A radical loudspeaker concept that challenges
audio rules
Hart Audio may not be a household name but
David Hart’s Isle of Wight-based business has a refreshing approach to audio
design and high-quality UK manufacturing, as well as a growing number of
passionate customers appreciating service and bespoke production. Hart Audio
sells its speakers direct in the UK so you won’t find its speakers at your
local hi-fi dealer.
The new incarnation of the imposing EVO1
commands attention even when it’s silent. Two large, understated enclosures per
channel, each boasting a purposeful 12in driver hints that you’re about to hear
something different.
Hart
Audio EVO1 three quarter view
At the heart of the EVO1 is David’s
passionate belief that many traditional speaker designs are fundamentally
compromised by underwhelming and highly colored bass. This latest design sets
out to fix this perceived compromise.
The EVO1 is based on a similar design
brought out in 2010 without the lower 12in driver. The new version is claimed
to build on the original’s strengths while adding even greater bass extension
and refinement. As before, it employs Tannoy-sourced primary drivers housed in
extremely rigid, high- density fiberboard enclosures, hand assembled and
seamlessly finished in a choice of real wood veneers.
At first glance this substantial twin box
per channel design looks like a ‘spot the difference’ competition with a near
identical pair of 12in Tannoy drivers located in a similar pair of unfussy
enclosures. Closer inspection of the front faces reveals that only the top
driver contains Tannoy’s dual- concentric tweeter with the new lower driver
employing a form of bass port where the tweeter would be. Looking at the back
of each box reveals more remarkable differences. Immediately apparent in the
top unit is a beefy, built-in amplifier complete with cooling fins and control
knobs covering phase, frequency contour, high and lower-level gain alongside
balanced and unbalanced inputs and mains input. Around the back of the base
cabinet is the biggest surprise - eight custom-commissioned 4.5in long-throw
drivers neatly concealed, firing in phase with the primary 12in drivers, but
rearwards.
The
ABM (Active Bass Module 16Hz-120Hz flat response) Consists of 8 drive units
David states that the top 12in driver
“deserves to be left to focus on point-source treble and vital mid-band
detail”. The addition of the lower box to the ‘stack’ and additional drivers
is, therefore, to focus exclusively on extended bass duties. There is minimal
overlap in frequency response between top and bottom boxes, but the use of two
near identical 12in drivers ensures that sound quality is highly coherent.
The two boxes are separated by four near
rigid nitryl rubber balls. These serve to decouple the two boxes by an intended
amount. Four further steel balls are seated under the bottom box creating
strong points of contact with the floor while enabling a degree of fine tuning
in positioning.
The
two boxes are separated by four near rigid nitryl rubber balls
The bottom box is arguably where the most
radical audio thinking is happening. Internally, there is no damping material
and baffles are claimed to be arranged to focus the bass energy generated by
all lower drivers to a notional ‘point source’ flowing through the throat of
the primary 12in driver.
This lower bass port is clearly vital to
this new design, as David believes that “trapped bass can only color the output
by exerting unwanted pressure on the cabinet walls and smearing vital detail”.
