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  1. R

    Need Kef 103.2 crossover Schematic and caps

    I found a KEF 103.2 schematic without protection circuits: Kef 103.2 crossover Schematic (see 3rd post) You can find all the crossover parts you need at Parts Express or Madisound.
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    CAOW1 / Salk Song (Dennis Murphy) Experience

    Yes, the bass response of the CAOW1 is adequate in my room. When I first built it, I drove it with an old Marantz 2230 stereo receiver. With 30 wpc, most music (60s & 70s classic rock) sounded good, but some demanding symphony orchestra music (Beethoven's 7th Symphony) sounded small and...
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    JBL 4311 and 4312 crossover rebuilds help

    @FONSguy I agree with homebrew. Replacing the JBL paper cone drivers with aluminum cone drivers will make an entirely new and different speaker. Using a crossover designed for different drivers will, at the very best, work very poorly. Which paper drivers do you want to replace? Which...
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    JBL L100 crossover kit--Murphy or Troels Gravensens

    I also thought the LE5 driver was good. At least the JBL marketing buzz had led us to think that back in the 1970s. And then I saw it's unfiltered frequency response. Yes, it took the most work to correct its many flaws. Compared to the LE5, the woofer and tweeter were pretty good. Most of...
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    JBL L100 crossover kit--Murphy or Troels Gravensens

    Thanks for the feed back and photos. They will help other owners make up their minds. You may be the first person who installed the Dennis Murphy crossover in JBL 4311 speakers. You are the first person, I know of, who told me of your results. Thanks! I'm glad to know you like how it works.
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    Bi-amping and change in nominal impedance

    @RTally already answered the OP's question. See post #2, above. 3MY's question comes up often enough here. He hasn't told us what speakers he has, so I spent a few minutes looking for an example of a 3-way speaker where we know the crossover frequencies and have an impedance vs. frequency...
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    Does really old copper speaker cable degrade the sound?

    In the same spirit, Richard Feynman, the Nobel Prize winning physicist, said this: "The first principle of scientific inquiry is that you must not fool yourself – and that you are the easiest person to fool."
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    Does really old copper speaker cable degrade the sound?

    I don't know how to avoid Chinese made copper wire with PVC insulation. I throw it out when it begins to oxidize enough to offend me. AC signals do tend to travel on the outer surfaces of copper wire. It's called the skin effect, and is an often-repeated claim for exotic high-priced speaker...
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    Does really old copper speaker cable degrade the sound?

    This man knows his chemistry. As the correct answer, this should be the last post on this thread. Thanks. For what it's worth, it's been my non-scientific observation that this kind of copper corrosion was rarely, if ever, seen until PVC insulation copper wires began to come from China. When...
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    Mundorf & Jantzen E-Caps Off Spec and Seller Excuse, Opinions?

    I almost never buy non-polar electrolytic (NPE) capacitors, regardless of price, unless I want to pay as little as possible for a large capacitance value. The cheap NPE caps are often out of spec when they're new. And now I see the high-priced ones can as well. I don't see any benefit in...
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    Mundorf & Jantzen E-Caps Off Spec and Seller Excuse, Opinions?

    Capacitance values that are 16-32% higher than the printed values are inexcusable for any reason, especially inexcusable for premium priced electrolytic caps as those you mentioned are. Sloppy tolerances of electrolytic caps, beyond ±10%, are the main reason why I never use them in rebuilds of...
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    JBL L100 crossover kit--Murphy or Troels Gravensens

    Years ago, when I first got my L100s, I used them with a Marantz 2230 receiver. It still works today. Here's what I've been able to learn about the 4312c speakers that might help answer your questions: JBL 4312c specs From JBL's specs, it looks like the 4312c uses similar woofer & mid-range...
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    What are some ways to move heavy speakers around?

    Get one of these. I'm holding out for the audiophile-grade oxygen-free version. I'm told it's in the works ;).
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    Crossovers & L-Pads

    Can't emphasize this enough. Variable L-pads offer the promise of a simple way to vary the loudness of drivers in a 2-way or 3-way speaker. But if you measure the SPL vs. frequency of each individual driver, as homebrew described, you can see how their individual loudness curves look...
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    jbl l110 crossovers

    It's worth remembering that Dennis did this work as a favor to me. When he designs speakers that will be commercially sold, for Salk or Philharmonic Audio, he did a lot more work before they were ready. After finding a crossover that worked well, he then worked at achieving the same...
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    jbl l110 crossovers

    For what it's worth, when Dennis Murphy designed new a crossover for my L100a speakers, he only used one speaker. I live nearby him and drove to his house hauling both of those heavy speakers. He briefly listened to both, but said he would only need one to do the work. He didn't charge me for...
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    speakers crossover upgrade?

    OK, I do have one comment on the great debate about bi-wiring or bi-amping. When I first started learning about DIY speaker building, I used to go to a lot of meetings of DIY builders. There was plenty of talk about speaker drivers and crossover design – no big surprise there. And I heard...
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    speakers crossover upgrade?

    I don’t ever bi-wire or bi-amp speakers and have no comments about an imagined or real advantage for that. In a small 2-way design, I did build woofer crossover circuits on a separate board from the tweeter's circuits, but I did that only because it was easier to install two smaller boards into...
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    speakers crossover upgrade?

    In two coils of the same inductance value, the difference in DCR that comes with larger gauge wires is small, less than 1Ω. Steel core inductors made with similar gauge wire will have lower DCR and lower insertion loss. On Madisound, a 1 mH air core inductor made with 16g wire has DCR = 0.34Ω...
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    speakers crossover upgrade?

    Generally, inductors don’t fail or even wear out. If your concern is keeping vintage speakers running, stop there. If it ain’t broke, don’t fix it. My main interest has been DIY speaker building. I always try to minimize insertion loss that comes with smaller gauge inductor coils, especially...
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    JBL 100 wheres the magic?

    The question becomes which crossover version is the real Frankenstein's monster? Here's the acoustically measured frequency response curve with the JBL original crossover. And here's the frequency response of the same speaker with Dennis Murphy crossover.
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    JBL 100 wheres the magic?

    I agree with your comments about that woofer. No 12" woofer should operate at that high a frequency. Here's the unfiltered frequency response of that woofer. It's breaking up somewhere above 2.5 kHz, but the crossover had no low-pass filter at all. In the redesigned crossover, that woofer...
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    JBL 100 wheres the magic?

    When my L100A speakers were measured to see what could be done for them, I was surprised to see the frequency response of the unfiltered LE25 tweeter. It wasn't as good as most modern dome tweeters, but it was robust enough to go down to about 1 kHz. In that last octave of treble, between 10...
  24. R

    JBL 100 wheres the magic?

    Please don’t do that. Yes, there are problems with the L100A's mid-range driver, but eliminating it isn’t the solution. See what's done to the midrange in Dennis Murphy's crossover design.
  25. R

    JBL 100 wheres the magic?

    This has been done before at least once. Check out posts from leesonic. He did build a new crossover, designed by Dennis Murphy, while keeping the old L100A crossover. He wired switches so he could easily switch back and forth between the two crossovers. It was hard work, and he did a good job...
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