Do not run the sub with a high-level input derived from your power amp’s outputs – run the sub at line-level.
Do not use the sub’s crossover to roll-off the bottom end of the main speakers – instead roll the sub in underneath them.
Do not skimp on the cables – you need to use the same interconnects and power cord that you are using through the rest of the system.
Do not rely on DSP to dial in the sub’s response – optimise placement, crossover point, output level and phase setting first, with DSP as a last resort that’s best avoided.
In many ways, the Focal sub 1000F is an object lesson in how to build a sub-woofer that will actually work in a cost-effective but ambitious two-channel rig. It’s not perfect: I’d like to see a variable phase control, rather than a simple 0/180 switch, but I can live with the positional compromises that imposes. Beyond that, I love the focussed simplicity of its control options, its lack of spurious features and the sheer quality of the driver it uses. It even looks nice. It’s promise is borne out in practice, with pitch definition and an agile sense of temporal authority to match the impressive clarity and performance of its chosen partners.
The Greenwich/Sub 1000F combination is an unqualified and highly recommendable success. Adding the sub-woofer doesn’t just make the Greenwich an even better speaker, it makes it a far more versatile one too. In a somewhat ironic twist, it allows the Jordan speakers to make even more of those distinctive and rather special drivers. One can only speculate as to just how much more a second sub would add to the experience. But as impressive and heavy-hitting as the Jordan/Focal hybrid is, what’s really interesting is extrapolating the potential implications for speaker design as a whole.
Wider implications and opportunities…
Active sub-woofers are not exactly new, although the advent of DSP, class D amps and AV systems has led to an explosion in their numbers and affordability. It has also led to an increasing number of part-active speaker systems, with on-board amps driving the bass. That’s an approach that, in my experience too often simply replaces one set of problems with a different set, although that’s generally down to issues of execution. DSP crossovers allow phenomenal control over and tailoring of a speaker’s bottom-end. Unfortunately, that generally leads designers to overplay their hand, suggesting that DSP adjustment can compensate for room and placement issues. Sadly, that starts from the wrong end of the equation, with heavy-handed DSP (and the latency issues that go with it) having a musically more destructive impact than a well-engineered passive cross-over. Start with the assumption that you are going to set the speaker up as best you can with the settings flat – and then gently trim the bass response to minimise (rather than eliminate) any room related problems and you might have half a chance of success. The problem is that with the bass cabinet being integral to the speaker as a whole, there’s no way of eliminating associated timing problems – unless you apply a compensatory delay to the mid and treble, which really is akin to throwing out baby with the bathwater…
