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About ligs

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  1. 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
  2. AR9ls crossover slopes

    Here is a nice illustration of the frequency responses of all the drivers in AR90, driven through the crossovers.
  3. 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:)
  4. 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.
  5. 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.
  6. 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.
  7. 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.
  8. Unbelievable find, NOS

    Shipping is only $17.49 for something weighing about 150lb each. That is a bargain:)
  9. 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.
  10. AR1 Rear panel jumpering?

    Good luck to you!
  11. AR1 Rear panel jumpering?

    Mine works with the rear panel like this. The amp goes to 3 and 4 . There is a red jumper wire goes between 1 and 2. See the picture attached. George
  12. Acoustic Research AR3a Woofers Correct?

    The woofer has plastic screen and round magnet similar to the AR 3a woofer I just came across. The dust covers are not original. Personally during refoaming, I like to keep the original dust covers in place without touching them. I have not had any problem even with the tiny Bose 901 drivers.
  13. AR 1 Find

    Jeffs, you are right, mine has a pleated surround. Interestingly, some of today's pro woofers still use pleated surround. My JBL 1400 Pro woofer has a pleated fabric surround and is supposed to have + or - 7.6 mm linear travel for the vc. My first order of action is to refoam the woofer in AR3a using looneytune2001's kit. It has a round magnet with a top plate, to my eye, thicker than the later square magnet AR 12" woofer. The midrange of AR3a also seems to work once I took it out of the cabinet. After years of on-and-off relationships with AR, I am back again. Over the years, I had AR3a,3, 2ax,4x, 9, 18s, 1MS, and High Res 17.
  14. AR 1 Find

    Wow! for my AR collection, one nice AR1 would be quite enough. But again, another AR1 in mahogany cabinet may be waiting for me somewhere if I keep working on my Karma:)
  15. AR 1 Find

    You are probably right about Karma. I went into ReStore and did not see anything interesting first. Then I asked one of the technicians if there were more speakers in the back. He led me to the repair shop and showed me about half dozen speakers sitting on the floor and told me that they have not been tested yet. I noticed there were two AR3 size speakers among them and said I would take them even without testing and named a price and he agreed right on the spot. It was not until I got into my car I found they were AR1 and AR3a.