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resonance equalizer

product review

Pro Audio Review magazine by Alan Silverman

The REQ-2.2ME is "better vintage than vintage. It is a gentle giant of an EQ."

In 1995, Tim Farrant -- Buzz Audio's owner and lead designer -- first experienced the sound of a Neve 1073 equalizer, a classic discrete-circuitry EQ with variable frequencies, but fixed Q. Up until that point, Tim had been using an IC-based Soundcraft console with fully parametric op-amp based EQ.

The difference in musicality and sound quality was a revelation: Tim decided he needed to discover why there was such a huge difference between the two equalizers, and to learn how to apply that knowledge in creating an EQ that would combine the superior sound quality of the Neve with the flexibility of a true parametric. The answer seemed to begin with the use of ferrite-core chokes, providing the needed inductance in a classic LC resonant circuit as opposed to simulating inductance with an op-amp based circuit such as a gyrator.

The road to realizing a successful design was a long one, though. Eleven years later, a prototype of the REQ-2.2 was built, with two more years of refinement and debugging until the first production model was offered for sale in 2008. One of Buzz Audio's major advancements in equalization is the switching network and its capability to provide a large number of inductor/capacitor/bandwidth combinations -- all done with discrete components.


The REQ-2.2 is an enormously flexible, four-band stereo parametric EQ with completely independent L and R channel controls, a six-position transformer-based saturation circuit, and a five-position high-pass filter set. The amp circuits are all Class A. All bands are hard-switched via rotary switches and a micro-controller-based relay network operated by feather-touch illuminated push buttons. The mastering edition features Elma rotaries and a tighter range of high-pass filter corner frequencies than the standard edition. The mastering edition offers a boost/cut range of +/- 8dB versus +/- 16dB in the standard. In both editions, each band offers 12 frequency positions, 12 Q positions, and 23 boost/cut positions, plus a range button which doubles the number of frequency choices in the two mid bands, and switches between bell and shelf in the low and high bands -- that's a huge number of combinations waiting to be explored. Each band can be individually hard-switched in and out of circuit. There's plenty of overlap in the available frequencies; the number of choices and possibilities is both staggering and inspiring.

The transformer saturation circuit is built around the distortion characteristics of a proprietary steel-core transformer and a variable load impedance network. The tonal effect ranges from an apparent bass increase at the lowest setting to a mild bass roll-off at the highest, with measurable distortion ranging from 0.07 to 0.22 percent, measured at 100Hz. With the saturation and high-pass filters off, the REQ-2.2 measures flat from 5Hz to 125kHz with distortion of 0.004 percent with all bands on and set flat.

The REQ is quite transparent when it needs to be, yet offers a very usable range of coloration when desired. Peak level indication is provided by a single LED for each channel, which turns on at +22dBu, sensed at multiple points within the signal path. A final handy feature is a second set of balanced outputs for each channel, useful for driving alternate paths in the signal chain.

In Use

Upon first auditioning the REQ-2,2, my immediate impression was that each band, even the high band, has a depth and richness that I've rarely encountered in any other equalizer, whether authentic vintage or modern. The midrange has a "reach out and touch it" credibility -- full and natural. The Q's tend to be broad; half a dB of boost or cut goes a long way.

Surprisingly, the individual frequency points sound different than I am used to with other equalizers, and consequently the REQ-2.2 requires a longer than expected learning curve; it presents a new language of numbers and host of new frequency friends. There is plenty of overlap and range, so I have yet to run into a situation where the frequency I am looking for is unavailable. Where there is overlap, there is actually a second level of choice; for example, 80 Hz on the low mid band sounds tighter and faster than 75Hz on the low band, which has a warmer, heavier cast to it -- in effect, offering two complimentary bass tonalities, both useful.

The saturation options are especially brilliant. I am generally disappointed by most saturation implementations, which I find to be too dull and too thick to be useful except for the thinnest and harshest mixes. By contrast, saturation on the Buzz is warm, clear and airy. On the milder settings, it is subtle but still effective. One of my first applications of it was on a grainy-sounding project originally tracked on the first series of ADATs. The transformation wassheer magic.

All good mastering gear has a physical feel that facilitates interaction with the music at hand. The open and spacious layout makes navigating though the myriad possibilities easy. Operating the REQ-2.2 is akin to playing an instrument; as with any instrument, practice is essential.

There are some quirks to the controls that require familiarity. For example, the PIC micro-controller for the system, saturation, and high-pass circuits, presently can only switch one side at a time. I soon learned not to attempt to press both of the feather-light push buttons together or I'd end up with only one of the two desired functions engaged. Fortunately, the visual feedback on the box is excellent. The LEDs light up the lenses well, and the choice of colors, soft green and soft blue, is pleasant on the eyes. I eventually learned to use a rolling hand motion, not unlike "punching in" on an analog tape machine.

When the review unit arrived, one of the bands would not pass signal when engaged, but the channel functioned normally with that band switched out, verifying that there is true bypass for each band; Tim sent a new card out immediately. The replacement required no special tools or soldering, as the cards are modular and are secured with a good mechanical design and press-fit multi-pin connectors. The repair went quickly and easily.

The unit performed beautifully as the primary EQ on "Roots & Bells," a new CD from the NYC band, Town Hall, produced by Brooklyn's own Mason Jar Music. The songs, voices, and instrumentation are complex, driving, and delicate; the REQ imparted a warmth and musical clarity that seemed to be tailor-made for this music. The uniqueness of the group's sound and the personality of the EQ blended seamlessly. I have found the REQ-2.2 to excel for vocal projects and for all kinds of music from classical to heavy metal.


Buzz Audio has created a new classic in equalization, offering idealized historical-quality sound and modern versatility. The combination of the REQ's transparency and powerful tone-shaping capabilities make it a new benchmark in equalization. The REQ 2.2 has become my first choice analog EQ over the other mastering-grade pieces available here; it invites creativity and its exceptionally broad palette of colors has been a pleasure to explore. The design lives up to the mythical promise of unobtainable vintage gear, which rarely materializes and then only at astronomical prices. The Buzz Audio REQ-2.2ME seems more vintage than true vintage pieces. It is a gentle giant of an EQ.

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