Well now take a closer look at some of the terminology used surrounding monitor speaker specifications:
This is the measurement which people often get a bit over-excited by and is also the figure which is most frequently misinterpreted. The power rating alone doesnt tell you how loud your speakers will go - other specifications such as the sensitivity and impedance of a speaker all make a difference to the actual volume that it can achieve, not to mention how liberal the manufacturer is with their specifications! The power rating is measured in Watts and can be described as RMS, program or peak power. As mentioned in the text above, it is now most common to match the RMS rating of an amplifier with the program rating of a speaker. Peak power can have so many different meanings that it is best avoided altogether.
Frequency response is a measurement of the range of frequencies a speaker can reproduce. Although there are a multitude of theories concerning the range of human hearing, it is most commonly defined as ranging from 20Hz to 20,000Hz (20kHz). Most modern speakers extend up to 20kHz at the top end, but smaller enclosures can find it difficult to reproduce lower frequencies, with many cutting off at around 60Hz. These frequencies are particularly important to producers of some genres of music, dance in particular, and anyone involved in mastering should have speakers capable of reproducing these frequencies. Those with smaller monitors may want to supplement the low frequency response of their near-fields with a separate subwoofer. As with all specifications, the devil is in the detail, and its important to compare like with like. The most common definition of the upper and lower limits of frequency response are the points where it starts to drop by 3dB or more figures without a definition of the cutoff point are meaningless!
Bi-Amping / Tri-Amping
This is an amplification method using multiple amplifiers connected to a speaker cabinet in such a way that individual amps drive individual speakers - this means that the crossover is placed before the amplifier stage rather than after. Active speakers use this system by default, but passive speakers can be driven with multiple external amps and active crossovers in this manner, and this is the method typically used with larger monitoring setups. Bi-amping describes a 2-way system, tri-amping a 3-way and so on.
Speakers that feature a high pass filter or low pass filter will usually either have a pre-determined cutoff frequency, or have a choice of two or three user-defined selections. These filters are used to adjust the speakers frequency range to suit different room acoustics, or to raise the low-end cutoff when used with a subwoofer in a 2.1 or surround-sound setup.
Woofers are designed to reproduce bass frequencies, whereas tweeters are specifically for high frequencies - a crossover is therefore required to send the relevant frequencies to the separate drivers. The crossover frequency is the frequency at which the audio signal is divided.
Measured in Ohms, impedance is the combination of the electrical resistance of a speaker and its reactance. This figure is not as important as it once was due to the prevalence of powered and active designs, but is vital when matching amps and speakers, particularly when connecting a number of speakers together such as in a PA system. Most single speakers are now rated at either 4 or 8 Ohms, and most modern amplifiers are capable of driving a variety of different impedances.
The term SPL is an abbreviation of Sound Pressure Level, and as with power rating it is a measurement that can be confusing as it is commonly presented in several different ways. The basic measurement involves playing a sine wave through the monitor with an SPL meter positioned at a set distance - usually one metre. As all manufacturers measure this specification differently though in terms of how long the measurement is taken over, at what frequency and at what level of acceptable distortion, it is very difficult to use this figure for accurate comparison. There currently being no industry standard, manufacturers often use this vagueness to their advantage, calculating impressive on spec sheet results, with some even providing purely theoretical figures based on the speakers design characteristics.