What is an SPL Calibrator?

Created by Jake Bedard, Modified on Tue, 10 Sep at 10:19 AM by Jake Bedard

What is an SPL Calibrator?

If you've read a guide to calibrating a microphone for SPL (such as the guide we have here), you may have noticed references to SPL calibrators... but what exactly is an SPL calibrator?

An acoustic calibrator operates rather simply. When turned on, it will emit a 1 kHz sine wave reference tone at a specified level: typically 94dB, but sometimes 114dB or 110dB. There are some calibrators that have the ability to switch between these two levels. With these models, it is paramount to ensure the proper level is selected so as to not skew your readings by ~20dB.

An acoustic calibrator has an open port on one side. Simply place the tip of your measurement microphone snugly inside of this port and activate the calibrator to feed it your desired reference signal level. Be sure to use the correct size adapter for your microphone, otherwise you may see inaccurate measurements. Many calibrators come with an adapter to fit a second size of microphone, and some microphone manufacturers offer microphone specific calibrators. We offer a selection of standalone adapters through the rationalacoustics.com online store.

While there are many calibrators available, we'll be outlining the 2 models of calibrator we have on the Rational Acoustics online store: The iSEMcon SC-1 and the Cirrus Acoustic Calibrator, the latter of which is available in options for both Class 1 and Class 2 measurement systems.

The iSEMcon SC-1 is a single-frequency, dual-amplitude calibrator that generates a 1kHz reference tone at either 94 or 110 dB SPL. It ships with both a 1/2" and a 1/4" mic adapter and requires a 9 Volt battery for power.

The Cirrus CR: 515 is designed specifically for Class 1 measurement devices in order comply with the current IEC 60942:2017 standard for acoustic calibrators with Class 1 specifications. It has a 1/2" port and ships with a 1/4" adapter. It emits a 1 kHz sine wave reference signal at a fixed level of 94 dB SPL.

The Cirrus CR:514 also produces a 1kHz reference signal at 94 dB SPL, but is engineered for current IEC 60942:2017 Class 2 measurement standards. Like the CR: 515, its port is 1/2" and it ships with a 1/4" adapter.