I looked first at the Balanced Audio Technology VK-3iX's solid-state phono stage and assessed its performance at the tape-out jacks. However, this was somewhat difficult to assess with the internal switch in its high-gain position, as it needs to be fed from a very low source impedance, akin to that of a moving-coil cartridge. Even with the Audio Precision System One's source impedance set to 25 ohms, the interaction between the generator and the phono stage meant that the output waveform was massively distorted. The solution was first to insert shorting…
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Sidebar 3: VK-3iX Measurements
Sidebar 4: VK-55 Measurements
This amplifier's two output transformer taps are labeled "4–6" and "6–8"; I assume these numbers refer to the recommended load impedance in ohms. The VK-55 offered a fairly low voltage gain into 8 ohms from either tap: 22.1dB and 23.67dB, respectively. It also inverted signal polarity from both taps. The input impedance was usefully high, at 290k ohms at 1kHz, this dropping slightly to around 160k ohms at the band edges (footnote 1). The amplifier will therefore be a perfect match for the VK-3iX preamp.
The VK-55's source impedance was very high from…
As I write these words, it's the height of the fall catalog season in the Atkinson household. Whole old-growth forests must have died to ensure the everyday stuffed state of our mailbox, which adds to the sense of guilt I feel as I pitch the offenders into the trash without even giving their insides a passing glance. But there are three catalogs I do look forward to receiving, that I read from cover to cover, that I deface with multicolored Post-It notes. The Audio Advisor catalog is, of course, a no-brainer for an audiophile. But the Griot's Garage and Levenger catalogs get equal billing…
The top plate also carries the analog input level controls and level meters (called by Nagra "modulometers") for the four channels. Each computer-controlled meter has an overload LED that lights at -1.16dBFS and can be switched between Peak and Peak Hold; each channel also has a Safe/Ready-to-Record switch.
Each input level control consists of a dual pot: an inner Fade control, normally set to its "calibrate" position to allow for lowest noise/highest overload headroom; and an outer sensitivity control, marked in dB and ranging from -34dB to +3dB. It's this outer control that adjusts the…
Sound
My impressions of the Nagra-D were gleaned on three separate occasions: in November 1993, when I recorded Canadian pianist Robert Silverman performing the Liszt Piano Sonata in b and other works by Liszt; and in July and October '95, when I recorded, then edited, five days and nights of concerts and rehearsals at the 1995 Santa Fe Chamber Music Festival to produce our Festival CD.
My impressions of the Nagra-D were gleaned on three separate occasions: in November 1993, when I recorded Canadian pianist Robert Silverman performing the Liszt Piano Sonata in b and other works by Liszt; and in July and October '95, when I recorded, then edited, five days and nights of concerts and rehearsals at the 1995 Santa Fe Chamber Music Festival to produce our Festival CD.
Operationally, the unit was a dream. Once I had found my way around the menu (and discovered the essential Escape key combination), used the menu to set the tape tension to that appropriate for the…
Sidebar 1: Specifications
Description: Open-reel, computer-controlled, 4- or 2-channel, 24-bit, rotary-head digital recorder with: four balanced analog inputs (each switchable between transformerless line and phantom-powered microphone); four balanced, transformerless outputs; two pairs of stereo headphone outputs; two pairs of AES/EBU digital inputs; two pairs of AES/EBU digital outputs; external sync input; time-code input and output; and 9-pin RS-422 computer-control port. Scanner rotational speed: 3750rpm. Tape type: ¼" (6.35mm) digital tape (Ampex 467 or equivalent). Tape speed: 49.…
Sidebar 2: Measurements
The D's analog line input impedance measured 9.2k ohms at 1kHz; the analog output impedance was 87 ohms at the same frequency. With the inner Fade pot at its calibration point and the outer sensitivity pot at "0dB," 100mV in at 1kHz corresponded to -21dBFS on the modulometer; 1V just lit the overload LED at an indicated -1dBFS.
Fig.1 shows the line analog input/analog output frequency responses at an indicated -2dBFS with the front-panel control set to "Flat," "LFA," and "Speech," and the sampling frequency set to 44.1kHz. The sharp rolloff above 20kHz is…
I reviewed JMlab's Mezzo Utopia loudspeaker in the July 1999 Stereophile (Vol.22 No.7). By chance, the Mezzos had followed a pair of B&W Nautilus 801s into my listening room, and the substitution had proved rather interesting. For all their many fine qualities, the 801, with its 15" bass driver, was distinctly bass-heavy in my room, whereas the 11" drivers of the Mezzos seemed just right in this regard.
I began pondering that there might be a Goldilocks relationship between speakers and rooms—that there's a "just right" size of bass driver for any given room size. This makes some…
The tweeter is mounted on a precision-machined metal sub-baffle. Its interesting motor system uses a combination of a samarium-cobalt alloy (which has a high Curie point, footnote 1) close to the coil, backed up by a neodymium "focus ring" to give a very high field strength of 2 Teslas. The motors used in the cone drivers are also unusual, using seven small magnets to form a ring around the voice-coil in what JMlab calls a "power flower." This provides very high flux, and also makes better physical contact between the magnets and the polepiece metalwork, with therefore greater sample…
How a speaker distributes its sound throughout a room plays an important part in the final listening experience. This is one area in which there is no definite right or wrong; personal taste plays a crucial role. The GUBe steers an attractive middle road somewhere between such wide-dispersion designs as B&W's Nautilus series, with their separate mid and treble enclosures, and the Shahinian "omnis" on the one hand, and relatively narrow-dispersion models like the Quad ESL-988 and other dipoles, or speakers like the Tannoy Dimensions or JBL K2, which control directivity by horn-loading the…