WAJ on AUDIO; for truth in hifi/stereo/high-end audio  



System Design for Accurate Bass;

(The Double-Bass System)

by W.A.J.

Perhaps special mention should be made of the bass as it presents near insurmountable difficulties in design if one uses one, or one set of, driver(s) to cover the whole bass region, as is the common practice by manufacturers.

The compromises employed usually result in limited deep bass (cut off above 30hz), and a soft inaccurate mid-bass which is also modulated whenever the program requires the simultaneous reproduction of the deeper bass the driver couldn’t properly supply in the first place (This is the most common compromise). Those designs that do a fairly good job at a tighter mid-bass, are even more limited at deep bass than the first example (cut off above 40hz). And those that try at the deepest bass are even less competent at mid-bass than the first example – all things being equal.

My own experiments have shown that the accurate (mid-bass) reproduction of the kick-drum so pervasive in popular music, for instance, requires the use of a small, light-coned, stiffly suspended (low-compliance) driver with a high free-air resonance point, similar to the Yamaha NS10’s 7” mid-woofer. That kick-drum in reality produces a quick, initially sharp and relatively tough sound, and drivers which are best at reproducing this sound are usually useless in the lower range. Indeed, most can’t even properly reproduce the last 25% to 50%, the weight, of that same note.

A more suitable high-compliance driver (with a lower free-air resonance point) is therefore required to supply that weight, and the deeper bass of the guitar and other bass instruments. This is the system, more or less, employed by the $300k Goldmund and the $240k Wilson WAMM speaker systems. (The WAMM, however, uses the KEF 9”x 11” flat-piston driver for mid-bass. This is a genuine woofer capable of  28hz response even in the WAMMs specialized application. It is crossed over at 40hz to an 18” sub).

The NS10’s I use are much more specialized for mid-bass (this is good) and therefore cannot by themselves provide the weight necessary for the optimal cross-over point at 40hz. I therefore use a pair of them per side (ie; one operates ‘full-range’ as a mid/woofer - soon to be moved to the full-range tower where it belongs - and the other operates as a woofer only) in concert with a pair of high-compliance 8” drivers operating from 100hz to 40hz – the NS10’s provide the super-quick response, and the 8”s provide the weight. (I believe this to be the more ideal system, overall, but then that’s only my opinion, Also, configurations may vary as experiments continue. The principle, however, will likely remain the same).

From 40hz to 20hz an 18” high-compliance woofer provides the deep bass. All are tuned to seamlessly augment the bass from the double KLH 12’s of the  full-range towers. The sub-woofer system - or ‘double-bass system’, as I call it - is separately amplified with regard to mid-bass, and deep-bass.

The result of all this experimentation is unprecedented bass performance, in my experience. This combination provides an extremely rare combination of all the desirable attributes not normally found in one system at the same time; definition, articulation, power, and extension. That kick-drum is now accurately reproduced, from the initial strike of the mallet on drum-skin to the ending of the note. The shape of that note is now blatantly apparent and clearly defined. What’s more, the authentic ‘card-boardy’ tone of that note - from some, difficult to emulate, drums - is accurately replicated (thanks to the NS10’s and Goodmans’ sonic characteristics) more-so than in any other speaker I’ve encountered. (For an expansion on this point, refer to my article, ‘System-Building for Lifelike-sound’) On well recorded material, the introduction of the deeper bass of a guitar, for instance, has virtually no effect on the that kick-drum note, the tone and complete shape of that note is still clearly defined even in the midst of gut-wrenching bass notes from other instruments – unprecedented! This is the epitome of ‘the steel fist in a velvet glove’; the ability to supply that tough sharp sound of the kick-drum while also supplying that soft round sound of deep bass is utterly  uncommon.

Be advised, though, that those seeking the spectacular, massive, over-blown, and bloated (mostly MID) bass of a disco, for instance, should look elsewhere, this is not about that. This is much more accurate, this is not even the bass you’d find at a live concert with amplified instruments passing thru massive speaker-boxes. This is actually the sort of bass you’d find at, yes, a live concert, but with UNAMPLIFIED instruments. This is the bass more representative of the ACTUAL instruments; the actual organ, the actual bass guitar, the actual drum, especially that ever-present kick-drum most systems fail to properly replicate.

If this is what you seek, then go for it.

This is real bass, this is - The Bass Reality.


Copyright 2010