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  1. M

    Flaws in Recording: DC?

    I've got a recording that has a quiet section that looks like this: Looks like a DC offset for a couple of seconds. It's not audible, but I figured it could act like a DC offset which could be bad since my preamp & amp are direct coupled. I figured a high pass filter should fix it, so I...
  2. M

    MPEG4-SLS Streaming

    When it comes to high quality audio streaming, I've read a lot about MQA but not much about MPEG4-SLS. References, measurements, comparisons seem hard to find. The Wikipedia article doesn't say much. Primephonic's highest quality streaming uses the SLS format with Orastream, where Idagio's...
  3. M

    Trevor Pinnock Interview Series

    I just found this series of brief interviews of one of my favorite musicians. I hope you enjoy it as much as I do. I found this while researching his latest recording of The Well Tempered Clavier, which is a joy to listen to.
  4. M

    Simple Dynamic Compression & Expansion

    To compress or expand dynamics, I was wondering why a simple algorithm isn't used: convert each sample to a floating point in the range -1 to 1, then take it to some power P. If P = 1.0, the signal is unmodified. If 0 < P < 1.0 it compresses dynamics. If P > 1.0 it expands dynamics. Of course...
  5. M

    LSO Live Recordings

    I find LSO Live recordings sound anywhere from excellent to fantastic. I have a lot of large ensemble classical music recordings from 1940s Toscanini to modern, and the LSO Live are consistently among the best sonically. They have big unstrained dynamics, natural voicing with no boxiness...
  6. M

    Human Ear Polar Patterns

    As we measure rooms to improve response, we should ensure the microphone hears what our ears do. For example, when I measure my room, the UMIK-1 mic shows a bass null that doesn't appear with Rode NT1As. I think this is because that null is caused by sound reflecting off the back wall, which the...
  7. M

    Mic Calibration for Rode NT1A

    I have a pair of Rode NT1A mics that I use for recording local acoustic music events. These mics have lower noise and distortion than the UMIK-1, but they have non-flat frequency response and they don't have individual calibration files. I created detailed calibration files for these mics, so I...
  8. M

    HDCD in Practice

    In summary, as I understand the HDCD spec, it uses the LSBs of each sample as a bitstream to encode flags telling the DAC to trigger various functions that the HDCD spec requires to be programmed into the DAC, like different AA filters or amplitude shaping curves. I'll ignore the AA filter...
  9. M

    Ideal DAC+Headphone Amp?

    I typically use my phone or tablet for music listening only in noisy environments like cars or airplanes, where sound quality is less important. That's also why I never invested in expensive IEMs because what would be the point a noisy environment? But recently due to working from home I was...
  10. M

    Loudness Wars and Classical Music

    Note: it turns out that my PC had a background app that was boosting the level by +10 dB. This didn’t show up in the audio panel, which had everything set to flat / zero. There was nothing wrong with this recording. However, I’ll leave this here since it talks about how to identify overly hot...
  11. M

    Best Piano Recordings

    Piano is difficult to record well and can be revealing of flaws in recording technique or playback systems. And there's so much great piano music nobody could listen to all of it in a lifetime. Here are some of the best piano recordings that I have heard. By "best" I mean they sound the most...
  12. M

    Classical Music Guides & Reviews

    I listen to all kinds of classical and more generally acoustic music: from medieval, renaissance, baroque, classical, romantic. My interest fades around 1900 when this music stopped sounding like music to me (with a few exceptions like Rachmaninoff and to a lesser extent others like...
  13. M

    Room EQ Wizard Import Sweep

    I've used REW for a while now, taking measurements, importing sweeps, no problems. I just ran into one that I can't figure out. Using version 5.20 Beta 4, I generated frequency sweep files. Played them back while recording. Then I go back to REW (same 5.20 Beta 4) and import the sweep recording...
  14. M

    TV Screens and IR Remote Interference

    This is tangentially audio related, since it's the IR remote volume control on my DAC/preamp. It sometimes works perfectly, other times intermittent and simply doesn't respond. With some troubleshooting I realized one correlating factor was it always worked perfectly when the TV was off...
  15. M

    DAC shuts off with all 0 input?

    What is a DAC supposed to do when the input signal is all zeroes? I've seen some that turn off or disable output, others that stay on and emit a "flat" analog signal. This makes DACs behave differently between tracks or similar situations. Is there a specification for the proper way for a DAC to...
  16. M

    Theoretically Ideal DA Reconstruction

    Learning more about how DACs work, I read about the Whittaker-Shannon interpolation formula. I created a spreadsheet implementing that formula, so I could plug in some test sampling points and see the analog wave it constructs. I realized that each sampling point has a diminishing ripple that...
  17. M

    Time vs. Frequency Domain

    Reading about perception in the time vs. frequency domains, I came across this study from several years ago: https://phys.org/news/2013-02-human-fourier-uncertainty-principle.html It's not an Earth shattering revelation that human hearing acuity is different in the time and frequency domains. I...
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