Fig.26a shows the output spectrum from the test DAC using a 0dBFS, 10kHz CD test tone with no jitter introduced into the interface. (The test unit…
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In the following tests we introduce sinusoidal jitter to the interface timing by connecting a signal generator to the PLL control voltage. (Note that the PLL control voltage governs instantaneous clock frequency, so we must follow the law of Equation 14 in order to accurately predict injected jitter amplitude.) The DAC output is then digitized using a 16-bit ADC with an independent clock, and analyzed for jitter-related artifacts using a PC.
In addition, practical low-bit DACs often possess high levels of high-frequency quantization noise that has been shaped away from the audio band, and if very-high-frequency jitter is introduced into such a conversion process, intermodulation products can fall back down into the audio band, causing further degradation of dynamic range and noise modulation (footnote 17). (Our simulations employ a sampling rate of 44.1kHz, and thus can not model such secondary jitter artifacts.)
Analogy to Phase-Intermodulation distortion in Audio Amplifiers: Amplitude errors caused by timing jitter at the…
We now progress to an examination of simulated DAC errors due to band-limited interface jitter. Fig.36a shows the jitter-error spectrum for a 100% DAC reproducing a 0dBFS, 20kHz audio signal with an interface RC time constant of 40ns; the PLL cutoff frequency is set to infinity so that any jitter on the interface won't be attenuated before reaching the DAC. The error contains discrete frequency components rising from the noisefloor—this is because bandwidth-limited interface jitter can contain components that are well correlated with the audio signal (see "Interface Noise").
Fig…
When I was first getting interested in "high fidelity," as we called it back in the 1960s, there was an audio dealer in Worthing, England called Bowers & Wilkins. Their advertisement in the February 1966 issue of Hi-Fi News features their annual sale, with a Quad Electrostatic Speaker priced at £30 instead of the manufacturer's recommended £37 (footnote 1), and offering other bargains, from ReVox, Quad, Rogers, Leak, and Armstrong. Conspicuous by their absence from the ad are Bowers & Wilkins speakers. The first reference to those I could find was in the August 1968 issue of what was…
I had two first impressions of the 705. The first was that its sound, while not mellow, was very smooth. The second was that while it didn't seem to lack sensitivity, it did appear to need quite a lot of drive for the music to come to life. But come to life it certainly did, the sweep of the orchestral sound on our September 2002 "Recording of the Month," Joshua Bell performing the Beethoven and Mendelssohn violin concertos (Sony Classical SK 89505), being reproduced in a most generous manner. Despite that, the image of the solo violin was well-focused and stable, without any tendency to…
Sidebar 1: Specifications
Description: Two-way, reflex-loaded, stand-mounted loudspeaker. Drive-units: 1" (25mm) aluminum-alloy dome tweeter, 6.5" (165mm) woven-Kevlar cone woofer. Crossover frequency: 3.7kHz. Frequency response: 46Hz-25kHz, ±3dB; -6dB at 43Hz & 50kHz. Sensitivity: 89dB/2.83V/m. Nominal impedance: 8 ohms (4.6 ohms minimum). Harmonic distortion (second & third harmonic at 90dB, 1m): ±1%, 90Hz-20kHz; ±0.5%, 150Hz-18kHz. Power handling: 50-120W, unclipped.
Dimensions: 16.5" (420mm) H by 8.75" (222mm) W by 11.4" (290mm) D. Cabinet volume: 16 liters. Weight: 21 lbs…
Sidebar 2: System
Digital sources: Mark Levinson No.31.5 CD transport & No.30.6 D/A processor; dCS 972 upsampler; Musical Fidelity Tri-Vista SACD player; Technics DVD-A10 DVD-Audio player; Mark Levinson No.390S"> CD player.
Preamplification: Mark Levinson No.380S.
Power amplifiers: Mark Levinson No.33H and Musical Fidelity kW monoblocks (the latter using dual power supplies)
Cables: Datalinks: Kimber Illuminations Orchid AES/EBU, AudioQuest SVD-4 S/PDIF. Interconnect: Madrigal CZ Gel-1 (No.390S, balanced), Ayre Signature Series (Levinson, balanced), DiMarzio (Musical…
Sidebar 3: Measurements
The 705's sensitivity was to specification, at an estimated 89.2dB(B)/2.83V/m, which is a little above average. Its impedance (fig.1) remained above 5 ohms throughout the audioband, dropping to 4.2 ohms only above 15kHz and staying above 6 ohms for almost the entire midrange and treble. The small blip at 31kHz implies that the tweeter's fundamental dome resonance lies much higher than usual. The saddle at 40Hz in the magnitude trace indicates the tuning frequency of the big-mouthed port. Blocking this with the supplied foam plug produced a classic sealed-box…
While large, floorstanding speakers appear to offer the most material for the buck, I feel that small stand-mounted speakers both offer the best value in sound quality, as well as standing the best chance of sounding good in moderate-sized listening rooms. In recent months Stereophile has reviewed a varied group of such speakers. In order of descending price, these include the Acoustic Energy AE2 Signature ($5495/pair, November '95); Dzurko Acoustics Jaguar ($4500/pair, reviewed elsewhere in this issue); Totem Mani-2 ($3995/pair, February '96); Platinum Audio Solo ($2498/pair, November '95…
Sound
The original PSB Stratus Mini was a soundstaging champ, throwing well-defined, stable, accurate stereo images with depth a-plenty. The New Mini built on its predecessor's performance in this area. While its soundstaging didn't quite have the palpability of the JMlab Micron Carat, it was the equal of the B&W Compact Domestic Monitor 1. The orchestra on Stereophile's Festival CD (STPH007-2) was arranged in a deep but narrow configuration live. The piano on Aaron Copland's Appalachian Spring, for example, should sound as if it were at the left rear of the stage. This was the case…
The original PSB Stratus Mini was a soundstaging champ, throwing well-defined, stable, accurate stereo images with depth a-plenty. The New Mini built on its predecessor's performance in this area. While its soundstaging didn't quite have the palpability of the JMlab Micron Carat, it was the equal of the B&W Compact Domestic Monitor 1. The orchestra on Stereophile's Festival CD (STPH007-2) was arranged in a deep but narrow configuration live. The piano on Aaron Copland's Appalachian Spring, for example, should sound as if it were at the left rear of the stage. This was the case…