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Bidirectionalt.bone RM700

Bidirectional Ribbon Microphone

The RM700 is a Chinese-made ribbon mic, and is believed to be identical to Nady’s RSM-4, which is believed to be a rebadged Alctron HRM-15, manufactured by Shanghai ShuaiYin, whose original model number for this microphone is SYR-30.

The published specs for the RM700 are identical to the RSM-4. Both differ in numerous ways from the HRM-15 (and SYR-30), but neither Alctron’s nor Nady’s specs are known to be particularly accurate. Further, production changes are often not reflected in the mics’ documentation.

At least some RM-700s use an “offset ribbon” arrangement, in which the ribbon is mounted toward the front of the mic, rather than centered; this provides two different sounds for the front and back, as in the Royer R-121; it also provides higher SPL handling for the front side than would a symmetrical-ribbon mounting, and a brighter sound on the back side. Royer advertises this feature as “two mics in one,” and their patent on the idea has generally prevented Chinese manufacturers from copying the idea, although apparently not in this case.

Like all the “lollipop” style ribbon mics from China, the RM-700’s ribbon motor is the “medium ribbon/long path” design, as described by Michael Joly.

The mic includes a 3-year warranty. Ships with a shockmount, wooden storage box, and aluminum flightcase.

The t.bone RM700 is also known as: RM-700.

The mic was released in 2005.


Pickup Patterns Pads & Filters
Bidirectional (1.8 mV/Pa; 30 - 18,000 Hz)
Ribbon Construction Impedance SPL/Noise
Offset, 6-micron aluminum ribbon 200 Ohms (Low) Max SPL: 165 dB
Weight Length Max Diameter Interface(s)
794g (28.01oz) 165mm (6.50'') 76mm (2.99'')
  • 3-pin XLR male (1)
Power Specifications

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