[wplash]

Mr. Tanner,
Hi, I own a 4B-NRB( 93 model) and a BP-25 (2002 model) and have noticed that the pin 2 and  pin 3  polarities are opposite. Does that make a sonic difference or do I need to make a pair of interconnects with the
+ and - leads switched at the amp end?
                                                      Thanks, wplash

[James Tanner]

Hi,

Pin 1 is ground so having pin 2 and 3 reversed would just have the effect of reversing "absolute phase".

james

[wplash]

Just wondering, I noticed with the 4B-NRB amp that I have pin 3 is possitive and that the 4B-ST amps and I assume the SST amps that pin 2 is possitive in the balanced connection. Why the change?
 
PS: I also own a BP-4 pre-amp , if I were to relocate the power transformer from the chassis of the preamp into a seperate chassis of its own, would I achieve close to BP-20 results? Just curious.
                                               Thanks.

[James Tanner]

Hi wplash,

There use to be two accepted methods of connecting balanced lines. Pin 1 is always Ground. The USA used Pin 3 as positive and the Europeans used Pin 2 as positive. I forget what year but the AES decided to adopt Pin 2 as positive worldwide and we made the change accordingly.

There would not be much advantage in removing the power supply because the BP4 has excellent shielding on the supply.

If you want to maintain 'absolute phase' throughout your system then you have to know which components retain 'positive signal in' and 'positive signal out'. All Bryston components maintain absolute phase from input to output. The problem is that some components are designed with absolute phase in mind and some are not. So the chances are about 50-50 that one of your components or your software (CD DVD) etc. is not maintaining positive phase throughout the signal chain. With multi-mic recordings this is a tough thing to predict because specific instruments depending on the mic used and the signal chain can be different from another instrument in the same mix.
So changing the speaker leads around would be one way to confirm that you are getting positive phase from the Bryston preamp through to the speakers at least.

But hey here is another issue - the speakers themselves may not have all the drivers in phase with each other. It is very common to see the woofer moving forward when fed a positive signal and the tweeter or mid moving back. You can test your speakers with a battery.

james