Floorstanding loudspeakers — Zu Audio SOUL 6

The Soul 6 is a two-way tower speaker hand built by Zu Audio in the USA, built around a ten inch full-range driver with a coaxial super-tweeter. It is a high-efficiency design intended for low-power amplification, and it starts at USD 7,900 per matched pair in Black Okoume, with a 5-year warranty, a 60-day guarantee and a typical lead time of nine weeks.

Key specs that matter

Sensitivity is rated at 100 dB SPL with 2.8 V at 1 m under ground-plane measurement, and the nominal impedance is 8 ohm with a minimum of 5.1 ohm. Zu gives a bandwidth of 38 Hz to 28 kHz within 3 dB, measured within 10 degrees of axis at listening distances beyond 2 m. The listening window is 45 degrees at -6 dB both horizontally and vertically, and group delay stays below 5 ms. Each cabinet stands 81.5 cm tall without footers on a square footprint of 32.5 cm and weighs 18 kg, or 22 kg packed.

Engineering and use context

Full bandwidth power handling is 150 W. If the speaker is fed through an 80 Hz high-pass at 12 dB per octave, for instance when a subwoofer takes over the bass, it accepts up to 400 W RMS. Zu publishes a usage guide showing that 2 to 4 W is enough for moderate listening levels, 5 to 20 W for loud playback and 20 to 150 W for concert levels, which explains why the Soul 6 is often matched with small valve amplifiers. The cabinet is made entirely of okoume, a light African hardwood used here for every panel rather than MDF. The full-range driver can be fitted with a black or silver aluminium trim ring, and each speaker ships with a press-fit driver cover, a microfiber cloth, stainless steel footers and carpet spikes. Finishes beyond Black Okoume include Natural Okoume at USD 200 extra, Dark Rub, Red, Blue and Dark Blue Okoume at USD 800 extra, and Cosmic Carbon, Black Starlight and Olive at USD 1,100 extra.

Pairing

Because a few watts already produce moderate levels, single-ended triode and other low-output valve amplifiers are a natural match, while the high impedance minimum keeps the load easy for them. A transistor amplifier within the full-bandwidth rating can also be used, and a system with a subwoofer can take advantage of the higher rating available once the bass is filtered off.

Alternatives

The Zu Audio Union Supreme 6 is a floorstanding model that uses the same 10.3 inch widebander as the Soul 6, paired with an Eminence ring radiator.