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Microphones & preamps

RCA Type 77-DX microphone

A ribbon mic that makes you turn a screwdriver to change its mind—and rewards that labour with unmatched pattern consistency.

Worth your time?4/5Yes.Use the whole thing.What works, what does not, who it is for ↓
8:24in productionCh. 1 · What kind of mic is it?/ 8:24 · ceiling 15 min
4 chapters · 8:24Ceiling 15:00

The brief is written and checked. The video joins this page when it is cut.4 chapters · 1 min read · 8:24 planned

Read the brief

The RCA Type 77-DX is a 1954 poly-directional ribbon microphone with mechanical pattern control, low-tension 2.5-micron ribbon, and user-selectable impedance and low-frequency rolloff.

Chapters & takeaways4
  1. 1:00
    What kind of mic is it?

    It is a poly-directional ribbon microphone—not an electret, not a condenser, not switchable by button.

  2. 2:28
    How do you change its direction?

    You adjust its pattern with a screwdriver on a rotating backshutter—not a dial, not software, not presets.

  3. 3:59
    What else do you set by hand?

    Low-end roll-off and output impedance are set manually—three positions each, no auto-sensing.

  4. 5:11
    How loud does it speak?

    Its output is weak: -50 to -56 dBm at 1 kHz—enough to expose preamp noise and limit placement options.

1 more chapterFewer chapters
Worth your time?

Yes. Use the whole thing.

4/ 5
What works
  • mechanical pattern variation
  • consistent off-axis rejection
  • user-configurable impedance and LF rolloff
  • pressure-gradient ribbon response
What does not
  • deliver high output
  • tolerate phantom power
  • offer electronic pattern switching
  • include modern noise suppression
Use it if
  • engineers with ribbon-optimised preamps
  • broadcast historians
  • studios prioritising tactile control over convenience
Skip it if
  • beginners
  • live performers
  • anyone without high-gain, low-noise preamplification
Who should use it, and who should skipHide who it is for
The written brief1 min read

What it is and what it was built for

A poly-directional ribbon microphone built for broadcast and studio use in 1954. Designed for voice, orchestral, and ensemble capture where pattern flexibility and tonal neutrality mattered more than raw output or durability.

How it works, in terms a player would use

It uses a 2.5-micron corrugated metal ribbon suspended under very little tension. Voltage is induced at right angles to both ribbon velocity and magnetic field direction. A rear-mounted rotating backshutter — adjusted with a screwdriver — changes directionality from omnidirectional to cardioid to figure-8. A 3-position switch controls low-frequency rolloff. Output impedance is user-selectable between 30, 150, and 250 ohms.

What it does better than anything else

It gives direct, physical control over polar pattern via a rotating backshutter—no electronics, no switches, just acoustic labyrinth adjustment. That mechanical precision, combined with its pressure-gradient ribbon design, yields consistent, smooth off-axis rejection across patterns.

What it does badly

It delivers low output: -50 to -56 dBm at 1 kHz, demanding clean, high-gain preamps. It offers no high-pass filtering beyond the fixed 3-position low-frequency rolloff. Its ribbon is fragile and cannot handle high SPLs or phantom power.

What people made with it

Broadcasters, radio engineers, and recording studios used it for voice-over, live orchestral pickup, and vocal tracking in the mid-20th century. Its directional versatility made it suitable for multi-source environments without repositioning.

Who should use it, and who should not

Studio engineers who own ribbon-optimised preamps and value hands-on pattern control. Not for beginners, live sound technicians, or anyone without a dedicated ribbon mic signal chain.

Is it worth your time

Yes—if you need a variable-pattern ribbon with tactile, tool-assisted pattern control and accept its modest output and fixed frequency response. No—if you require high sensitivity, modern noise floors, or plug-and-play operation.

Same bench · Microphones & preamps4 of 55
9:08
RCA Type 44RCAThe RCA Type 44 is a bi-directional ribbon microphone introduced in 1931. Its thin corrugated metal ribbon generates voltage when vibrating in a magnetic field. It hears only front and back. It breaks under wind, phantom power, and loud transients. It flatters voice and acoustic instruments with smooth mids and gentle highs. It belongs in a vintage studio chain—not on a podcast desk or a stage.
8:46
Shure SM58Shure · 1966The Shure SM58 is a professional cardioid dynamic microphone introduced in 1966. It is commonly used in live vocal applications. It has been produced since 1966 and is still the industry standard for live vocal performance microphones. It is the most popular live vocal microphone in the world. Like all directional microphones, it is subject to proximity effect, a low-frequency boost when used close to the source. Its cardioid response reduces pickup from the side and rear, helping to avoid feedback onstage. The SM58 uses an internal shock mount to reduce handling noise. A distinctive feature of the SM58 is its pneumatic suspension system for the microphone capsule. The SM58 was introduced in 1966 as part of the SM series. The SM58 was originally developed for the TV studio market with a non-reflective finish and no on-off switch. The SM58 has been one of the two bestselling microphones in the world since the late 1960s. The SM58 shares nearly identical features with the SM57, differing mainly in grille design.
9:19
Shure SM57Shure · 1965The Shure SM57 is a low-impedance cardioid dynamic microphone introduced in 1965. It uses the Unidyne III capsule, shares design DNA with the SM58, and features impedance balancing via XLR. Its frequency response runs from 40 Hz to 15 kHz. Its cardioid pattern reduces background noise and feedback. It was built for TV studios — non-reflective, no on-off switch — and tested under torture. It has been used for every U.S. presidential speech since 1965 and remains one of the world’s two bestselling microphones since the late 1960s.
10:28
Neumann KM 86NeumannThe KM 86 is not a KM 84 variant. It is a dual-capsule small-diaphragm condenser that delivers three virtual polar patterns — and a sound described as 'more pais'. It was sold with XLR or Tuchel connectors. That is all the source tells us.
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