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SE-U55

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WIN MAC

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DIO AL AU R DIGIT USB OCESSO PR 5

5 SE-U

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USB DIG PRO ITAL AU DIO CES SE-U SOR

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Sutherland Engineering 12dAX7 USB DAC/preamplifier

Your E-ma

Michael Fremer, December, 2002
Computers and vacuum tubes go together like Trent Lott and flyaway hair, right? The last time filaments glowed in computers was during the 1960s, when a computer was a building. I remember laughing at the ponytailed computer-science dweebs back then, who spent their college days playing nursemaid to a football field's worth of electronics capable of little more than adding two plus two. Chained to a computer half the day, as most of us now are, guess who had the last laugh?

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So if you're going to be plopped in front of a screen all day, the least you can do for yourself is squeeze some decent sound out of your computerespecially if you work at home, or in an office where you can pump up the volume. Adding a highquality satellite-subwoofer system like Acoustic Energy's Aego2, Eminent Technology's LFT-11, or Cambridge SoundWorks' Megaworks 210D would be a good place to start. But there's much more you can do, and if your computer is equipped with a universal serial bus (USB 1.0) port, you can do it without messing with internal soundcards, which, while offering upgradeable audio, still must operate in a difficult environment. The high-frequency noise produced by digital processing does bad things to both the power supply feeding the audio circuitry and to the postconversion analog signal on its way out of the computer. USB 1.0 offers single-jack multi-function connectivity with reasonably high-speed data transfer, so even without a dedicated digital audio output jack on your computer, you could still take the D/A conversion and the rest of the audio circuitry out of its foul environsif, that is, you could get an outboard DAC with a USB interface. Now, thanks to Sutherland Engineering's 12dAX7, you can, and because it uses smooth-sounding 12AX7 tubes in its analog preamplifier circuit, you can also round off the audio jaggies inherent in MP3 recordings and make them not exactly listenable, but less noxious to the ear. Even if your computer doesn't have a USB port, you can add one. Keyspan, for example, makes a Mac/PC-compatible USB 2.0/FireWire card that fits into PCI expansion slots for $99, complete with installation software. [USB 2.0 is backwardcompatible with USB 1.0 devices.Ed.] Yes, some computer dweebs will be satisfied with nothing less than the higher data-transfer rate of IEEE-1394 (FireWire) connectivity, but for CD playback, USB 1.0 will do fine. The 12dAX7 About the size of a standard rack-mountable audio component, the PC/Maccompatible 12dAX7 will not be welcome on an overcrowded desk. But assuming you have the space, its transparent Plexiglas facedisplaying the circuit boards, LEDs, and glowing tubeswill make a neat addition to any workstation, and a real conversation piece. A chassis of cold-rolled steel provides a rigid platform for the dual-mono modular design, which uses printed-circuit boards of high-quality FR-4 fiberglass. There are modules for the power supply and digital circuitry and two for the tubed gain stages. Name-brand parts are used throughout, including 1% Dale metal-film resistors and Wima polypropylene film capacitors. There's also a toroidal power transformer, and
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Russian-made 12AX7 tubes with a claimed life expectancy of "at least" 10,000 hours. The digital circuit is based on Burr-Brown's surface-mount PCM 2702 chip, a 16-bit two-channel DAC with an integral 8x-oversampling filter and a USB 1.0 data input port. Hookup is simple: you run the supplied USB cable from your computer or USB hub output to the 12dAX7's USB port, run analog cables (or an RCA/RCA-to-stereominiplug cable) from the 12dAX7's RCA jacks to your amplifier or powered subwoofer-satellite system, and plug the 12dAX7 into the wall via the IEC AC jack. (Yes, you can even play with power cords. Knock yourself out.) Computer operating systems include bit-trimming digital volume controls that should be cranked full on or you'll be diminishing the digital resolution reaching the 12dAX7's DAC. The idea is to control volume in the post-conversion analog domain using the 12dAX7's analog volume potentiometer. When I switched on my computer, the 12dAX7 came to life: during the short warmup period, the turn-on relay clicked, the filaments glowed, and the yellow Mute LED came on. By the time my Mac G4 computer was booted up and ready to use, the 12dAX7's Suspended light had begun to glow as the computer looked for peripheral devices. Then it was the Zero LED's turn, until I inserted a CD into the Mac's CD-ROM drive and pushed Play. When the bitstream hit the 12dAX7, its green Play LED fired up and music poured from the speakers. When I shut the computer down, the relay clicked again, shutting down the Sutherland. Article Continues: Page 2

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Sutherland Engineering Web Site P.O. Box 1633 Lawrence, KS 66044 (913) 841-3355

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Okay Computer Sound I've been using a pretty-good-sounding and very inexpensive (ca $200) Onkyo SEU55 outboard USB-based converter with my Mac G4. It has optical and coaxial digital as well as analog line inputs and outputs, and built-in A/D and D/A converters so that, with the appropriate recording software (I use Peak LE 2.58 for Mac), I can feed it a cassette deck's analog output and store it digitally on the G4's hard drive. The Onkyo also has a headphone jack with volume control, which the Sutherland 12dAX7 doesn't, so for sheer versatility, the SE-U55 can't be beat. But while the Onkyo sounds pretty good, and much better than the G4's internal converter, it didn't come close to matching the 12dAX7's sound: rich, warm, sweet, airy, a bit fat on bottom, and, overall, BIG. In a computer-based sound system of small satellites and a sub listened to in the nearfield, "accuracy" in the usual audiophile sense isn't the issue. It's more about compensating for the limitations of the associated equipment and, especially when listening to MP3s, the software. Although I have a DSL line, I have no interest in downloading MP3sbut for this review I went to www.geffen.com to listen to a track from Peter Gabriel's new album, Up. Gabriel's albums have always been wellrecorded, even the digital ones, so I'm sure what I heard at 95.8kbps via RealPlayer was a shadow of what Classic Records' two-LP vinyl edition will sound like. The MP3 didn't sound bad, mind you, especially the bass, which was robust and well-

controlled, but from the midrange and up it sounded gauzy, kind of flat, and cartoony. But compared to Evatone "sheets"which is how I got to hear promo music as a kidthis was da bomb! The 12dAX7 greatly improved the sound of all three satellite subwoofer systems I used it with, providing a cushion of air where otherwise there would have been a parched sonic landscape. It smoothed over jagged edges and softened the impact of barbed-wire transients. Most impressive were the improvements in imaging, soundstaging, and harmonic development. Images became more solid and threedimensional; the soundstage widened and deepened, with far more coherent centerfill; and the stingy harmonic envelope positively bloomed. The added midbass warmth meant that I needed to adjust the various subwoofers' levels and/or placements, but once I'd achieved that balance, the sound had a rich, addictive, honeyed glow that was particularly effective for classical music and acoustic rock. Beck's new Sea Change is a string-drenched, minor-key acoustic set magnificently recorded at Ocean Way Studios. The CD sounded dramatically full-bodied and detailed without giving up transient clarity or the resolution of inner details. As good as the Aego2 system sounded connected directly to the Mac's analog audio output, it sounded cleaner, clearer, and more detailed using the USB-based Onkyo SEU55. The 12dAX7 took the Aego2's performance to a higher level, and did likewise for the two other computer speaker systems I tried. Another Configuration I tried the 12dAX7 in my main stereo system, driving it with my Mac iBook. I got the same rich, full-bodied sound as with my G4 system, but something about the overall presentation bothered me. I didn't take the time to analyze precisely what was going on, because I suspect that most purchasers will be using the 12dAX7 on their computer desktops, and not as a component of their main systems. But if you are thinking of using the Sutherland with a laptop in your big rig, don't let my experience deter youespecially as Sutherland Engineering offers a money-back guaranty. Conclusion Sutherland Engineering has come up with a unique, fine-sounding, computerfriendly DAC/vacuum-tube preamplifier. It should enrich and improve the sound of any computer-based sound system. However, the $1600 asking price seems steep. I'm not sure what justifies this price, given that the 12dAX7 is sold factory-direct and is basically a full-function USB receiver, digital filter, and DAC, all on an over-thecounter chip to which has been added a case, a decent power supply, and a pair of one-tube gain stages with volume control. With a 12dAX7 in the system, there's no reason not to invest in a good powered satellite-subwoofer system, or even a pair of high-quality conventional speakers driven by an external amplifier. The Acoustic Energy Aego2 now sells for $399; add a 12dAX7, and the total of $2000 spent offers a level of sonic performance I hadn't > Recent Additions > Budget Components > > > > > > > > > > > >

thought any desktop rig could provide. If you spend a lot of time at your computer, can crank it up, and have $1600 to drop, the innovative 12dAX7 is definitely worth considering. Article Continues: Specifications

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Description: USB-based vacuum-tube D/A converter and preamplifier with USB 1.0 data input. Sample rates supported: 32, 44.1, 48kHz. Digital word length supported: 16 bits. No specifications given. Supplied with USB cable and setup CD-ROM. Dimensions: 14.75" W by 3" H by 8" D. Weight: 10 lbs. Serial number of unit reviewed: None visible (pcb is marked "0001"). Price: $1600. Approximate number of dealers: 5. Manufacturer: Sutherland Engineering, P.O. Box 1633, Lawrence, KS 66044. Tel: (913) 841-3355. Fax: (913) 841-3737. Web: www.12dAX7.com. Article Continues: Associated Equipment > Recent Additions > Budget Components > > > > > > > > > >
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