Steve F

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  1. Where has the dome midrange gone? When AR introduced the domed drivers in the AR-3, things changed forever in the speaker world. The dome tweeter is still with us, some 59 years later, going reasonably strong. (Although, in all honesty, it does seem like the Heil/ribbon tweeter is gaining fast on the dome tweeter in recent new designs.) But the dome midrange enjoyed a far briefer time in the spotlight. There are still a few dome mids here and there from random companies, but the mainstream, right-down-the-middle-of-the-road dome mid is pretty much gone. The AR 1 ½-inch dome mid had a pretty long run, from around 1967 in the 3a until the mid-80’s with the 9/98/78 LS/LSi’s. ADS utilized their own excellent dome mid throughout this approximate time period as well, and it was a suburb driver in its various guises. The Allison 3-ways could be considered as having a “dome” mid. Yes, we all know it was not peripherally-driven like a conventional dome, but it looked dome-ish, so we’ll cut it some slack and include it. The Avid 330 12-inch 3-way of the mid-1970’s used a nice dome mid, 2-inch IIRC. That was a nice-sounding speaker. But AR’s big competitors at that time—Advent and EPI—were mostly 2-ways, and JBL used cone mids. Likewise for Boston Acoustics—mostly 2-ways and cones when they were 3-ways. I worked at BA for 11 years. Andy [Kotsatos] knew I liked AR speakers, but he never knew to what extent, nor did he know that I was a member of this Forum during that time. (And the Forum didn’t know I worked at BA then, either—I was very careful to keep my posts totally free from conflict-of-interest suspicion and complication.) I did sneak in a few questions to Andy during my BA tenure about his recollections of AR, since he was the main product manager at Advent before co-founding BA, so he knew first-hand about AR Classics and ADDs from a competitor’s standpoint. (BTW, he generally hated them, thought the 3a was ‘lousy,’ the 4x ‘totally muffled,’ but said the 2ax could be a ‘sneaky’ speaker if you weren’t careful.) Anyway, he always said that the concept of a dome midrange was a ‘fraud’ (his exact word—I’ll never forget it). He felt that they were inefficient, yet also had a shorter excursion than a good 5-inch mid, so the dome couldn’t play as loud. “It can’t handle the same power, it can’t go as loud and yet it needs more power than a cone. Why bother? The “dispersion” advantage is simply untrue, because in the frequency regions where you’re going to use a mid in a well-designed 3-way, neither a cone nor a dome midrange is directional in any meaningful way over its operating band. Do the math. The 3a’s mid ‘clips’—you can hear it running out of excursion at high power levels. It’s a joke. But it looks cool with that screen and AR played the ‘technical dispersion angle’ to the hilt with lots of graphs and curves and the reviewers bought into it. All fine on paper, except that they didn’t sound that good.” Was he right? Is the superior dispersion of a dome mid vs. a 4- or 5-inch cone not particularly important from 300-4000Hz? AR did blow a lot of mids (both my cousins blew their 3a mids playing jazz, not hard rock, in the late-60’s/early-70’s). BA never replaced blown mids under warranty, and I mean never. I’m not talking about voicing. I always fought w Andy when I voiced a BA speaker, because I like the AR ADD balance and he liked a more forward mid-rangy sound. We’d go back and forth, mostly on woofer choke values. I want to keep this discussion to the importance of mid-dispersion for forward-facing single-driver-per-band designs, and whether there is truly an audible/meaningful difference between a 1 ½-inch dome and a 4- or 5-inch cone when the listener is sitting in a normal position (less than 10 or 15 degrees off axis from the left and right speakers of a stereo pair). Thoughts? Steve F.
  2. What modern speaker to use as a center-channel speaker with Classic ARs in a home theater system? A very common question and a worthwhile question. First off, I’ll repeat what I’ve said many times before: I’m not a fan of using AR-3a/5/2ax-era speakers in a modern home theater system. They weren’t designed for digital peaks of 107dB, they’re 50+ years old, their adhesives are drying out, they’re priceless. Why anyone would risk those gems playing modern trashy movies with high-SPL exploding Death Stars is beyond me. I have two Classic AR systems, one with 3a’s and one with 9’s. They are music-only systems. The 3a’s never, ever, ever go above “moderately” loud. The 9’s get “loud” occasionally, but carefully. If I want to do home theater, I use my modern BA VR-M system + BA PV1000 1000-watt subwoofer. Sounds great, does a great job and my classic ARs are protected from needless abuse. Still, the question remains: What modern centers go well with Classic ARs? I was at Atlantic Technology for 10 years, as head of Product Development and Marketing. I planned all the products, managed their engineering and production, made all the calls and voiced them all. I have always loved the AR approach to sound—smooth, accurate, natural and if you have to err, err on the relaxed side, not the harsh side. As such, we never used metal tweeters and our stuff was never “spitty.” We had some truly excellent center speakers—the 6200C, 4400C, 4200C, 2200/2400C. They were properly designed in such a way that they had far superior dispersion with far less lobing than a conventional M-T-M 2-way center and they were voiced (by me) to be neutral, accurate, but not harsh. I had the Classic ARs in mind when I did these. The 4400C in particular is a terrific speaker. http://www.atlantictechnology.com/index.php/products/floor-standing-bookshelf-speaker-systems/4400/ I’m five years out of AT at this point and have no connection whatsoever to the company. I no longer work in the “hi fi” business (I’m in the Pro Music biz now), so this suggestion is totally altruistic. Steve F.
  3. Now Tom, I would never glaze over at one of your fascinating explanations! Steve F
  4. To everyone on the Forum-- For 2017, may your frequency response be smooth and level, may your dispersion be wide and uniform, and may all your voice coils stay perfectly centered. Most importantly, G-d of the Speakers, may we all continue to be blessed with hearing that goes past 10kHz, even as we age. Steve F.
  5. The CR8 (7"woofer) and CR9 (8" woofer) were voiced very similarly. The CR9's bass extended about 10Hz lower, enough to be audible to a meaningful degree. One of our engineers (Gerry S, also a poster on this forum) used the CR9 as reference speakers in his lab, to compare new speakers to as a benchmark. They had a very smooth and level frequency response and plenty of bass. It was an absolutely terrific speaker. The thing to remember was that in 1995-ish when it was introduced, "bookshelf" speakers had already started to shrink. The CR9 was almost identical in size the the AR-4x of 1965, yet the 4x was tiny by the standards of its day, while the CR9 ended up being too big to be a really good seller. The CR9's bass response was easily the equal of the AR-2ax and 5, and far superior to the 4x. I liked the CR8 the best of the CR line, because it used the 'good' 1" Boston-built Kortec tweeter (as did the CR9), but the CR8 was smaller and better-looking, while still having a completely respectable low end. But if you currently have the CR9's and like the way they sound and look, I see no reason to change. That was a fine series of speakers. Steve F.
  6. I beg to differ. There is a great deal of difference between the 5 and 2ax. I remember very distinctly in 1973 when my cousin got his 3a’s and he brought them over our house to A-B against my 2nd-gen 2ax’s. The bass differences were to be expected. What we didn’t expect was the difference in midrange detail, openness and delineation. I remember it like yesterday: Playing Weather Report’s album Sweetnighter, the cut “Boogie Woogie Waltz,” the contrast between the two speakers couldn’t have been more striking. That tune has multiple layers of percussion, densely packed. The percussion is the heart and soul of the cut. Switching from the ‘good’ 2ax to the 3a was a revelation: The percussion—which is all midrange—just “jumped” out of the speaker. It was like removing blankets from around the 2ax. Detailed and open, but without a trace of harshness, the 3a really showed its acoustic mastery on this cut. The 2ax was a very good mid-priced speaker, but the 3a was in another class. That was the midrange difference between the 3 ½-inch 2ax crossing over at 1400 and the 1 ½-inch dome crossing over at 575. If anything, the midrange difference between the 5 and 2ax would be even greater, since the 5 had slightly less of that upper bass/lower mid “heaviness” of the 3a, so the 5’s midrange performance would be even better. I loved my 2ax’s, but the 5/3a’s mid performance was far superior. As to the 5’s value at $175 vs. the $128 2ax and the $250 3a, that’s another discussion for another time. Steve F.
  7. I wrote that long article in the thread of S vs. P and I had written an even longer one on these pages way back in 2002 or 2003. The main reason that AS tends to have lower distortion than vented is not because “the simpler AS front propagating wave is less prone to distortion than the mixing which has to occur with the vented systems.” It’s primarily because an AS woofer depends on the “perfect” motion of compressed/expanding air to supply the restoring force and control the woofer’s motion, whereas a vented woofer must depend on its mechanical parts (surround/spider etc.) to supply its restoring action and control the cone’s motion. Air compresses and expands in a perfectly predictable manner; the same is not true of man-made contrivances. Many of today’s AS systems do not utilize the pure Villchur-type AS system. In his speakers, virtually all of the restoring force was air-derived and his woofers had extraordinarily-low FAR’s. Today’s “sealed” woofers typically have FAR’s as much as 50% higher (say 17Hz to 25Hz) and even in those “sealed” woofers, their mechanical parts are playing a much bigger role than in an AR-1 or AR-3a. I’d be shocked—shocked!—if Velodyne’s 12-inch woofers has an FAR of 17Hz. Remember also, that in a powered subwoofer, all bets are off, off, off, because 1) you can electronically EQ the system for any response you want (within reason) and 2) today’s sophisticated DSP/Distortion detection-prevention circuits can yield lower distortion than in a purely passive system like a 3a. Steve F.
  8. The topic of 3 vs. 3a will no doubt get lots of people here to chime in. This statement by ar_pro certainly rings true: “...my recollection of the era is that guys who went from the AR-3 to the 3a didn't look back.” That said, let me give you my impressions. While the 3 was an incredibly important and successful speaker, to my ears, the 3a was a definite advancement. Yes, it was a bit “thicker” in the lower midrange than the 3 (despite the 3 crossing over much higher, 1000 Hz compared to 575 Hz), but the much wider dispersion of the mids and highs of the 3a gave it a notably ‘unboxy’ sound and in this regard, it was an improvement over the 3. I also found the 3a tweeter to be a bit more detailed and “sweeter” than the 3. The 3 had no obvious audible vices, but the 3a just sounded a bit more open, even with the trace of lower-mid heaviness. Later 3a’s had a different woofer choke that reduced the output at very upper end of the woofer’s passband by about 2dB. That change seemed to correspond to the re-spec’ing of the 3a’s woofer-midrange crossover from 575 to 525 in 1974. From a bass extension and impact standpoint, I never noticed any real difference between early alnico/cloth woofers and later foam/ceramic woofers, as long as they were all made in MA. Later Tonegen Japanese woofers—from the early 80’s on—seemed to have very slightly less extreme deep bass, but that was in the 91 era, not the 3a era. Steve F.
  9. Tom makes many good points and his experiences with those three superb speakers back up the contention that with modern speakers, great bass is really a matter of design skill and execution, not the inherent advantages or disadvantages of a particular design approach. I was simply pointing out that the old cliché of "ported speakers are always flabby, bloated and boomy compared to acoustic suspension" is no longer true. the vented systems of today still have some compromises in their design relating to the mechanical suspensions at very low frequencies below their normal cutoff frequency. Pick the speaker that fulfills the mission you have for it. I certainly wouldn't recommend a 6 1/2-inch 2-way vented bookshelf speaker if you like organ music with fundamentals below 35Hz. You can't EQ it, the woofer "unloads" below the system tuning, etc. But for popular music/jazz at moderate SPLs in a normal-sized room, without a sub? Sure, they'll be great, and assuming good design, they'll go lower -3dB than a sealed system of the same size. If you need to carry a 4 x 8, don't buy a Miata. If you want to go darting around corners, don't buy a Honda Odyssey. But in the middle of these two extreme use scenarios, there are lots of great choices. Same with speakers. Steve F.
  10. The BA CR 9 8-inch two-way, barely larger than a 4x, was dead flat to 40Hz. Dead flat. Deeper than the 10-inch 2ax/5. Just good modern ported design, nothing magic. Oh, designed in 1994, so this is nothing new. Computer-aided ported designs have been great for a loooong time. Steve F.
  11. From the Cat Dragged in LST thread: Hi Jerry, What great replies! First of all, I, too, didn't realize that speaker companies who built vented enclosures paid too much attention to small air leaks; however, I can see where it could give a problem. I think what Steve is referring to regarding the "their lower 3dB down points" is the lower fc of many vented designs, but the 24 dB/octave rolloff below resonance in vented vs. the 12 dB/octave in acoustic-suspension designs. Thus the vented design obviously rolls off very rapidly below resonance compared with a/s designs. Vented designs are certainly more efficient, and I agree about the ported designs' tendency to exhibit "one-note bass," and although there is usually plenty of punchy low-frequency energy, it always seemed (to me at least) muddy or less well-defined than sealed systems, but there were some exceptions. If one is listening to a lot of jazz with kick drum or orchestral music with big orchestral bass drum, organ or electronic music with lots of low-frequency energy, the acoustic-suspension system seems to have a significant advantage. Ported or vented systems do just fine with probably 90% of all recorded music, especially rock or popular music. But overall, I think acoustic-suspension systems are much cleaner than vented systems in reproducing fundamental energy, usually with flatter response and lower harmonic distortion, but many will argue that some vented designs that are certainly excellent as well. I'd written about this topic in great length (over 1500 words--about four pages) back in 2002. I guess it's time to summarize that post again now, so here goes. Yes, the “tuning frequency” of a correctly-designed vented speaker with a woofer of appropriate T-S parameters will allow it to reach a lower -3dB point for a given enclosure size compared to a sealed speaker of the same size. In the early 90’s timeframe, for instance, the PSB Alpha was reaching, say, -3dB in the low 50’s Hz compared to our sealed Boston Acoustics HD5, which was down 3dB at about 65Hz. That was terrifically audible in a retail A-B demo comparison. The fact that the HD5 had more output at 30 or 35Hz because of its 12dB/oct rolloff compared to the PSB’s 24dB/oct rolloff was essentially meaningless, for two reasons: 1. They were both so far down in level at 30Hz (these were small 5 ¼” 2-way bookshelf speakers for about $200/pr. at the time) that it didn’t matter at all if one was down 15dB and the other was down 24dB. Neither had any impactful output down there, so the HD5’s sealed “advantage” was no advantage at all. 2. These were speakers that would be used to play popular music in stereo, where the lowest bass content in the program was in the 40-60Hz range. The PSB just sounded so much “fuller” and richer than the HD5. The fact that the sealed HD5, 7 and 8 were getting killed at retail was the driving factor that lead to the CR Series that replaced them being ported speakers. Which leads us to the next big point: It’s waaaaaay past time to totally debunk that tired old cliché about “Ported speakers are boomy and one-notey and ‘thick’ sounding compared to the ‘fast, tight’ sound of acoustic suspension speakers.” That may have been true in the ‘50’s and ‘60’s, but only because designers didn’t have fully fleshed-out T-S parameters and modern computer modelling to work with. So, ported speakers were hit-or-miss, “cut-‘n-try,” etc. A lot of shooting in the dark. Not any more. I defy anyone to listen to a really excellent Aerial or B&W or KEF or Legacy Audio—name a good company, your choice—and tell me that their bass isn’t excellent. It is excellent. “Tight, crisp, well-defined, fast, articulate, musical, muscular, athletic, accurate, natural,” etc. Pick your adjective. Pick your music. Sealed had a huge advantage when design practices were unsophisticated, because the acoustic suspension design principle enabled designers to optimize a truly excellent system by jockeying and adjusting only a few variables. Presto: Combine 17Hz Fs, high compliance, 1.7 cu.ft. enclosure and you get 3a bass. Duck soup. But to build and test dozens of variations of woofer parameters, port length, port diameter, vent shape, vent location, etc., etc. and come up with an optimized vented design was just not practical in 1966. However, it is now. Press a button and see 12 vented design options in a second. Press the button again and see another 12. You couldn’t build and measure 24 of them in 1966. Now you can do it in an hour. So, you can now get that lower -3dB down point and get bass that’s all the above good things. Why do you think nothing’s sealed any more? Don’t misunderstand my point—the 7, 4x, 2ax, 3a, et al. had—and have!!—terrific bass. It just that now there’s no barrier to getting great bass from ported designs, with their advantages, but without the drawbacks of 50 years ago. Steve F.
  12. The stethoscope was still an essential part of engineering and production testing well into the early 2000's, during my tenure at both Boston Acoustics (1991-2003) and Atlantic Technology (2003-2013). BA went from sealed to ported in 1994, when the sealed HD bookshelf speakers (HD5, 7 and 8) and sealed T830, 930, 1030 floorstanding speakers became the ported Compact Reference (CR) booksheves (CR6,7,8,9) and the ported Video Reference (VR) floorstanders VR20, 30 and 40. BA's 'new gen' engineers liked vented designs, with their lower 3dB down points (at the expense of faster rolloff below that, which didn't really matter in the real world), and Andy Petite-Kotsatos relented, since the various Paradigms and PSB Alpha's were eating the HD's lunch in retail A-B comparisons. Interesting: Air leaks are even more important in vented design, because the only "leak" you want is the vent. Any other "unintentional" leak wrecks a vented speaker's bass. And yes, we called them 'birdies.' Steve F.
  13. I remember this series quite well. I was with BA at the time and we noted the introduction of these speakers, wondering if they'd make an impact. In true AR fumbling marketing fashion, they flopped from a sales standpoint, being a high-end, specialized series aimed at 2-ch music listeners just as the early-mid 90's home theater craze was taking off. But considered from an engineering/product standpoint, they were quite good. A bit "dryer" and having that M-T-M focused imaging thing going on, the Classics were true audiophile-oriented speakers. I heard them at AR's CES display and I heard them on a BAS tour of AR in fall 1992. The 30's were impressive, very clean, solid bass reach, very "3-dimensional." I remember talking to a BA engineer who'd been at AR at the time, and he told me that they had trouble with the first ones from a shipping damage standpoint, since the cabinets were so unusually shaped, but they got that squared away pretty quickly. Definitely worth checking out, without question. There is lit in the Library from me. Steve F.
  14. I realize this is the AR speakers discussion forum, not a jazz discussion forum. But....I write very detailed, well-crafted (I know, that's just so nervy and egotistical of me to say) and tongue-in-cheek humorous articles on jazz on a fairly regular basis. If you'd like to be on that e-mail distribution list (I'll bcc you, to preserve your privacy), PM me through this forum with your e-mail address. My out-of-proportion interest and enthusiasm for jazz is at least equal to my out-of-proportion interest and enthusiasm for AR speakers. Steve F.
  15. I have listened to my full-sized (3a/2ax/LST-2/11/91/50t/9) AR speakers with everything from a Dyna SCA-80 integrated amp (36 wpc RMS into 4 ohms once the FTC got through with it) to various Kenwood integrateds, Mits and Adcom power amps and currently a Parasound 2250 Classic power amp that delivers 400 wpc RMS into my fully-restored 9’s in a smallish 13 x 17-ft room. In my experience, the Dyna was by far the “worst,” but not because of the modest power. I know amplifier differences aren’t “supposed” to exist (and in reality, all those so-called ‘differences’ can likely be attributed to very slight FR deviations that result from particular pre-amp/power-amp/speaker couplings—impedance and the like—s/n issues, distortion spectral content, perhaps—perhaps—“damping factor,” etc.), but even when the amps are not pushed into gross clipping, I can hear differences. It’s the amp’s quality and comfort with the speaker’s load that seems to matter the most, not the raw power. My Kenwood KA-7002 amplifier, although at 50wpc, less than 1dB more powerful than the Dyna,, sounded light years better with the 2ax and 3a. Light years better. My listening tastes are Miles, Freddie, Buddy, Jones/Lewis, Weather Report, Shorter, Brecker, Mr. T, Cobham, Metheny, Tyner, Hutcherson, Chick, Farrell, Horace, Henderson, etc. So it would seem that sb0357 could sit right down in my listening room any day and enjoy himself. 36 watts or 400. Steve F.