I get calls all the time from BP26 customers asking "what the hell is this for"?
james
You took the words right out of my mouth...I've always wondered what the polarity thing meant 
Keith
Hi Keith,
The concept of 'Absolute Phase' is that you maintain the integrity of the phase throughout the recorded and playback signal chain. So a positive impulse on the input of a component has a positive impulse at the output of the component. All Bryston gear is designed to maintain absolute phase throughtout the signal path.
Some components 'invert phase or reverse polarity' and therefore a 'positive impulse' at the input produces a 'negative impulse' at the output. In the recording studio's some engineers try to maintain a positive phase - non inverting polarity - recording by making sure that all the Mic's the Preamps and the recording equipment provides this absolute phase integrity. The problem is that with many of today's multi-miked recordings some of the instruments may be in absolute phase and some may be out of absolute phase. So unless the recording takes into account all the phase relationships of all the different microphones used and all the components in the recording signal path the chances of getting it correct is 50/50.
So how does this apply to me sitting in my home listening to Music you may ask? Lets say we are recording a drum. The drummer hits the bass drum and the drum skin moves outward (positive pressure) or forward - the Microphone picks up the sound wave and moves inward (negative pressure) - it then travels through the complete audio system and the speaker should then move outward to exactly replicate the positive pressure of the drum.
The absolute phase switch on the BP26 allows you to 'invert' the phase 180 degrees on BOTH channels. This is totally different than inverting phase on ONE channel which would then put the speakers "OUT OF PHASE" with each other - (no bass-no image etc.). Transients like that in brass and plucked instruments and sometimes voices will sound more 'in the room' and better defined if the absolute phase is correct. So when listening switch the phase button on the BP-26 and see if you can detect a difference.
Some CD's or Computers may invert phase so this just allows you to decide which position sounds the best with a given recording.The main problem is you have no way of knowing unless the recording engineer states on the recording or CD that they have maintained Absolute Phase throughout. - the old Sheffield Records made a point of mentioning this on the record jacket.
james