search
With Sony's latest flagship single-box player ($1700), we find yet another variant on 1-bit D/A technology—High Density Linear Converter, or HDLC. At the heart of this Pulse Length Modulation (footnote 1) D/A technique is Sony's CXD-2552 Pulse D/A converter (two per channel in complementary mode in the CDP-X77ES). This complex LSI chip incorporates a third-order noise shaper, the PLM converter, and a digital sync circuit receiving its input from the system clock. Preceding the Pulse D/A converter is an additional CXD-1244 noise-shaping digital filter which performs the initial oversampling;…
Sidebar 1: Is a Bit Bits?
If you haven't seen reams of copy on the latest 1-bit D/A conversion schemes, you haven't been paying attention. Suffice it to say that all of these techniques abandon the common multi-bit, resistive ladder D/A converter topologies. Instead, the 16-bit signal is processed in the digital domain to convert it (requantize it, to use the technical term) to a series of identical amplitude pulses which vary in either their width (so-called Pulse Width Modulation, or PWM) or their density (Pulse Density Modulation, or PDM).
The result of this is that the signal…
I got an early start on computer audio. At the end of the last century I was using WinAmp with first a CardDeluxe PCI soundcard, then a similar card from RME, to play files on a Windows PC. After I became a MacPerson, I used FireWire audio interfaces from pro-audio company Metric Halo and an inexpensive USB-connected ADC/DAC from M-Audio. But it was with the USB version of Benchmark's DAC 1 that the computer began taking over from physical discs for my music listening. At first I used iTunes au naturel, but as I acquired more high-resolution files, I began using Pure Music to handle all the…
Sidebar 1: Specifications
Description: USB line (VBUS) and signal (data) filter. Input: USB Type-A male. Output: USB Type-A female.
Dimensions: Very small. Weight: very little.
Price: $49. Approximate number of dealers: 1200.
Manufacturer: AudioQuest, 2621 White Road, Irvine, CA 92614. Tel: (949) 585-0111. Web: www.audioquest.com.
Our small hobby contains many even smaller subgroups, some of them openly hostile to one another—itself a partial explanation for the whole small-hobby thing. I have been a card-carrying member of some of those groups, have lurked at the edges of others, and have ignored only a few—most notably that community of manufacturers who believe that the surest way to make a better piece of playback gear is to make it bigger and heavier and more expensive than anything else on the market: a group sadly notable for its influence over much of the reviewing community. Those exceptions aside, almost…
Sidebar 2: Associated Equipment
Digital Sources: Ayre Acoustics C-5xeMP DVD-A/SACD/CD/MP3 player, Apple 2.7GHz i7 Mac mini running OS 10.10.3 & MacBook Pro running OS 10.7.5, both with iTunes 11, Pure Music 2.0, Audirvana Plus 1.5.10; AudioQuest DragonFly, Meridian Explorer, PS Audio PerfectWave DirectStream D/A processors.
Preamplification: Ayre Acoustics KX-R Twenty line preamplifier, Bel Canto Black ASC-1 digital preamplifier.
Power Amplifiers: Ayre Acoustics MX-R Twenty, Bel Canto Black MPS1, MBL Corona C15 (all monoblocks).
Loudspeakers: GamuT RS7.
Headphones:…
Early in their existence as a manufacturer of amplification separates, Naim took that concept a step deeper into Audioland and designated the ground point within an outboard preamplifier power supply as the central signal-ground point for a complete Naim-based system—hence the company's famous insistence on driving the power amp with a signal picked up at that power supply instead of at the preamp itself (footnote 3). Similar attention has been given to the obviously related matter of mains grounding within a Naim system: In the late 1980s, some of Naim's UK dealers began experimenting with…
Sidebar 3: Measurements
It's difficult to decide how to characterize the measured performance of products, such as AudioQuest's JitterBug, that don't operate directly on the analog signal. Yes, there exist USB bus analyzers—available from such companies as Tektronix—that Wavelength's Gordon Rankin, one of the JitterBug's designers (along with Garth Powell), uses. These can examine various issues affecting data transmission: data-packet errors, jitter, noise, etc. However, they cost tidy sums—too much for me to be able to justify to my paymasters that Stereophile buy one for use in a…
Sidebar: Contacts
AV Options. Tel: (847) 329-9549. Web: www.avoptions.com
Sundazed Music, PO Box 85, Coxsackie, NY 12051. Tel: (518) 731-6262. Fax: (518) 731-9492. Web: www.sundazed.com
In a bizarre but happy turn of events, recent consumer trends have given even the most socially awkward audiophile something to talk about at cocktail parties and family gatherings at which normal people predominate: the PonoPlayer and vinyl. These are hot topics; each is among the best-sounding music sources available, and both offer hope for our hobby, if not for music lovers in general. But vinyl has the advantage of appealing to a much wider range of budgets. LPs can be had from anywhere to "We'll pay you to haul these away" to "Your loan officer is on line one." Likewise, vinyl playback…