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    Well, lots of people are looking, but none...

    Well, lots of people are looking, but none posting. :banghead:
    With a little more sleuthing, I found the following:

    L100 (early) = 2" d x 1" l (thickness of panel)
    L100A (late) - 3"d x ~8" ("L"...
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    Tuning of 4310/L100

    I have searched the forum, but cannot find any specific info on the tuning freq (or vents used) on the various 4310/4311/L100 models.
    These all had an interior cabinet of ~1.75 cf (if my math is...
  3. Thread: Diy L220

    by dmtp
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    Diy L220

    OK, this may be something only I am interested in, but here are my thoughts on a DIY L220. I have a pair of LE14A's. I just got 4 10" PR. Now two 10" PR are just about equal to one 15", so I am...
  4. Thread: Fixed L-Pads

    by dmtp
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    For those more interested in the sound than the...

    For those more interested in the sound than the looks, here are my final plots. Note that these are taken with the mike placed right at the cneter of the curved front touching the front. There is...
  5. Thread: Fixed L-Pads

    by dmtp
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    Results!

    OK, so it has been a long time, but the speaker is finally together and in the den. Yes, an HD TV on the wall will be an improvement as will finishing the grill covers, but I thought you might like...
  6. Thread: Fixed L-Pads

    by dmtp
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    Yes, I suspected that was the problem with the...

    Yes, I suspected that was the problem with the H91 - the mouth is too small to support 500 Hz. One of the nice things about a tractrix horn is that it has a defined mouth that cannot be exceeded...
  7. Thread: Fixed L-Pads

    by dmtp
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    IMpedance plots

    Finally had time to do impedance plots on my LE85 driving both the tractrix and H91 horns. I discovered that my Freq. generator falls off in output at high freq. so this time I recalibrated for...
  8. Thread: Fixed L-Pads

    by dmtp
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    Is no boost best?

    Looks like Robh might be right. Here is a recap of boost with just a cap
    green=0
    blue = 0.4uF
    Aqua=0.5
    Orange = 0.68
    Yellow = 1.0
    Magenta = 1.5
    20653

    Per Zilch's suggestion, here are the...
  9. Thread: Fixed L-Pads

    by dmtp
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    LCR

    OK, I have some interesting results. First the calculations:
    Based upon a 10dB hump, I calculated R= 3.5
    With F0=8750, F3h=15000, F3l=6300, I got L=0.05, C=5.37. I had a 0.06mH coil so used that...
  10. Thread: Fixed L-Pads

    by dmtp
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    Off axis HF response

    To answer Zilch's questions about polar response, I took measurements @ 0, 10, 20, 30, 45 degrees off axis. (The actual degrees may be a bit off, I was using a plastic protractor held on the horn's...
  11. Thread: Fixed L-Pads

    by dmtp
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    Smaller caps

    OK, I finally had a chance to do some SPL plots. As follows:
    1. No HF bypass (green)
    2. 1.0 uF only (no L, no R) (magenta)
    3. 0.68 uF (yellow)
    4. 0.33 uF (orange)
    20642
    Now with the smaller...
  12. Thread: Fixed L-Pads

    by dmtp
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    Do I correctly interpret this to mean that the...

    Do I correctly interpret this to mean that the SPL response we are seeing is what was considered "desirable" for a "Rock & Roll" speaker? "The JBL sound" with "forward" MF? Hmmmmm
  13. Thread: Fixed L-Pads

    by dmtp
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    So if I understand it correctly, the best we...

    So if I understand it correctly, the best we could hope for from this circuit is something on the order of 4dB from 12k-20k (assuming I keep increasing C6 until there is no "boost" @ 12k). If OTOH, I...
  14. Thread: Fixed L-Pads

    by dmtp
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    I had a break at work and was working on the...

    I had a break at work and was working on the calculations for the LCR, but I have a question: How do I calculate the value for R? I realize that the easy thing to do is use the 16 ohm side of an...
  15. Thread: Fixed L-Pads

    by dmtp
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    Thanks, Zilch. Although I haven't gotten to...

    Thanks, Zilch. Although I haven't gotten to trying to duplicate your impedence measurements yet (Work getting in the way again!), I am glad to see that you have essentially duplicated my results, so...
  16. Thread: Fixed L-Pads

    by dmtp
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    Sorry for the confusion. The bottom curve is...

    Sorry for the confusion. The bottom curve is with NO HF BYPASS (i.e. NC= not connected). I then did three curves with the HF BYPASS consisting of a 16 ohm section of L-pad followed by just a 1.0 uF...
  17. Thread: Fixed L-Pads

    by dmtp
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    Original as far as I know. red wax seals intact....

    Original as far as I know. red wax seals intact.
    DCR = 6.9 on each
  18. Thread: Fixed L-Pads

    by dmtp
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    It will probably be a couple of days before I can...

    It will probably be a couple of days before I can get the impedence maeaurements, but I did some more SPL measurements.
    I am using the entire network as published by Zilch earlier "as built" with...
  19. Thread: Fixed L-Pads

    by dmtp
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    Interesting. As Bruce suggests, the tractrix...

    Interesting. As Bruce suggests, the tractrix seems to have far less variation than the exponential horn in terms of peaks and valleys. (of course I only started @ 500 so did not include the...
  20. Thread: Fixed L-Pads

    by dmtp
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    I didn't state, but the L-pad (MF) is set at mid...

    I didn't state, but the L-pad (MF) is set at mid position, the circuit has both the fixed 2.5/5 L-pad and the following 8 resistors. The HF bypass had the 16ohm Lp2 but I set it at a measured 5 ohms...
  21. Thread: Fixed L-Pads

    by dmtp
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    HF boost

    OK, I'm doing SOMETHING wrong here. Based upon formulae earlier in this thread
    http://www.audioheritage.org/vbulletin/showpost.php?p=126752&postcount=4
    I derived the following:
    Lowest freq for...
  22. Thread: Fixed L-Pads

    by dmtp
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    I am certainly not the best one to explain a...

    I am certainly not the best one to explain a tractix horn, but I will give it a try. A tractrix horn is neither exponential nor constant directivity. It would be closest to a catenoid. Tractrix is...
  23. Thread: Fixed L-Pads

    by dmtp
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    H91 v Tractrix

    OK, well the H91 does have better response above 10k
    20359
    Here is the Tractrix taken at the exact same settings
    20361
    Here is full range comparison
    20360
    While it is lacking over 10k, I like...
  24. Thread: Fixed L-Pads

    by dmtp
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    Yes, my typo. Here are the results of my HF...

    Yes, my typo. Here are the results of my HF boost with L3=0.06 which is as close as I can come until I get a new order in. As you can see, just about 3 dB variation is all I get. Zilch got ~ 10dB...
  25. Thread: Fixed L-Pads

    by dmtp
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    52,303

    I am totally imbarrasssed, but in the interest of...

    I am totally imbarrasssed, but in the interest of science I will expose my stupidity.
    First, the circuit I am using is Zilch's except for the value of L3 in the hi-pass circuit (I didn't have a 0.08...
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