[PRELUDE]

Here is a great book to read before make or buy any speaker.
[ACOUSTICS AND HEARING] by Peter Damaske.
You can buy it at www.amazon.com

[JRace]

James or Danny (or anyone) - can you elaborate on the term Power Response?

Any comments on how the positioning of the measurement microphone can alter the measurements?
I'm interested to know how crucial the relative mic position is in taking comparative measurements of different speakers.

Thanks.

[Phoenix]

James or Danny (or anyone) - can you elaborate on the term Power Response?

Any comments on how the positioning of the measurement microphone can alter the measurements?
I'm interested to know how crucial the relative mic position is in taking comparative measurements of different speakers.

Thanks.

On Power Response look here (though it's very technical):

http://www.musicanddesign.com/Power.html

@James:

It would be also very interesting to know if you could build two amps with the identical (really everything you can measure) specs, and still have a difference in sound. And if yes, how does Bryston investigate such phenomenons?

[James Tanner]

On Power Response look here (though it's very technical):

http://www.musicanddesign.com/Power.html

@James:

It would be also very interesting to know if you could build two amps with the identical (really everything you can measure) specs, and still have a difference in sound. And if yes, how does Bryston investigate such phenomenons?

Hi Phoenix,

I would say that over the years we have been doing this we have found that some specs seem to have more importance than others. Generally if two amplifiers measure equally within the window we considered to be the most important areas they will sound the same or very similar. In fact that is one of the things we try to do by checking all the parts that go into the amplifiers durnig production to make sure a 4B built last year sounds the same as one built this year.

So I think depending on the manufacturer amps that may measure the same in specfic areas will usually have other areas where they differ - by design or on purpose (voicing) so some differences will still be heard even if the more traditional specs look similar.

Bryston's philosophy has always been to provide as linear and accurate an amplification stage as technology allows in all the areas that can be legitimately tested. In other words tell the truth - good or bad.

james

[Danny Richie]

It would be also very interesting to know if you could build two amps with the identical (really everything you can measure) specs, and still have a difference in sound. And if yes, how does Bryston investigate such phenomenons?

You can simply go into an amp and by-pass the power supply caps with some small fast discharging caps and make a notable change in the performance of the amp, and I don't think that mod will change any of the measured parameters.

[stonedeaf]

The only specs I look at are efficiency and impedance curve. The rest has to be listened to. This NRC data set is very interesting reading and Canadians are very lucky to have access to this facility. Few loudspeaker  manufactures have anything like this type of physical  testing facility to work with. One result of this is that there are lies ,dammed lies and statistics - used as published data.The NRC data is rigorously collected and therefore comparable model to model. Manufacturer's spec sheets/brochures are a whole 'nother animal. My rule of thumb on speakers was that in most cases the worse the "spec" the better the speaker. And I can understand why some speaker co.'s simply don't want to play the game. it really isn't all that hard to hear the difference. If the dealer hasn't set up a reasonable demo facility - then ya really gotta wonder what exactly ARE they selling ?