AEA RPQ2 Full-Rack Preamp with EQ & DI
High-gain, high-impedance, 2-channel, full-rack preamp with EQ & DI
The AEA RPQ2 Ribbon Preamp provides two channels of high-quality, high-gain, low-noise preamplification with a rich and musical sound that complements the natural tonality of your microphone. Specifically designed for ribbon microphones, the RPQ2 excels at drawing out the warmth and lush sound that ribbons are uniquely known for. With 81dB of gain, JFET circuitry, and an input impedance of 63K Ohms, the RPQ2 delivers the precision, quietness, and headroom needed for today’s high-resolution recordings.
The RPQ2 is AEA’s second iteration of the high-performance RPQ preamp with the addition of some new and useful features. It is now possible to plug your instrument directly into the RPQ2’s high impedance circuit with its front-panel direct inputs. The RPQ2 also includes a Mic/Line switch for balanced line inputs and outputs, as well as inserts for patching compressors or other effects between the preamp and CurveShaper EQ section.
The RPQ2’s CurveShaper EQ gives you the tools to control your ribbons right at the start of the signal path. Switchable and tunable low frequency (LF) and high frequency (HF) controls allow you to tame proximity problems and provide high-frequency extension and slope control.
Engineers have discovered that the RPQ2 is a perfect fit with condensers and moving coil microphones. By virtue of its sonic qualities and versatility, the AEA RPQ2 is the tool of choice for all microphones whenever a true and pristine signal path is desired. Detailed and accurate, the AEA RPQ2 is a high-quality, high-gain choice for all microphones.
Two Peas in a Pod: Musical Preamp, Sweet EQ
The CurveShaper’s high-frequency filter boost enables you to add a little extra “presence” or “air” to your source. The circuit functions in a similar manner to a conventional parametric shelving boost, but with a significant difference: the slope varies as both the CurveShaper and HF Gain controls are adjusted. This unique bell curve was designed with the intention to compensating for the high-frequency roll-off that is inherent to most ribbon microphones. But beyond ribbon mics, the smooth HF filter is remarkably well suited for brightening up condenser microphones used at a distance, restore presence in overly “dry” acoustical environments, or even as a clean and transparent air-band boost on the 2-bus.
The CurveShaper’s low-frequency control easily removes boxiness and boominess in a fast and unobtrusive way. Ribbon microphones are capable of delivering strong subwoofer lows, and can have a significant bass proximity effect. Such strong low-frequency content can mask high-frequency intelligibility, so the tunable LF filter was engineered to tame low-frequency energy to appropriate levels. Its -20dB shelving curve is ideally suited to reduce excessive proximity effect, opening up new possibilities to use ribbons in close-up applications.
Your Sound At Your Fingertips
With mixing consoles disappearing from control rooms, dedicated preamps can take on the role of providing a high-quality front end, giving you intuitive control to make critical decisions during tracking rather than “fixing it in the mix”. It’s no wonder why many mixing and mastering engineers turn to the RPQ2 purely for its post-processing EQ and routing functionality.
The RPQ2 provides a secondary line level balanced output for sending an additional line signal to a separate recording device or mixer. In Line Mode, the preamp and EQ section become two independent units with separate inputs and outputs. This allows you to insert compressors or other effects between the preamp and CurveShaper EQ section.
The Impedance Matching Myth
Passive microphones like ribbons and moving-coil transducers interact with the input impedance of the preamp. If the impedance of the preamp is too low, the microphone will have to work harder to send a signal down the line. Additionally, the bandwidth (particularly in the low end) will be limited.
For best voltage transfer, the impedance of the preamp should be at least five times the microphone’s output impedance. Many microphones have a nominal impedance of about 200 Ohms, leading to the assumption that a preamp impedance of 1.0 to 1.5K Ohms should be fine. However, passive microphones and ribbons, in particular, have an output impedance that rises towards low frequencies and can easily get as high as 1000 Ohms at resonance, resulting in a 6dB loss at this frequency with a low impedance preamp. A preamp impedance of significantly more than the commonly seen 1.0 to 1.5K Ohms is beneficial for all passive ribbons and moving-coil microphones.
– Two channels with 81dB of sweet and quiet JFET gain
– High frequency CurveShaper EQ and low frequency proximity control
– NoLoad 63k ohm high-impedance circuitry providing better overall transients, frequency response, and higher output sensitivity
– High-resolution, high-impedance front-panel 1/4″ DIs
– Mic/Line mode with Post-Mic and Pre-EQ Inserts for alternative and convenient routing options
Applications & Audio
Using the HF CurveShaper EQ
The RPQ2 features a unique CurveShaper circuit that enables you to add a little extra “presence” or “air” to compensate for high-frequency losses that are inherent to most ribbon microphones, the result of distant mic placement, or to restore presence in a “dry” acoustical environment.
The circuit functions similarly to a conventional parametric shelving boost but with a significant difference: the slope and bandwidth varies as both the Curve Frequency and Curve Gain controls are adjusted. From a technical standpoint, it is evident the EQ shape of the CurveShaper is a bell. At its lowest setting, the peak frequency of the CurveShaper is 30k while at its highest setting, the peak frequency is 120k. In many instances, a bell with a peak at 120k is not very practical since it is above the human frequency threshold of hearing. But the CurveShaper has a very wide bandwidth that allows the left side of the bell to essentially act as a high-frequency shelf. The Curve Frequency knob, at its lowest setting, will yield a gentler slope and wider bandwidth. As the frequency is raised, the slope becomes steeper while the bandwidth narrows.
To activate the CurveShaper EQ section, depress the High Frequency IN switch (ref. #3). Start by adjusting the continuously variable Curve Frequency control (ref. #4). The frequency markings on the Curve Frequency dial indicate the +3dB break-frequency when the Curve Gain is at max. Select the desired frequency with the Curve Frequency knob, and then dial in the amount of boost you desire with the Curve Gain knob. The two controls are interactive. Use your ears to determine at what frequency and gain setting sounds best.
In Line Input Mode, the CurveShaper becomes a versatile EQ to add presence or air to any line level signal on a mix or even in mastering.
Be careful when you add Curve Gain because this also affects the overall gain structure of the preamp and could introduce overload distortion. After you make this adjustment, you may need to reduce the Output Level control to compensate for the CurveShaper’s signal boost. When the Curve Gain is fully counter-clockwise (set in the “0” position), no EQ will be introduced into the signal. It essentially the same as having the HF In switch (ref #8) disengaged.