If you want to compare the power ratings of speakers and power amplifiers, you have to make sure that you're not comparing apples and oranges. Some manufacturers deliberately exploit widespread ignorance to conceal the actual quality.
Many HiFi and home cinema buyers are still impressed by the P.M.P.O., peak or maximum power ratings, which are mostly given by dubious suppliers. Thereby you can be sure: Anyone who, for example, certifies an output power of 800 watts to a compact system for 150 euros is cheating and also violating European law.
In order to drive comparison possibilities worldwide to unity, authoritative organizations have adopted new standards. Electrical Engineering (IEC), Standardization Organization (ISO) and Telecommunication (ITU) defined the IEC standards which are binding for all manufacturers. For loudspeakers, ten minutes of pink noise is not to be the decisive factor for power handling, as was previously the case. The IEC standard "nominal" tests the continuous power handling in a 100-hour test. The IEC standard "long term" applies a signal for one minute, takes a two-minute break with the load and repeats everything ten times. The IEC standard "short term" sets a signal of one-second duration, then also pauses for one minute and repeats the procedure 60 times.
Since the adoption of these standards, devil has followed suit, naming the power handling of its speakers according to the very strict requirements of the IEC long term standard. When it comes to the recommended amplifier power, devil follows the IEC short term standard. It goes without saying that this has not changed the quality of devil speakers. More information on the different power specifications can be found on our website.
Other common specifications:
RMS power: The specification of power in watts (RMS) is the only other internationally meaningful statement beside the IEC specifications. RMS means Root Mean Square and is an elaborate measurement method that records the power over the entire relevant frequency range by means of a so-called pink noise. Pink noise has a level drop of 3dB/octave upwards compared to white noise, which ensures that the energy content of the signal is constant at any frequency.
Sinusoidal continuous tone power: This measurement method is outdated and only applicable to power amplifiers. Loudspeakers would easily be destroyed when measuring the maximum power handling with sine tones. However, because of the popularity of the term "sine-wave continuous tone power", it is still occasionally used. The values are close to those obtained by the RMS method.
Peak power: The peak power is the power that a power amplifier can deliver for a short time (in the millisecond range) or that a loudspeaker can handle for a short time. The peak power is always much higher than the RMS value. However, its importance lies more in its advertising effectiveness than in its informative value. At most, the comparison of the ratio of peak power to RMS power still makes sense. Higher values can pay off in better impulse processing.
Music power: This is an outdated measuring method, which is based on the idea that music has no constant levels and therefore the power of a system can be significantly higher than after the measurement with sine tones. But the real background might be the advertising effectiveness of the values which are about twice as high compared to the sine continuous tone power.
Nominal power: Another term that contributes to the ambiguity... Actually, it comes from power engineering. In the context of power amplifiers, it corresponds approximately to the RMS power. However, it is not certain that the measurement method was standardized for it was used.
Power dissipation: A part of the power taken from the socket is not converted into usable signals but into heat loss. The power dissipation gives information about this part converted into heat. If it is high, then appropriate cooling may be required.
Dependence on impedance: The power output of a power amplifier depends on the impedance (ohm number) of the connected speakers (this does not apply to tube guitar amplifiers with switchable impedance!). The power amplifier usually delivers more power at lower impedances than at higher ones. Thereby side effects have to be considered:
- low impedances put more strain on the power amplifier and heat it up (ensure sufficient air circulation)
- if the impedance is too low, the safety circuit may switch off the power amplifier
- low impedances require thicker (or shorter) speaker cables because cable losses increase considerably.
Higher impedances result in principle in a better sound because of the better damping ratio of the loudspeaker/power amplifier combination. So it makes sense not to use a power amplifier to its full capacity and e.g. to operate it with 2 ohms, even if the data sheet says so. The datasheets usually give information about the impedance and the power output.
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