The modern 2-way bass cabinet is very much an evolutionary design, having developed from the single-way bass guitar speaker systems that were originally the norm. Likewise the standard way of adding a high-frequency driver or 'tweeter' to existing bass guitar cabinets is definitely not the best way to get a high quality sound.

Inherent Compromise

A typical 4x10" cabinet (without a HF horn) relies upon each driver to reproduce the entire frequency spectrum of a bass guitar, and additionally attempts to be as efficient as possible. This causes an enormous amount of compromise in the driver design. An ideal bass driver should be very stiff (and consequently heavy), with a soft surround and large excursion capability. However such a driver would have little midrange and high frequency output and therefore be of little use for even the most dub obsessed bass guitar players. Hence the speaker cone has to be made more flexible to achieve sufficient midrange output (yet still fails achieve useful HF output) at an enormous cost to both low frequency extension, transient ability and distortion levels. Furthermore as bass amplifiers were much less powerful when these cabinets were first used, the maximum cone excursion and voice coil length were reduced to increase the 'apparent' full-range efficiency and maximum loudness with a highly detrimental effect upon the maximum low frequency sound pressure levels attainable.

Simply adding a tweeter increases the problems

The spate of 2-way cabinets that cropped up in the '80s attempted to improve upon this design by adding a simple tweeter and low-cut filter in parallel with the existing speakers. Although this does increase the high-mid and high-frequency ouput it does so at very high levels of distortion, with odd phasing effects due to both 10" drivers and the HF horn sharing the load of producing the high-midrange frequencies. This means that the most expressive area of bass guitar tone has to suffer from the worst sound reproduction, especially as both drivers are operating towards their frequency extremes.

Acme's 3-way design has none of these limitations

In light of this, the Acme Low-B speaker system doesn't seem so much like a revolution but more like a really obvious way to design a bass guitar speaker system.

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