TWEAKS
FOR YOUR SPEAKERS
by Steve
Deckert
Nov. 1997
To TWEAK: Taking something and altering
portions of it to effect better performance. ...also a disease
afflicting some audiophiles unable to stop tweaking:
audiosystematatweakitis.
A loudspeaker is
a necessary evil that is required to convert sign waves into
sound waves. It is in most cases a balance of compromise.
Many people do not realize that a loudspeaker cabinet is
responsible for around 70% of the sound quality and performance.
The actual woofers and tweeters are less important than the
cabinet if choices must be made. Below are some things you
can do vastly improve a speakers fidelity.
SPECIFIC
TWEAKS
-
Installing strategically located bracing
to reduce cabinet resonance makes such a tremendous improvement in
the solidness and focus of your sound that you would be
amazed.
-
Measuring the woofer's specs and tuning
the cabinet exactly to that woofer will get you maximum
performance with the flattest response. Most are found to be more
than 20% in error!
-
Carefully reinstall a port that is
aerodynamic with flared or rolled edges will remove coloration,
wind noise and improve power handling.
-
Installing adjustable spikes on the base
of the cabinet will reduce or eliminate cabinet rocking which
happens on a microscopic level will greatly enhance the focus of
high frequencies and the solidity of the bass.
-
Installing sound absorbing materials such
as cork, or felt on the baffle will reduce rarefaction making it
difficult to localize your speakers. This enhances sound stage
topology in the stereoscopic array. Makes you speakers have a
chance at disappearing when the music is on.
-
Reinstalling drivers to be exactly flush
with the baffle will improve the flatness of the frequency
response of each driver.
-
Reinstalling high frequency drivers with
composite isolation (poured flexible sealant) tremendously
improves the bond between driver and cabinet while at the same
time dissipates cabinet resonance into heat so that they do not
smear or color the sound from those drivers.
-
Reconfiguring the array when necessary
and possible to a line source array will usually improve imaging
and depth enough to justify the new baffle.
-
Installing the tweeter on the top of the
cabinet at the proper angle will physically time align the array,
completely flatten its response, require less crossover
components as a result. Makes your sound stage presentation
acquire dramatic depth.
-
The
worst sound you've ever heard in your life comes from hard
metallic chamber created by the magnetic pole piece and voice
coil assembly and dust cap. 90% of all drivers I've inspected
(1000's) are built with the voice coil former protruding past the
cone by as much as a half inch or more. This thin aluminum
cylinder rings like any pipe does when vibration is introduced
into it. Eliminating this excess and dampening the harsh metal
pole piece with a domed felt plug removes perhaps the most major
downfall of cone speakers - that cone speaker sound referred to
by electrostatic speaker owners.
-
Dampening the dust cap or installing a
soft butyl rubber dust cap or eliminating it by installing a plug
helps hide the remaining nasty sound described above.
-
Securely re-gluing the voice coil to the
cone can evenly dissipate nasty resonance's from the voice coil
into the cone where they can become lost. It also improves the
balance and precision of energy transfer through the assembly.
About 50% of the drivers that come through our shop were not glued
with this precision.
-
On
woofers - welding the pole piece to the basket rather than the
centrally located spot welds, will stop the magnet/pole rocking
that happens at high output levels.
-
One
of the most common tweaks for all drivers (other than tweeters) is
the application of anti-resonance pads on the basket. Most speaker
baskets ring like a bell when struck, so when music excites the
frequency of the basket, the sound suddenly becomes harsh.
Vico-elastic dampening laminate, the technical name, is what I use
to solve this problem.
