to have the original-style drivers in an AR-3 this far along. --Tom Tyson
  7. Are these AR3's?

    The grills may be attached with Velcro, but likely AR used hot glue to hold them in place. Gently try to pry the grills away from the cabinet, but watch the walnut grill molding. It's easy to scratch the molding. Use a wide putty knife and use care.
  8. Are these AR3's?

    Great work! For sure, man-handling two 52-53 lbs loudspeakers down stairs would be stressful. Hope you didn't hurt your back. Serial number 69923-69935 were definitely manufactured by Acoustic Research at the 24 Thorndike Street, Cambridge, Massachusetts factory in May-July 1972. The AR-3 was produced through 1973 and finally discontinued in early 1974. For nearly ten years after it was introduced in 1958, the AR-3 was considered to be the finest, most accurate loudspeaker available anywhere for any price. To this day, a pair of properly functioning AR-3s is still a wonder to behold! These particular speakers you have likely used AR-3a-type cabinets, and probably have ferrite woofers! Send pictures when you can. Remember, when you first connect them to an amplifier, be sure to gently rotate the level controls back and forth a great deal to get contact. Don't be surprised or dismayed if you hear nothing from the midrange and tweeter drivers at first! You might have to spend ten or twenty minutes turning them back and forth until finally you will begin to hear some light "crackle" of sound through the midrange and tweeter. Sometimes, you can come back later and you will easily find those "contact" points. AR level controls work sometimes in the "paranormal" world, so don't be surprised. Don't apply too much power at first! Congratulations! --Tom Tyson
  9. Is this 3a woofer toast?

    With the surround gone, and spider (inner suspension) will cause the cone to collapse down below the "center" position, and frequently it will be tilted and will rub. This woofer (in question) is the original-type 200003-0 AR-3a version, second iteration short-wire version, likely 1971-1973 or so, and it is actually one of the more desirable versions of this superb woofer. This woofer is extremely compliant, and you must shim this woofer when you re-foam it to be sure of proper voice-coil alignment. Do not cut the dust cap all the way off (see my pictures below), just cut it very carefully with a razor blade or similarly sharp knife blade around a circle (watch carefully for the lead-in wires to the voice coil assembly under the dome) and leave perhaps 10-20 degrees out of 360 degrees (perhaps 10mm) enough to fold the dust cap back away, exposing the voice coil assemble and cone apex. Never replace the dust cap with a new plastic or paper version! This dust cap is slightly porous, and it lets air from under the dust cap escape very slightly. You risk raising the free-air resonance of the woofer if you replace the dust cap; leave the original in place, but you must shim the voice coil. When you use a proper 5/8-inch foam surround (check with RoyC and others to get an idea of the best surrounds available today) and shim it properly, you should end up with a free-air resonance ("fs") of 17-19 Hz, and the speaker will have the proper system resonance of 41-43 Hz. Distortion will be extremely low with this woofer. It is possible that someone over-drove the woofer and caused the voice coil to slam against the back plate and damage the coil assembly; it's also possible that the woofer has been damaged by a defective or inadequately powered amplifier (most properly working amplifiers will do no harm to this woofer under normal music and speech playback) or extreme over-drive or clipping by an amplifier. Some amplifiers go bad and produce excessive dc offset in the output, and this will damage the woofer. AR9Lsi 12-inch woofer, similar to the 200003-0 AR-3a/AR-LST-type woofer. AR9Lsi woofer AR-12-inch voice coil and dust cap shimming. --Tom Tyson
  10. Bill Bush—1963 - 2015

    John, Thanks for your contribution regarding Bill Bush. How did you happen to know him? Were you in the hi-fi audio industry? In my view, Bill was an under-appreciated, but highly talented engineer at NHT and AR during the 1990s. He did a good deal of the "heavy lifting," and KenK will probably reaffirm this, but this is also what is expected of the engineering staff! Bill was also exceptionally bright, witty and approachable, and he was always helpful to me, as was Ken Kantor. While on a visit out to Benicia, California, I rode to lunch one day with Bill in his black Corvette. He was proud of that car, and we had a great time together. Bill and I also exchanged a lot of emails about riding motorcycles. At that time, I was riding a Suzuki GSX-R1000 and doing track days at the several race tracks around the area, and Bill approved of my activities immensely. He loved motorcycles and fast cars. Also during this time, Bill developed a health issue and struggled with an irregular cardiac rhythm (arrhythmia) that persisted for several years. This was/is not completely abnormal, but it dogged him a great deal, and he couldn't completely eliminate the problem. Thanks to Hewlett-Packard, my employer, and in appreciation for all he had done for me in the past, I shipped on loan, a $35k Hewlett-Packard portable, bedside-patient monitor to use to home-monitor his heart rate, etC02, Sp02 (oxygen saturation or "pulse ox"), blood pressure, ECG management and a 50mm strip-chart recorder to run off strips. With this instrument, he could keep closer track of any issues he might be having with his occasional irregular rhythm and let him know if he was having bouts of irregular rhythm, and I think it helped him stay aware of what was going on. It could be set to alarm -- and record -- if he was having too many PVCs or bouts of irregular rhythm and that sort of thing. It didn't fix his issues, of course, but it helped him understand what was going on. He was very appreciative of that unit, and he enjoyed using it for a couple of years and learning about patient-monitoring technology! I told him he could take it apart as long as he put it back together properly, and he did just that, commenting on the gold-plated circuit boards and surface-mount technology! He could run strip-chart recording strips and take it to his cardiologist for review. Nevertheless, his condition worsened over time, and he eventually returned the monitor, so I knew that the doctors didn't have things under complete control. Bill was a fine, talented person, and he will always be missed! By the way, if you've heard a NHT 3.3 or the AR 303, and many others, you have a sense of the talent of this engineer. He had a great deal to do with the design of each speaker, obviously under the direction of Ken Kantor. This was akin to Chuck McShane's contribution at AR: he did much of the heavy-lifting on the AR-3a, AR-4x, AR-5, AR-6 and so forth under the oversight of Roy Allison. --Tom Tyson
  11. Dating AR-5's by serial number

    Measure the existing caps first. I recently measured several AR-3 caps -- much older -- and they were not really out of spec. The spec for this 2-part AR ICC capacitor (and practically all crossover capacitors) is around 10-15%, and this 53-year-old AR-3 combined-value capacitor fell inside that value for this one and the same for about six or seven others that I just measured. Some caps get wildly out of spec, so each capacitor should be measured. Some of the AR Callins (and even Spraque) capacitors fall out of spec over time. So, you should disconnect (unsolder) the capacitors from the crossover network and check them individually first before changing components. PE sells a decent capacitor meter; I checked mine with Hewlett-Packard test gear, but most testers work okay for this level of measurement. It certainly won't hurt to put in new capacitors, but it may not be necessary. You don't need high-precision, high-dollar capacitors. Even with the most-expensive capacitors you can buy, you will never get a bright, forward sound like the Dahlquist speaker, and you may hear no difference whatsoever in the AR-5 if the current crossover is working properly. You will almost surely need to remove and clean the level controls, and that will make the biggest difference. You will likely find that you will never want to run the level controls "wide open," as the recommended "dot" settings usually give the best or most-natural sound with possibly the treble control advanced higher than the mid position. If everything is working properly, you will find that the AR-5 is significantly more natural-sounding than even the Dahlquist, but it will lose in the brightness category. --Tom Tyson
  12. Dating AR-5's by serial number

    According to warranty and production records, which are sketchy, AR was building 604 AR-5s/mo during the spring of 1972, and in July, 1972, AR-5 S/N 24408 was manufactured. At the production rate (which varied from "heavy" in the fall and winter to "light" in the summer) averaging 600 units/month, AR-5 S/N 20604 and 20608 would have been manufactured somewhere around January 1972. AR continued to manufacture the AR-5 well into the mid-1970s with serial numbers beyond 45000, but this was somewhat less than half the number of AR-3a sold. If a potential customer had enough money to spend on the AR-5 at around $175, an additional $75 could be spent to move up to the significantly more powerful AR-3a at $250; thus partly accounting for the lower sales of the AR-5, not to mention the emergence of the top-selling Advent with better bass response, nearly equal to the AR-3a. The less-accurate Advent (bright and somewhat peaky midrange/treble) with powerful bass very nearly as good as an AR-3 or AR-3a, costing about the same as an AR-2ax and significantly than the AR-5, put a huge hurting on the AR-5 sales . Ironically, the AR-5 had a slightly better overall acoustical balance than the more potent AR-3a. AR continued to manufacture loudspeakers throughout the slow season rather than lay off workers. AR actually had very few layoffs ever during the 1954-1970 period. Production-line workers were retained in the slow months and were put to work painting the factory, rebuilding production facilities and so forth. This was part of AR's culture of taking care of its workers. AR also had a higher pay scale than most competitive plants, and this enabled the company to hire the best available trained workers. After aerospace conglomerate Teledyne bought (1967) AR -- and beyond the 5-year stabilization period after purchase -- things began to change at AR. By the way, the earliest AR-5 woofer was special to this speaker and also the first (October 1968) to utilize urethane-polymer "foam" surround material in conjunction with a special asphalt-paper cone material. This was an early AR-5 woofer -- not the very earliest -- characterized by the treated-cloth dust cap. This is the earliest-type AR-5 with the vertically aligned midrange and tweeter, later changed to the staggered arrangement because of production problems with the cabinet. If one is found like this (this was the prototype with the top plates unpainted), it is a fairly rare version. Later version of the AR-5 showing the "generic" 10-inch woofer (this one with the yoke-type Alnico magnet) and the staggered-midrange-tweeter arrangement. After 1973, the AR-5 went to the ferrite-magnet 10-inch woofer and back-wired drivers, Velcro grill attachment and new-style crossover. AR-5 "file" photo from 1968. A great ad on the early AR-5! Note this earliest woofer and the midrange-tweeter arrangement. Note how close the midrange is to the cabinet side, causing some manufacturing issues and ultimately resulting in the AR-3a-type staggered arrangement. Also, the staggered arrangement more nearly resembled the appearance of the AR-3a. The flush-in-the-ground woofer-testing method was established years ago and widely used by AR with the original AR-1. This method gave an exact solid angle of 180 degrees (2-Pi steradians) facing into pure anechoic half space. This difficult and cumbersome test method is still considered to be the best and most-accurate method to measure a direct-radiator woofer's low-frequency system. Close-miking comes close, as do various computer-derived methods, but actual physical measurement techniques are always based on pure anechoic measurements. --Tom Tyson
  13. Are these AR3's?

    JeffS: The very first AR-3s, at the beginning, had a plywood grill frame, and then sometime later in 1959 (first actual year of manufacture for the AR-3), AR designed a molded-plastic frame. The wood frames are easier to remove, for sure, and don't seem to distort as easily as the plastic frames. Certainly, removing the plastic frame of an original, unmolested AR-3 is perilous and tedious—particularly since it has to be bowed slightly to remove—resulting in probably a 50/50 chance of snapping the plastic in places (the plastic is less pliable and more brittle after 50 years). Getting it back together without sagging or distortion is a miracle, and I've never seen a replaced AR-3 grill with plastic frame that matched the factory original. Also, AR did not wrap the saran grill material around the long edges of the frame; instead, the grill was bowed slightly and inserted under the molding (small amount of glue applied beforehand to the entire molding area). At the short ends, the grill was wrapped around and glued and stapled. When AR repaired an AR-3 at the factory, they simply cut the grill down the middle and ripped out the old frame and grill. When finished, they replaced the grill with a brand new frame and grill, retaining the brass "AR" logo plate and "3" pin. I stand corrected on the "shrinkage" of saran; maybe probably does shrink some, but saran and nylon are nearly identical, and I don't remember nylon shrinking too much, particularly in this thick a setup with it being woven, etc., but obviously it is pulling on the Masonite frames used later, causing them to distort. Masonite, too, absorbs moisture and bends very easily. AR told me once that any pressure on the frame would cause it to distort over time, and the weight and tightness of the saran weave (it had to be pulled hard to get it to lay flat) put constant pressure on the Masonite frame, causing it to bend or bow over time. Since saran doesn't "stretch" like the later beige linen cloth, there was greater likelihood of the constant tension on the Masonite to cause it to gradually distort over time. That frame image on the left in the picture is definitely the 1974-later Norwood grill frame for replacement AR-3s. An attempt was made to strengthen the material, but nothing could keep it from distorting. The AR-3a grill on the right, which is also a newer post 1974-Norwood "Velcro" grill for the AR-3a, uses the newer linen which, like the original beige linen, does not distort, simply because the material easily stretches. —Tom Tyson
  14. This is sad news about George Grand, "Toasted Almond." I regret that I just now saw this topic. George was an interesting, knowledgeable fellow audiophile and always very nice and polite in his postings on this site. I didn't know him personally, but I think we all get to know each other more or less through the vicarious connection on this website, and George was always a great contributor to this AR site. --Tom Tyson
  15. Are these AR3's?

    Oops. Well, I see that I am confused on which AR-3s are which! We're talking about two different sets of AR-3s, and both were absolute "steals."