A new take on a rare tube-classic
Review by Paul Vnuk Jr.
In the April 2021 installment of A Family of…Compared, we took a look at the Mojave MA Series of microphones showcasing the condenser creations of David Royer. Like the MA-1000DS (reviewed October 2017), some are David’s refinement of classic vintage designs like, in that case, the ELA M 250. This month we are looking at a flavorful new spin on the rare, coveted Sony C37a, reimagined as the Mojave MA-37.
A classic, unique design
The original C-37a was released in Japan in 1955. Over the years, it has become a bit of a secret weapon for many audio engineers for its smooth, warm tonality.
Petite by European tube-mic standards, the C37a swung in a U-shaped yoke, similar to vintage ribbon mic designs. The mic’s 37mm one-sided, single backplate capsule design offered a choice of cardioid or omnidirectional polar patterns. Changing patterns was uniquely accomplished by physically turning a mechanical vent in an acoustic chamber on the back of the diaphragm.
Inside the mic was a 6AU6 vacuum tube wired in triode mode (rather than the more common pentode) and nothing except a few resistors. All other components, like the transformer, were housed in the mic’s external power supply, where you could also find multiple high-pass filter options.
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Visually the MA-37 sticks close but adds modern flair to the original’s style and design. The 5.75″ x 2″ body retains the vintage swivel yoke and attached multi-pin pigtail. The head basket, multi-layered windscreen and yoke sport a classy matte nickel finish, while the dark gray body is perforated with small pinholes for looks and ventilation. The whole thing is rounded out with a Mojave badge and looks quite classy.
The capsule in the MA-37 is custom-made in California by Josephson Engineering. It sticks to the original design, manually turned vent and all. This capsule is also used in the Josephson C715 and Manley Reference Silver microphones. The tube is an EF806 vacuum tube, and the external power supply houses a Lundahl transformer.
The 8″ x 7.25″ x 4.5″ external power supply (larger than the original Sony PSU) features a fixed front side handle, LED-equipped power switch, cable I/O and a three-position rotary switch. This switch selects between the optional bass cut (hi-pass) settings: M (flat) V1 (-6dB at 50 Hz) and V2 (-6dB at 100 Hz).
The mic, power supply, and cables are housed in a sizeable pelican-style briefcase.
Like the C37a, the MA-37 has a 30 to 18,000 Hz frequency response. On paper, their plots are similar, but the MA-37 boasts a bolder low-end, with a 3.5dB peak from 60 to 400 Hz. The neutral mid-range remains identical, while the MA-37 has a wider gentle 2 dB presence spanning 8 to 18 kHz. The C37a had pronounced dips between 1 to 4 kHz and 6 to 12 kHz. Consequently, the MA-37 a touch more clarity than the Sony, nicely balanced by its weighted low-end.
Sticking to the original’s design, the -46dBv sensitivity of the MA-37 is a tad low by modern standards, but this gives the MA-37 a >135 SPL, perfect for louder sources. I never found the lower sensitivity to be an issue in my use, even on quiet acoustic sources.
While I try and avoid the descriptive ‘vintage vibe’ (usually translated as thick and warm) when describing microphones – the MA-37 is vibey as hell! Words that come to mind are thick, rich and bold. Having said that, the MA-37 is not an overly dark or muddy microphone. Its color and weight are well balanced by a glassy smooth top end.
It has a robust proximity effect that rolls off quickly and wonderfully tight off-axis rejection.
To adjust the polar pattern, you must insert a small flat head screwdriver and gently turn. I found the omni pattern of the MA-37 a bit different than the norm. While wider, more open and less weighted, there is still a discernible loss of level on the sides of the capsule, while the top of the mic retains an omnidirectional openness. Reading through a vintage C37a manual, the top of the capsule is listed as its 90º axis rather than the sides, so this could be inherent in the unique design.
In use, the MA-37 offers a full, even smoothness that sounds great on crooning vocals, string instruments, electric guitar cabinet, and any bright source that needs a bit of sonic soothing. I could see this as a fantastic brass mic.
My favorite use of the MA-37 was as a drum overheard (I only had one, but I can guess this to be a great option in a stereo Glyn Johns setup). It highlighted the punch and power of the snare and toms while blending the cymbals into the drum mix rather than highlighting them as many condensers do. It also helps that the mic weighs a pound and is easy to position.
The bass cut filters are well-chosen to clear out low-end rumble, thumps and excessive proximity effect.
I also compared the MA-37 with three other high-end tube mics. Overall it was noticeably more rounded and warm than my Chandler Limited REDD mic. It was more laid back and less upper-mid forward than my U47 flavored Pearlman TM-47. It was closest in top-end tone to my Manley Labs Ref. Silver mic (with which it shares a capsule), yet I found the Mojave MA-37 had a bit more weight and low-end fullness. All in all, it sat proudly in this high-end crowd offering new tonal variations to explore.
The Mojave MA-37 brings the sound and style of a rare classic tube mic to the modern recording world. It has fantastic build quality, top-notch components and a stunning, smoothly weighted, vibey as hell sound. Personally, this is my favorite Mojave microphone yet.
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