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Bill Brown

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  1. Wow! They still look very good with the 60 db scale. Great. Sometimes I have zoomed in even closer (on the FR and CSD graphs) to see the exact modes and their width, to design my PEQs. But yes, maybe it is time to call it good :) Bill
  2. Nice progress, per the spectrogram you have really helped the 32 Hz mode, but perhaps worsened 82 and 130 hz? Agree re. the scaling of your frequency response graphs. I think you really need to look in closer. A 230 db scale (-9db to 140db) is astoundingly high. In the positive, it will help you identify problem areas, while the negative is that your frequency responses won't look nearly as good to the eye. Bill
  3. Yes, my mistake, you are correct. Sorry. 2V is typical (what I meant to write first and noted before instead referencing the standards, oy), but there is more variation than seen in professional DACs. Bill
  4. This is getting bizarre, heck, borderline ridiculous. @March Audio and @bluesman are absolutely correct. There is a conversion of an analog signal to digital (ADC). You CANNOT encode a music signal with one and zeroes above 0 dbFS, it will all be (terrible) noise, there is no headroom recording digitally. In fact, you should not approach 0 dbFS, as they said, to avoid intersample overs when the ones and zeroes are converted back to analog (DAC). When a DAC chip converts the digital signal back to analog (in a DAC designed for pros or consumers), it produces either a
  5. While I don't doubt your experience, all of the Prima Lunas' measurements I have seen have a fairly high output impedance. This will lead to some frequency response changes based on the impedance of the Tekton's. Where there are impedance peaks in the speaker there will be peaks in the output. Of course this may have nothing to do with his dislike of them. It is simply a factor that must be considered and makes system matching more important than ever. With his ear, my first thought would be towards Harbeth or Spendor's "classic" range to see if their balance of strengths and w
  6. @cjf Happy you are getting good results, and yes, it can certainly be tedious... I wonder if there is the possibility of using minimum phase EQ below the Schroeder frequency and linear phase above. Applying min phase EQ to a minimum phase system corrects frequency response and maintains the overall phase curve (someone may correct me if I am wrong). Bill
  7. @cjf Certainly the difficulties you describe are real. I was limited with outlets for the rear subs. Thankfully I could use some old power boxes with captive cords to reach and they are hidden by the couch. One of the notions that I had to overcome and that then provided a real jump was re. crossovers on mains/ sub XO frequency. Based on my experiments, I think the traditional thinking re. localization isn't completely true. Raising the XO to the subs adjacent to the fronts and trying to match the phase of the frequencies coming from the mains' ports and woofers was fruitful.
  8. Re. your subs, I would encourage you to look at the work of Geddes and Welti re. the multiple sub approach. I now have four and saw stepwise improvement while adding (3 was great, the 4th didn't add a huge amount). Many of the longstanding audiophile beliefs are turned on their heads by this research/approach. Acoustics and measurements below the room's Schroeder frequency are very different from those above. Some of the reasons I haven't delved deeply into DRC is that I would like to do as much acoustically first and that it isn't clear to me how to incorporate measurements --> filters
  9. I believe the initial standard for the output of CD players was 2V. Really, all of this comes down to proper gain-staging rather than any standards, i.e. the lowest gain that drives your amplifier to full output, such that you minimize attenuation in preceding components, either analog or digital. Significant gain in a preamp that is only subsequently attenuated is suboptimal at best. My DAC outputs at the professional standard. My amplifier on its lowest gain setting (which minimizes noise, the goal of all of this) typically leads to -5 to -12 dbs of total system att
  10. I shared the article from which Putzeys obtained his data yesterday in the update I do. It is, ummmm, math rich so is much more in his wheelhouse than mine...... It does demonstrate well the huge outbreak months ago in the choir, and suggests that maybe we should all be breathing softly through our noses. :) https://www.pnas.org/content/pnas/118/17/e2018995118.full.pdf Bill
  11. If interested- a nice, up to date table re. vaccines, efficacy against variants, etc., though not much is known about the Indian variant at this point. Haven't watched the above video, perhaps just a different way to take in the data. I follow all of this daily at work, my recent apprehension was re. the SA strain, now will begin watching for data re. the strains from India. I am thankful we got Moderna at my hospital (and that my elderly parents received an mRNA vaccine):
  12. Yes, it was still called that until the early 90s when identified and named (so couldn’t be detected in the blood supply before then, as of course you know). I was rounding with residents once who wanted to transfuse a post-partum patient. I reminded them of prior blood-borne illness disasters. “But we can test for those now.” I explained that early in my training we thought we could test for everything also, that they didn’t know what they didn’t know. “What about a future hep G or H” I said. HHV-6 has been added to the list since then. I wonder about the epidemiologic da
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