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Gerry S

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  1. I always felt the "bi-amp" option that ADS offered to consumers was a mistake. There is more opportunity to screw up the sound than to improve it (I once owned a pair of 910's using just the built in passive crossovers). Effective bi-amping requires pretty detailed knowledge of the raw drivers individual performance. It also requires test equipment to set amplifier gain levels, as well as the crossover frequencies and slopes. Pro's use bi-amping in sound reinforcement for increased output capability and reliability, and when the performance space has been defined. With pro use,the cost and complexity of additional amplifiers and electronic crossovers is justified over the long haul. With consumer use, I don't think it's justified, from either a cost or performance point of view. Let's assume the ADS passive crossover was properly designed, and yields what is generally acknowledged to be "good sound". With bi-amping, audible changes to the system should be SUBTLE. The primarily benefit should be less audible distortion as the woofer amplifier "clips" (overloaded) with heavy bass content. The distortion generated with this clipping is produced by the woofer(s) only, where it's mostly inaudible. It's inaudible because woofers naturally rolls off highs, and the passive crossover reduces the highs further. The trouble with bi-amping occurs when any additional filtering created by the electronic crossover upsets the INTENDED "blending" occurring between upper woofer frequencies and midrange lower frequencies. Not to mention any changes in the "radiation pattern" at the crossover frequencies. I'm not saying that bi-amping isn't a valid way of improving sound. I'm saying that in the hands of the average consumer, it's not likely to do so. Gerry S
  2. The T1030 crossover pictured above is a genuine BA part. It is a "quasi-second order" SERIES network between the woofer and midrange. With this type of network, any change in X-O values affect both the woofer AND the midrange SIMULTAINIOUSLY (because the drivers are effectively in series). It is much harder to "voice" because of this inter-dependent relationship. Note that If you disconnect either the midrange or woofer from the crossover, you will get no sound from either! The T930 Series 2 also used this "quasi-second order" configuration. I'm pretty sure the T830 Series 2 also used a quasi-second order network. The midrange and tweeters should be identical for the T930, T930 Series 2, T1000, T1000 Series 2 and T1030. There is NO "Series 2" T1030 (probably because it's hard to "improve" the T1030). Lessons learned from the T1030 development work resulted in the Series Two versions of the T930 and T830.
  3. Gerry S

    ADS L730 Mods

    As a loudspeaker designer (retired), I wouldn't do "mods" for ADS loudspeakers. As is, they are well built and well designed. Unless you possess the technical knowhow, as well as access to necessary test equipment, ANY change you make will most likely just ALTER system performance; NOT "improve" it. These are loudspeaker SYSTEMS, where each driver is meant to work with their associated drivers, and in that particular enclosure. If you change/substitute just ONE driver (woofer, midrange, tweeter), you've essentially changed the whole system (probably for the worst). Even if a driver swap is miraculously "successful", you would have to do the same for both speaker systems to get reasonably matched "stereo performance". I believe that "modifying" any loudspeaker system for personal preference can be fun. But if the mods are made to a "classic", that product is no longer a classic.
  4. Honestly, I can't remember. If I had to guess, the newer version had the terminals on the back. Here's how I would test/distinguish them just by LISTENING TO THEM (preferably using pink noise). Keep in mind that crossovers determine the "radiation pattern" where the various drivers "meet", aka "crossover". With the original, smoothest response between the midrange and tweeter is pretty much "on axis" of the midrange/tweeter drivers. When listening "sitting down" or "low" to the floor, response is uniform. However, as you stand up, the sound balance can change noticeably, perhaps by seeming perhaps "duller". That's due to a "dip" in in the response (at/near crossover) as you move up from the speaker axis. The newer version minimizes this "lobe"; not much tonal change between listening "sitting down" and "standing". Listening evaluations can be performed using just ONE speaker (instead of a stereo pair). I prefer "pink noise" as a source, since it's repeatable and continuous. Lacking that, music with mid/high frequency content should reveal differences. Listen in the "near field" (about 2 meters away) so that the drivers "integrate" fully, but before the room alters what you hear. Listening to "a stereo pair", the newer version should have a more "focused" central image with a mono source (pink noise or a vocalist). That "focus" is also better maintained as you "stand up". Again, the differences are most noticeable when listening in the "near field". .
  5. Please refer to: Boston T1000 vs T1030 Started by morkys, Mar 16 2009 10:01 AM The driver alignment difference alone would make replicating the T1030 "sound" on the T1000 difficult (if not impossible) in the "near field". The T1000 and T1030 use identical drivers and enclosure volumes, but the crossovers are NOT interchangeable. That's because the two systems have different physical driver alignments, requiring a different approach to crossover design. As far as specifics, the T1000 crossover uses three "parallel" networks (one each for the woofer, midrange and tweeter section). The T1030 uses a "quasi-second series" network between the woofer and midrange sections, a parallel network on the tweeter. The crossover frequencies and slopes are also different, resulting in different "near" and "far-field" responses. As far as replacing caps, I don't think it's necessary. It could actually be detrimental to system performance and reliability (because of changes to the crossover frequencies). I would not operate both systems in the same room because of likely acoustical interference between the two. Also, each system has an impedance of 4 ohms at low frequencies; operating both systems at once (from the same amp) would tax the amp.
  6. Regarding T 830: no change in drivers, just crossovers.
  7. The A400 isn't meant to be be "pulled away" from the wall behind it. Doing so will weaken the bass considerably. Nor was it designed to be "toed in" (which pulls the speaker slightly away from the wall behind it. The T1030 can be used near or close to walls, but also several feet away to minimize wall reflections which can slightly "blur" the stereo image. You can also toe theT1030's in..also to minimize blurring the "first arrival" stereo image. I personally believe that speaker spacing is best between 6' to10' apart depending on size of the room (for either system) and how far you can sit behind the speakers and still have good imaging AND good, smooth bass at the listening location. There is no hard/fast rules to exact distance..depends on the room and aesthetics.
  8. Dear Mystery. Regarding post #11. The A400 was "before my time" at BA. It was Andy Kotsotas's VERY FIRST SPEAKER when he founded the company. I did listen briefly to the A400 flagship, but did not use it as "a reference" while doing the design work for the T1030. Note that they are VERY different speakers as far as loudspeaker placement is concerned. The A400 was designed to tackle the "Allison effect" by having the woofer very close to all the boundaries (for smoothest bass into the room). The wide baffle minimized diffraction from the cabinet edges. For the system to work as intended, it must be placed against the wall. With a smaller "footprint", the T1030 was designed to give the user greater flexibility in it's room placement options. When I "voiced" the T1030, I gave particular attention to it's "nearfield imaging" capabilities. I don't know whether Andy did the same for the A400. I do know that the A400 was/is highly regarded in the audiophile community. For all I know, the A400 could "image" as well or better than the T1030. Again, I have not "A-B 'ed" the two to see which is "better". IMO, really pointless to do so because it's really like compairing apples to oranges. I've found that when comparing two systems that are competantly designed, the differences heard can be attributed as much to the recordings and room acoustics as to the speaker themselves. Sometimes, these two variables can SWAMP differences in "design philosophy". Which is why I don't pay much thought to exotic (expensive) cables and such.
  9. todtubbi.... "The T930's make a very nice 2.0 system for my big screen tee-vee, but I want to upgrade to 5.0 (I'm thinking that with the T930's I shouldn't need a sub--do you agree?)" As good as the 930's bass is for music,"Movie Bass" is a whole other animal. It can't hurt to add a powered sub for "home theater". I personally use a Hsu Research model with fantastic results.
  10. The LMR driver is deliberately filtered below 200 hz thru the crossover to NOT reproduce bass. This is done to prevent bass frequencies from interfering with the cleanest possible reproduction of program material in the lower mid range frequencies (like vocals). Introducing bass into this driver would defeat the purpose of having the driver in the first place (lack of intermodulation distortion from bass-heavy material).
  11. Gerry S

    ADS L1590

    I remember reading brochures on the Series II. On paper, it seemed to have enough engineering improvements to justify it as a replacement for my 910's. So, I went to listen to them...forgot where. What I saw was impressive: tall, elegant towers with all drivers vertically aligned. Metal grills designed for minumum difraction. Compared to my relatively "squat" 910's, they certainly LOOKED more apealing to me. But, when I heard them, I wasn't "hit-over-the-head" impressed. If I AB-ed them at length, and at home, I might have thought differently. When I asked about the price, THAT'S when I decided the audible improvements (I did hear some in that showrooom setting) were not large enough to warrant lugging them home for extended listening. I think I would have been impressed if I did. Having done my share of crossovers at BA, I can attest to how important ADS's improved crossovers can be in determining overall sound quality. At the same time, many improvements can only be heard if the system is properly set up, AND quality recordings are used to reveal these improvements. I believe under normal conditions, many of these improvements would be inaudible or very subtle. I know that there IS a "night and day difference" between an AR 3a and a AR10 pi. Despite having similar/identical drivers, I could easily and repeatedly distiguish one from the other blindfolded. Probaly not as much between the AR 10pi and the AR 9 as far as tonal balance...probably reasonably similar! However, the AR 9 would have been my speaker of choice (tremendous dynamic capabilities AND "imaging") if I had to own something "vintage". I can't help but wonder if I would feel the same way about the ADS Series II if I had purchased them. The ADS Series II towers (an idustrial designer's speaker) LOOKED more advanced than the AR 9 (an audiophile/enginner type product). I wonder.... which product sold better?
  12. Thanks, Tom Tyson and Dynaco Dan. Brings back VERY distant memories. The published "protection data" given by AR was so detailed for a consumer product...never been equaled since to the best of my knowledge. A zillion decades ago, I did order those "special" FNM fuses directly from AR for my AR 10pi's . I was surprised how physically large the fuse (and the fuse holder) was compared to a "regular" glass-type fuse. I permanently wired them into my speaker harness: 14 gauge Romex (in lieu of Monster Cable) with banana plugs on both ends. The harness was pretty unwieldy and ugly looking, especially when contrasted to the walnut veener finish of the speaker cabinets. I never blew a driver (OR the fuse as best as I can recall). And, I drove them pretty hard with my Dunlap-Clark Dreadnaught 1000. So, the ugliness was worth it. If I were to get these fuses (and holders) today, I would probably have to go to an industrial electronic parts store; Radio Shack probably wouldn't stock them.
  13. I'm thinking the FNM slow-blow fuse approach is the simplest and least sonically intrusive. Those fuses are relatively huge and would require LOTS of "instantaneous current" to blow (as in catastrophic amplifier failure). The trick is finding the correct value offering protection without blowing on musical peaks. These fuses can add DCR in series with the woofers if heating is gradual and continuous (gradually altering the bass response). But output levels would be such that your ears may bleed before you would notice it, or the woofers threatened.
  14. Phil, I believe you are correct; fuses can only do so much. And fuses can alter the frequency response as the fuse heats up. The D.C.R of the fuse increases from it's theoretical zero value and acts as a voltage divider that changes with frequency. Wheather this is audible to the listener is something I don't know about. Also, the amps of the 70's and 80's can suffer from excessive "dc offset" (my Dynaco 400 did), which at low levels could cause the woofer's cone to migrate from it's theoretical "neutral" or "resting position". I suppose if this offset was high enough, it could heat up the woofer's voice coils and the owner wouldn't even be aware of it happening (since DC isn't audible). Again, I don't have personal experience of woofers failing from this. Perhaps others here can chime in. I wonder if today's amplifiers suffer from this. It's easy enough to check with a dc voltmeter or by looking at the woofers as the amplifier is switched on; woofers should show no displacement when there is no music being played.
  15. How about in-line fuses for protection? Didn't AR recommend a slow-blow Fusetron for the AR3a and 10Pi?
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