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Internally, the 27ix's construction reveals impeccable attention to detail. Separate subenclosures, again constructed from thick panels of machined aluminum, house the data input circuitry and the power transformers. A large printed circuit board carries the power-supply rectifiers, capacitors, and voltage regulators, and a sandwich of three smaller multi-layer pcbs. These are plugged together and carry the data receiver chip, the D/A converters—four Burr-Brown PCM1702s per channel, operated differentially, one mounted above another to cancel stray field effects—the DSP/digital filter…
Listening
With the 270 driving the 27ix and the latter connected directly to the Levinson power amplifiers, the sound quality was jaw-dropping. Only the Linn Sondek CD12, which Wes Phillips reviewed in February, was in the same league for CD playback. Even my own Mark Levinson No.31.5/No.30.5, which I purchased a few years back, fell a little behind when it came to the sheer transparency of the Wadia's presentation.
With the 270 driving the 27ix and the latter connected directly to the Levinson power amplifiers, the sound quality was jaw-dropping. Only the Linn Sondek CD12, which Wes Phillips reviewed in February, was in the same league for CD playback. Even my own Mark Levinson No.31.5/No.30.5, which I purchased a few years back, fell a little behind when it came to the sheer transparency of the Wadia's presentation.
Tiny recorded details were laid bare, yet without the presentation being spotlit or forced. When I used the Wadia 27ix as the monitoring converter for the mixing of…
Sidebar 1: Specifications
Wadia 27ix: D/A processor with remote, digital-domain volume control (0.5dB steps). Sample frequencies accommodated: 96kHz, 88.2kHz, 48kHz, 44.1kHz, 32kHz. Digital filter: DigiMaster algorithm running at 64x rate (16x in software-based filter, 4x in hardware). Inputs: two ST-type glass-fiber optical, two coaxial S/PDIF on BNC jacks, AES/EBU, TosLink optical. Outputs: balanced on XLR jacks, single-ended on RCA jacks (both outputs can be used simultaneously). Output impedance: 15 ohms. Maximum output level: user-adjustable in 16 steps, 410mV-9V. Frequency response…
Sidebar 2: Associated Equipment
Digital sources: Mark Levinson No.31.5 CD transport and No.30.5 DAC, connected with Illuminations Orchid AES/EBU link; Wadia No.270 CD transport and No.27ix DAC, connected with ST-glass links. (The Levinson '31.5 was also used to drive the 27ix via an ST link.) Nagra-D open-reel digital recorder at 44.1kHz (and at 96kHz via the dCS 972 D/D converter) and Panasonic SV-3700 DAT recorder, all connected via a Meridian 518 reclocking unit and Canare 110-ohm AES/EBU cables; California Audio Labs CL-20 and Denon DVD-5000 DVD players for 96kHz material.
Analog…
Sidebar 3: Measurements
The Wadia 27ix's output is noninverting from both its unbalanced and balanced outputs (the latter with pin 2 hot). The source impedance was a very low 8.1 ohms across the audio band from the unbalanced outputs, approximately double that from the balanced jacks at 15 ohms. Both are low enough to drive long interconnects and awkward loads without problem, facilitating the Wadia's use without a preamp. The maximum output level as supplied for review was 4.34V from the unbalanced outputs, 4.28V balanced. Channel balance was a superb 0.01dB.
The time-domain-…
Wadia's DigiMaster filter gives a very good squarewave shape (fig.3), with just a single overshoot cycle. The overshoot is preserved when the sample rate is doubling to 96kHz (fig.4), but its period is halved. And while a 96kHz-sampled, 12kHz squarewave is not particularly square (fig.5), it does have a very good fundamental-plus-third-harmonic shape.
Fig.4 Wadia 27ix, 1kHz squarewave at 0dBFS, 96kHz sampling.
Fig.5 Wadia 27ix, 12kHz squarewave at 0dBFS, 96kHz sampling.
The Wadia 27ix injects extremely low levels of noise into its analog output. Fig.6…
The linearity was also superb, as can be seen in fig.8. The amplitude error is negligible down to -110dBFS. This and the low noise are confirmed by the waveshape of an undithered 1kHz tone at -90.31dBFS (fig.9), where the three voltage levels and the transitions between them are clearly defined. With 24-bit data, the result was a reasonable if noisy sinewave (not shown).
Fig.8 Wadia 27ix, balanced outputs, departure from linearity. (Right channel dashed, 2dB/vertical div.)
Fig.9 Wadia 27ix, waveform of undithered 1kHz sinewave at -90.31dBFS (16-bit data).
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Intermodulation distortion was low (fig.12), with the 1kHz difference component below -90dB from peak level. (Note that, with this test signal, the peak level is 6dB higher than the level of either of the individual tones.) However, you can see images of the tones reflected back down from the sampling frequency between 12kHz and 16kHz. The price paid for the Wadia filter's excellent time-domain behavior is poorer rejection of ultrasonic spuriae. Interestingly, the intermodulation products rise a little into a 600 ohm load (fig.13), but so do the aliased images.
Fig.12 Wadia 27ix,…
This can be seen graphically in fig.14. Without the clock link (grayed-out trace), the first three lower, data-related sidebands (red markers "2," "3," and "4") are higher in level than the upper sidebands. Adding the clock link drops these sidebands in level to match the lower ones. It also eliminates pairs of sidebands at ±15.6Hz and ±340Hz. However, it does not appear to affect the higher-harmonic sidebands (red markers "5" through "11"), and a pair of low-level sidebands at ±174Hz can now be seen (purple marker "1").
Fig.14 Wadia 270 & 27ix via ST-optical connection with…
Jonathan Scull wrote a Follow-up in January 2002 (Vol.25 No.1):
I was stunned when I unpacked the Wadia 270 CD transport. For $7950, it's a beautifully built component—more than 30 lbs of machined aluminum, down to the brackets, clamps, and chassis components. Even the two damping plates sandwiching the clock and output circuit boards are each machined from a solid block of aluminum. The 270 is big and heavy, with a solid disc drawer and an easy-to-read display, and comes with wide, easily adjustable spiked feet and elegant gray spacers for docking with the $8950 27ix Digital Decoding…