NHT Evolution System User Manual
Page 48
When oriented horizontally, the null is directed at
the ceiling or floor (depending on tweeter posi-
tion) improving mid-range detail.
11.3 Boundary Switch
A loudspeaker’s mid-bass response is very
dependant on its room placement. For exam-
ple, if a speaker is tuned for placement away
from walls and is then placed on a bookshelf,
the reinforcement of mid-bass frequencies will
make the speaker sound somewhat “thick”. The
M5 and M6 feature a unique dual mode
crossover that adjusts the monitor’s response in
the mid-bass range for either placement situa-
tion. The graph below illustrates the decrease in
bass energy from 80Hz to 500Hz when the
switch is in the “1” position, making placement
on a shelf or television possible while maintain-
ing proper frequency response. The “0” position
optimizes the monitor for placement away from
room boundaries.
11.4 High Dynamic Range/Low Power
Compression
The increased dynamic range of digital media
can make much greater demands on the output
capabilities of speakers than in the past. As
speakers are pushed towards their limits, the
temperature of the drivers rises. Heat causes
the drivers impedance (resistance to AC current
flow) to increase, reducing the amount of power
the amplifier can deliver to the driver. Dynamic
range is reduced, distortion increases and
sound quality suffers.
Evolution monitors and subwoofers are
designed to minimize this phenomena in a num-
ber of important ways.
1)
The 12” woofer contained in all Evolution
subwoofers and tower bass modules employs,
in addition to a massive motor structure, an alu-
minum cone attached to an aluminum former.
The cone acts as a heat sink for the driver, min-
imizing the rise in impedance and resulting dis-
tortion.
2)
The Wonder Bar, mounted to the tweet-
ers in the Evolution monitors, dissipates heat
from the most fragile driver in any loudspeaker.
3)
Evolution monitors are 3-way systems
with dual woofers. The input power is spread
over multiple drivers, minimizing heat build up
and distortion.