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ligs

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  1. “Your comment about the "heavy 12-inch AR woofer having relatively high distortions at higher frequencies" is vague, incorrect and appears to be based on assumption. "Relatively high" compared to what? “ Tom. I am comparing the distortions at 300 hz vs 80 hz from the same speaker, 4.2% vs about 1% at the same 100 db spl. The latter is exceptionally low and is probably still unchallenged even today. I have the 1976 edition of High Fidelity’s Test Reports. The harmonic distortion figures of AR-LST are similar to yours. Interestingly the 8” AR-6 woofer is no slouch either.
  2. Another consideration is the distortion figures of the woofer. The heavy 12" AR woofer, while it has very low distortions at low frequencies, has relatively high distortions at higher frequencies. If the goal is to have the cleanest sound then cutting off the woofer at a relatively low frequency is probably the way to go. The very competent NHT 1259 woofer used in NHT model 3.3 is used only to 100 hz !
  3. I just listened to a pair of NHT 1.3 at my friend's house. They have very realistic, pristine mids and highs when auditioned on stands, away from the walls and directly toward you about 8 ft away. The bass was limited yet very clean and well defined too. I don't have AR speakers with 6.5" woofer and 1" tweeter for comparison. Therefore, I am wondering if the AR bookshelf speakers( designed mostly for use against the wall or 2 pi placement) will sound if placed well into the room?
  4. Here is an article about converting a good 2-way speaker into a 3-way full range speaker by adding a woofer and a passive crossover between the woofer and the 2-way speaker. This is a DIY approach. https://app.box.com/s/a4bqr447s7ox7v9kt7r9tjui0h7yqkrv Here is another one for DIY. https://audionostalgia.co.uk/rogers-ab1-diy-project/#&gid=psgal_43_11&pid=1
  5. Since you mentioned NHT and 6" midbass, I remember NTH 3.3 using a cast frame long throw 12" sealed woofer and a 6" sealed midbass and crossover at 100 hz. Whether NHT 3.3 sounds like AR is not the question but it is a very capable speaker and is said to have more defined midbass!
  6. How about the humble pair of AR 8B speakers that sound like a pair of reference speakers costing 15x as much. Perhaps the reviewer has a point here in terms of considering duplicating AR sound with modern equipment. Quoted from http://www.hifi-classic.net/review/acoustic-research-ar8b-349.html “Although it is hardly reasonable, we could not resist making an A/B comparison between the AR8B system and our reference speakers, which cost about fifteen times as much. Strange as it might seem, the similarities between their tonal characteristics far outweighed the differences. This is not to suggest that they are in any way equivalent speakers but only that a flat, reasonably well-dispersed output from 100 to 10,000 Hz is a key to good high-fidelity reproduction, and these two very different systems share that property. Once you have met that basic requirement, it is the refinements-such as extended response at both ends of the frequency spectrum, higher power-handling ability, and different dispersion patterns-that distinguish most speakers from each other and are responsible for much of the price differences between them.”
  7. AR9ls crossover slopes

    I can not recall the original source of this graph because it was a screenshot using Windows 'sniping tool" In terms of the hole between the LMR and UMR, I am not sure it is a problem. Here is a white paper on the design of a modern Revel speaker with a steep crossover slope. Apparently the hole is a part of the design for flat on-axis and off-axis response. Revel is a highly regarded speaker manufacturer and a part of Harmon International with some of the most sophisticated testing and designing capabilities. https://revelspeakers.com/tl_files/catalog//LuxuryCars/Revel/Manuals/Revel_Concerta2_White_Paper.pdf
  8. AR9ls crossover slopes

    Here is a nice illustration of the frequency responses of all the drivers in AR90, driven through the crossovers.
  9. AR sliding crossover frequencies

    Chris, I think you are correct in your analysis. Depending on the position of the pot, both the apparent crossover frequency as well as the sound level will change. The actual slope of the tweeter is affected by the raw response as well. A 6 db/oct electrical high pass (such as a single capacitor in the case of AR3a tweeter) can become a much steeper 18 db/oct. According to the graph below, there is a substantial overlap between the midrange and tweeter. The crossover over point for the mid and tweeter in Ar3a is difficult to call:)
  10. Has anyone mentioned the system Q value of the woofer and the perceived sound quality of the bass. As I recall AR 12" systems typically have Q values less than 0.8. AR 10" systems typically have Q values around 1.15. AR 9 with the twin 12: woofers in a large enclosure has a published Q value of 0.5.
  11. I'm afraid it has happened?

    I am sure some of you are well versed at crossover designs or computer modelling. In theory, you can tailor the level, slope and crossover frequency from any drivers if you have measurement capability.
  12. I'm afraid it has happened?

    I don't think the burst power test with a single frequency is realistic. In my simple mind a tweeter simultaneously produces a wide range of frequencies, covering perhaps thousands of different frequencies. Each frequency contributes a little bit of heat in the voice coil.
  13. Why No Big-Boy 8" Three-Ways?

    Generally speaking, both the sensitivity and bass extension increase with larger cone area. For the same spl, the smaller cone has to work harder than the bigger cone, so distortion tends to be higher. Therefore there are three strikes against a small cone for sounding big. The big-boy AR9 uses a 8" for midbass and is high-passed at around 200 hz. so it can absorb a tremendous amount of power.
  14. Unbelievable find, NOS

    Shipping is only $17.49 for something weighing about 150lb each. That is a bargain:)
  15. AR 9 Crossover Rebuild

    You can double the wattage by either connecting two resistors in series or in parallel. Just remember use two resistors and each is 1/2 of the target value in series. In parallel, you need two resistors and each is 2x the value of the target.
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