Dynaudio pmn manual The Subwoofer - Background Info, Bass management, L C R Ls Rs Σ Sub

Air_US_rev_111.qxd 16-12-2004 14:18 Page 40

THE SUBWOOFER - BACKGROUND INFO

The Subwoofer

A subwoofer is a monitor that reproduces low frequencies. The purpose is to take over from the main monitor(s) as frequencies approach the lower end of the frequency range. I.e. approximately below 120 Hz. When used in professional monitor systems it is commonly preferred to use subwoofers below approximately 80 Hz. But of course it depends on the performance of the main monitors.

The low frequency contents of just one or all the main channels can be directed to one subwoofer.

From the psycho-acoustics we know that there is no directional information in audio signals below approximately 120 Hz. Hence the advantage of placing the subwoofer in a position where the best distribution is achieved.

However it is very important that the distortion in the subwoofer is reduced to an absolute minimum because distortion results in the production of harmonics (2, 3, 4 etc. times the frequency reproduced). Especially the third harmonic may dominate. Reproducing a frequency of 100 Hz can result in the generating of an audible frequency component at 300 Hz, which presents directional information to the human hearing system.

Bass management

Bass management (sometimes called bass redirection) is a very important feature - and it is in general an absolute necessity if you want to make a 5-channel set-up in a small room! There are several reasons for this.

The bass management system is designed to subtract the bass contents of all main channels and reproduce this by the use of a sub woofer. The AIR-series provides a number of possible cross-over frequencies that can be determined by the user.

L

C

R

Ls

Rs

Σ Sub

Principal set-up for the bass management. It can be used with any number of main monitors up to five.

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