Articles for Audiophiles by Steve Deckert
AUDIO PAPER #005
TWEAKS FOR YOUR SPEAKERS
by Steve Deckert
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 sine 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.
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. Visco-elastic damping laminate, the technical name, is what I use to solve this problem.