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Thread: Altec 9844-8B

  1. #76
    RIP 2011 Zilch's Avatar
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    Hi, Skywave!

    No problem.

    We just keep rattling here while we wait....

  2. #77
    Senior Member hmolwitz's Avatar
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    I have a pair of these as well, and am watching this eagerly./
    Thanks Zilch
    Harry

  3. #78
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    One 414-16b alnico per side

    Ok. I will give it a try. I have one per side. The enclosure is altec 614 style. Mine is about 5 Sqft. But take a way the speakers, bracing, etc, The internal volume will give me about 4ft which is very close to 614. I will try zobel. But I can't measure anything. Me and my brain.

    But I used to run the LF with 3.9mh+8.2uf and the HF with first order 10uf motor run. As of yesterday, I changed the xover to n800f. The LF has not changed much. But HF sounds more balanced. I tried 20ohm+25ohm pot combo verse 16ohm Lpad. The 20ohm+25ohm pot sounds more controlled.

    The first order sound much warmer, meaning a lot of mid?

    Hey Zilch. I have more speakers that I am hanging onto just for the emotional value such as JBL d216s which I believe is 96db and very clean mid. Should I turn these into 3 way? Oh. I forgot. The valencia thread seems to say that you favor 2 ways.

    Ok Zilch. I will try zobel. 2 weeks ago, zobel-door bell sounded the same to me. Did not ring a bell to me. I am not a tech person. You know? My Single ended friends will call me crazy. But I have to try everything .

    By the way. I am running my speakers with a couple of eico 14s. Top to bottom-tubes. Hummmmm.... You say mush. I say warm.

    Tim

  4. #79
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    Zobel

    By the way.

    Am I using the same values for the zobel as Skywave's?

    Thanks

    Tim

  5. #80
    Senior Member Russellc's Avatar
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    Quote Originally Posted by Zilch View Post
    Here's the "T-filter" standing alone, top. Altec used it to provide supplemental HF compensation after some stock crossovers.

    As you see in the M19 crossover, R2 may be varied to adjust the amount of compensation.

    At the bottom here is shown a Zobel, which you'll also find discussed in Dickason, used to flatten the reflected impedance of the woofer as illustrated by Earl, above, so that the main filter behaves more predictably.

    Yeah, 6.2 uF for C1 and 4 Ohms for R1s are fine. R2 and the Zobel components vary with the application. You can see that if R2 goes to a high value, providing the minimum of 6 dB compensation, it's basically 8 Ohms in parallel with C1, what I have suggested you try for starters here, as there's already some compensation in N800-F (maybe)....
    What wattage should the resistors in the "T filter" be?

    Russellc

  6. #81
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Russellc View Post
    What wattage should the resistors in the "T filter" be?
    Not much power happening with compression drivers, so you could probably get away with something smaller, but I'd use non-inductive 10W Dayton or 12W Mills....

  7. #82
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    Xo with Zobel

    Hi Zilch

    I tried the 414 with zobel 8.2uf+16 ohm. Here is the graph. I have to say that I did not use any fancy program or microphone. So this is my disclaimer. If anyone of you object, I will erase this graph. I do not want to mislead someone with my ignorance. The first is 414 without zobel. And the second is with the Zobel.
    Attached Images Attached Images   

  8. #83
    Senior Member Skywave-Rider's Avatar
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    How did you generate these graphs, T?

  9. #84
    RIP 2011 Zilch's Avatar
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    Seems to be rolling off better above the crossover frequency, as Earl suggested above.

    Sounds better now, I betcha, without that nasty hump at 1250 Hz....

  10. #85
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    The graph

    Hi Skywave

    Here is how I did it. An el cheapo mic, a laptop, white noise, and 12 inch from the woofer.

    I think your gears will be much better for measuring the compression drivers.

    Tim

  11. #86
    RIP 2011 Zilch's Avatar
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    We have some measured parameters for that woofer to work with, right?

    Plug them into what Elliot says at 3.1.1 here:

    http://sound.westhost.com/lr-passive.htm#6.0

    I get 11.4 Ohms and 40.87 uF.

    If you confirm, try something close to that and measure again.

    Then, switch to pink noise, if you have it, and let's see that result, also....

  12. #87
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    an other one?

    the parts and pink noise i do not have. I want to shift my attention to 806s. They are good to 10000k, I think. A good and sweek midrange. With What I have 16 ohm vintage sansui horns, I may want to go three way. Or Zilch,
    do you want to follow up with Danald's time delay xover as Earl suggested and see how far we can push the 806s? please!

    And I will do another test with the values you suggested. But I am sure people are dying to see the show going. As far as I as concerned you are the show!

    Tim

  13. #88
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by MrT View Post
    the parts and pink noise i do not have. I want to shift my attention to 806s. They are good to 10000k, I think. A good and sweek midrange. With What I have 16 ohm vintage sansui horns, I may want to go three way. Or Zilch,
    do you want to follow up with Danald's time delay xover as Earl suggested and see how far we can push the 806s? please!
    Pink noise files are available online, and also on CD. If you use that, we can correlate your findings with the voltage drives in the sims.

    Donald's LF filter with delay is for the 605A Duplex, with a specific offset. I'll likely do sims on the HF, tho.

    Before I went three-way, I'd go active with CD compensation. That'll get you out to 14 kHz with the 806As, and dialable delay or sub augmentation facility.

  14. #89
    Senior Member Skywave-Rider's Avatar
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    Quote Originally Posted by MrT View Post
    Hi Skywave

    Here is how I did it. An el cheapo mic, a laptop, white noise, and 12 inch from the woofer.

    Tim
    Looks easy to read and crisp to me. What software generated the readout?

  15. #90
    RIP 2011 Zilch's Avatar
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    Patten 605A HF Filter Sims

    Design frequency presumed to be 1.6 kHz, marker "a".

    L6 DCR estimated 7.5 Ohms.
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