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The 2011 Richard C. Heyser Memorial Lecture: "Where Did the Negative Frequencies Go?" “What Happened to the Negative Frequencies?” & Science, a Digression

"What Happened to the Negative Frequencies?"
Nothing happened to them, of course, as I will show, but you mustn't forget that they are always there.

Everyone in this room will be familiar with the acronym "FFT." The Fast Fourier Transform is both elegant and ubiquitous. It allows us to move with ease between time-based and frequency-based views of audio events. You will all be familiar with the following example. Here is the waveform of a short section of a piece of music:

And here is the spectrum of that music:

This usefulness of the FFT algorithm—…

The 2011 Richard C. Heyser Memorial Lecture: "Where Did the Negative Frequencies Go?" Is There Something There?

Is There Something There?
Over the almost 35 years during which I have taken part in or organized listening tests, I have become convinced that what is fundamentally important is to respect the listeners—to listen to what they tell me. Yes, there may be a trivial explanation for what they hear. But there may be something there. When I first heard of so-called LP "demagnetization"—where an LP sounds better after being subjected to the action of, for example, a bulk tape eraser—I was skeptical. But I didn't dismiss the reports; I just filed them away for further investigation, if and when…

The 2011 Richard C. Heyser Memorial Lecture: "Where Did the Negative Frequencies Go?" Measuring Sound Quality, The Art of Reviewing

Measuring Sound Quality

Table 1: What is heard vs what is measurable

This is a table I prepared for my 1997 AES paper on measuring loudspeakers. On the right are the typical measurements I perform in my reviews; on the left are the areas of subjective judgment. It is immediately obvious that there is no direct mapping between any specific measurement and what we perceive. Not one of the parameters in the second column appears to bear any direct correlation with one of the subjective attributes in the first column. If, for example, an engineer needs to measure a loudspeaker's…

The 2011 Richard C. Heyser Memorial Lecture: "Where Did the Negative Frequencies Go?" Case Study 2: Loudspeakers

Case Study 2: Loudspeakers
During a visit to Canada's National Research Council many years ago, I noticed, stuck to the wall of the prototype IEC listening room, a page of results from one of Floyd Toole's seminal papers on the blind testing of loudspeakers. The scoring system was the one that Floyd developed and that I subsequently used for blind tests at Stereophile: "0" represents the worst sound that could possibly exist, "10" the perfection of live sound. On this scale, a telephone, for example, rates a "2." The speakers in Floyd's test pretty much covered the range of possible…

The 2011 Richard C. Heyser Memorial Lecture: "Where Did the Negative Frequencies Go?" Case Study 3: Digital Recording & Playback

Case Study 3: Digital Recording & Playback
The title of this lecture asks "Where did the negative frequencies go?" Once we enter the world of digital audio, they are very much present. Here is the spectrum of the music waveform I showed earlier:

And this is the spectrum of the same signal after it has been sampled in the time domain:

The positive (red) and negative (blue) spectra are mirrored around the sampling frequency and all of its harmonics, the latter extending to, if not infinity, then to something practically close to it. If you wish to play back…

The 2011 Richard C. Heyser Memorial Lecture: "Where Did the Negative Frequencies Go?" Case Study 4: Amplifiers

Case Study 4: Amplifiers
To many audio engineers, the amplifier is a solved problem. Static distortion and noise levels can be restricted to well below the threshold of human hearing at all audible frequencies and at all power levels short of clipping. Yet the darned things continue to surprise by sounding different—perhaps only slightly different, and sometimes for trivial reasons, such as too high an output impedance. But over the years I have been measuring amplifiers, some things have fallen out of the cloud of measured data: factors that are shared by amplifiers that sell well to…

Musical Fidelity M1 DAC John Atkinson January 2013

John Atkinson reviewed the Musical Fidelity M1DAC in January 2013 (Vol.36 No.1):

Sam Tellig enthusiastically reviewed this inexpensive solid-state D/A processor in March 2011. "What I mainly heard from the M1DAC was nothing: an absence of artifacts, if you want to get fancy," he wrote. "There was no fudging of detail, no smearing of transients. Purity of tone was exceptional."

Some months after that review was published, the M1DAC was updated. Whereas the original version's USB input was limited to 48kHz sample rates and below and 16-bit data, the new version uses the popular…

There's a lady who's sure all that glitters is gold...

Here in the age when rock stars like Jagger and Richards are not only still breathing, but are now turning 70—“I’d rather be dead than sing “Satisfaction” when I’m 45,” Mick once said with a straight face—seeing older bands reunite and “play” can be very disappointing. There are some, who shall remain nameless, that I have sworn off of completely. The past can never really be recaptured. And no one escapes the ravages of time. Neither they nor you are as young as you once were.

Before I sat down to write about the new Led Zep concert film, Celebration Day, I watched the old Led Zep…

First Time Ever: Mahler Download in DSD

Just in time for the New Year, Cookie Marenco of Blue Coast Records has released the first-ever DSD (Direct-Stream-Digital) download of the San Francisco Symphony Orchestra's recording of Mahler's Symphony No.1. Recorded live in Davies Symphony Hall in September 2001, shortly after 9/11, and first released as a hybrid SACD in 2003, the recording is one of the only four Mahler symphonies in SFSO's complete Mahler cycle that were recorded directly to DSD.

The Mahler 1 files, available in four formats, are all derived directly from San Francisco Symphony's master, not from a copy of the…

Recording of January 2013: Wagner: <I>Der Ring des Nibelungen</I>

Wagner: Der Ring des Nibelungen
Birgit Nilsson, Hans Hotter, Wolfgang Windgassen, George London, Gustav Neidlinger, Gerhard Stolze, Gottlob Frick, Dietrich Fischer-Dieskau, Kirsten Flagstadt, Set Svanholm, James King, Régine Crespin, Christa Ludwig, many others; Vienna State Opera Chorus, Vienna Philharmonic, Georg Solti
Decca 0289 478 3702 2 (17 CDs, 1 BD, 1 DVD). 1958–66/1997/2012. John Culshaw, prod.; Gordon Parry, eng.; James Lock (1997), Philip Siney (2012), remastering. ADD. TT: 14:36:56 (Ring only)
Performance *****
Sonics *****

Gramophone called it "the recording…