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Kel Audio HM-7U

Pricing & Availability

  • MSRP: $399
  • Discontinued


HM-7U Documentation

SupercardioidKel Audio HM-7U

Supercardioid Condenser Microphone

The HM7U is a large-diaphragm transformerless FET condenser, with a cardioid K47-style capsule.

HM-7U circuitThe mic is manufactured in China to specifications developed by Kel Audio. The design avoids the pitfalls of most imported microphones by omitting the tube and transformer circuits that frequently are populated with low-fi parts; instead, the HM-7U uses a transformerless dual-FET design.

The mic’s amplifier was designed to be linear or transparent, to allow the sound of the capsule to be heard.

Kelly Dueck

It is the sound of the capsule that mostly characterizes this mic. We were after a mic that was brighter than the HM-1 and HM-2D without having problems with sibilance, and the K47 is the capsule to do that.

The mic body is made of aluminum, making it lighter weight than many mics of similar size. The lack of a transformer also contributes to its light weight.

The capsule has dual 34mm diaphragms, although only the front diaphragm is sputtered with gold. The diaphragm material is 3-micron Mylar. Like Neumann’s K47 capsule, the HM-7U capsule is a single-backplate design.

HM-7USwitches on the body provide access to a high-pass filter and a -6dB pad. Note that some resellers and advertising state that the pad is a -10dB design, and that was true of the prototypes; the design was changed to -6dB for production to make it more neutral-sounding. An LED indicates the presence of phantom power.

The mic ships with a shockmount, a swivel mount, and a flight case. Its introductory price of $299 was raised to $349 in mid-2009.

HM7U photos by DJS-NJ

The Kel Audio HM-7U is also known as: HM7U.

The mic was released in 2008.


Frequency Response - SupercardioidClick Graph to Compare!
HM-7U Supercardioid Frequency Response Chart
Pickup Patterns Pads & Filters
Supercardioid (12.6 mV/Pa; 20 - 20,000 Hz)
  • Pad: -6dB (Via Switch)
Capsule Dimensions Impedance SPL/Noise
Diaphragm diameter: 26mm
Capsule diameter: 34mm
Diaphragm gauge: 6 microns
55 Ohms (Low) Max SPL: 132 dB
Self-noise: 14.0 dB(A)
Weight Length Max Diameter Interface(s)
n/a 182mm (7.17'') 51mm (2.01'')
  • 3-pin XLR male (1)
Power Specifications
  • Requires phantom power

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