“Almost universally, loudspeaker drive units can accurately reproduce only a proportion of the full ten octaves of audible bandwidth. Hence almost all loudspeaker systems incorporate two or more drive units. The loudspeaker crossover splits the audio signal into frequency bands suitable for each drive unit’s capabilities.

The crossover is connected between the power amplifier and the drive units, typically inside the loudspeaker enclosure, but occasionally mounted outside. The power amplifier cannot have complete control of the drive units because of the crossover components between them. What’s more, these components are likely to introduce some level of distortions and microphonic degradation.

To overcome this limitation, and in the pursuit of the highest resolution reproduction, several power amplifiers can be used – with each loudspeaker drive unit directly driven by a power amplifier channel. The audio signal is then divided before the power amplifiers at signal level. This is accomplished using “active” filters using high quality signal level components and multiple transistor or op-amp circuits.

However well designed, these circuits, and their required high-quality DC power supplies, add noise and distortions to the signal and so deviations from neutrality. These are especially obvious in an active system, due to its very high resolution.

For SIGAO DRIVE, Kudos Audio has adopted a third way. It is an unpowered crossover but it is connected between the preamp and the power amplifiers, again allowing the power amplifiers to grip and control the drive units by direct connection. Being unpowered, the Kudos crossover has no active electronics or power supply to add their inherent character to the sound, and the invasive components are eliminated.”