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  2. This is a fascinating set of curves by Julian Hirsch at Electronic World magazine. Electronic World published parallel test reports by Hirsch to the ones published in Stereo review, but the EW reviews revealed more of JH’s technical results, including a speaker’s frequency response curve, which Stereo Review never published (as a matter of policy). Presumably SR felt that a frequency response curve was too subject to misinterpretation by SR’s emotionally-charged hobbyist readership, while their sister publication of EW had a more mature ‘technical” readership, so the publication of detailed technical specs/graphs was deemed ‘safe.” This is a deep dive, so stay with me here or else I might as well be writing a private letter to Tom Tyson. When the AR-5 was introduced, it generated a bit of controversy because Julian’s review in Stereo Review made note of a deep dip in the 5’s frequency response at around 2000 Hz. He said it gave the speaker an unacceptably distant sound and only with the mid-range control advanced all the way up did Julian say the speaker sounded good. (He actually used the word “superb,” but only with the mid control advanced “to the reviewer’s liking.”) Roy Allison, the 5’s designer, took vociferous objection to Julian’s findings. He insisted to Julian that the 3a and 5 used essentially identical MF and HF drivers and their x-o topology was nearly identical, so it would actually be impossible for the 5 to have this trait and the 3a not to. He further insisted that in all of AR’s tests, measurements and listening, the only difference between the 5 and 3a occurred below about 45hz or so. Their response and sound was identical from the mid-bass on up. There was no mid dip on either speaker. Julian didn’t buy it, saying that he measured the 5’s dip in two completely different set-ups and the 3a did not have the dip. Julian never actually gave a reason for the 5’s apparent problem, but he insisted it was real and different from the 3a. Julian and Roy’s disagreement was aired in public, in succeeding issues of Stereo Review in Julian’s Technical Talk column. To Julian’s credit, he gave Roy ample space to have his say, and in all candor, Julian liked AR so much he probably wanted to hear a legitimate explanation that would take AR “off the hook.” Nonetheless, like any good scientist, Julian stuck by his findings, since he measured them according to his own legitimate methods. The AR-5 was caught from a marketing standpoint between the prestigious, highly-reviewed top-of-the-line 3a and the amazing 90%-that-anyone-would-ever-want value of the 2ax, at half the 3a’s price. So the AR-5 was already struggling from a sales standpoint. This review—a tenuous, conditional recommendation, with a serious wart—didn’t help the AR-5 at all. Now, to the matter at hand. This is a frequency response of the four main AR speakers in early 1970s—the 4x, 2ax, 5 and 3a—superimposed on each other and normalized to 1000Hz. These curves were made by Julian for EW magazine and published, although it’s not clear if these are the actual curves made for the test reports or whether these are additional curves made at some later date, just for interest’s sake. Here’s the really interesting thing: The 5’s and 3a’s curves are within about 1dB of each other all the way from around 90hz on up! Within 1 dB! The AR-5 has no 2000Hz “dip” in the midrange. None. And these curves were made by Julian. Explain that, Julian: The 5 and 3a are essentially identical above the mid-bass, exactly like AR says they are. Julian? Julian? Here’s another interesting thing: the 2ax upper mid response is a few dB lower than the 5/3a’s, which is exactly how they sounded relative to each other. I A-B’d the 3a and 2ax in my home many times and the amount of increased inner-mid detail on the 3a vs. the 2ax was apparent, just like these curves show. Also interesting is the 2ax’s apparently stronger extreme (above 10k) on-axis treble response: This is because the 2ax was really a 2-way speaker with a super-tweeter add-on, where the 3 1/2-inch driver (remember that was the tweeter in the AR-4 and ‘early’ 2x) goes full out, as high as it can go, and the 2ax’s ¾-in tweeter is brought in as HF reinforcement. In the 2ax, the 3 ½-in driver is essentially flat and level with the woofer all the way out to about 13-14kHz, so it is combining with the ¾-in tweeter for a pretty healthy on-axis treble output. In the 3a and 5, they are true 3-ways, where their mids are rolled off as the tweeter is brought in. The 2ax has both drivers pumping out HF above 5kHz, whereas the 3a/5 have only the relatively weak ¾-in dome doing all the HF work above 5khz. (“Weak” as in limited ultimate output level, not “weak” from a quality/performance/dispersion standpoint.) These curves show all of that quite clearly. And prove, once again, AR’s honesty, QC (the way the 3a and 5 mimic each other is pretty remarkable) and high performance. Steve F.
  3. Today
  4. Newly acquired AR-LST

    Hi John, Thanks for the link to your speakers stands build. I would like to do similar if not exactly the same design. Unfortunately my woodworking skill isn't up to your standard and my tool set are minimal. But I will give it a go with what I can get my hands on. Watch this space and I will update with any progress. Best regards, David.
  5. I was able to get a pair of AR3's this past weekend, and I'm in the midst of restoring them. I've already worked on 2x, 2ax, 3a's, 4x and 4 ax, 5, 6 and 7's. These will be a real challenge, I can see...aluminum wire and all. First things first: the serial numbers on the pair are 09040 and 09063. I'm assuming they are around 1960. Anyone have any information more specific than that? I've only opened one cabinet thus far and have found no dates stamped inside. I believe I'm the first one in since manufacture. Cleaning the tone controls, new Erse poly-film caps (6 uf and 24 uf) etc. BTW, short of sending them out, what's the technique Roy suggested for dealing with "petrified" mids? I have sound, but not sure it's what it should be. Lots of highs, but then the crossover, as I understand it, for the AR3 began at 1000 hz. Operating them through the crossover with less than 1 watt and less than full output through the mid control. Input appreciated.
  6. The Electronic Subwoofer

    Exactly! The Allison ESW was ok back in the day when these speakers were NEW....but now, BAD IDEA. Subwoofer is the way to go. Great bass extension alternatively, without stressing these precious and now scarce drivers. There has been an explosion of small, effective outboard powered (and some passive) subwoofers that are great with small to mid sized loudspeakers. Unheard of choices compared to what you could do in the seventies. Bill
  7. AR3 capacitor drift

    Tom Tyson wrote back in 2004: "You raise an interesting point regarding the capacitor changes in the AR-3a from the early (1967-1972) to the later versions (1973-1975). The first-generation AR-3as did indeed use the Industrial Condenser Corp paper capacitors up to about 1972; the later-generation AR-3as used Callins or Sprague Compulytic electrolytic capacitors (50 to 60 V). The second generation AR-3a (not including, in this instance, the AR-3a "Improved" version which was a European model) was indeed changed in several important respects: (1) the crossover frequencies" From: http://www.classicspeakerpages.net/IP.Board/index.php?/topic/953-speaker-voicing-and-capacitor-types-used/ I search this forum from google rather than using the internal search feature.
  8. KLH Model Six

    I cut a gasket out of some laminate floor underlayment and attached the plate with some small brass pan head screws.
  9. Yesterday
  10. The Electronic Subwoofer

    The excursion requirements go way up with EQ like this, when pushed of course. This is expecially bad for small speakers, perhaps just use it at low listening levels. Just about everything on EQ: http://www.roger-russell.com/equalizers/equalizers.htm
  11. AR3 capacitor drift

    I believe those old dual capacitors are NPE
  12. No. Consider the volume displacement, piston area times Xmax.
  13. AR3 capacitor drift

    My measurement system plots impedance vs. frequency 10 Hz to 20 KHz and the cursor can be placed at any point on the graph providing capacitance and ESR. The free software Arta should be able to do the same thing with a laptop and some custom cables with clip ends. Just looked this up, you'd use the associated LIMP program: http://www.artalabs.hr/ It tests at low voltage and it is important to know if there is leakage at the rated voltage for an old cap, simplest thing is to just replace them at least to the fragile dome drivers.
  14. AR3 capacitor drift

    I have posted this before, note his comments on measuring leakage, and important comments toward the end:
  15. AR3 capacitor drift

    There are even meters that charge the cap with a constant current and measure the time constant, which would be a very low frequency measurement, not even putting AC on the cap.
  16. Woofers are sold for use in a pair of AR-5's, local sale, easy, good to see them go for a good use.
  17. AR3 capacitor drift

    This is helpful, I suppose, but also very discouraging to hear that red's meter might be useless for his intended purpose. If this is true, short of purchasing an expensive measurement tool to evaluate 30 or 50-year-old aged NPE caps from old salvaged speakers pleading for a new lease on life, what reliable and inexpensive options does the weekend hobbyist have for measuring these old components to provide useful data to answer the age old question? "To re-cap, or not to re-cap, that is the question." (With apologies to Shakespeare.)
  18. AR3 capacitor drift

    Check for leakage on the Meg ohm scale, what do you find? Isn't that a paper cap and not NPE?
  19. AR3 capacitor drift

    I had a meter with those same parameters. A Parts Express purchase. It will be fairly accurate for film caps but not electrolytic. There is no conversion. I went and bought an expensive handheld Agilent meter so I could accurately measure NPEs. Roy and Carl (RIP) always said NPE's need to be measured at 1kHz to be accurate. NPEs swing more to frequency than film (very little swing):
  20. Last week
  21. AR3 capacitor drift

    Looks like red's meter is testing them at 80Hz and 8Hz. How does that information translate to or adjust his readings for 1kHz accuracy?
  22. AR3 capacitor drift

    What frequency is the meter testing them at? It should be 1kHz to be accurate for NPE's. A lower signal will give you a higher reading.
  23. How Long Have You Owned AR Speakers?

    My first AR speakers, a pair of late '50's AR-2, were acquired in 1972 when I was a sophomore in high school. I have since had at least one pair of AR in the stable, usually many more, although now I'm down to one pair of AR-2X, one pair of AR-2ax and one pair of AR-3a. All of my AR's were first gen speaks.
  24. AR-5 advice needed

    I'm widening my understanding of L-pads and pots through various online reading, it's not quite as simple as it seems just replace an ohm for ohm etc part. The picture should become clear to me soon and I can order the chosen parts and move onto another piece of the restoration puzzle
  25. This is still the on topic. I have been looking at the specs for small speakers. Almost all are bass reflex and many tout specs that challenge credulity. For instance, I came across this speaker from Human; The stated freq parameters are -/+ 2db from 38hz to 26khz which are better than the original Advent and is believable down to 100hz or so. I have never heard any 2way 6 inch speaker that could challenge an OLA below 100hz. This is AR 3 series territory. What should I believe. On paper, this Human model, can outperform an AR3a. Questions: Is this possible with today’s state of the speaker art? If possible then is it plausible for $425? Adams
  26. AR-5 advice needed

    Hey thanks for putting up those dimensions, I had considered their size but didn’t find the specs so thats very handy to have now seen. Yep I thought I'd understood the wattage factor too as just as you described. Now if I could get any more of an explanation just as to how the 8 ohm and 16 ohm would work differently? As I've noticed through cleaning and testing the rheostat, at the "mid" point it reads 8 ohm then decreases to 1 ohm and up to 16 ohm depending on the direction of turn. Will the 16 ohm l-pad mimic this same readings at the same positions too, will the 8 ohm l-pad? Sorry if I seem to ask many questions on the same topic, I'm not challenging at all the advice passed on to me, I know it does work well, its just I analyze things somewhat and hey it could lead to a discovery of a new approach to an application! Many thanks
  27. Hi, New With New To Me AR-2ax Pair

    If you ever have the chance, try the 2ax's with some vintage tube gear. I'm running mine with a Fisher X-100-B integrated as I type this and the sound is silky smooth and extremely realistic. Toe tapping to be sure. Of all the AR speakers that I have heard, the 2ax's(and original 2's, too) seem to really thrive on quality tube power.
  28. AR-5 advice needed

    The 8-ohm L-pad is the correct L-pad for this application. The higher wattage rating is unnecessary but would work fine - - - however, you should be aware that the 50w L-pads are dimensionally larger. In pic attached, the round 25W is 1-5/8" (41 mm); the octagonal 50W is 2" (50 mm); and the round 100W is 2-1/2" (64 mm), so you need to take this into account when planning your replacement components.
  29. AR-5 advice needed

    Hi again, Thank you for the sound advice you have given and yes the guide does make an excellent reference. My curiosity though is still dwelling on what will differ from a comparison of the two variables A) using a 16 ohm l-pad over the 8 ohm B It being rated for 50W instead of 25W Would the 16 ohm would react to adjustments closer to the original rheostats than the 8 ohm? As this is still rather new ground for me I'm sure I could be unclear here (and why I ask before carrying out the task) but also possibly on the right track with this option? Btw I noticed a seller on an auction site selling a 15 ohm l-pad described as an AR factory replacement. Hope to hear back some more helpful advise, It's all very encouraging to me.. Regards Ben
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