Aphex Model 207

Back before outboard preamps were all the rage, Aphex Systems made a splash with its model 107, a dual-channel mic preamp priced for the personal-studio

Back before outboard preamps were all the rage, Aphex Systems made a splash with its model 107, a dual-channel mic preamp priced for the personal-studio market. That was 1996 — practically ancient history considering the rapid turnover of today's audio marketplace. In the wake of the outboard-preamp explosion, Aphex has wisely updated the 107, keeping the price competitive and adding some unique and attractive features.


The 207's single-rackspace faceplate, finished in a soft-looking silver powdercoat, is logically laid out with two sets of identical left- and right-channel controls. At the left side of each section is a ¼-inch high-impedance instrument input for DI connections. Five switches are labeled from left to right as follows: Phantom (48V phantom power for condenser microphones), Polarity (reverses polarity when engaged), Pad (20 dB), Low Cut (70 Hz at 12 dB per octave, plus additional compensation at 120 Hz), and MicLim.

The MicLim circuit is an Aphex innovation. Essentially, it is an automatic and nonadjustable peak limiter placed before the mic preamp to keep input levels under control, thus avoiding the common problem of input-stage clipping and distortion. When the MicLim feature is engaged, an adjacent yellow LED lights up any time the input level is sufficient to trigger limiting.

The on/off switches are a neat, attractive touch: they glow a cool alien green when engaged and are shiny and clear when disengaged. To the right of each channel's button array are an easy-to-grasp gain knob and a recessed output trim pot (0 to -12 dB.) The trim can be adjusted with a small screwdriver, and it enables users to match the 207's metering and output to diverse analog and digital recording setups.

Ten-segment LED ladder meters, located in the center of the front panel, register output headroom for both channels. The meters are implemented as a typical digital dBfs display (with 0 dB of headroom and red indicator lights at the top) rather than like conventional analog meters. An AC power on/off switch with indicator light is mounted on the far left of the front panel. When the unit is powered up, the meters surge for a few seconds, but output is muted to prevent the possibility of audible voltage spikes and blown speaker cones.


All inputs and outputs are found on the 207's back panel (see Fig. 1). In addition to a balanced XLR mic input and line-level output, each channel has a balanced ¼-inch TRS output and a ¼-inch TRS insert jack. Output level is switchable on each channel (+4 dBu or -10 dBV.) Also located on the rear panel is a standard IEC power-cord connector. The unit is designed to operate from all nominal power sources from 100 to 240V. There is no external access to fuses (the manual claims the internal fuse will “never blow unless the power supply fails catastrophically”), nor is there provision for digital output or an A/D converter card.

The model 207's all-metal chassis has no vents, which is a bit unusual for a device using a vacuum tube. A single American-made ARS brand 12AT7/ECC81 is housed inside, and the remainder of the model 207's circuitry is solid-state. During testing, the unit ran much cooler than any of the all-tube gear in my racks, and even cooler than other Aphex products I use.


The 207's 28-page manual is the most thorough I have seen for a product of this type; it explains every feature in exhaustive detail. In addition, the documentation offers ample diagrams, as well as supplemental information on wiring, balanced lines, and stereo-microphone recording techniques.

The only flaws in the exemplary text are occasional lapses into marketing-speak. Repeated assertions that the 207's solid-state/tube hybrid design is “real tube,” “true tube,” “new and better,” and “unmatched for sonic detail and dimensionality” detract from what is otherwise good, solid technical information.


I tested two Model 207s for this review and was impressed to find that the units sounded virtually identical — something that can't be said for some other preamps I have reviewed.

Equally impressive, in a stereo-matching test, both channels of the two units calibrated easily and identically according to gain-knob settings and internal and external metering. In addition, each set of two channels matched sonically when fed the same split-mic input. Clearly, Aphex maintains careful control over its manufacturing.


Sonic differences between various makes and models of mic preamps are typically subtle — much more subtle, usually, than dissimilarities between different microphones. Drawing a clear bead on a mic pre's sound requires, therefore, careful comparison testing. I compared the Aphex Model 207 with several more-or-less comparably priced preamps, including an A.R.T. Tube MP (tube-hybrid), a PreSonus MP20 (solid-state), a Peavey VMP-2 (all-tube), a Focusrite Green (solid-state), a Grace 101 (solid-state), a Drawmer 1960 (a combined preamp and compressor; a tube-hybrid), and a stock preamp in my Soundcraft Spirit board (solid-state). Of those preamps, two (the Soundcraft and Tube MP) cost less per channel than the 207, one (the PreSonus MP20) costs about the same, and the others cost more.

I recorded a number of instruments, including acoustic and electric guitars, bass guitar (using the 207's DI input), saxophones, and several percussion sources. My main trial for the 207 was undertaken with the assistance of a multi-instrumentalist acquaintance who agreed to overdub a composition for my testing purposes. Each instrument was recorded, using Blue Kiwi cables, through a matched stereo pair of microphones (Oktava MC012s or Neumann U 87s), with one mic patched through the 207 and the other hooked up to one of the comparison preamps. I monitored all tracks on both Tannoy PBM8s and Dynaudio Acoustic BM 15s.

Overall, the 207 produced a uniformly present, detailed, and up-front signature sound. In most cases, however, it sounded a bit dull or dry, slightly compressed, and a little shy on bass content, and it consistently captured less room sound and sense of space than the other preamps.

For example, on a set of conga drums, the 207 provided a detailed and intimate sound with plenty of skin attack. The overall tone, however, was drier and less roomy than that provided by the Focusrite Green. With tambourine and jingling keys (a test of the unit's handling of complex, high-end transients), the 207 provided more accuracy and detail than the Tube MP. But it sounded a bit fuzzy and compressed in contrast to the MP20's more clearly etched realism. On an electric-bass-guitar track, which sounded full and warm through the Peavey VMP-2, the 207 came across as midrangey and a bit thin. And on an electric-guitar solo, I was surprised to find that a preamp in my Spirit board offered a richer tone, including lusher treatment of the Fender guitar amp's spring reverb.

For dense, electronic, or highly processed mixes, this kind of dry, compressed character may have its advantages. But for acoustic recording, the Aphex always came in second place. It consistently lacked depth, room sound, richness, and other subtle sonic attributes of good tube gear, and it often sounded edgy and one-dimensional compared with the solid-state preamps.


On some sources, such as electric bass (through the DI), the Model 207's MicLim feature was generally transparent and useful for catching occasional peaks, as long as input levels were moderate and limiting was not excessive. On a conga part, engaging the MicLim circuit helped tame the drummer's fluctuating levels. Unfortunately, it also dulled the percussive attack a bit.

Because there are no adjustable parameters, MicLim is probably most useful as a “set it and forget it” fail-safe for the unpredictable world of live-sound recording.


The Aphex Model 207 provides all the features one could want in a basic mic pre, including commendable options such as adjustable metering, polarity reverse, and switchable output levels. To its credit, the unit runs coolly and quietly, and has plenty of headroom. Sonically, it adds an up-front presence and slightly compressed sound to many sources, which may offer recordists a more exciting flavor than the sound of some stock console preamps or other solid-state/tube hybrids. However, based on what I heard, I am forced to disagree with Aphex's claim that the Model 207 is “unmatched for sonic detail and dimensionality.”

Myles Boisenis a guitarist, producer, composer, and head engineer/instructor at Guerrilla Recording and The Headless Buddha Mastering Lab in Oakland, California. He can be reached by e-mail atmylesaudio@aol.com.

Model 207 Specifications Amplifier Typetube/solid-state hybrid, transformerlessTube Type12AT7/ECC81Inputs(2) balanced XLR (mic); (2) balanced TRS ¼" (insert); (2) unbalanced TS ¼"Outputs(2) balanced TRS ¼"; (2) unbalanced ¼" (line)Operating Level+4 dBu; -10 dBV (switchable)Gain Range20-65 dB (mic, +4 dBu), 8-53 dB (mic, -10 dBV); •-65 dB (line, +4 dBu), •-38 dB (line, -10 dBV)Maximum Input Level0 dBu (mic); 10 VRMS (line)Maximum Output Level+21 dBu (+4 dBu); +6.75 dBV (-10 dBV)Frequency Response30 Hz-30 kHz (+0, -0.5 dB)Dynamic Range113 dBEquivalent Input Noise-129 dBu (input shorted)Total Harmonic Distortion + Noise<0.18% (10 Hz-22 kHz @ -11 dBfs)Crosstalk-79 dB (10 Hz-22 kHz)Highpass Filter70 Hz, 12 dB/octaveAttenuation Pad20 dBPhantom Power48VDimensions1U × 7.5" (D)Weight9 lb.


Model 207
2-channel microphone preamp


PROS: Adjustable metering. Polarity reverse. DI input. Switchable output levels. MicLim feature. Thorough and informative manual.

CONS: Mediocre sound quality. Sounds are slightly compressed as well as bass-lean on many sources. Lacking in depth, warmth, and other sonic attributes of tube gear. Absence of parameter adjustments diminishes MicLim usefulness.


Aphex Systems, Ltd.
tel. (818) 767-2929
e-mail sales@aphex.com
Web www.aphex.com