Recent content by jackocleebrown

  1. jackocleebrown

    KEF's Breakthrough VECO Speaker Technology to Lower Distortion–Explained by Its Inventors

    It depends on the driver. The distortion reduction comes from two parts. First from the current output amp. If you have a very simple motor without any special features for controlling inductance distortion then this alone could be a decent 15dB reduction (see below) and in relatively audible...
  2. jackocleebrown

    KEF's Breakthrough VECO Speaker Technology to Lower Distortion–Explained by Its Inventors

    No models involved. With a current output amplifier (high output impedance) the Qts becomes equal to Qes because the motional emf has no effect on the current. If negative velocity feedback is added around the outside of this the effect is the same as adding damping back into the system, so it...
  3. jackocleebrown

    KEF's Breakthrough VECO Speaker Technology to Lower Distortion–Explained by Its Inventors

    The video title wasn't chosen by us. The trouble is that speaker engineering is an 80 year mature topic. Nothing is totally new and we're not trying diminish the achievements of anyone whose already implemented servo control. The main thing is the new sensor approach allowing us to apply it in...
  4. jackocleebrown

    KEF's Breakthrough VECO Speaker Technology to Lower Distortion–Explained by Its Inventors

    Maybe do hold your breath for veco in 2-way. Volume displacement is limited, so we can't use it to extend the bass, but there are still benefits. Not least that we can use a current output amplifier which avoids power compression in the midrange and gains a small amount of inductance related...
  5. jackocleebrown

    Do KEF Aluminum cone speakers have a serious design flaw?

    Hi Everyone, I can understand that these pictures look dramatic and alarming to anyone that is a KEF loudspeaker owner, or that might potentially be considering purchasing KEF loudspeakers. I asked our operations team to collect some statistics for worldwide Uni-Q failures on some of our most...
  6. jackocleebrown

    KEF ci250RRM-THX In-ceiling Speaker Review

    Hi @ssashton , the details of this aspect of the design are explained in the white paper. It's downloadable from the specification table on the product page: https://uk.kef.com/products/ci250rrm-thx
  7. jackocleebrown

    KLIPSCH Jubilee measurements

    @Zvu , thanks for the shout out, but I should clarity that my work on the Axi2050 was a very small part of the total project. Mark Dodd at Celestion was the driving force behind it, and deserves all the credit, along with the rest of the incredible team there. My bit was on the theory of how a...
  8. jackocleebrown

    KEF LS60 Wireless Just Announced

    Hi @Mnyb, you originally tagged me for a reply, but when I came to answer I saw that @AOR beat me to it. @AOR is one of our very talented KEF engineering team and nobody knows the way LS60 perform better because AOR did the DSP tuning .
  9. jackocleebrown

    Kef LS60 wireless review by ErinsAudioCorner

    Thanks for the suggestion. I agree it's something we can improve. Our spec sheet max SPL figure is based on 1m 1speaker instantaneous max peak SPL on pink noise. I think that what you suggest is better. A couple of extra notes. On active speakers we do as much limiting as possible with average...
  10. jackocleebrown

    Kef LS60 wireless review by ErinsAudioCorner

    What you see here is thermal protection kicking in on the tweeter. This occurs because a test sweep has extremely high average spectrum at high frequencies. On real music this isn't the case and this protection will almost never be triggered.
  11. jackocleebrown

    Speaker Break-In and Environmental Measurements

    Hi @MAB, I really admire the thoroughness of your study. My experience is a bit different. Only today we have a driver in development where we are discussing Fs shift after production. Using this prototype as an example, the Fs directly after assembly was 57Hz and after sweeping in free air at...
  12. jackocleebrown

    Which way is up? (Which way does a loudspeaker driver move?)

    Shameless plug for this thread which answers some of the questions you pose https://www.audiosciencereview.com/forum/index.php?threads/how-does-a-loudspeaker-cone-generate-acoustical-pressure.48261/
  13. jackocleebrown

    KEF R3 Meta - Review & Measurements by Erin

    It's unfortunate that I can't post the Klippel paper. Anyhow, in the slides you can clearly see the "break-in" period marked on the graphs and distinct from the fatigue behaviour. In the paper Klippel defines this non-reversible change as "Initial exposure to mechanical load opens some bonded...
  14. jackocleebrown

    KEF R3 Meta - Review & Measurements by Erin

    Hi Guys, Driver suspension break-in is a well known effect. For example, please see this paper from Klippel on the topic. https://www.aes.org/e-lib/browse.cfm?elib=16000 You can also find some slides from the paper here...
  15. jackocleebrown

    Audio Engineering Society 2023 Conference

    I'm involved with two papers on the program. @amirm, one is in the same session as yours and I look forward to meeting you in person. https://aesny23.sched.com/event/1SsKE/paper-presentation-iterative-metric-based-waveguide-optimisation...
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