Snapshot Product Reviews

GRACE DESIGN MODEL 901 Reference Headphone Amplifier There are times when only headphones can reveal fine details and nuances that engineers need to hear


Reference Headphone Amplifier

There are times when only headphones can reveal fine details and nuances that engineers need to hear when choosing preamps and mics, listening for background noises or doing quality control. Unfortunately, the headphone jack on any piece of equipment is, at minimum, a convenience feature used to confirm signal presence. Some have noise, hiss or interference, inadequate headroom or other sonic deficiencies. By eliminating this often-overlooked weak link in the chain, Grace Design's Model 901 helps encourage users to match the quality of this device by listening on better-than-average headphones.

The 901's more than five-pound heft is due to its thick steel chassis, toroidal (no wall wart!) transformer and ¼-inch, aluminum-slab front panel. Inside, the build quality and components are top-notch in keeping with its impeccable specs, such as a 22 to 120kHz (±0.25 dB) bandwidth.

As a converter, the Grace 901 justifies its $1,495 list, with its high-quality, 24-bit/96kHz DAC interfaced to AES, S/PDIF co-ax and Toslink ports. Few pieces of gear have this type of quality conversion, in terms of components and execution. Plus, the converter subassembly can be upgraded to a higher sample-rate module if and when it becomes available. A front switch selects a digital or analog input (XLR or RCA), and a rotary switch handles level settings with precision resistors for trouble-free operation and channel-to-channel stability. It's followed by a high-quality/high-power output amp. A Range switch ensures that the Model 901 can drive any-impedance headphones.

My first test was recording a jazz trio (acoustic bass/drums/piano) in a live space without a control room. [Visit for full session details and an MP3 sample.] While recording, I worked exclusively in the headphones: It was heavenly, because there was no isolated control area. The session was recorded to a Fostex DV-40 4-channel DVD-RAM recorder. Two channels came direct from the board, and another pair came from an Audio-Technica stereo shotgun in the balcony.

Audition various source materials over numerous headphones (Sennheiser HD-600 and HD-280 Pro, Sony V-6/7506, Fostex T20, AKG 240 and Audio-Technica AT D40FS and AT M40FS), and you'll find that the 901's silence is impressive; there's no hint of hiss, extraneous noise or hum. Partnered with the Sennheiser HD-600, the sound was open, effortless, extended and spacious. The top is delicate and the bottom full. Nearly everyone knows what the Sony cans sound like — not as nice as the HD-600 — but very good considering that they're one-third the street price. Concerning the impedance difference (300 ohms and 70 ohms), the Model 901 had no difficulty driving either pair.

Anyone who relies heavily on headphones in classical and jazz environments will quickly recognize this product's value. For users doing difficult sonic comparisons where it's tough to distinguish whether the gear or the source material is at fault, the Grace 901 is highly recommended.

Grace Design; 303/443-7454;
Eddie Ciletti


4-Channel A/D Converter

Swiss manufacturer Swissonic recently updated its AD96 4-channel A/D converter by adding a wide-ranging calibration trim pot for each analog input, and a new power supply and PLL circuit. The new model — dubbed the AD96 mk2 — outputs a 16, 18, 20 or 24-bit signal (with dither and noise shaping automatically applied to shorter word lengths) at 44.1, 48, 88.2 or 96kHz nominal sample rate. The half-rack unit is compatible with +4dBu nominal levels. You can globally switch the range/resolution of its four 16-segment, tri-colored LED input-level meters or set up the meters to count digital “overs.”

The AD96 mk2 generates, locks to and converts between wordclock (including half-speed sample clocks) and x256 Superclock via rear panel BNC I/O connectors. Other rear panel connections include four balanced XLR analog inputs and two XLRs for “single-wire/double-speed” AES/EBU outputs. (An internal jumper can switch outputs to consumer-format signals in lieu of AES/EBU.) Double-wire AES/EBU format is not supported. One AES/EBU output serves channels 1/2, and the other serves channels 3/4. You can also route the four digital-output signals to channels 1 to 4 or 5 to 8 on the provided ADAT Lightpipe output.

The Lightpipe out can also be used in S/MUX and/or B/MUX (bit-packing) modes to record high-resolution digital audio to legacy 16- and 20-bit MDMs/DAWs. S/MUX mode maps each channel of 24-bit, 88.2/96kHz data to two Lightpipe channels that transmit at 44.1/48kHz. B/MUX mode maps each 24-bit, 44.1/48kHz channel to two Lightpipe channels by assigning the upper 16 bits to channel 1 and the lower eight bits to channel 2. The AD96 mk2 can also use S/MUX and B/MUX modes simultaneously to encode two channels of 24-bit, 88.2/96kHz audio to eight tracks of a 16-bit MDM.

Given its modest $1,349 list price, I was surprised at the AD96 mk2's impressive 118dBA dynamic range. In subjective A/B tests, stereo tracks recorded with the Swissonic unit exhibited a little less depth and channel separation than those recorded with my Apogee Rosetta (a much more expensive unit on a per-channel basis), but the differences were quite subtle. The AD96 mk2 imparts a darker, warmer timbre as compared to that produced by the Rosetta. (Neither converter's spectral balance sounds better than the other does — just different.) Of all the numerous premium-quality A/D converters I've used, the Swissonic AD96 mk2 offers the best price for value.

Distributed by Plus24; 323/845-1171;
Michael Cooper


FireWire Hard Drive

Known to supply hard drives with high-quality enclosures and power supplies to the audio industry, Glyph Technologies has recently added FireWire drives to its SCSI-based product line. Some of these drives are being marketed as complementary products to specific DAWs. Companion is a desktop FireWire drive with a form factor matching Digidesign's Mbox.

Companion comes in 40, 80 and 120GB flavors (by presstime, these will be 60, 120 and 180 GB), comfortably allowing up to seven hours of 24-track recording at 24-bit/48kHz. The ATA drives run at 7,200 rpm with a sustained data transfer rate of >36 MB per second, and the ATA-to-FireWire bridge circuitry uses the high-bandwidth Oxford 911 chip specified by Digi, in conjunction with Glyph for use with Pro Tools systems.

Made out of metal and built to withstand musician's abuse, Companion's casing is much more rugged than the Mbox. All elements are assembled to minimize acoustic vibrations and resonance; the drive didn't seem any quieter than a run-of-the-mill Maxtor FireWire unit, although the Maxtor unit has an external power supply and is fanless. While Companion's noise level is not obnoxious, I wish computer and drive manufacturers would explore combinations of whisper fans and baffling technologies to lower the background din. The Companion is heavier than you'd expect, but quality power supplies and fans weigh more than the normal stuff. Glyph's thermal-sensing cooling is designed to activate the fan to keep with the drive's temperature, although I never noticed a change in fan noise or speed.

Connection/use of Companion is straightforward. The Glyph ships with Mac and Windows FireWire drivers on CD, and comes formatted for the Mac. Reformatting the drive for Windows is trivial. Testing Companion with a Mac iBook and desktop G4, it performed like a champ.

I tested the Companion with two Pro Tools systems: the Mbox and the Digi 002, both attached to a 600MHz Apple iBook G3 laptop. With the Mbox, the Companion recorded and played back 24 channels of 24-bit, 48kHz digital audio with plenty of edits and fades. For the torture test, I recorded and played back 32 simultaneous tracks of 24-bit/96kHz audio on a Digi 002. The Companion handled this chore effortlessly, although adding many more edits and fades eventually exceeded the drive's capacity. All in all, I was mighty impressed with the Companion's performance.

A bonus: Companion also features S.M.A.R.T. Manager diagnostic software, which monitors the “fitness” of your drive and warns of imminent drive failure.

Companion's case is designed to match the Mbox, with a similar form factor and matching curved-blue faceplate — a nice touch. On the downside, the case is somewhat larger than many FireWire enclosures, and the long flanges on the bottom make it a tad inconvenient to transport. On the other hand, the power supply is built-in, rather than the wall wart and line-lump designs of many off-the-shelf drives.

Glyph makes great stuff, and Companion is no exception. If you are willing to pay an enhanced price (40GB, $549; 80GB, $599; 120GB, $799) for an enhanced drive with high-quality components, then Companion is worth checking out.

Glyph Technologies; 800/335-0345;
Nick Peck


Dynamic Kick Drum Mic

I use a variety of mics for kick, such as a Sennheiser MD-421, Beyer M88, E-V RE20, AKG D112 and even E-V's 664 “ray gun,” which transforms any bass drum into the '70s dry thud Steely Dan kick. Another fave, Audix' D4 offers thunderous LF, but requires some experimenting to find its sweet spot. With this in mind, Audix offers the new D6, a $349 cardioid using a very low mass (VLM) dynamic diaphragm in a 4×6-inch rugged aluminum body. The D6 has a stand adapter (on mine, the swivel wouldn't cinch securely), but it also fits the Audix D-flex, other D-Series mounts and lots of other clips — A-T, E-V, etc.

In session, the D6 delivered exactly as promised. It's voiced for kick miking, with 144dB SPL handling and a response emphasizing the 60 to 120Hz “boom,” while attenuating the wobbly 200 to 600Hz range and then extending to 15kHz to catch those beater-snap transients.

Forget EQ. You don't need it. Outside, six inches from double-headed jazz drums (1962 Gretsch 18-inch and 1914 Ludwig & Ludwig 26-inch calf), the sound was rounded, full and woolly. Inside a 22-inch Premier rock kick, the result was punchy and tight, with soul-shaking lows. The D6 was consistent nearly anywhere within the kick, with a solid, no-hassle sound, although it can be easily tweaked by moving it slightly — i.e., closer/more on-axis to the beater. Onstage or in session, the D6 rocks — literally!

Audix; 800/966-8261;
George Petersen