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SupercardioidHeil Sound PR-40

Supercardioid Dynamic Microphone

The Heil PR-40 is a premium dynamic microphone designed for voiceover, broadcast, and instrument applications, both live and in the studio.

Billed as, simultaneously, “Absolute most natural voice response for talk show hosts” and “Best kick drum microphone ever,” the PR-40 introduced deeper low-end response to the Heil PR series of dynamic mics, while retaining the midrange articulation that is characteristic of all of Heil’s designs.

The mic’s large moving-coil cartridge has a 1.125'' diameter. Its low mass, “quilted aluminum” diaphragm is coupled to a rare-earth magnet made of neodymium, iron, and boron. The entire assembly is shockmounted via Sorbothane©.

Two wire mesh screens and an internal blast filter reduce plosives.

PR 40 end-fire logoNote that although the case looks like a side-address design, the moving coil points out the top of the microphone. The large wraparound screen provides easy access to the bottom of the dynamic element — the phasing plug — which gives the PR 40 such high levels of rear or “off-axis” rejection.

The PR-40, like the other Heil mics, produces balanced output from the voice coil without the need for an output transformer. A humbucking coil reduces EMF noise.

Bob Heil

I designed the element to have an entire 360 degree opening — the entire BOTTOM of the element that focuses all of those rear signals into the phasing plug. I mounted the element on top of a ‘collection tube’ — a 1 1/4'' diameter by 2.5 inch long tube that the element sits on top of — right up against the end fire screen. Since the signals vary in length according to frequency, I allow them to enter through the 2.5'' of side address screens, 360 degrees around. The rear signals ‘flow’ into the screens and collect on the tube as they flow up into the bottom of the element. The result is an amazing 45 dB of REAR rejection.

Heil Sound has since backed off on the claim of “45dB rear rejection;” product literature does not quantify the rejection, either in level or direction.

See The Ultimate Podcast Mic Shootout for our own rear-rejection test results: with pink noise, the PR-40 turned in ~12dB rejection at 180° and ~14dB at 135°. It was the most sensitive at 180° of all the Cardioid mics in the test.

It is worth noting that at the time of the mic’s introduction, it was described in product literature as having a SuperCardioid pickup pattern — which implies the presence of a higher sensitivity at 180° than around ±135°. Heil later changed its product description, as well as the published polar-pattern graph, to Cardioid.

MIX review, 2005

With the PR 40 on kick (an 18-inch Slingerland using a wood beater), I got more subsonic frequencies and a brighter attack than with the other mics. The M88 was rounder in the low midrange but had less snap in the attack. Both mics sounded good, but the Heil pulled a surprising amount of subsonic low end out of the small kick drum. Repositioning the PR 40 so that it was aimed away from the beater, it produced less attack and more roundness.

RadioWorld, 2005

I measured on the console VU meters an approximate 13 to 14 dB attenuation when annunciating into the back of the mic.

The Heil Sound PR-40 is also known as: PR40.


Frequency Response - SupercardioidClick Graph to Compare!
PR-40 Supercardioid Frequency Response Chart
Pickup Patterns Pads & Filters
Supercardioid (2.0 mV/Pa; 28 - 18,000 Hz)
Coil Diameter Impedance SPL/Noise
n/a 600 Ohms (Low) Max SPL: 145 dB
Weight Length Max Diameter Interface(s)
383g (13.51oz) 170mm (6.69'') 52mm (2.05'')
  • 3-pin XLR male (1)
Power Specifications

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