MEMO: To All Bryston Customers
SUBJECT: Bryston Subwoofer Measurements
Hi Folks:
I have been asked how we get accurate measurements for our Bryston Subwoofers given that anechoic chambers (which we also have) have measurement limitations at very low frequencies.
Here is our outdoor Subwoofer Measuring Tower!

One of the limitations of an anechoic chamber comes from measuring very low frequencies. Even very large anechoic chambers have limited accuracy below about 85 Hz.
In order to obtain completely accurate measurements of the very long sound waves that come from low notes, we utilize a 90 foot tower upon which we hoist subwoofer prototypes.
In order to obtain 4-pi 360-degree measurements, the tower must be used in early morning or evening, when the wind is still.
James Tanner
Bryston