Speaker Installation
M1 ACTIVE REFERENCE MANUAL 25
For the technically-minded, here is an approximate chart of SPL levels for various
settings of the INPUT LEVEL control, measured at 1 meter from two speakers
simultaneously (all settings, especially near the extremes of the range, are subject to a
plus or minus 2 dB error):
Mark -10 dBV
nominal +4 dBu
nominal
0 (MIN) -- dB SPL -- dB SPL
1 -- --
2 57.0 69.0
3 63.5 75.5
4 68.2 80.2
5 71.0 83.0
6 73.0 85.0*
7 78.0 90.0
8 83.5 95.5
985.5* 97.5
10 (MAX) 86.5 98.5
* denotes recommended setting for control room use
Avoiding damage
The best protection against speaker failure is to mix at a reasonable listening level.
With a +4 dBu input and the input level control set to “6”, the M1 Active speakers
produce a sound pressure level (SPL) of 85 decibels at 1 meter, which is a good
working level for mixing. At maximum output before clipping, they can generate
peak levels ≥ 118 dB SPL at one meter – a level which may cause hearing loss after
prolonged exposure. While the biamplified design of the M1 Active avoids the
common “blown tweeter” problem of conventional designs (when a broadband
amplifier clips on a bass note, it sends unusually high energy to the tweeter, which
tries to reproduce the square wave), it is not invulnerable. If you need higher power
levels, you are not using the speaker in a near-field application. For extremely loud
mid-field and far-field monitoring, we recommend the Alesis Monitor Two speaker
with a 300-watt per channel amplifier. Many studios will check recordings on both
systems, alternating to avoid ear fatigue and to gain perspective on the mix.