Exodus Audio
Owner’s Guide 6
Exodus Audio
Owner’s Guide 6
Copyright 2007 Exodus Audio. All Rights Reserved.
Subwoofers by nature are inefficient devices. Most subwoofers are around 1-3% efficient,
meaning that for every 100W of power delivered to the transducer, only 1-3W is actually
converted into acoustical output. What
happens to the other 97-99%? It is given off as
heat and dissipated to the environment, primarily (> 95% of it) through convective heat loss
as air passes over the voice coil & former.
Obviously, the movement of the coil & former is critical to the device being able to dissipate
heat. Consequently, if you run a 1K test tone into the driver at high power under continuous
conditions in a small sealed & stuffed box, it is easy to thermally damage a driver. If you
use a 20Hz test-tone in free-air, the same driver may be able to withstand the same power
indefinitely. For these reasons power ratings are just guidelines. Ultimately the user
must understand the conditions under which the driver is going to be used and plan for an
appropriate amount of power for the application. This is the same design paradigm that
manufactures use. Note: Highly equalized systems quickly reach thermal limits. Careful
design is required under heavy equalization especially with test-tones. Music or movies are
typically 1/8
th
power. Test tones present a MUCH higher thermal load on transducers. Be
careful testing drivers with test tones in high SPL conditions.
It is often best to be conservative with amplifier power. If you under-power the system
you will clip the amplifier at the limits of output. That will MOST LIKELY not damage the
transducer. Overpowering the transducer can quickly damage the device before the user
has a chance to adjust the system levels.
Also, amplifiers are capable of power output that
exceeds their specifications under short duration transients. These short transients can
be enough to damage the system if you are running it under full power conditions. The user
is ultimately responsible for operating the transducer within its limitations.
So what is a consumer to do? We recommend building a subwoofer like you would a bridge.
No responsible engineer would build a bridge to operate at its limit. You don’t design a
bridge to support EXACTLY the weight that it will carry under use. You design a bridge so
that it can EXCEED not only the worst-case load, but typically you would design it to have
capacity beyond its maximum expected load. While a subwoofer isn’t a bridge and it’s
failure wouldn’t be as catastrophic, it is a very good idea to build the system such that it has
MUCH higher capacity than your highest output need. Only through good design and
common-sense use will you prevent damaging the system. Since output levels required
depend upon the room, program material, user preference etc… It is beyond the scope of
this document to determine output needs.
Limited Warranty:
Exodus Audio warrants its products to be free of defects in material and workmanship for
a period of 1 year from date of purchase. Exodus Audio and/or its designated
representatives shall have all final determination about the validity of a warranty claim.
