M-Audio has built a reputation for manufacturing affordable quality hardware for music-production applications. A case in point is the company's new Octane preamp, which has features that enhance the analog interface of any digital multitrack at a price that won't break the personal-studio budget.
FIG.1: The M-Audio Octane is a versatile 8-channel mic preamp and A/D converter that features dedicated instrument preamps on channels 1 and 2.
The Octane is an 8-channel microphone preamp and A/D converter, replete with ADAT Lightpipe digital outputs and ¼-inch TRS analog outputs. The unit also has -20 dB pads, insert options, phase-reverse switches on four of the channels, phantom power, two direct instrument inputs, and selectable M-S matrix encoding circuitry on channels 7 and 8 for stereo-recording applications.
The 2U Octane offers individual gain controls and a three-color LED for each of the eight mic preamps. The meters indicate levels of -20 dBu, -10 dBu, or clipping (green, yellow, and red, respectively). Channels 1 and 2 include an instrument input with a ¼-inch TS jack and separate gain control (see Fig. 1). These inputs have dedicated high-impedance instrument preamps that are designed to give a better signal-to-noise ratio than what you'd get from a unit that shares a single preamp for the mic and direct inputs. Plugging into the instrument input disables the mic preamp on that channel.
Channel 1 also has a low-cut filter with a 12-dB-per-octave slope below 80 Hz, which affects the mic and instrument inputs. In addition, the even-numbered channels have phase-reverse switches, which are useful for correcting phase problems that arise when more than one mic is used on a single source.
The M-S matrix encoder on channels 7 and 8 is engaged with the In/Out button next to the Width control. The three-position Sample Rate selector has settings for 44.1 and 48 kHz sampling rates for the A/D converter, and an external (Ext) setting that locks the Octane's digital output to an external source connected to the rear-panel word-clock input. A pair of buttons are used to send phantom power to sets of four mic channels, which are grouped 1 through 4 and 5 through 8.
BEHIND THE SCENES
The rear panel has eight XLR mic inputs, eight ¼-inch TRS analog preamp outputs, and eight TRS A/D line inputs (see Fig. 2). The preamp outputs can be used to send analog signals to the analog inputs on a mixing board or digital interface, or they may be used to insert a dynamics processor into the signal path. These outputs are half-normaled to their respective A/D Line Inputs, allowing them to be used as insert sends for connecting to, for example, a compressor/limiter. Returning the processed signal to the A/D line inputs breaks the normaled connection of the XLR Input, just like inserts wired up in a patch bay.
If you want to use the Octane's converter, the A/D line inputs accept ¼-inch connections from any line-level device. Inserting a cable into the line inputs breaks the connection of the XLR mic input to the A/D converter. However, the preamp output is still active, and the mic signal can be sent from that jack to the input of an external A/D converter or digital-recording device.
FIG. 2. In addition to XLR mic inputs, the Octane gives you preamp outputs and A/D line inputs for each channel, word-clock I/O, and an ADAT Lightpipe digital output.
The rear-panel ¼-inch jacks are constructed of molded plastic. Although the connections seem solid, I am a bit concerned about the long-term durability of these jacks. There are no nuts and washers to anchor the jacks to the chassis and provide strain relief for the circuit-board connection points.
Jutting out about two inches from the rear of the unit is a heat sink, and to the right of that is the unassuming Lightpipe digital output and two female BNC jacks for word-clock I/O. An AC input jack accommodates the large lump-in-the-line power supply that comes with the Octane. While the connection seems solid, I noticed that the plug does not insert completely into the jack. As a result, the housing is not flush with the chassis.
I used the Octane at my home studio — recording to Alesis ADAT XT20 and Digidesign Pro Tools LE — and at the studio facilities of the Ex'Pression College for Digital Arts in Emeryville, California, where I recorded to a Pro Tools setup. The sources I recorded included nylon- and steel-string acoustic guitars, electric bass, female vocals, a drum kit, and a variety of percussion instruments.
The Octane performed admirably in all cases, giving an honest representation of the sound sources, with little coloration. When I used the Octane for the drum mics during a blues session and a rock session, its sound was clean and clear, and the setup was straightforward. The Octane's midrange is round with plenty of body, which served to accentuate the toms when miking the kit. It also had a crisp high-end response.
Considering its moderate price tag, the Octane sounded surprisingly good and was quite punchy on the drum kit. It imbued the kit's small bass drum with a somewhat compressed sound, which allowed the kick to fit nicely into the mix.
The midside option on channels 7 and 8 was an added benefit, allowing me to use the M-S configuration on a stereo-mic array for the drum room. I used a pair of the multipattern Shure KSM44s to set up the cardioid center mic on channel 7 and the bidirectional side mic on channel 8. With the M-S Matrix switch engaged, I was able to increase the width for a more expansive sound. Although the Octane lacks an onboard limiter, I appreciated its insert capabilities.
I tried out one of the Octane's instrument inputs with an Epiphone Sheridan semi-hollowbody electric guitar and later a Fender bass, and it delivered a clean and defined signal on both occasions. I was impressed with the Octane's A/D converters, which were good for a unit in this price range.
Overall, the Octane's features are comparable to more expensive 8-channel preamp/digital converter combos. If you are looking for an affordable analog front end for a Lightpipe-compatible digital multitrack system, the Octane is well worth considering.
Karen Stackpoleteaches Studio Maintenance at Ex'pression College for Digital Arts and operates Stray Dog Recording Services. Special thanks to Steve Orlando, Assaf Lotan, and Kevin Patzelt.
8-channel mic preamp and A/D converter
FEATURES4.0EASE OF USE4.0AUDIO QUALITY4.0VALUE4.0RATING PRODUCTS FROM 1 TO 5
PROS: Versatile. Good-sounding preamps and A/D converters. Channel inserts. Pad switches on every channel. Phase-reverse switches. M-S matrix encoding.
CONS: Plastic ¼-inch jacks unanchored to the chassis. AC plug doesn't insert all the way into jack. Phantom power only in groups of four.
Analog Inputs (8) XLR mic, (2) ¼" TS instrument Analog Outputs (8) ¼" TRS Additional Analog Ports (8) ¼" A/D line inputs Digital Ports (1) ADAT Lightpipe 24-bit optical format, (2) BNC word clock Bit Depth 24-bit Sampling Rates 44.1 kHz, 48 kHz Input Impedance 3 Mž (front-panel instrument inputs), 20 kž balanced, 13.3 kž unbalanced (rear-panel line inputs) Signal-to-Noise Ratio 120 dB, A-weighted, mid gain (XLR inputs); 110 dB, A-weighted (A/D inputs); 133 dB, A-weighted, mid gain (instrument inputs) Frequency Response 20 Hz-20 kHz, ±0.11 dB, mid gain (XLR inputs); 20Hz-20 kHz, ±0.04 dB (A/D inputs); 20 Hz-20 kHz, ±0.03 dB, mid gain (front panel instrument inputs) Phantom Power 48V, switchable in groups: channels 1-4 and 5-8 Low-Cut Filter -12 dB/octave below 80 Hz (channel 1 input only) Power Requirements 18 VAC (16.5 VAC minimum) @ 3.5A inline power supply Dimensions 17" (W) × 3.5" (H) × 5" (D) Weight 7.1 lbs.