[Affordable$$Audio]

Everyone:
Affordable$$Audio is pleased to announce that the October issue is now available for free download in both single and dual column formats.  This month's issue includes a blind shootout between several monitors.  Thanks for your continued support.
www.affordableaudio.org

[mcullinan]

YEEEAHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH HHHHHHHHHHHHHHHHHHHHHHHHHH!
Mike

[randytsuch]

Liked the monitor shootout article, interesting read.  Didn't hurt that I recently picked up the Sierra's.  I also considered the Swan 2.1SE's, but I already had to stretch my budget for the Sierra's.  Also, this was mainly for my HT setup, and the Sierra's seemed better suited for HT.

Randy

[tex-amp]

Dave Fabrikant of Ascend Acoustics noticed all the higher efficiency speakers lost in the blind tests. He thinks that how the level matching box was built is the issue.

...I then looked a bit deeper into the results of the listening sessions and found a glaring discrepancy – something I found quite disturbing. In every single comparison test, the speaker with higher sensitivity scored lower. In fact, it seems that the larger the discrepancy in speaker sensitivity, the greater the difference in the result scoring.

I would expect from a “blind” listening session such as this that perhaps 50% of the higher sensitivity loudspeakers to be preferred and 50% of the lower, or at least perhaps 40% - 60% -- but DEFINITELY NOT 100%. Once again, a few warning signs went off in my head… What exactly was taking place? I know Craig was level matching but just how was he doing this?

Further research revealed that Craig was using a passive remote switchbox. This is a speaker selector box that is placed directly in-between the loudspeakers and the amplifier. This particular switch box is made up of high-power potentiometers, which are variable resistors. In order to level match, series resistance is used to pad down the power being received by one of the two speaker pairs. The higher sensitivity speaker must have series resistance applied to the signal in order to bring the output level down enough to match the lower sensitivity speaker (which would not have resistance applied).

This is a problem and a “No-No” in the audio world. Adding series resistance to a loudspeaker completely changes the character of the loudspeaker’s crossover and complex impedance. It can be very dramatic as I will detail. A loudspeaker crossover is designed specifically to “see” a very specific impedance load, the load presented by the drivers. Adding series resistance changes that complex impedance load and the crossover no longer functions as it has been designed to. If we have an 8ohm rated loudspeaker and we add 4ohms of resistance, the loudspeaker now becomes a 12ohm loudspeaker yet the crossover components have been optimized for an 8ohm load.

Generally speaking, and this depends on the design of the crossover, the more complex the crossover the worse the effects. As an example, if we have a 4 ohm loudspeaker, whereby 4 ohms of resistance have been added – in order to keep all things being equal, all inductor values would have to be doubled and capacitor values halved to keep things consistent with the addition of the series resistance. While this it is not as simple as my example here, from a mathematical standpoint, it is correct....

http://forum.ascendacoustics.com/showthread.php?t=2965