[James Tanner - Bryston]

Generic Active Crossovers vs Bryston BAX-1 Crossover

Hi Folks,

The above comments on the Bryston BAX-1 Active Crossover has motivated me to write this short explanation.

Can the Bryston BAX-1 Electronic Crossover be used with other active or passive loudspeakers? The short answer is ‘NO’ due to a very critical design factor regarding how ‘loudspeaker drivers’ and ‘passive or active crossovers’ interrelate with one another.

Generic active electronic crossovers provide the customer with a 'generic' approach to speaker adjustments. By that I mean you can choose the slope and the crossover point and sometimes the Q but they do not take into account the ‘Sound Power’ or total radiated energy of the speaker. ‘Sound Power’ is the result of the loudspeakers radiation pattern into the listening room.

The two most critical parts of any loudspeaker system choice is the listening ‘Room’ and the loudspeakers ‘Sound Power’. Recognizing how the room imposes its boundaries (floor, ceiling, walls) on the speaker and how that speaker radiates its energy (polar response) into a specific room is critical to the understanding of the overall performance of any loudspeaker.

DIRECT and RELECTED SOUND:
When you are listening to a loudspeaker in a room you are always listening to a balance between the ‘Direct Sound’ and the ‘Reflected Sound’ from the boundaries of the room – this is referred to as the ‘Sound Power.’ It is that balance between direct and reflected energy which changes depending on the frequency radiation pattern (polar response) of the given speaker and the boundaries of the room the speaker is placed in. Dipoles, Bipolar, Omnipoles, Direct Radiators, Horns etc. all behave differently due to their specific radiation patterns and therefore exhibit different power responses in any specific room.

The ‘direct sound’ is the sound radiating from the front of the loudspeaker and the ‘reflected sound’ is all the sound your ears perceive after the sound waves have interacted with all the different boundaries in the room. It is important given real world conditions that the on axis response and the off axis frequency response of a loudspeaker be as uniform as possible. The smoother and more uniform the on and off axis polar response of the speaker the better the tonal balance between the direct sound and the reflected sound will be. In other words, the reflected sound will have the same overall tonal balance and sonic characteristics as the direct sound if ‘on and off’ polar response is smooth and even.

CROSSOVERS:
So when you design a ‘Passive’ or ‘Active’ crossover for a specific speaker you are attempting to achieve the best Sound Power possible. Generic crossovers have their place but recognize that without sophisticated anechoic chambers and very specialized measuring tools getting the ‘on and off' axis as smooth as possible with the various drivers and speaker cabinets out there is not an easy task.

The Bryston BAX-1 Active Electronic Crossover on the other hand is designed with a specific Bryston speaker in mind (Model T, Middle T and Mini T) We design and manufacture all our own drivers as well to facilitate optimizing the sound power. The Model T has different software than the Middle T and the Mini T has different software again. The reason for that is we put each of the Model T's in our anechoic camber and we make over 300 measurements but vertically and horizontally around the speaker and adjust the software to provide as accurate as possible the best ‘Sound Power’ for the specific Model T speaker.

Hope this helps explain it a bit.

Sorry this went on a bit longer than I planned.

james