Rational Acoustics RTA-420

SKU: RTA-420

48v phantom-powered, free field, omnidirectional measurement microphone ***ask for option with Calibration Files***


About this item



The Rational Acoustics RTA-420 is an ideal budget-friendly measurement mic. It’s a great choice if you’re a student, just starting out with system measurement, an established pro looking for a backup mic, or putting together a “B” rig. It’s also a cost-effective solution for multi-mic measurement setups. The RTA-420 offers very respectable frequency response, heavy-gauge steel construction, and measurement performance to rival high-end microphones costing many times more.

The RTA-420 has a relatively low maximum SPL, so it is not ideal for critical or concert-level SPL measurement applications, however, it is still capable of generating accurate data at modest levels. Where critical SPL measurement is an important factor, consider purchasing at least one microphone that is better suited for SPL measurement and reserves the RTA-420s for your spatial frequency response measurements.

The Rational RTA-420 comes with a mic clip and a bright yellow windscreen, which is great for spotting your mic in dark venues. It also includes a custom-designed soft carrying case that accommodates and organizes 2 microphones plus accessories.

NOTE: The Rational RTA-420 is PIN 3 HOT and requires the 10mm calibrator adapter for use with the iSEMcon SC-1 Microphone calibrator.


  • Capsule: ¼” Electret Condenser (housing diameter at capsule: 10mm)
  • Polar Pattern: Omnidirectional
  • Frequency Response Characteristic: Diffuse Field (Random Incidence)
  • Frequency Range: 20 Hz – 20,000 Hz
  • Nominal Sensitivity: 7 mV/Pa, +/-3 dB typical
  • Operating Voltage: 9-52V DC Phantom Power
  • Max SPL: approx. 110dB (1 kHz @ 1% THD)


  • 1 RTA-420 Microphone
  • 1 soft-sided dual-mic carrying case
  • 1 mic clamp
  • 1 windscreen


The RTA-420 carries a one (1) year warranty against defects in materials and workmanship.  The warranty is valid from the date of original retail purchase and is a non-transferable warranty that extends only to the original purchaser.  Rational Acoustics will replace the product at no charge if the product proves to be defective upon evaluation.

Warranty does not cover or apply to (a) misuse, mishandling, and abuse, (b) products that have been modified, altered, or repaired by an unauthorized party (c) normal wear and tear, (d) damage that has occurred during shipping, (e) loss or theft, (f) damage caused by accident, fire, flood, lighting or other force majeure events.

The RTA-420 contains NO field-serviceable parts, so if your mic stops working correctly please do not attempt to open the mic or repair it yourself, as this will immediately void the warranty.

For warranty claims, email Rational Support with a description of your mic’s malfunction and proof of purchase (your order receipt, or order # & date of purchase).


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