Proceed CD player
The Proceed was a long time in development, reflecting Madrigal's care and thoroughness before releasing a new product. Many technical innovations have been incorporated into the Proceed, and the machine's unusual appearance exemplifies the "start from scratch" attitude behind its development. With its nearly square proportions, grey cabinet, and sparse front-panel controls, the Proceed may set a new trend in audio component styling.
The Proceed's design philosophy reflects the more recent trends in digital audio thinking. One of these ideas, which challenges conventional wisdom, places a high priority on the transport mechanism's sonic characteristics. Although it can be proved that virtually all CD transports produce an identical bit stream (at least the same ones and zeros), there is mounting evidence that CD mechanisms do make a sonic contribution to the decoded signal (footnote 1).
Madrigal chose the high-quality Philips CDM1 Mk.II metal transport for the Proceed. In addition, the Philips decoder electronics used with the CDM1 Mk.II have been modified to produce a cleaner "eye pattern." According to Madrigal, slight temperature changes affect the "eye pattern." The eye pattern, so called because the RF (Radio Frequency) signal produces a fuzzy waveform with a clear "eye" in its center when displayed on an oscilloscope, is the signal produced at the photodetector when struck by laser light reflected from a spinning disc. This raw signal contains all the information on a CD, and is subsequently decoded to retrieve the audio and subcode data. A high-quality RF signal is vital to error-free data retrieval. However, it is greatly affected by the pit shape created when the CD master glass is cut, and varies between CD plants (footnote 2).
The Proceed has an extensive power-supply system. According to Madrigal, the transport affects sonic performance through interaction with the power supplies. Without adequate care given to power-supply design, transport servos (focus, tracking, rotational) can affect the DC supply to analog audio circuitry. Madrigal has given the Proceed two master power supplies and 11 distributed supplies to ensure isolation between sections. These separate power supplies are individually regulated, an improvement over capacitive decoupling or filtering. Most of these regulators are three-pin TO-220 types. Four of these supplies provide DC to the analog section (one for each rail of each channel), four supply the DACs (again, one for each rail of each DAC), and there is one each for the transport logic, decoder, display, and digital filter. The regulators are scattered about the Proceed's circuit boards, in close proximity to the circuits they supply. In addition, the single power transformer has separate taps for digital and analog circuitry. Attention was paid to grounding, including large circuit-board traces to provide noise a free path to ground. The analog and digital sections each have their own ground plane.
This power-supply system is elaborate and impressive, especially in such a reasonably priced product. The digital decoding section features the ubiquitous Philips SAA7210 decoder chip and SAA7220 4x-oversampling digital filter. The latter chip is only partly used, however, to implement the error correction. The corrected digital signal is fed to an 8x-oversampling digital filter chip (the same, apparently, as that used in the ultra-expensive Accuphase player).
Usually, the Philips TDA1541 dual DAC is part of this chip set. However, Madrigal has chosen the Burr-Brown PCM58P DACs for the Proceed. I have noticed a tendency toward Burr-Brown DACs and away from the TDA1541 in the more sonically ambitious digital decoders. The PCM58P is an 18-bit unit with fast-settling, glitch-free current output and a Schmitt-trigger input. A Schmitt trigger reshapes the incoming signal into a near-perfect squarewave, providing the DAC with a clearer transition from one to zero at the signal's rising edge. After burn-in and just before shipping, each DAC's performance is optimized by adjusting an external MSB trimmer.
The analog audio section (electrostatically shielded from the rest of the digital circuitry) uses, according to Madrigal, "devices from a new generation of high-performance integrated circuits." These op-amps are said to maintain the advantages of discrete circuitry with external compensation using precision capacitors and resistors. Inside the Proceed, I saw 8-pin ICs that looked like op-amps, but could not distinguish their type: they were not marked. The Proceed's deemphasis circuitry is passive, and switched in the circuit by FETs.
Fully balanced outputs on XLR connectors, and unbalanced outputs on RCA jacks, are provided. In addition, a third RCA jack supplies a digital output to an external digital processor or DAT recorder. Output impedance is a very low 1 ohm.
Removing the Proceed's heavy metal cover revealed a unique and impressive layout. The Proceed's unusual shape allows optimum positioning of the circuitry, both for thermal considerations and for keeping analog and digital circuitry discrete. In addition, the circuit boards are mounted at right angles to each other, minimizing interaction between them. The transport and transformer are mounted on the bottom for stability. The audio board is mounted on the chassis's rear panel so the output jacks can be connected directly to the board. Parts quality appeared very high, including double-sided glass-epoxy circuit boards. I was particularly impressed with the Proceed's construction quality and level of thought put into its design and layout. It clearly represents some original thinking in CD-player design. The innovation and build quality would be impressive in a product twice the Proceed's price.
In addition to rethinking the inside of a CD player, Madrigal has also radically revamped the outside, both in appearance and functionality. The unusual shape and grey color set the Proceed apart from other CD players. The machine also eschews the trend to loading CD players with elaborate features, most of which are never used. Instead, the front panel is very plain. Just above the drawer are Stop, Play, Pause, Previous, and Next pushbuttons. The only other controls, on the right side of the panel, are marked Drawer (open/close), Next/Previous (index), Scan (forward/backward), Program, and Repeat. The machine is very straightforward and easy to use. In addition, the rubberized control buttons have a unique and comfortable feel.
Footnote 1: I do, however, disagree with Madrigal's assertion that better transports create fewer interpolations, thus improving the sound. Interpolations are rare events on most discs. In addition, since they occur periodically, not continuously, they would not affect the overall sound.
Footnote 2: Watch for an article next month on CD quality, including a survey of discs made at various factories around the world. Error-rate graphs, RF-signal photographs, and tips on how to detect poor-quality CDs will be included.