The Audio-Technica AT4033a represents an important stage in the development of the company’s professional 40 Series microphones. Its predecessor, the AT4033, was introduced in 1991 and became one of the first large-diaphragm studio condenser microphones to offer professional recording performance at a price significantly below that of many established competitors. Developed with input from producer Phil Ramone, the original microphone helped establish Audio-Technica as a significant manufacturer in the professional studio microphone market.
In 1996, Audio-Technica introduced the revised Audio-Technica AT4033a, incorporating improvements to the original microphone’s internal electronics and capsule suspension system. These modifications were intended to reduce handling noise and mechanically transmitted vibrations while preserving the sound and operating characteristics that had established the AT4033’s reputation.
At the centre of the Audio-Technica AT4033a is a permanently polarised condenser capsule employing a fixed-charge back plate and a specially contoured, vapour-deposited gold diaphragm. Measuring just 2 microns in thickness, the diaphragm undergoes a five-stage ageing process designed to maintain consistent performance characteristics over time. This precision manufacturing process contributes to the microphone’s sensitivity, transient response and ability to reproduce subtle high-frequency information.
Unlike externally polarised true condenser microphones, the Audio-Technica AT4033a employs an electret-based capsule design that retains its polarisation charge. This approach allowed Audio-Technica to develop a professional large-diaphragm microphone with a fixed cardioid polar pattern while avoiding the additional circuitry required to generate a separate capsule polarisation voltage.
The microphone’s cardioid polar pattern provides maximum sensitivity to sound arriving from the front of the capsule while reducing pickup from the sides and rear. Its symmetrical housing assembly surrounds the capsule with an open acoustic environment designed to minimise unwanted internal reflections. This construction also contributes to consistent off-axis behaviour, allowing sound arriving outside the microphone’s principal pickup axis to retain a relatively natural tonal balance.
One of the distinguishing characteristics of the Audio-Technica AT4033a is its transformerless output circuitry. By eliminating the conventional audio output transformer, the microphone reduces the potential for low-frequency distortion and provides improved reproduction of rapid transient signals. This electronic design is particularly beneficial when recording instruments with complex harmonic structures or pronounced attack characteristics.
The Audio-Technica AT4033a has a frequency response extending from 30 Hz to 20 kHz, providing broad coverage of the audible spectrum. Its acoustic design produces a strong, forward presence while maintaining detailed high-frequency reproduction. These characteristics made the microphone suitable for a wide range of studio applications, including lead vocals, backing vocals, acoustic guitar, piano, strings, percussion and amplified instruments.
The microphone provides an open-circuit sensitivity of -32 dB, equivalent to 25.1 mV at 1 Pa, and an output impedance of 100 ohms. Its relatively high output sensitivity allows it to operate effectively with professional microphone preamplifiers without requiring excessive additional gain.
With a self-noise figure of 17 dB SPL and a signal-to-noise ratio of 77 dB, the Audio-Technica AT4033a accommodates both close-microphone applications and the recording of quieter acoustic instruments. Its dynamic range of 128 dB enables it to reproduce substantial variations in sound pressure, including performances that move between delicate passages and much louder musical sections.
High sound pressure level handling is another important aspect of the microphone’s design. The Audio-Technica AT4033a accommodates levels up to 145 dB SPL at 1 kHz with 1% total harmonic distortion. Engaging the integral 10 dB attenuation pad increases this capability to 155 dB SPL, extending the microphone’s suitability to loud guitar amplifiers, brass instruments, drums and percussion.
A switchable high-pass filter operates at 80 Hz with a slope of 12 dB per octave. This allows unwanted low-frequency information, including mechanical vibrations, environmental rumble and excessive proximity-effect bass, to be reduced before reaching the microphone preamplifier. The filter can be bypassed when full low-frequency extension is required.
The revised capsule suspension assembly incorporates a floating construction intended to isolate the sensitive condenser element from mechanical vibrations transmitted through the microphone body and stand. Combined with the redesigned electronics, this represented one of the principal improvements introduced with the Audio-Technica AT4033a revision.
Audio-Technica also incorporated a precision-machined, nickel-plated brass acoustic element baffle, providing mechanical support and contributing to the microphone’s acoustic performance. Surface-mount electronic components were employed to improve manufacturing consistency and reliability.
The Audio-Technica AT4033a operates from standard 48V phantom power and provides a balanced output through an integral three-pin XLR connector. Its cylindrical housing measures 170mm in length and 53.4mm in maximum diameter, with a weight of 380g. The microphone is designed for side-address operation, with the front of the capsule identified by the Audio-Technica emblem on the body.
The microphone is supplied with a dedicated AT8449a shock mount, stand adaptor, protective dust cover and carrying case. The shock mount provides additional mechanical isolation when the microphone is installed on a stand or boom, reducing the transmission of vibrations during recording.
The Audio-Technica AT4033a continued the development of one of the company’s historically significant studio microphones. By retaining the fundamental capsule design and acoustic character of the original AT4033 while refining its electronics and mechanical suspension, the revised model maintained the established microphone’s versatility across vocal, instrumental and broadcast recording applications.
Features
- Professional large-diaphragm cardioid condenser microphone introduced in 1996
- Permanently polarised condenser capsule with fixed-charge back plate
- Specially contoured, 2-micron-thick vapour-deposited gold diaphragm with five-stage ageing process
- Fixed cardioid polar pattern with consistent off-axis response
- Transformerless output circuitry for reduced low-frequency distortion and improved transient reproduction
- Precision-machined, nickel-plated brass acoustic element baffle
- Floating capsule suspension assembly for improved isolation from mechanical vibrations
- Wide 30Hz to 20kHz frequency response with high sound pressure level handling
- Switchable 80Hz high-pass filter and 10dB attenuation pad
- 48V phantom-powered operation with balanced XLR output and supplied shock mount