The S/PDIF and AES/EBU interfaces used to connect a CD transport to a digital processor are a perfect example. When the digital interface was standardized, no one considered that its design could…
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Making digital audio sound good appears to be a much more difficult job than its developers first realized. When digital audio was in its infancy, there was a tendency to think that digital either worked perfectly, or didn't work at all. This belief led the engineering community to devise ill-considered and flawed standards that affect the musical quality of digitally reproduced music today.
The current-to-voltage converter (I/V) is a discrete design first used in the Theorem, but with some modifications that reportedly result in better transient performance. This is followed by a fully discrete, class-A, direct-coupled analog output buffer that runs on ±35V rails (most output stages run on ±15V). The output low-pass filter is a newly designed third-order Bessel type. The I/V converter, low-pass filter, and output buffer are integrated into a single stage that uses very little feedback. Moreover, the output transistors are hefty TO-220 packages that can reportedly drive half an…
Sidebar 1: System
I treated the Axiom and Theorem primarily as a CD player in two boxes: the advantages of a separate clock suggest that these two products will work best together. I also evaluated the Axiom and Theorem separately, driving the Theorem with Mark Levinson No.31 Reference and Theta Data Basic transports. Similarly, the Axiom drove the Theorem II and Adcom GDA-600 digital processors. Digital interconnects included AudioQuest Diamond x3 (AES/EBU), Parasound DataBridge (coaxial), and a Prisma coaxial cable.
The processors under audition drove an Audio Research LS5…
Sidebar 2: Measurements
The Theorem II's maximum output level was 2.03V, conforming with the CD standard of 2V output. The output impedance was a low 70 ohms at 20Hz, decreasing to 50 ohms at 1kHz and above, making the Theorem II insensitive to preamplifier loading. DC levels were negligible, measuring just 0.2mV (left channel) and 0.1mV (right channel). The Theorem II's polarity button works: set to positive polarity, the Sumo doesn't invert absolute polarity from its RCA outputs. Because pin 2 of the XLR connector is the signal conductor and pin 3 is grounded, the Theorem II will be…
Sidebar 3: Specifications
Theorem II D/A converter: Frequency response: 20Hz–20kHz ±0.5dB. THD: <0.004% at 2V output. Signal/noise ratio: !w100dB. Channel separation: >80dB. Induced jitter: <80ps. Conversion system: 18-bit hybrid DAC. Digital filter: 8x-oversampling. Analog section: discrete, DC-coupled. Inputs: TosLink optical, RCA coaxial, clock (RCA).
Dimensions: 19" W by 2.75" H by 11" D. Weight: 20 lb.
Serial number of unit reviewed: 1000956.
Price: $899 (a version with true balanced outputs costs $1099) (1995); no longer available (2019).
Axiom CD…
Spectral analysis of a live blues band recording made by John Atkinson, showing content up to 40kHz, from "What's Going On Up There?"
With a few exceptions, audiophiles have long advocated high-rez music formats, believing that music should be recorded and presented in the highest fidelity possible, for our pleasure and posterity.
And yet a few people in our community, and many more outside it, have long maintained that CD is good enough—that, indeed, as a general principle, music at CD resolution is indistinguishable from high-rez music. And until recently, scientific evidence…
Think of the greatest commercial LPs made during the past 72 years: the Solti-Culshaw recording of Wagner's Der Ring des Nibelungen, Magda Tagliaferro's D'ombre et de lumiere, Ornette Coleman's The Shape of Jazz to Come, John Lennon's John Lennon/Plastic Ono Band, and a thousand or so others.
Music lovers were able to buy those records because somebody believed that selling them could be profitable. If that's capitalism at its best, then capitalism at its second-best is surely those somebodies who rescue long-unavailable LPs from commercial and/or sonic oblivion by investing time and…
Until about a week ago, I thought Classé Audio was out of business. Imagine my surprise when I discovered that Classé was not just alive but also kicking, with a new line of high-end electronics, which were being showcased, along with flagship products from Marantz and Polk Audio, at Montreal audio-video importer Sherpa Group's offices. What's more, it was happening tomorrow–that is, the day after I found out about Classé's resurgence.
Turns out that US-based Sound United, which also owns Marantz and Polk, among other well-known audio brands, acquired Classé in 2018, a transaction that…
Yup, it sounds weirder than hell, even if talk of hell is best tabled at Christmastime. But never mind: The New Orleans Jazz Band of Cologne’s Santa Claus is Coming to Town is the real swinging thing. Masterfully recorded live in 24/96 “direct 2-Track Stereo digital” by Andreas Otto Grimminger during a concert at Bad Homburg Castle on December 9, 2018, mastered by Grimminger and Josef-Stefan Kindler, and released on what I believe to be the KuK label, the recording finds the seven members of the band in prime form. Swinging in a venue that’s far from a joint in the French Quarter of N’Orleans…
Subjectivist audiophiles have long maintained that long-term listening is necessary to assess the quality and character of an audio component. Scientific testing methodologies such as ABX, which require quick and conscious evaluation of a change in the sound, have long struck many of us as insufficient, seeming to miss much that affects our enjoyment of music. A pair of Genelec researchers—Thomas Lund, an audio professional with a medical background, and Aki Mäkivirta, a research and development manager and a Fellow of the Audio Engineering Society—have published two articles (footnote 1) on…