Audioholics Subwoofer Measurement Standard Part I

When it comes time to size up a subwoofer's performance, the proof is in the measurement! Audioholics takes a hard look at the science of subwoofer measurements in a two-part series covering a broad spectrum of measurement methods, useful to both pro and enthusiast alike. Let the science begin!"

This article began life as an ongoing series of conversations, carried out over the past couple of years with Gene. He recognized Audioholics’ need to bring a degree of organization to its own in-house subwoofer measurement procedures. I was tasked with that challenge and present here Part I.

Part II, to be published later, will cover other topics such as linear & nonlinear distortion measurement, mechanical noise floor measurement, amplifier measurement and so forth. Part II will also include a collection of worked examples and conclude with a table summarizing all results.

Projects of this size are seldom a solo effort and this was no exception. To that end, a huge debt gratitude
is owed to Charlie Hughes, Jeff Szymanski, Siegfried Linkwitz, Don Keele, Neville Thiele and many others who contributed their time and expertise in helping me knock this manuscript into shape. Thank you, gentlemen! And of course, a big thanks to Gene as well for his almost supernatural patience as he waited for me to bring this to completion. Thanks, Gene!

Scope

The purpose of both documents is to present a set of measurement guidelines by which a comprehensive objective assessment of a subwoofer’s performance can be developed. Included within this document’s definition of a subwoofer are: single & multiple driver subwoofer systems; powered and passive systems; systems featuring vented or totally enclosed cabinets; along with less common items such as dipole subwoofers.

Though industry professionals can (and do) make use of the methods or approaches presented here, this document is intentionally structured and organized to make it particularly useful to the audio enthusiast. Given the particular type and/or characteristics of a sub you may be interested in measuring you may find it unnecessary to apply all the measurement procedures covered in Parts I & II. In any event, with the variety of software-based measurement tools currently available, it is now possible for the audio enthusiast to work up a collection of accurate measurements at very little expense. Certainly much less expensive than what it would have cost 20 or 30 years ago!

If you’ve spent any time at all contributing to the development of any sort of industrial standard, you’ll know the process tends to be evolutionary in nature. Similar in character to the more formal standards (AES, IEC, etc) from which parts of this work are drawn, nothing here is written in stone. As new research and/or measurement technologies/techniques appear on the horizon they will be included, whenever/wherever appropriate and/or applicable. This is a living document that will evolve over time and improve with age.