About the M1 Active
12 M1 ACTIVE REFERENCE MANUAL
• Improved transient response.
• Better amplifier/speaker coupling for woofers.
• Better crossover performance working into a constant impedance load.
• Better subjective sound quality than high level (passive) networks.
• Easier control over driver sensitivity differences.
• Easier manipulation of phase, time delay, resonance, and various kinds of
shaping, contouring and equalization.
• Specifically in the case of the M1 Active, the wide, mid-frequency polar response
of the tweeter can be utilized down to a low 1500Hz thereby mating more
cohesively with the 6.5 non-woven carbon fiber (NWCF) woofer. This low
crossover is only possible through the use of a very steep, electronic eighth-order
(48 dB per octave rolloff) high pass filter.
The M1 Active power supply
The M1 Active employs a regulated switching power supply. This type of supply
has previously only been available in amplifiers sold at the very high end of the Pro
Audio market.
Most power amp customers are familiar with the large transformer and output
capacitors in high quality amplifiers. These large components are used to keep the
amplifier’s supply rails as close to DC as possible. For traditional supplies, bigger is
better.
But by using Pulse Width Modulation (PWM) and output voltage feedback in the M1
Active, we have the equivalent of near-infinite transformer and output capacitors,
but at a fraction of the cost. PWM provides protection from line voltage surges that
would otherwise destroy the amplifier. No user-replaceable fuse is required because
nuisance tripping is eliminated. And finally, PWM practically eliminates hum
because the line frequency (60 Hz) transformer is replaced with a very high
frequency (130,000 Hz) transformer.
The regulated supply rails increase the amplifier dynamic range and reduce clipping
distortion under heavy loading. The compact size of the supply does not
significantly reduce the internal air volume of the speaker cabinet. And lastly, full
power can be maintained even with low or “flat-topped” line voltages.
Note, however, that this switching supply is NOT a universal
voltage type that may be used with any input voltage in any
country simply by changing the cord. If you wish to use the M1
Actives in a country whose line voltage is other than 120 volts AC,
they must be internally modified or used with a step-down
transformer.