AEA RPQ-500
A ribbon-mic preamp in a single 500 Series slot, with enough clean gain to drive a Coles 4038.
Overview
The RPQ-500 is AEA's 500 Series version of its own RPQ preamp. It's a single-channel module built around one problem with ribbon microphones: they're quiet, and most preamps get noisy long before they get loud enough. AEA's answer is a three-stage gain design that stacks up to +81 dB of clean gain. A 12-step Grayhill input gain switch covers +7 dB to +56 dB, an output gain control adds +19 dB, and an FET output stage adds another +6 dB. That headroom is meant for a ribbon on a soft fingerpicked acoustic guitar or a hushed vocal. Pro-Sound (December 2013, p.36) walked through the gain stack and singled out the +81 dB figure as what makes the module suited to low-output ribbon mics on quiet sources.
The front end matters as much as the gain. The mic input is a balanced 10 kohm design. It's deliberately high so the preamp doesn't load down a ribbon and shift its tone, which is a real concern with vintage ribbons whose sound depends on how they're terminated. Around that input AEA built its CurveShaper high-frequency shelving EQ. An HF Gain control sweeps from flat to +20 dB, an HF Frequency control moves the +3 dB corner from 2.1 kHz up to 26 kHz, and the slope shifts interactively with where you set both. The result is a treble lift that adds air without gutting the warmth underneath. A separate LF section inserts a 20 dB low-cut shelving filter with a variable -3 dB corner running from 18 Hz to 360 Hz.
The rest of the panel has phantom power, polarity invert, and a mic/line switch. The line input lets the EQ section be used on its own during mixdown, or as a tone-shaping stage behind a different preamp. Metering is three LEDs. Green lights at -6 dBu to show signal present, yellow brightens progressively from -3 dBu to +20 dBu, and red fires at +23 dBu as an overload warning.
Physically it's a standard 500 Series module: 14.5 oz, a zinc-plated steel chassis, and a 0.125-inch anodized aluminum front panel. The Mix review (June 2012, p.78) of the rackmount RPQ noted its clean gain and tone shaping for ribbon mics. The 500 Series version packages that into the smaller format.
The Pro-Sound reviewer (December 2013, p.36) reported running the module on kick with an AKG D112, snare with a Heil PR20, vocals with a Sony C-800G, and acoustic guitar with a Neumann KM-86i. There's hardly a ribbon in the bunch. The reviewer described the tone as clean and punchy without being sterile or overly colored. The same piece noted that the LF shelf and CurveShaper could approximate a familiar ribbon-vocal EQ curve, a low-shelf dip around 300 Hz paired with a high-shelf boost near 5 kHz.
It's a specialized tool, and the CurveShaper is not a full channel EQ. It's a high shelving lift with a sweepable corner and a separate low-cut. Owners who want surgical midrange control will need something else in the chain. The module exists for gain and impedance matching with low-output mics, so if that's not a problem you have, the premium over a plain 500 Series preamp is harder to justify. The RPQ-500 is also modern production, not a vintage artifact.
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