Esoteric DV-50 universal player Measurements
The Esoteric DV-50 had a maximum balanced output level at 1kHz of 5.05V RMS for CD and DVD playback, 5.11V for SACD. The unbalanced output was a little less than half this at 2.34V, which is an audible 1.4dB greater than the standard CD output. The output impedance was moderately low across the audioband, at 448 ohms unbalanced and 664 ohms balanced. Error correction was good, the player coping with gaps in a CD's data spiral of up to 1mm in length without audible glitches.
The frequency response for SACD playback (fig.1) extended above 20kHz, but showed that the ultrasonic rolloff mandated by the SACD license prevented high levels of RF noise from affecting the playback system. The response can be seen to be 3dB down at 62kHz. For CD and DVD playback, the response depended on the digital filters chosen. With the standard 8x-oversampling low-pass filter—labeled "FIR" on the front panel and presenting the DAC with a 352.8kHz datastream for CD playback, 384kHz for DVD—the response is flat within the audioband (fig.2, top trace above 7kHz). But with the "RDOT" filter selected, or the RDOT plus the FIR filter, the response is down almost 2dB at 20kHz, which will be just audible.
Fig.1 Esoteric DV-50, SACD frequency response at -3dBFS (right channel dashed, 1dB/vertical div.).
Fig.2 Esoteric DV-50, CD frequency response at -12dBFS into 100k ohms with FIR filter only and de-emphasis (bottom), without de-emphasis (top), and with FIR+RDOT filters (middle above 7kHz). (Right channel dashed, 0.5dB/vertical div.)
However, the RDOT filter, like the similar filters used by Wadia, Sony, and Pioneer, gives better time-domain performance. Fig.3 shows the DV-50's reproduction of a 1kHz squarewave with the FIR filter selected. The tops and bottoms of the waveform show the Gibbs Phenomenon pre- and post-echo—though this may look like ringing, it's actually the result of the waveform missing its harmonics above half the sample frequency.
Fig.3 Esoteric DV-50, 1kHz squarewave response with FIR filter only, 48kHz sampling.
By contrast, fig.4 shows the same waveform when decoded by the DV-50 with the RDOT filter selected. Other than the single sharp overshoot at each transition point, it is a much better-looking squarewave. Is this improvement audible? It's hard to say, as the harmonic content that distinguishes between the waveforms in figs. 3 and 4 lies above 20kHz. Nevertheless, Paul Bolin reports that imaging specificity was improved with the RDOT filter, which is what other listeners have found (see this issue's "As We See It").
Fig.4 Esoteric DV-50, 1kHz squarewave response with FIR+RDOT filters, 48kHz sampling.
Fig.5 shows spectral analyses, performed with a swept 1/3-octave bandpass filter, of the DV-50's output while it decoded data representing a dithered 1kHz tone at -90dBFS from CD (16 bits, top below 6kHz), SACD (DSD, top above 6kHz), and DVD (24 bits, bottom). The increase in bit depth drops the noise floor by around 15dB, implying DAC resolution at around the 19-bit level, which is excellent. (Ignore the slight peak in the DVD traces around 16kHz, which is due to interference from the TV monitor I was using to navigate the Chesky test DVD's track menu.) The SACD traces overlay those of the 24-bit DVD below 1kHz, but above that frequency they start to be affected by the medium's rising noise floor. As a result, and as I've noted before, SACD actually has less dynamic range than CD in the audioband above 6kHz or so. As with other SACD players, the DV-50's ultrasonic noise peaks at around -45dB between 80 and 120kHz (not shown).
Fig.5 Esoteric DV-50, 1/3-octave spectrum of dithered 1kHz tone at -90dBFS, with noise and spuriae (from top to bottom at 10kHz): DSD data, 16-bit LPCM data from CD, 24-bit LPCM data from DVD (right channel dashed).