Speaker Asylum: Deep and accurate bass means...... by Sean

using either a sealex box, transmission line or vario-vent. Any other method will produce inferior results that suffers from ringing, high impedance peaks at resonance and a much sharper roll-off after resonance.

Each design does sound slightly different, but can produce quite usable deep bass with good pitch and definition. The vario-vent probably offers the highest efficiency of the bunch, as it is kind of like a partially stuffed port. This does allow the back wave to be vented at the lowest frequencies but still maintains a small amount of air-spring pressure on the woofer like a sealed enclosure does.

Transmission lines are difficult to build and tune accurately. They are low efficiency designs typically, but can sound very good. If you attempt to do this, you better make your boxes so that they can initially be taken apart several times. You may need to fine tune the box length or add / subtract stuffing in it. Once you've got it dialed in, you can do a permanent sealing of the cabinet.

Sealed and stuffed is the easiest and most reliable method. Either way, you need to pick up a copy of Vance Dickason's "The Loudspeaker Design Cookbook". This will let you know what your dealing with before the saw hits the wood. Good luck... Sean
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