Advanced Audio Microphones
CM28

Tube

CM28

$595

Currently out of stock

Compact tube condenser for tight spots, overheads, and detailed acoustic capture.

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Overview

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At this time we are unable to get the bodies manufactured

We are working on a solution for this but it may be 6 months away

The Advanced Audio CM28 is a pencil microphone with a unique hybrid topology. The CM28 offers the warmth of a tube circuit combined with the detail of the Class "A" discrete circuits used in German condenser microphones from the 1970s. The smooth, detailed response of the CM28 makes it an excellent choice for acoustic instruments. It can also be used in high-SPL situations such as the recording of percussion.  The CM28 has also been lovingly used over woodwind sections at London's Angel Studios.

Pheonix Drive perform featuring the CM28 on acoustic. Take note of the other "stars" in the video, recorded at The West Barn in Nashville.

Each CM28 microphone is supplied with cardiod, hyper-cardioid, and omni- directional capsules.

The head grill threads off to reveal a capsule similar to those used in the venerable Neumann KM84. These capsules have been designed with no grating and an extremely low rim recess in order to minimize audio reflections close to the diaphragm. The mesh head grill provides protection to the capsule that the KM84 lacked, while minimizing reflections.

The fet front end is designed to preserve all the detail captured by the 22 mm capsule. The signal is then delivered to a 6J1b tube circuit. This sub-miniature pentode is configured much like a grounded grid/triode circuit to drive rthe BV11 transformer, an approach that takes full advantage of the low-noise characteristic of the fet circuit as well as its very fast transient response.

The tube provides the fet with a very high impedance load so the fet's headroom is maximized. The tube circuit does not need to provide any gain, so its output impedance is very low. The lower output impedance and higher output swing of the tube circuit over the fet provides greater transparency.  The tube output circuit in the CM28 can provide 6dB more headroom than the Class "A" transformer-coupled fet-only circuits used in the 70s German condensers.

The CM28 has a -15dB external pad for high-SPL situations, and a low-frequency switch that rolls the low end out 6dB/octave at 80hz.

A remote power supply is provided that activates the tube and the fet.

22 mm, low profile externally-polarized condenser capsule

Omni, Cardioid, Wide-cardiod and Hyper-cardiod pickup patterns

30' 7-Pin Microphone cable

Frequency response

Measured at FOX Audio Research, Toronto · CM28

Cardioid · 20 Hz – 20 kHz
CM28 Cardioid frequency response
Omni · 20 Hz – 20 kHz
CM28 Omni frequency response

Specifications

Circuit
Class A fet/tube hybrid featuring a 6J1b tube
Frequency Response
20Hz to 20kHz (response relates to pattern type)
Impedance
200 ohms(load impedance < 1.2K).
Max SPL
124 dB/139dB with -15dB pad.
Distortion
< 1% THD @ 1KHz) 120dB, or at 135dB w/-15dB pad
Equivalent Noise
14dB (A-weighted)
Sensitivity
15MV/Pa = -37dB (0dB = 1v/Pa) -10dB
Pad
-15dB (Via Switch)
Filter
HPF @ 80Hz (Via Switch)
Weight
4.2 oz (119 g.)   Size: 5 1/2" (140mm) length x 13/16" (21mm) diameter
Power supply
Included · 7-pin umbilical
Warranty
Service-backed, in-house