MOTU's 8pre is a FireWire audio interface and 8-channel mic pre-to-optical converter designed to let you conveniently add eight mic-preamp/instrument inputs to your computer-based recording setup. You can use the 8pre as your primary audio interface or connect it to an ADAT port on another interface or digital mixer. The 8pre uses the SMUX extension of the ADAT protocol, which allows for transfers of up to eight channels of audio at rates as high as 96 kHz.
Using the unit's FireWire ports, you can connect up to four 8pres to your computer, which would provide 32 channels of mic/instrument inputs into your recording application. You can monitor all these sources using the supplied MOTU CueMix Console software, which also gives you talkback and listenback functionality.
FIG. 1: Among the 8pre''s many features are eight mic-pre/instrument channels, each with individual phantom-power and pad switches.
The 8pre works with Power Macs and Intel Macs running Mac OS X 10.3.9 or later. Windows users need XP or Vista and software that supports standard WDM, ASIO, and GSIF drivers. Mac OS X users get the added benefit of MOTU's AudioDesk 2 digital recording software, which makes the package a high-quality all-in-one solution for those who are new to Mac-based recording or who are interested in setting up a mobile Mac-audio system.
Each channel of the 1U 8pre (see Fig. 1) sports a trim pot, a switch for 48V phantom power, and a -20 dB pad switch. The controls for all eight channels, as well as a headphone jack and main volume pot, take up only three-quarters of the front panel. The rightmost quarter holds eight five-step LED meters (labeled Analog In) for the channels, along with a vertical bank of LEDs (labeled Mode) that indicate the unit's status as interface or converter, the current sampling rate, and ADAT port status.
There's also a circular rocker switch for power. It's about twice as big as any of the individual trim pots, which are somewhat hard to turn without grazing the adjacent phantom-power switches. In practice there's no danger of accidentally switching the power status, because the phantom-power toggle switches, though small, are sturdy and stay put once set. However, I would have preferred larger knobs and switches. According to MOTU, this design was necessary in order to fit all the circuitry without increasing the unit's price point.
The Analog In LEDs can function as meters or indicate status changes. Channel-volume changes are indicated vertically. The LEDs' horizontal readout indicates level or status for whichever function the main volume knob is set to control. Out of the box, the knob controls headphone volume. Press the knob twice, and it controls master output volume. The knob is a push pot that changes functions when you press it or hold it down for a few seconds. It maintains the selected function until you press it again.
Hold the knob down for five seconds, and it becomes a selector for the two types of high-sampling-rate optical I/O that the unit supports: SMUX or MOTU's proprietary version, which you would use with other MOTU hardware. These two schemes, which support 88.2 or 96 kHz sampling rates, are referred to as 2x on the front panel. Standard ADAT I/O is labeled 1x. You can tell which 2x mode you're selecting by a single flashing LED in either the first or second column of LEDs.
If you're using the unit as a converter only, with no FireWire connection, then holding the volume knob down for three seconds lets you change the clock source. The current setting will flash in the Mode LEDs under Clock. Turn the volume knob to change the setting, and then press it again to exit the mode.
Using the volume knob as a mode selector and different arrangements of LEDs to indicate status is not very intuitive. (None of the nonmeter functions of the meter LEDs are labeled on the front panel — you just have to learn them.) Nevertheless, after spending a little time with the unit, you'll find its front-panel operation to be easy. With the unit rackmounted, you will most likely use the MOTU Audio Setup program for changing settings (on a Mac, all selections are available from the program's icon in the Dock) and the CueMix software for monitoring functions.
Round Back and Inside
The 8pre's rear panel (see Fig. 2) supplies eight combination XLR/TRS connectors, dual ¼-inch Main Out jacks, two FireWire ports, MIDI In and Out, and four digital optical ports. The top two optical ports are for standard 8-channel ADAT in and out or channels 1 through 4 of SMUX or MOTU 2x operation. The bottom two optical ports are for channels 5 through 8 of SMUX or MOTU 2x operation. A jack for the AC cable (the unit has an internal power supply) is also on the rear panel.
FIG. 2: The 8pre''s rear panel includes four optical ports for high-resolution digital connections and two FireWire ports for connecting to a computer and daisy-chaining other FireWire devices.
Enabling MIDI in my system (a dual-processor Apple Power Mac G5 running MOTU Digital Performer 5 under Mac OS X 10.4.9) was a simple matter of clicking on the 8pre's icon in the Audio MIDI Setup utility and drawing lines to and from my keyboard controller. With that I had full communication with the few outboard MIDI devices I still use (a couple of sound modules and multi-effects boxes). The 8pre's seamless integration with OS X's Core Audio and MIDI over FireWire made that communication trouble-free.
For Mac users, the supplied CD-ROM includes the required FireWire and MIDI drivers for the 8pre, along with the MOTU Audio Setup and CueMix Console programs, which let you control the unit from a Mac. (Optionally, you can install the AudioDesk recording application.) For Windows users, there are versions of MOTU's MIDI Driver, Audio Setup, and CueMix Console, along with ASIO, WDM, and GSIF drivers for the 8pre.
Cue It Up
The CueMix Console window gives you access to the 8pre's mixing features, which let you monitor the mic inputs with zero latency and no drag on your CPU. You can route any combination of inputs to any stereo output pair and set up four completely independent mix configurations, which can be saved and loaded according to your needs. Each mix can support all 16 inputs (8 XLR/TRS analog and 8 ADAT optical digital). These CueMix functions can be used in tandem with your recording software or independently.
You can record any of the four CueMix DSP mixes back to the computer. The program's Talkback and Listenback buttons let you temporarily dim all audio and talk to musicians in the live room or listen to them. You'll need to set up dedicated mics and allocate inputs for these features, though.
When the 8pre operates as an optical expander (no FireWire connected), CueMix Console automatically routes each analog input to its corresponding optical output channel — analog in 1 to optical out 1, analog in 2 to optical out 2, and so on. If you use the 8pre's 1x sampling rate (either 44.1 or 48 kHz), the analog input signals are duplicated and sent to both optical output banks. This lets you send the analog input signals to two separate digital destinations.
After I learned the 8pre's basic functions, I had little else to do except plug in mics and start recording. I set up a small session involving vocals, piano, bass, and acoustic and electric guitar. I connected three different mics: a large-diaphragm condenser for the vocalist, a “pencil” condenser mic for the acoustic guitar, and a dynamic mic on a combo amp for the electric guitar. I plugged an electric bass and synth into channels 4 and 5. With 40 dB of gain, the 8pre's TRS inputs had plenty of juice for instrument inputs and plenty of headroom as well. I padded down the guitar amp's mic because the amp sounded best turned up loud in another room.
I was impressed with the unit's mic preamps. Although I generally prefer all-analog circuitry and tube mic preamps, the 8pre's sound was excellent, and of course the convenience of multiple channels was perfect for a quick band demo. I can't keep eight high-end tube mic pres in my home studio for these situations, and I wouldn't hesitate to employ the 8pre on any kind of ensemble session. Its converters were transparent sounding, allowing the color and clarity of my various mics to come through.
For anyone who needs multiple mic or instrument inputs to record a band in a studio or even a live setting, the 8pre is a handy box to have. It can work fine as your main audio interface, and will provide you with eight high-quality preamps for mics or instruments and eight additional channels of optical/digital I/O. It offers pristine high-resolution recording through excellent converters, as well as plenty of expandability. In short, it's a box that does just about everything except play and sing for you.
Rusty Cutchin is a former editor of EM and a producer, engineer, and music journalist in the New York City area.
FireWire audio interface
|EASE OF USE
RATING PRODUCTS FROM 1 TO 5
PROS: Good-sounding converters and mic preamps. Supports high sampling rates. Expandable. Individual phantom-power switches. High-quality software.
CONS: Small knobs. Unintuitive front-panel controls.