Nobel Studio Recording · Oslo
Studio / Utstyr / The Type 4040
The instrument · Utstyr

Brüel & Kjær
Type 4040 Gold Tube + FET. Handcrafted in Denmark.

SerialNo. 058
Edition1 of 100
OriginDenmark
StatusIn service
The brass engraving plate on the Type 4040 — Serial No: 058, handcrafted by Brüel & Kjær, Denmark
Engraving plate · Serial 058
Provenance

A measurement microphone that was never supposed to sing.

In the late 1990s, the Danish acoustics firm Brüel & Kjær released the 4040 — a hundred handcrafted microphones built around the same Type 4006 capsule that had won them their measurement-grade reputation. The 4040 was their answer to a question they were not, strictly, in the business of asking: what does a measurement microphone sound like, in a room, on a voice.

Most of the hundred went to artists and engineers who paid to have their names cut into the brass. Number 058's plate ends “for:” — and the space after it is still blank. It found its way to Nobel Studio without a name. It still doesn't have one.

Number 058 has lived here for two decades. Originally calibrated for orchestral classical. Still in active use.

Engraved on the body “The 4040 — Serial No: 058. Handcrafted by Brüel & Kjær, Denmark — for:” — still blank.
Through the transparent body of the Type 4040 — handcrafted electronics visible inside
— Through the glass —

Every component placed by hand.

The 4040's outer tube is left transparent on purpose. You can see the discrete electronics, the hand-soldered joints, the tuning capacitors — the actual labour behind it.

The capsule

The Type 4006 head. The thing that makes it what it is.

The brass capsule head sits proud of the body, ringed with the same radial vent pattern Brüel & Kjær use on their reference measurement microphones. It's the same hardware that calibrates concert halls and aircraft engines — pointed, in this room, at a singer.

One diaphragm. Two amplifier stages. The matched preamp splits the signal into two parallel channels — tube and FET — both fed by the same single membrane. Because the source is one, there is no phase offset between the two outputs, and no comb filter. The engineer gets both signals on separate channels and blends them in the studio in any ratio.

Tube warmth and FET accuracy, aligned by design.

For vocal recordings, Serial 058 feeds a Millennia HV-3D — a minimum-phase preamp with as close to no character as anyone has ever managed. From diaphragm to digital, the signal passes nearly untouched. What you hear on the record is what was in the room.

The 4006 capsule design has had a longer trajectory than most. Brüel & Kjær's pro-audio team spun off as DPA in 1992; the same capsule lineage now sits on NASA's Perseverance rover, recording the surface of Mars. The mic in this room, and the mic on Mars, are siblings.

References by request.

The brass capsule head of the Type 4040, showing the radial vent pattern
The complete instrument

It never came as just a microphone.

Serial 058 arrived from Denmark in a Samsonite Style 2000 briefcase — brass-plated Brüel & Kjær, with foam machined to the mic, its dedicated preamp, the matched shockmount, and the cable. Two decades on, the case still does what it was made to do.

The complete Brüel & Kjær Type 4040 kit, foam-nested in the open Samsonite case — mic, preamp, shockmount, cable Case opened
The brass Brüel & Kjær nameplate on the case lid Brass plate · same finish as the mic

A matched preamp, hand-built for this one microphone.

The black panel inside the case is labeled “Microphone Preamplifier for Brüel & Kjær Type 4040.” Dedicated input, three-step pad at −20 / −10 / 0 dB, single power LED. Not a generic preamp — the mate of Serial 058.

Still in its case between sessions. Not for sale. (Unless twenty million. Probably not even then.)
Microphone Type 4040 · 058 / 100 Brüel & Kjær, Denmark
Preamp Tube + FET One diaphragm · two stages · no comb filter
Shockmount Original B&K clip Foam-nested in lid
Case Samsonite Style 2000 Brass plate · custom foam
— In the room —

What it sounds like.

Recorded through Serial 058 at Nobel Studio, Oslo. Released by Nobel Records.

Nora Augustinius Ain't No Sunshine Bill Withers cover · 2017
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In service at Nobel Studio, Oslo.

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