CD Player/Transport Reviews

By contrast, Wadia's DigiMaster filter looks at a number of samples and calculates what the shape of the curve should be between them using a "spline" algorithm. This has a much simpler impulse response (fig.2), and it can be seen that it is free from almost all the pre- and post-ringing. This better-behaved time-domain behavior, this better representation of transient information, is the raison d'être of the Wadia filter.

Figs.1 and 2 were generated using special digital data—digital "black" with a single sample high. In practice, all transients on a CD will have passed through an A/D converter with an antialiasing filter, which will impose its own impulse response on the shape of the transient. This might be thought to render moot the shape of the player's own impulse response.

Fig.1 Conventional digital reconstruction filter, impulse response (digital silence with just one sample at 0dBFS).

Fig.2 Wadia DigiMaster digital reconstruction filter, impulse response (digital silence with just one sample at 0dBFS).

To investigate this, I used an analog generator to output a short rectangular pulse and digitized it using a 20-bit/44.1kHz A/D converter. This signal, too, has a single sample at 0dBFS, but there are now ADC filter pre- and post-echoes present, the latter overlaid by the inevitable impulse response from the analog high-pass filter. Feeding these data into a D/A with a conventional filter (fig.3) and into the Wadia (fig.4) gave superficially similar waveforms. However, if you look closely, you can see that the conventional filter does appear to ring more than the Wadia's, presumably due to the convolution of the two similar sinc impulse responses.

Fig.3 Conventional digital reconstruction filter, response to a high-pass-filtered sinc-function pulse.

Fig.4 Wadia DigiMaster digital reconstruction filter, response to a high-pass-filtered sinc-function pulse.

The Wadia Sound
I auditioned two samples of the 850, the second differing only in that it was fitted with the optional digital input board. The two sounded identical. Comparing the sound of the 850 used with the line preamplifier with it used direct into the power amplifiers, with levels matched at 1kHz, it was obvious that even a good-sounding preamp reduces the player's sense of immediacy.

It was in the palpability of images that the Wadia scored—big time. I dug out a CD I hadn't listened to in years, Tony Faulkner's 1984 recording of Mahler's Symphony 4 with Kathleen Battle and Lorin Maazel conducting the Vienna Philharmonic (CBS/Sony MDK 44908). Mahler may use a big orchestra, but his scoring depends on small tonal contrasts as themes are handed around between the different instrumental groupings. With the Wadia, such delicacies as the tonal difference between the oboe and the english horn, and the fact that the pizzicato bass line in the third movement (Ruhevoll) is doubled by a lightly strummed harp, were laid clear, but without the presentation becoming oppressively overlit.

And with the Wadia used balanced straight into the Levinson amplifiers, there was a weight to the low frequencies that had to be heard to be believed. I don't want to use the much-overused audiophile word "slam," but slam is what the 850 delivered in truckloads. At the end of the Mahler's third movement, following contemplative segments, the timps slam in on a tonic and dominant riff that literally jumps from the speakers courtesy of the Wadia. The contrast between those high-level dynamic sounds and the delicacy with which the player subsequently treated Kathy Battle's lyric soprano in the final movement was delicious.

It wasn't just on classical recordings that the Wadia's combination of dynamics and clarity served the music. On Bobby Bland's rendering of "I Wouldn't Treat a Dog...," from his 1974 Dreamer album (MCA MCAD-10415), the Wadia propels the track along, bringing out the atomic combination of Ed Greene on drums and Wilton Felder on bass, and laying bare the great horn arrangement hinged on the kind of baritone sax line that I used to dream of playing along with when I was in a soul band.

And on poor recordings, the Wadia neither bowdlerized nor exaggerated the faults, but just let the music through unfettered. For example, I just picked up the CD rerelease of the album (Turn It Over) from the late Tony Williams and his 1970 band Lifetime (Verve 314 539 118-2). I saw this extraordinary group—featuring guitarist John McLaughlin, bassist Jack Bruce, and organist Khalid Yasin (Larry Young)—live just the once, but it was a formative experience. Williams had recently vacated the drum chair of Miles' Silent Way band, Bruce had just left Cream, and McLaughlin had just released his groundbreaking Extrapolation album. Their dark, complex, antagonistic music opened unimagined vistas about what I expected from jazz. (And no, I had not smoked any herbal cigarettes at the gig.)