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The RPQ500 has a clear front panel layout. The R84 evokes the classic RCA radio days.
The RPQ500 has a clear front panel layout.
The R84 evokes the classic RCA radio days.

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By Paul Vnuk Jr.
Date: August 2012

Wes Dooley's Audio Engineering Associates (AEA) is known for its line of high-end ribbon microphones as well as being one of the world's foremost restoration specialists of vintage RCA ribbon models. AEA also manufactures a line of high-end microphone preamps that, as you can guess, are designed to literally get the most out of your ribbon microphones.

Today we are looking at AEA's newest mic pre model, the RPQ 500, which is a few evolutionary steps up from AEA's TRP (short for The Ribbon Pre) released in 2006. Reviewer Scott Dorsey gave us the lowdown on the TRP in our March issue of that year and commented on the clarity it brought out in a ribbon microphone.

Two years after its release came the RPQ, and while its raison d'etre was still primarily the world of ribbon microphones, there were other improvements as well that went beyond ribbons: optional phantom power, a sweepable high-band eq called the Curve Shaper, and a variable low-frequency filter.

The newest member of the AEA family, the RPQ 500, is a single channel from the 2-channel RPQ, designed for use in an API 500-Series style enclosure (For this review, I used the Radial Workhorse enclosure, reviewed in our October 2011 issue). All of the RPQ’s features are included as well as a new variation or two.

Style, build, and functions

The RPQ 500 is a single-slot module that is fully enclosed in a zinc-plated steel chassis with a 0.125" black tinted anodized aluminum front plate. It uses the same full-sized silver knurled knobs as its 19" rack mount sibling -- it looks quite imposing sitting next to many other 500 series devices with their tightly spaced miniature controls and pots.

As with the RPQ, signal flow starts with a 12-stepped Grayhill pot that goes from +7 dB up to +56 dB of preamp gain. This is followed by a variable output level control that goes from minus infinity (muted) up to +19 dB. The FET output circuit also adds +6 dB of gain, so at full throttle the RPQ 500 can give you +81 dB of clean gain -- yes, 81 dB, you read that correctly.

In between the input and output is a Low Frequency Filter control that is fully sweepable from 18 Hz to 360 Hz and drops the selected frequency down -20 dB, shelving, with 6 dB/octave slope. Next is the Curve Shaper, a sort of high-band shelving eq. One control adjusts the circuit's gain from 0 dB up to +20 dB, while the other selects the frequency from 2.1 kHz up to 26 kHz. Both the Curve Shaper and the Low Freq Filter include bypass buttons so they can be taken in and out of the signal path. Additionally the RPQ 500 has a phase button, a phantom power button, and a 3-stage signal level/clip LED meter.

About the 500 Series' use of phantom power: On the original RPQ, there were two sets of XLR inputs, one for use with ribbons and devoid of voltage, and a second standard input with phantom power for use with typical condenser microphones. On the 500-Series version there is of course only one XLR input and its phantom power is switchable in and out, so the same care needs to be taken as when using any mic pre with a ribbon microphone.

The last feature is also specific to the RPQ 500, and that is a Mic/Line switch that changes the input from mic level to a line-level signal. This takes the input stage and phantom power out of the path and allows you use the eq section alone during mixdown, on any source.

Sound and use

The RPQ 500 falls squarely in the Millennia Media, John Hardy and Grace Designs camp and holds its own with them all. Of those three I found it sonically closest to the John Hardy. It is clean and clear and simply stays out of the way and imposes no tone of its own to the mic.

Where it differs from the pack is more in function than sound, as its impedance load is specifically tailored to ribbon mics, and, again, it offers +81 dB of gain, more than the competition’s +65 to +70 dB of gain.

It’s easy to get a great level when tracking loud sources like drums, guitar cabinets and brass sections with a ribbon microphone, but on delicate acoustic guitar, soft crooning vocals, violins and voiceover work, I often end up pushing my mic pres to their limits, thus boosting their noise floor to the point where it becomes a detriment to the intimate recording I was attempting in the first place. With the RPQ 500 I achieved the single quietest signal with the lowest noise floor I have ever experienced with a ribbon microphone, and it plays no favorites in that category, from a Royer R-121 to AEA's own R84 with a few Chinese-made suspects in between.

On condensers like my Neumann KM 84s and my Brauner Phantom and even most modern tube microphones, gain typically is not an issue and here is where the RPQ 500 treads similar ground to my Millennia Media HV-3D. However, my biggest surprise came when pairing the RPQ 500 with a moving-coil/dynamic Shure SM7B. I love this microphone and what it does for vocals and voiceovers, but too often I have the same experience as when I use low-output ribbons -- too much noise floor. The RPQ 500 gave me the most clear and clean and musical sound I have ever heard from my SM7B!

Curving the tone

While functionally simple, the Low Frequency Filter is not a typical highpass filter. Its cut is nowhere near as steep, so it’s more of a low-end 'lessener' than 'eliminator', but in most of my tests that was fine as it tucks the low end back into the mix rather than eliminates it.

The Curve Shaper also takes some practice to get the hang of, as the throw of both the boost and the frequency range are pretty extreme. Since adding just 2 dB of eq can change a sound's placement in a mix substantially, imagine what can happen with +20 dB. If your mic has any noise floor at all you can easily push it over the top, so be careful. Also this is one of those eqs with an "air" band, and once you move beyond about 18 kHz, especially up into the mid-20s, what is added is more perceived than directly heard.

Once you master these two features you can nicely tailor your ribbon mic from a dark traditional tone to a sound that is more condenser-like and modern, yet still smooth. Lovely!


It’s easy to pass by a mic pre like this if you don't own or do much with ribbon mics, but the RPQ 500 is so much more than a one-trick or one-mic pony. It holds its own comfortably with all the members of the "straight wire with gain" family and has some nice tricks up its sleeve that set it apart as well. Of course if you are a ribbon connoisseur and/or a 500-Series rack owner, then you really need to demo one of these preamps as soon as you can... it will change your expectations about what you can do with even the lowest-output mics.

Price: $584 street

More from: Audio Engineering Associates (AEA),




Revisiting the AEA R84

During this review, AEA was kind enough to send me one of its R84 ribbon mics ($990), and while this mic has already been reviewed in this magazine by ribbon mic guru Scott Dorsey back in our November 2003, I have never had the pleasure of using one myself.

Like many of us, I have and use a Royer R-121 and 90% of the time it lives on guitar cabinets with the occasional bout of brass work thrown in. In simple terms the R84 is the flip side of the R-121's coin. Where the R-121 is modern, forward and punchy, the R84 gives you a soft silky sound with a bigger bottom end. Now I have never used a true RCA 44 or any of AEA’s historic recreations, but to my ears the R84 is instant Bing Crosby, 1930s radio goodness.

With the exception of a Neumann KM 84 through my Millennia HV-3D as a 12th-fret position acoustic guitar mic, I used the R84 and the RPQ 500 as the only microphone/preamp combo in a recent Folk session, with two vocal tracks, two acoustic guitars, hi-hat and brushed snare, shaker and kick drum, and it gelled the track together in a nice warm classic way. 'Smooth' does not even begin to describe it.

This mic has been around for quite a while but deserves another mention, especially working in concert with the RPQ preamps. Thanks for the loan, AEA! -- PV



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