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Royer R122 MkII

Active Ribbon Microphone
Published December 2015
By Hugh Robjohns

When you already make some of the best ribbon mics in the world, improving on them isn’t easy — but Royer have done just that.

The original R122, launched in 2002, was “the world’s first phantom-powered active ribbon microphone”. Other companies have claimed the same precedent in recent years, but Royer are the true titleholders. The R122 has proved very popular over the last 13 years or so, with over 5000 being sold since the product’s launch.

Royer R122 MkII

Royer’s R-series microphones are pretty robust and specifically designed for use in high-SPL applications, such as on guitar amps, drums, brass and vocals, as well as strings, acoustic guitars and pianos. They all use a corrugated, 2.5-micron-thick ribbon element which is around 45mm in length. Neodymium magnets are employed in the motor assembly with an asymmetrical construction — something Royer have patented and called an ‘offset-ribbon’ design.

The offset-ribbon construction is all about maximising the mic’s ability to cope with high SPLs but, for close sound sources (within about a metre), it also imposes a distinct difference in tonal character for sounds arriving at the front and rear — essentially, rearward sources appear brighter (or frontal sources seem darker, depending on your perspective). This is quite a useful facility, allowing for some creativity in mic placement and orientation. Importantly, though, for more distant sources (beyond about a metre away) the tonal difference between front and rear sources becomes negligible, so the R122 can still be used as a Sides mic in M-S arrays if you’re working with reasonably distant sources. (For comparison, the ribbon transducer elements used in the company’s SF-series mics are constructed with a symmetrical motor system, and with a thinner 1.8-micron diaphragm.)

I reviewed the passive R121 ribbon mic in SOS April 2000 edition, but the original MkI version of the R122 never received a full SOS review.

Activated

The benefits of ‘active ribbons’ are manifold, but there are potential disadvantages too, of course. Among the more obvious benefits is inherent protection of the ribbon transducer from phantom power. Applying phantom power to a passive ribbon mic can, in certain circumstances, damage and even destroy the ribbon (although most modern ribbons can tolerate phantom power quite happily). However, by isolating the ribbon behind an active buffer circuit, phantom power can’t reach the ribbon and so that risk is removed completely.

A second benefit is independence from cable and preamp loading effects. Most ribbon mics are quite sensitive to the impedance that the ribbon transducer is required to drive. Distinct changes in tonal character (and output level) can occur depending on the preamp’s input impedance and the length of connecting cable. In active ribbon mics the buffer circuit can be designed to present the optimum (usually quite high) impedance to the ribbon element, minimising the load it has to drive, while simultaneously driving the mic cable from a very low-impedance source with complete independence from variations in load impedance and cable length.

With just the one moving conductor within the magnetic field, the output of a ribbon transducer is inherently very low, and a step-up transformer is traditionally employed to produce a more sensible output voltage. However, there are practical limits as to how much voltage step-up can be achieved passively because the output impedance rises dramatically. However, an active buffer can be configured to act as an ‘impedance converter’ — just as in a capacitor mic. The outcome is low noise gain from the transformer, but with a low output impedance from the buffer circuit, and an output level which is comparable with that of capacitor mics. This potentially reduces the requirement for specialist high-gain, low-noise preamps and makes the active ribbon mic a more practical proposition for project studios and those with budget equipment.

Balanced against these attractive benefits are a couple of potential drawbacks. Firstly, all active gain stages introduce some electronic noise which must, inherently, be higher than that of the passive ribbon transducer alone. This establishes the practical lower limit for usable signal levels. Secondly, all active gain stages will clip at some elevated signal level (usually determined by the internal power rails), and that establishes the upper signal level limit. These two attributes thus define the overall dynamic range capability of the microphone, and so active ribbons generally have a slightly smaller dynamic range than their passive siblings. The most relevant practical limitation is a greater risk of overload when the mic is placed in front of very loud sources — either by generating such a high output level that it overloads the connected preamp, or by overloading the internal buffer circuitry itself.

The challenge for the designer and manufacturer is deciding on the best compromise between sensitivity, maximum SPL, and self-noise, all of which are heavily influenced by the intended applications. For example, should the sensitivity be optimised for classical distant placement techniques, or the headroom optimised for close placement with loud sources?

Updating A Classic

At its heart, the updated Royer R122 MkII is the same as the original design. It still employs the original custom-designed toroidal step-up transformer, with a very high turns ratio to give around 15dB of voltage gain. The output from the secondary winding is fed into a pair of discrete, very low-noise FETs, which provide the impedance conversion, and then a pair of bipolar transistors configured as emitter followers to drive the balanced low-impedance output.

The issue of optimising sensitivity and headroom has been neatly circumvented by introducing a couple of recessed slide-switches on the rear of the mic body to allow the headroom and frequency response to be tailored to the situation. However, given the original mic’s sonic excellence and popularity, the Royer team were very keen not to ruin ‘a good thing’, and with the two switches in their off positions the R122 MkII has an identical signal path and performance to the original design.

When the original R122 was placed in front of seriously loud guitar amps it was possible to find its output level was so high that it overloaded the connected mic preamp, or the internal buffer circuit ran out of headroom (especially if the phantom power was on the low side, or the input impedance was particularly low). The new 15dB pad switch neatly circumvents both of these possibilities as it increases the headroom of the internal buffer circuitry while also reducing the overall output level to avoid overloading a connected preamp. Extensive testing has apparently failed to create any overload problems at all, and the specifications claim a maximum SPL of 135dB (at 30Hz).

With the pad switched off, the R122 MkII’s sensitivity is given as 15.8mV/Pa with self-noise less than 18dB SPL — both figures being about the same as for a typical small-diaphragm capacitor microphone. However, with the pad switched in the sensitivity falls to 2.8mV/Pa, which is almost 2dB lower than the passive R121’s sensitivity (3.2mV/Pa).

The second switch introduces a first-order (6dB/octave) high-pass filter, rolling off from 100Hz. The gentle slope of this filter makes clear that its intended purpose is to manage proximity effect, rather than to remove subsonic rumbles — although it will also help with that to some extent. Proximity effect is always very strong when a pure pressure-gradient mic like the R122 is placed close to a sound source, so the new filter switch enables the mic to sound properly balanced when used up close on vocals or guitar amps, for example, without having to resort to EQ.

Looking at the published technical specifications, the frequency response is given as 30Hz to 15kHz (±3dB), and the trace exhibits a mild dip in level between about 250 and 750 Hz, and another above 12kHz, both of which combine to give a subtle mid-forward tonality which helps things to cut through in a mix without needing EQ. The R122 MkII is not a heavy load for phantom power, its discrete buffer circuitry requiring only 4mA from a standard 48V supply.

Unlike the original, the R122 MkII has switches for applying a  15dB pad and a  100Hz first-order high-pass filter.Unlike the original, the R122 MkII has switches for applying a 15dB pad and a 100Hz first-order high-pass filter.

Open The Box

The R122 MkII is shipped in a velvet-lined wooden case, and supplied with a couple of Velcro cable ties, a CD-ROM of product manuals (not that most modern computers have optical disc drives any more), a plush dust bag to protect the mic when not in use, and a universal spring clip standmount. Amusingly, a label on the mic-clip bag says, “This complimentary clip is provided for convenience and is not intended for permanent use with this microphone...”

Instead, Royer recommend their own RSM-1 Sling-Shock accessory, which, to be fair, is a very well-engineered shockmount that does an excellent job of isolating the mic from subsonic rumbles and vibrations. This is important with ribbon mics because long ribbons typically have a resonant frequency somewhere between 7 and 15 Hz, so you really don’t want subsonic vibrations reaching the mic’s transducer. I was supplied with a pair of R122 MkIIs for the review, along with a pair of RSM-1 Sling-Shock mounts, and the universal spring clips stayed in their bags unused!

Not surprisingly, the R122 MkII’s body is a little longer than the passive R121, to house the electronics, but is unchanged from the original R122 at 206mm long by 25mm in diameter, and weighing 309 grams. As with its sibling, stubby ‘wings’ extend on either side of the grille slots to indicate the side nulls of the mic’s bipolar pickup pattern. The mic is available in either burnished satin nickel or matte-black chrome finishes. Royer offer a lifetime warranty to the original owner, with a one-year warranty on the ribbon element (the first re-ribbon is free regardless of how long the mic is owned), and matched pairs are available too.

In Use

The R122 MkII is a very easy mic to use thanks to its generous output level and robust ribbon. I had no concerns at all about placing it in front of loud sources, and if the output level started to get a bit hot then flipping the pad switch instantly resolved the matter. Similarly, whereas the original version could often sound a bit bass-heavy, switching in the high-pass filter restored a natural balance. Like all ribbons, the R122 MkII also ‘takes EQ’ very nicely — by which I mean that you can bring up the high end with a shelving EQ for some extra air and transient crispness without any nasty, scratchy resonances. The low end can be manipulated in the same way without any vices, although it pays to check for the presence of unwanted subsonic rumbles, especially if you’re not using the Sling-Shock mount.

Compared to the R121, the R122 has always enjoyed a slightly more tightly controlled low end and a better overall transient response — both welcome side-effects of the optimised impedance loading of the ribbon element through the transformer — and the MkII update hasn’t had any impact on that behaviour at all. Although the R121 is classed as Royer’s flagship microphone, I think the R122 MkII is actually the better option in many situations. I prefer its slightly tighter and crisper sound quality, and there is no doubt that it is a more versatile and flexible mic when it comes to partnering preamps. When paired with a very high-quality preamp purposely designed for use with ribbon mics, the R121 might have the edge in subtlety and noise floor, but the updated R122 MkII wins easily in terms of convenience and usability.

The elephant in the room, of course, is the price tag. The ribbon microphone market has developed enormously over the last decade and there’s a lot of competition now, and a lot of very strong yet cost-effective options from which to choose. Royer’s ribbon mics have always set very high standards in terms of engineering design, build quality, and sound character, but such excellence and precision comes at a price. It’s possible to buy matched pairs of passive (or active) ribbons from highly regarded manufacturers for the cost of a single R122 MkII, and there’s a very hefty price premium over the passive R121 model, too — although that needs to be weighed against not needing a specialist high-end mic preamp. 

Alternatives

Royer microphones dominate the top end of the ribbon microphone market, but there is now very strong competition in active ribbons from companies like AEA (N22 and N8 Nuvo, or A840), Audio-Technica (AT4080 and AT4081), Blue (Woodpecker), Cloud (JRS-34), Peluso (TR14), Rode (NTR and Classic 2) sE Electronics (RNR1), and Sontronics (Sigma and Delta), among several others.

Published December 2015