The Class-A Stereo Amplifier described in the May to September 2007 issues is an ultra-low distortion amplifier suitable for demanding applications. At $599.00, it’s not cheap to build but that’s a price many people are prepared to pay to achieve excellent performance.

By contrast, the prices of DVD players (most capable of playing almost any format you can think of) have dropped dramatically. As a result, you may be tempted to use such a player to listen to your CD collection through the Class-A amplifier, particularly if your CD player is old or "on the fritz".

Part of the problem is that dedicated CD players are no longer cheap to buy. Nor are they as readily available as they once were. To buy one, you now have to go to a hifi shop and the prices generally start around $400.00.

So how well do cheap DVD players perform as far as sound quality is concerned? Can cheap DVD players be used in place of much more expensive, better quality CD and DVD players? Is there a difference between CD and DVD players in terms of audio performance, even for the better quality units? We decided to find out.

To obtain an idea of the audio quality of a range of equipment, we used our Audio Precision Test Set to test a selection of players owned by various staff members of SILICON CHIP. The players tested included DVD players, CD players and CD ROM drives (including one in a notebook). The results are summarised in Table 1.

All players were checked using the 1kHz 0dB sinewave track from the Technics SH-CD001 CD test disc. In each case, we measured THD+N (total harmonic distortion) and SNR (signal-to-noise) ratio.

Fig.1: block diagram of the Zoran Vaddis chip, version 888. It is a single chip solution for DVD players and DV recorders. The device includes the motor drivers, an RF amplifier and a processor, as well as various digital interfaces for external memory and external memory cards. In addition, there are input ports for video and audio, and output ports for 5.1-channel surround sound and video. There are also optional connections to hard drives (for DVR applications) and USB ports. Finally, there is a display driver, button decoding and remote control inputs. Chips of this series are found in many different DVD players.

In summary, Table 1 shows: (1) the type of power supply used and whether it is inside or outside the case; (2) the RMS signal output voltage; (3) the SNR with and without audio band filtering; and (4) the distortion with audio band filtering (which is substantially better than the distortion measured without audio band filtering, especially for the switchmode equipment).

Note that although the cheap DVD players like the Tevion TEV1020 had quite good SNR figures, they exhibited relatively high distortion and audible hum. The midrange DVD players like the Magnavox MDVD50 and the Audio World AW-8032 both had better distortion figures. The more expensive DVD players like the Panasonic DMR-ES10 (a DVD recorder) also performed well, with good distortion and SNRs.

Note that all these DVD players are double-insulated with switchmode supplies and for reasons to be explained shortly, produce audible hum when connected to any earthed stereo amplifier. By "earthed" we mean an amplifier with a 3-core power flex and 3-pin plug.