Recent content by Duke

  1. Duke

    Why Are Audiophiles so Bound and Determined to Make Others Waste Money

    No, I didn't think it through at first. If you're trying to pick a fight, you're going to have to try harder than that.
  2. Duke

    Why Are Audiophiles so Bound and Determined to Make Others Waste Money

    Thanks for clarifying. On the one hand sometimes I'm a little dense, and on the other hand sometimes I'm a LOT dense.
  3. Duke

    Why Are Audiophiles so Bound and Determined to Make Others Waste Money

    In coming up with that 50% figure I made the simplifying assumption that half of all preamplifiers invert phase. The actual percentage is probably a lot lower. From what I have read, in practice it is primarily simple single-tube-per-channel preamps which invert phase (and mine did not fit...
  4. Duke

    Diminishing returns in the higher end

    I had forgotten that - THANKS for the reminder! I have made all the measurements necessary to begin that speaker's crossover design, but it hasn't worked its way to the front of the line yet.
  5. Duke

    Why Are Audiophiles so Bound and Determined to Make Others Waste Money

    I hosted an audio club meeting about twelve years ago. One of the attendees put on a couple of recordings he had brought and then asked if my preamplifier inverted phase. I said I didn't think so, and refrained from telling him that I'd investigated and tried to hear phase inversion in the...
  6. Duke

    Diminishing returns in the higher end

    My understanding (based on conversations with Amir and Erin) is that loudspeaker system size, weight, and complexity impose limits on what is practical to measure with the Klippel system. Neither seemed very enthusiastic when I described the fairly large and heavy polydirectional speakers I make.
  7. Duke

    Why Are Audiophiles so Bound and Determined to Make Others Waste Money

    "Why Are Audiophiles so Bound and Determined to Make Others Waste Money" is not the sort of question I'm totally comfortable with. It seems to me this kind of phrasing attributes sinister motives to those we are disagreeing with. It also assumes facts which are not in evidence, sort of like...
  8. Duke

    Speaker Testing: why mono is better

    Hi Tom, I agree that we don't want the speakers doing things which draw attention to themselves as the sound source, and ime such things are often (if not always) easier to pick out in mono than in stereo. But beyond that I'm not totally clear about what you mean. What are these "differences...
  9. Duke

    Perceptual Effects of Room Reflections

    Thanks! Credit to my partner James Romeyn for using the vertical plane like that. Based on various things I've read I would have said that keeping the reflections in the horizontal plane was the higher priority, but Jim didn't know any better so he just tried it, and the additional time delay...
  10. Duke

    Perceptual Effects of Room Reflections

    I'm not using electronic delay in order to keep the system from requiring that much complexity, but separate inputs for the rear-firing drivers are provided so DSP delay could be added if desired, and I have at least one customer who has done so. The rear-firing drivers are aimed up-and-back...
  11. Duke

    Perceptual Effects of Room Reflections

    Very interesting! Imo cross-firing dipoles are potentially an improvement over cross-firing monopoles if the backwave energy has a fairly long reflection path, such that it arrives after a decent amount of time delay. I used to also diffuse the backwave of SoundLabs, typically with a few...
  12. Duke

    Perceptual Effects of Room Reflections

    It seems to me that 20 milliseconds ballpark time gap is hard to achieve outside of a dedicated RFZ-type room. Imo there is still arguably worthwhile benefit from a 10 milliseconds ballpark gap, which is the target Geddes shoots for (he cites Griesinger as his source). Imo the ideal role of...
  13. Duke

    (Informal) Chat with Dr. Earl Geddes of GedLee Audio

    The solution Earl uses for the thermal effects he describes starting around 27:00 is a "brute force" approach: His speakers have a LOT of thermal headroom, such that the drivers are being operated at a small fraction of their rated AES power handling. For instance the 15" woofer he uses in...
  14. Duke

    What's going on with these bass horns? The mystery of the missing frequencies.

    I'm not a bass horn design guy by any means. A "whole room suckout" seems unlikely; my impression is that a global (throughout-the-room) issue tends to be a speaker issue rather than a room acoustics issue. And the sharpness of that dip in your throat measurement makes me think it's a...
  15. Duke

    JBL 4349 Review (Studio Monitor Speaker)

    The problem with the measurement technique is revealed in the section entitled "making the measurements": "For the measurements, the DC voltage across the voice-coil was recorded at intervals of 10 milliseconds... The data were then smoothed using a five-second moving average calculation..."...
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