With the Raven Spirit on the floor—it was too large for my Box Furniture equipment rack—and roughly midway between my preamp and the left-channel…
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Nonetheless, it was another day or two before I could get the Raven Spirit up and running: As with the mono versions, the review sample arrived without a manual, and the first tube chart I received, via e-mail, proved to be out of date. (I discovered that not with pyrotechnics, but by noting that the amp wasn't shipped with the same complement of tubes as described in the chart.) A new chart arrived soon thereafter, and proved correct.
Sidebar 1: Specifications
Description: Tubed stereo power amplifier. Tube complement: four 12J5, six 12SN7, four 300B. Input terminals: one pair of XLRs, one pair of RCAs. Output transformer taps: 4 or 8 ohms. Output power: 28Wpc or 36Wpc (load not specified). Frequency range: 20Hz–20kHz. Recommended speaker sensitivity: 90–96dB.
Dimensions: 19.4" (500mm) W by 10.5" (270mm) H by 11.5" (295mm) D. Weight: 64 lbs (29.1kg).
Serial number of unit reviewed: SP-RSA-05-23-2012-0001.
Price: $7295. Approximate number of dealers: sold factory direct.
Manufacturer: Raven Audio, 131…
Sidebar 2: Associated Equipment
Analog Sources: Garrard 301 turntable; EMT 997 tonearm; EMT OFD 25 & TSD 15 70th Anniversary pickup heads.
Digital Sources: Halide Designs DAC HD USB D/A converter; Apple iMac G5 computer running Decibel v.1.2.11 playback software; Sony SCD-777ES SACD/CD player.
Preamplification: Hommage T2, Bob's Devices CineMag Sky 30 step-up transformers; Shindo Masseto preamplifier.
Power Amplifiers: Shindo Corton-Charlemagne monoblocks.
Loudspeakers: Altec Valencia, DeVore Fidelity Orangutan O/96.
Cables: USB: AudioQuest Carbon, Nordost Blue…
Sidebar 3: Measurements
I used my sample of the top-of-the-line Audio Precision SYS2722 system (see the January 2008 "As We See It" and www.ap.com) to measure the Raven Spirit 300B Reference Stereo. I installed the tubes using the revised guide that had been sent to Art Dudley; the output tubes were the pairs of Sophia Electric Royal Princess 300Bs he'd used in his auditioning. As the XLR jacks are connected with pin 2 in parallel with the RCA jacks, I performed all measurements using RCA cables to connect the amplifier to the Audio Precision, and ran the amplifier driving 1kHz at 1Wpc…
Manufacturer's Comment
Editor: They say be careful what you wish for. We just weren't ready, but appreciate your time and efforts. We think we found the culprit in one of the monoblocks: a loose resistor lead, but no sign of a short. Tell you one thing—we'll never again send anything out without putting it under a microscope.
We were gratified that Art wrote: "That the sound of Raven Audio's Spirit 300B Reference Stereo so thoroughly impressed me speaks more loudly than usual of the product's innate quality. This is a very good-sounding, musically exciting amp."
Next…
"Physical discs are so 20th century," I wrote back in 2006, when I began experimenting with using, in my high-end rig, a computer as a legitimate source of music. These days I rarely pop a disc into my Ayre Acoustics C-5xeMP disc player, unless it's an SACD I want to hear, or a CD I haven't yet ripped into my library. But many audiophiles, even if attracted to the idea of using a file-based system as a primary music source, do not want a computer in their listening rooms. Nor do they want to be bothered by the fact that a computer demands too intimate a relationship with its user.
For…
Nor do those files have to be stored on the M52 Music Vault. I have a Netgear NAS drive on our home network with a 1TB RAID 1 array, on which I store one of my iTunes backups. When I selected "Configure Network Shares" with the iPad app, the M50 recognized the NAS drive. Selecting "Re-index Music Collection" from the "Configure Player" panel added to the M50's library all the songs on the network drive, which then could be played in just the same way as songs stored on the M52. And the ability to copy files from the M52 over the network means that it can also be backed up via that network to…
Sidebar 1: Specifications
NAD Masters Series M50 Digital Music Player: Remote-controlled, networked file player and CD transport with slot-loading CD mechanism. File formats supported: MP3, AAC, WMA, OGG, WMA-L, FLAC, ALAC, WAV, AIFF, at sample rates of 32, 44.1, 48, 88.2, 96, 176.4, and 192kHz, and bit depths of 16 and 24. Connectivity: Ethernet/LAN RJ45, 802.11n WiFi, USB Type A port for external drives. Outputs: four digital (AES/EBU, coaxial S/PDIF, TosLink S/PDIF, HDMI audio). User interface: Free Android app available at Google Play website, free iOS app available at Apple App…
Sidebar 2: Associated Equipment
Digital Sources: Ayre Acoustics C-5xeMP SACD/CD player; Marantz NA-11S1 media server; Apple 2.7GHz i7 Mac mini running OS10.7.5, iTunes 10, Pure Music 1.89; Auralic Vega, NAD M51, Electrocompaniet ECD-2 D/A converters; Ayre QA-9 A/D converter.
Preamplification: Pass Labs XP-30 line preamplifier.
Power Amplifiers: MBL Corona C15, Pass Labs XA60.5 (both monoblocks).
Loudspeakers: Joseph Audio Perspective, Vivid Giya G3, Wilson Audio Specialties Alexia.
Cables: Digital: Apogee 110 ohm (AES/EBU), AudioQuest Coffee, Belkin Gold (USB).…
Sidebar 3: Measurements
As the NAD M50 has only digital outputs, the most important thing to measure is the quality of those outputs. Using my top-of-the-line Audio Precision SYS2722 system (see the January 2008 "As We See It" and www.ap.com), I connected the M50's AES/EBU output, which I'd used for all of my listening, to one of its AES/EBU inputs using a 45' length of Apogee 110 ohm balanced cable.
The SYS2722's input impedance was set to 110 ohms; the NAD's AES/EBU output impedance was close to this at 125 ohms. Playing 24-bit files, all 24 bits were active in the M50's…