The advantages of full range electrostatic loudspeakers
In general, the world is not populated with many full range loudspeakers. A full range loudspeaker covers the frequency range from 10 Hz to 20.000 Hz and higher. Why is this important? Every musical instrument has a fundamental frequency. Added to the fundamental are the harmonic overtones (partials). The fundamental will create mirror images that are multiples of the fundamental frequency. The specific sound of an instrument depends on the distribution and balance of the harmonic overtones. That’s one reason why a trumpet and a saxophone do have a different sound. Suppose that you’re listening to loudspeakers that will start the frequency range from 45 Hz. Some instruments will miss their fundamental and will start at the second or third harmonic. The tradeoff is that such an instrument sounds less natural. Reproducing the complete harmonic spectrum is one of the important factors to get a natural and realistic sound.
Talking about dynamic loudspeakers, everybody knows that reproducing the full frequency range is only possible with large loudspeaker enclosures. But the industry developed some alternatives. Think about modern servo-controlled subwoofers in small enclosures working from 16 Hz. To get very low frequencies from a small enclosure and with less distortion, you need a servo, a powerful bass-driver (from 10 inch) and at least a 1.000 Watt (in build) amplifier. You can buy it nowadays as a single package.
Most electrostatic panels start around 100 Hz. To get some low frequencies, you need a subwoofer. It’s possible to apply a separate subwoofer, but most electrostatic loudspeakers are hybrid models. A hybrid combines an electrostatic panel with a dynamic woofer in one enclosure. The challenge is to let this combination perform as one single loudspeaker without distracting transition between the two very different drivers. Final did an awesome job to get a very homogenous and neutral sound from the hybrid models, but theoretically spoken it’s still some form of compromise. An electrostatic panel sounds neutral and most dynamic woofers, together with the enclosure, do exhibit some coloration.
The best solution is to build a full range electrostatic panel, like the Final Model 15. It’s a large loudspeaker because you need some square meters to reproduce the lowest frequencies with flat panels. On the contrary, it will bring you a very high-quality reproduction and the best possible transition between the low frequencies and the rest of the spectrum. Basically, in case of a full range electrostatic panel, there’s no transition at all.
Although the Model 15 is specified from 45 Hz (-3 dB), in real life the lowest possible frequency depends on your room’s acoustic properties, your power amplifier and the placement. So, consult your dealer to get the best advice. As a rule of thumb, you can get some deeper lower frequencies by diminishing the distance between the panels and the walls behind and to the right or left. The compromise is probably that you will lose some spaciousness in the reproduction of sound. Also, the power amplifier has some significant influence. The best amplifiers will dig one octave lower from the Model 15.