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Questions and answers
Whats' in a watt anyway?
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Power to the people
Q. How do dynamic power and continuous RMS power differ?
A. There's a lot of confusion about amplifier power ratings in general but this is a valid question because it relates to the two ratings or specifications that are most meaningful when describing power performance. Continuous RMS power is the rating that really lets tells know how much real power an amplifier can produce and it's expressed in watts.
A typical specification could be worded 100 watts RMS into 8 ohms from 20Hz-20KHz at 0.01 percent THD. This means that the amplifier will produce 100 watts into an 8 ohm speaker (the resistance the speaker presents to the amplifier), from 20Hz to 20kHz (which is the accepted audible range of the sound spectrum).
THD is an acronym for total harmonic distortion and it rates the amount of distortion introduced by the amplifier into the signal it's processing. Most high quality amplifiers today have low distortion ratings, but since it's difficult for the human ear to distinguish distortion below 0.5 per cent the rating can be ignored. However, the more watts under this specification, the better.
The dynamic power rating is a little more complex to understand. It's a test of the amplifier's capability to produce power in excess of its continuous RMS rating for short periods of time (milliseconds). It is needed to reproduce musical transient peaks, such as cymbal crashes and the like. Dynamic power is rated into 8 ohms, but are also quoted for lower speaker resistance (2, 4, and 6 ohm loads) where it's more difficult for the amplifier to operate.
Just like continuous RMS power ratings, dynamic power is expressed in watts. It's usually much higher than the RMS power rating, and should not be confused with continuous RMS power ratings. A dynamic power rating into 2 ohms doesn't mean the amplifier can drive speakers 2 ohms resistance. Most likely the amplifier will be damaged or the protection circuitry will be tripped if this is tried.
Power ratings apply equally to receivers (amplifiers with in-built tuner-radio sections). Why do I need spikes on my speakers Spikes applied to the bottom of speakers and speaker stands are designed to help with the overall stability of the speaker as it produces sound.
They are generally useful in carpeted rooms and are designed to pierce the carpet and underlay and bring the stand or speaker into firm contact with the concrete or wood (or other surface) underneath. A speaker generates sound by pushing air forward. This causes an opposite reaction which moves the speaker itself backwards.
The heavier the music, the harder the speaker pushes air and the more rear movement there is. If the speaker or stand is placed on carpet it is not very stable and so the pushing movements creates a 'rocking' motion in the speaker. When this happens the speaker can't work properly and so some fidelity in the music is lost.
By using spikes the speaker is more stable and doesn't rock nearly as much. The result is better sound. The spikes help isolate the speakers from vibrations in the floor.
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