Meyer Sound Labs CP-10 Complementary Phase Parametric Equalizer (1985)

Name: Sound Lab CP-10
Brand: Sound Lab

A ten-band stereo parametric that treats phase response as a design constraint, and got a TEC Award nomination for it.

Overview

The CP-10 is a 10-band stereo parametric equalizer from Meyer Sound Laboratories. The letters in the name matter: CP stands for Complementary Phase. According to Recording-Engineer (February 1985, p.188), the unit is a 10-band stereo parametric with five bands of equalization per channel. It was aimed at one of the least glamorous jobs in professional audio, taming room resonances in studios and controlling the behavior of reinforcement systems in the field.

The "Complementary Phase" name isn't decoration. Meyer Sound's documentation repeatedly groups the CP-10 with the company's other analog processors - the VX-1 program equalizer, the LD-3 compensating line driver, and eventually the digital Galileo 616 - as tools whose filtering is deliberately shaped to minimize phase shift. The manual material describes these as minimum-phase parabolic filters "designed specifically to optimize the interaction" between loudspeakers and subwoofers. It also warns that most commercially available DSP devices have no presets that emulate them. Whether or not an owner buys that argument in full, it explains why the CP-10 shows up in Meyer's recommended signal chains for array design, subwoofer integration, and compensation for acoustical conditions. The manual lists the CP-10 parametric equalizer alongside the VX-1 as "highly recommended" when measurement and correction tools come into play. This is a box meant to sit in a system, not on a shelf.

The CP-10 got its reputation early. Meyer Sound's CP-10 Complementary Phase Parametric earned a TEC Award nomination in the Sound Reinforcement Technology category in 1986, the awards' second year. The same nomination slate recognized the company's Source Independent Measurement (SIM) system in Acoustics Technology. A parametric EQ nominated in a sound reinforcement category rather than a studio-processing one points to where the unit earned its keep: on tour, in arrays, in rooms that fight back.

By 1991, Mix-Magazine (June 1991, p.90) was still field-testing the CP-10 alongside the then-new VX-1 stereo program EQ. The review noted that both exhibited "the same attention to detail and sound quality" that had built the company's reputation. Reviewer Bob Hodas described the CP-10 as the already-established model, the veteran of the pair, and identified its purpose as eliminating room resonances in studios, with applications in both the studio and live sound markets. The review also notes a practical detail for anyone racking one up today: the rear panel offers a choice of single-ended or balanced push-pull operation, along with voltage selection for 120 or 240 volts. That's handy for a piece of pro gear that has spent decades crossing borders and bouncing between fixed installations and touring racks.

In Meyer's system documentation, the CP-10 appears as the example of outboard processing inserted into a channel via an Insert switch. The manual's Figure 2.10 shows a CP-10 added to the signal processing chain via the Insert/Return inputs of an LD-3 line driver, standing in for "outboard signal processing such as parametric equalization." It's a small mention, but when Meyer needed a concrete example of what you'd patch into an insert point, the CP-10 was the unit they used.

What the CP-10 Was For

The CP-10's job, as the period press framed it, was resonance control. Room modes in a studio, low-frequency buildup in an array, the interaction between mains and subwoofers - a parametric EQ with five bands per channel and careful phase behavior is built to address these. Meyer's documentation is explicit that the company's approach is filter-shape-specific. The manual material warns against using filters higher than 2nd order to optimize loudspeaker/subwoofer interaction, arguing that the additional phase shift deteriorates impulse response without improving crossover behavior. The CP-10's "Complementary Phase" design is the analog-hardware version of that same philosophy.

That's a narrower brief than "stereo parametric EQ" might suggest to someone who knows the format from studio outboard. It's a correction tool, and the TEC nomination in a sound reinforcement category confirms which market adopted it first.

Reception and Standing

The CP-10's TEC Award nomination came in 1986, and the unit was still getting field-test coverage in Mix-Magazine five years later. Mix-Magazine (June 1991, p.90) paired it with the newer VX-1 in a single field test, treating the CP-10 as the established reference point against which the program EQ would be judged.

Meyer Sound kept the CP-10 in the conversation well past its introduction. The Galileo 616 loudspeaker management system, the company's digital matrix processor, is described in the manual material as including "digital implementations of popular features developed over years by Meyer Sound for its acclaimed analog processors, including air absorption compensation filters, array correction, and equalization from the CP-10 and VX-1."

Owning One Today

The CP-10 is pro rack gear from the mid-1980s, so the usual caveats apply to any surviving unit. Verify the rear-panel voltage setting before first power-up, and expect the balanced/single-ended push-pull output configuration to matter when you're matching it to modern interfaces. The 120/240-volt selection documented in the 1991 field test is a convenience, but it's also a switch that has had decades to be set wrong by a previous owner.

On the plus side, the CP-10's role in Meyer's recommended signal chains means documentation survives. The manual material is clear about how the unit is meant to be deployed, what it's meant to correct, and where it sits relative to atmospheric correction and array correction in a larger system. For an owner running Meyer self-powered loudspeakers, the CP-10 is a period-correct way to get the company's own analog EQ approach into the chain.