tysontom

Members
  • Content count

    1,587
  • Joined

  • Last visited

Community Reputation

0 Neutral

1 Follower

About tysontom

  • Rank
    Advanced Member

Contact Methods

  • ICQ
    0

Recent Profile Visitors

9,242 profile views
  1. AR 1 question

    With regard to the Advents vs. the AR-1s, they should sound better than a pair of AR-1s as far as the treble is concerned, because the AR-1 doesn't respond too much above 13-15 kHz due to the 8-inch diameter of the Altec 755A driver itself. However, if you add an AR-3st (AR-3 "super tweeter"), you would notice a significant improvement in the high-frequency region. Also, the addition of a JansZen 130 electrostatic tweeter or even the little Radio Shack electrostatic tweeter that was available back then, would make an improvement in high-frequency performance. In terms of smoothness of the AR-1s vs. an Advent throughout the midrange, that is a tough call. The Altec 755A is limited in upper bandwidth, but it is not lacking in linearity within its operating range. The AR-1 woofer is significantly smoother than the Advent woofer. As far as bass is concerned, the AR-1 is actually superior to the Advent, but not by a lot. The AR-1 woofer is more potent and more linear, but the very early pleated surround, though historically important, impedes the performance of the low-frequency output somewhat -- compared with the half-round surround that followed -- by slightly reducing linearity. Both the Advent and the AR-1 have nearly equal bass-resonance frequencies, but on intensive deep-bass output, the AR-1 will easily outperform the Advent, that is if the AR-1 is operating as originally intended. The AR woofer has more cone area and slightly longer voice-coil linear movement than the Advent, and the 2-inch diameter AR voice coil can handle more amplifier power. The pleated surround is an issue, but even so, it has less distortion than the Advent, but the woofers have to be performing properly, and that is a pretty tall order with a speaker as old as the mid-50s AR-1s. Lots of air leaks and so forth. --Tom Tyson Hey Roger, We really get into the weeds, don't we! The dimensions for The Advent Loudspeaker (aka "OLA") are 14-1/4 inches x 25-5/8 inches x 11-1/2-inches, but I'm not sure if that is the walnut cabinet or the vinyl version, which would be slightly smaller front-to-back. The AR-1 and AR-3/3a cabinets are 14 x 25 x 11-3/8 inches. In any event, the 1.7 cu. ft. enclosure volume is stated in the patent and elsewhere, but the true inside cabinet volume is closer to 1.5 cu. ft. The Advent cabinet is definitely slightly larger, but the AR woofer has a significantly lower free-air resonance, so the net result is that both speakers are in the 43-45 Hz range for cabinet resonance.
  2. AR 1 question

    With regard to the Advents vs. the AR-1s, they should sound better than a pair of AR-1s as far as the treble is concerned, because the AR-1 doesn't respond too much above 13-15 kHz due to the 8-inch diameter of the Altec 755A driver itself. However, if you add an AR-3st (AR-3 "super tweeter"), you would notice a significant improvement in the high-frequency region. Also, the addition of a JansZen 130 electrostatic tweeter or even the little Radio Shack electrostatic tweeter that was available back then, would make an improvement in high-frequency performance. In terms of smoothness of the AR-1s vs. an Advent throughout the midrange, that is a tough call. The Altec 755A is limited in upper bandwidth, but it is not lacking in linearity within its operating range. The AR-1 woofer is significantly smoother than the Advent woofer. As far as bass is concerned, the AR-1 is actually superior to the Advent, but not by a lot. The AR-1 woofer is more potent and more linear, but the very early pleated surround, though historically important, impedes the performance of the low-frequency output somewhat -- compared with the half-round surround that followed -- by slightly reducing linearity. Both the Advent and the AR-1 have nearly equal bass-resonance frequencies, but on intensive deep-bass output, the AR-1 will easily outperform the Advent, that is if the AR-1 is operating as originally intended. The AR woofer has more cone area and slightly longer voice-coil linear movement than the Advent, and the 2-inch diameter AR voice coil can handle more amplifier power. The pleated surround is an issue, but even so, it has less distortion than the Advent, but the woofers have to be performing properly, and that is a pretty tall order with a speaker as old as the mid-50s AR-1s. Lots of air leaks and so forth. --Tom Tyson
  3. AR 1 question

    Those turned out very nice! The cabinets were likely utility pine, most likely, and painted a flat white or whatever, just as AR intended. You could sand them, seal them carefully, and paint them a piano black or something and have a unique pair of AR-1s! I'm sure you realize that they are already worth quite a lot of money! --Tom Tyson
  4. Hi, I left this message for Roy, but i guess he's busy today. i applied that sealer to both speaker's woofers. The one passes the push test. On the other one, there is no effect. On that one, the dust cover is a domed affair and its material looks just like the surround. Can it be leaking air? Can I seal it as well? On the good woofer, the dust cover is a slightly domed felt.

    1. tysontom

      tysontom

      As I said before, make sure there is not a cabinet leak somewhere else.  You do not want an absolutely air-tight cabinet, but you do need an "acoustical" seal, thus the slow return of the woofer when depressed, or put another way, the woofer should feel like it is being moved through a viscous fluid.  The cone should not bounce back immediately when depressed.  The dust cap is probably not critical, since the space between the voice coil and the pole piece is very small and won't let much air pass through, but there are holes in the voice-coil former ("bobbin") that do allow air to pass through.  

      You could put the sealer on the dust cap since it is cloth, and see what that does.  When you push in the woofer, see if there is any air movement at the dust cap.  There is the risk of over-damping the woofer, but this probably isn't the case here.  Give it a try, but put a light coat on the dust cap.

      --Tom Tyson 

    2. DKinYORKpa

      DKinYORKpa

      I got impatient for a reply so I posted on the forum. As I said there, air is definitely passing thru that dust cap.

  5. AR 1 question

    The AR-1 was fabricated using both a 3/4-inch top panel and a 1/2-inch inner panel to accommodate the 755A, thus the appearance of multiple boxes. AR-2's also had this type of baffle, but by 1965s, AR had gone mostly to a single 3/4-inch panel on the front. The 755A did use wood screws, but it was one of the few AR drivers to be mounted in that fashion. Note the early use of slotted machine screws for the woofer. All of the AR-1/AR-3 cabinets had nine internal braces. Note that the 755A was a 4-ohm speaker (as was the 728B on which the AR woofer was designed), and thus Villchur and Kloss settled on 4-ohm impedance for that system. There may have been other reasons, but the 755A and 728B, both Western Electric designs, were 4 ohm impedance. The 755A dates back to at least 1947, maybe a bit earlier. --Tom
  6. AR 1 question

    The Altec Lansing 755A 8-inch driver used in the AR-1was an open-back driver (i.e., it is not sealed on the back) and the square cut-out on the AR-1 cabinet was designed by Edgar Villchur and Henry Kloss to allow an opening to the back of the speaker, but fiberglass (or Kimpac in early models) was placed in the square openings to prevent the box pressure behind the driver from impeding the proper response down to 1,000 Hz, and to prevent any back wave from significantly interacting with the direct output of the speaker. A circular portion was routed out to allow the 755A to be recessed in the cabinet face, and Kloss was probably responsible for this design element. The box for the 755A was carefully glued and sealed to prevent any type of air leak from within the main part of the enclosure. This design element was actually well-engineered, as the AR-1 had very clean, uniform response in the midrange and treble, but the treble dropped off above as a result of the natural roll-off of the 755A. Note that the 755A did have a decoupling section to the cone that improved the high frequencies, allowing the smaller portion to continue to respond to higher frequencies. Villchur and Kloss chose the Altec Lansing 755A because it was actually the smoothest full-range speaker available at the time that could be used down to 1000 Hz with the AR-1W woofer. There were many cone tweeters and horns available, but all had some sort of issue that prevented clean sound reproduction. The Ionovac tweeter showed promise, but it was somewhat unreliable and it was costly. Although Edgar Villchur was responsible for the acoustic-suspension principle and the AR-1 speaker itself (the box size and shape, crossover, driver recessed mounting and so forth) Henry Kloss is credited by Villchur as being 75% responsible for the production design of the AR-1 itself. —Tom Tyson
  7. AR 1 question

    An air leak can also occur as a result of a cabinet leak, so that possibility should be eliminated before putting any coating on the surround. Nevertheless, judging by the serial-number range and from the dark image, it appears that the woofer surround on this speaker in question is one of the early "pleated" versions, and this type is much more prone to air leaks around the surround than the later half-round surround. This surround may need treatment. AR-1 (internet picture) of pleated surround and felt dust cap. --Tom Tyson
  8. An AR cocktail revisited.....

    The AS-103A is identical to the AR-3a, even the crossover is very nearly the same. Heathkit supplied their own chokes, a fuse assembly, the cabinet and some terminal plates, input connectors, but otherwise the values are all identical. The capacitors supplied originally came from Chicago Industrial. The cabinet is a Heathkit design, but the inside dimensions give exactly the same internal volume as the original AR-3a, approximately 1.7 cu. ft. Heathkit's grill panel and Velcro mounting was easier to deal with than AR's glued-on frame, but the cabinet was much more utilitarian (pedestrian) than the original, classic AR-3a with its beautiful beige grill, at least in my opinion. This grill is more elegant than the kit AS-103A, but the speakers performed the same. --Tom Tyson
  9. First ADS'S

    audiofreak, it's fine; we all knew what you were trying to say. Just saying that the expression "tight bass," and "bass punch" are frequently used to describe an emotional experience that sometimes doesn't exist in the real world.
  10. First ADS'S

    audiofreak, the expression "bass punch is tight and fast" really doesn't mean anything. It's an old, tired, audiophile expression that's not based in actual science, and it probably originated at Stereophile magazine back many years ago. It's not the woofers that reproduce most low-frequency transients; it's the midrange and treble that reproduce those overtones and harmonics. The woofer reproduces mostly lumbering, steady-state sounds. If the bass sounds extra crisp and "dry," then the woofer could be over-damped. You don't really want this, but what you are trying to describe in the ADS is the clarity of the midrange and treble dome drivers. Bass-drum rim shots sound clear and well-defines, and plucked violin strings would sound crisp, etc. The woofer actually has very little to do with this effect.
  11. First ADS'S

    Just curious, what do you mean by "bass punch is tight and fast?"
  12. AR-LST mounting.............

    Frank, to answer your question about my AR-LSTs, yes, I am thinking about selling them in the near future. I've had such a large collection of AR speakers that the time has come to thin down the collection, and I have begun selling some AR-1s, AR-3s and AR-3as, etc. I might sell the LSTs in the fall or winter, but I haven't decided at this point. I stored the original grills and ordered a second set (the Norwood "white" linen) in the mid-70s to preserve the originals. Note the Norwood "white" linen in the center. The speakers are still 100% original with no modifications whatsoever, and they continue to work well. These AR-LSTs haven't been in regular use for several years and are stored in air-conditioned/humidity-controlled storage. --Tom Tyson
  13. AR-LST mounting.............

    I designed these wall mounts (and they do sort of look like "Frank's Urinals," now that you mention it!), and I sent drawings to AR to see what interest the company might have with them. There was interest -- probably out of politeness -- but due to the size, weight and high cost, nothing materialized as AR inched closer to the new-style ADD speakers later in the mid-70s. The LST was nearing the end of its career by 1974-1975. The important thing to me was providing enough strength to hold them securely to the wall without having to mount brackets on the back of the LST (AR did have the big-speaker "French Cleat" wall-hanging brackets, but it required screwing into the back of the speaker). Also important was the notion to protect the speakers and to have the stand blend in with the wall to make it appear as if the speakers were "built-in." Painted the wall color, the stands were barely noticeable in the presence of the prominently physical appearance of the AR-LST. The LSTs were mounted too high in this picture, but there was no choice because of headroom along a hall to the right side. Because the speakers were so close to the ceiling, the sound quality was compromised somewhat; I later inverted the speakers to put the woofer close to the ceiling, and this was an improvement but not ideal. --Tom Tyson
  14. Edgar Villchur On Multiple AR-3 Speakers

    This letter -- as with many that Ed Villchur wrote over the years to audio-magazine editors -- exemplifies the dry wit and high intelligence of the man. Villchur was nearly always on another level when he was confronted with these sorts of things. If you read Villchur's letter carefully, it's easy to see that he considered the question "of whether three AR-3s 'equal' one E-V Patrician" to be ridiculous in its context. Norman Eisenberg, a bit "off the wall" at times, was was forced to reply with a convoluted rebuttal that was largely meaningless double-talk, probably flying over the heads of most readers. Norman Eisenberg,not surprisingly, got his facts confused regarding AR's live-vs.-recorded concerts and demonstrations. He thought that Acoustic Research used multiple AR speakers for each channel; as Eisenberg said, "as witness the use of more than one AR system per channel to make such demonstrations more effective." That is certainly not so, but what he misunderstood was that multiple AR speakers were used for sound reinforcement in NY's Museum of Modern Art and other venues for background jazz, etc. --Tom Tyson
  15. 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!