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Objective Tests

These are relatively easy to determine and involve evaluating parameters such as:

  • Maximum SPL
  • Frequency response (including low frequency extension and crossover points)
    Frequency response and SPL are measured with a dB meter of known calibration and accuracy
  • Power input (from the supply)
    Power can be directly measured by P = IxE (current times voltage)
  • Power output (amplifier RMS, peak)
  • Impedance
    Impedance is directly measured by Z = E/I (voltage divided by current)
    **(For you EE's out there, I'm ignoring capacitive and inductive reactance for reasons of simplicity)**

  • Signal to noise
    Signal to Noise is given by dB = 20 x Log (V2/V1)

How Much Power Do I Need?

This is such a common question, I felt compelled to address it in it's own category. The bottom line is, it doesn't matter. Let me give you an example:

 
Rated Amp Power
Speaker Efficiency
Max SPL @ 0.5m
Speaker Set #1
1 W/ch
100dB SPL 1W/1m
112dB
Speaker Set #2
10 W/ch
90dB SPL 1W/1m
112dB
Speaker Set #3
100 W/ch
80dB SPL 1W/1m
112dB

Notice the power jumps by a factor of 100 from set #1 to set #3. Notice the total output (volume) stays the same. Why would a manufacturer sell a set like #3? In order to "fix" problematic frequency responses or most likely to add some funky low end (below 100Hz) eq curve, more power is required. If a woofer is 10dB down at 50Hz and the maker wants it to be effectively flat (0dB) then all they need do is put a 10dB boost in the amps and voila'--flat to 50Hz is now possible! But, that means the power output surges by a factor of ten (10dB = Power x 10).

Set #1 isn't exactly the cat's meow either. Locating drivers that sound musical and are incredibly efficient are few and far between. So the best and most common solution sits squarely in the middle: set #2. With a moderate amount of power and efficiency, the designer achieves a balanced design. Large amps and transformers aren't required and neither are incredibly high SPL drivers.

Conclusion

If it's simply not feasible to listen to a speaker setup with your own ears, then you must find reviews that convey not only the objective but also subjective qualities of the set of interest. Those genuinely concerned about great, long term sound quality, or what little of it there can be at the $50-$200 price level, can rest assured that my reviews at TargetPC are the most thorough on the web. No one else cares so deeply about uncovering manufacturer defects, power output claims, and overall listenability beyond the "makes your teeth chatter because they are sooo loud" group. Have I pissed off manufacturers? You bet. But dedication to truth in advertising is my primary goal. To that end, a few makers have contacted me specifically asking for more in depth reviews. Visit us often to see what develops in the very near future.

William Yaple
06/05/00





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