The idea for this Gramophone Guide came about when I was sitting in The Chord Company’s press conference at this year’s Bristol Show: trying to demonstrate the subtle benefits brought about by its latest network noise filter, the cable manufacturer was continually thwarted by the rumble and thunder from the subwoofer manufacturer exhibiting next door. I felt the pain in the room, not least because room-shaking needn’t be what these dedicated low-frequency speakers are all about. Indeed, they’re not just for action movies, where that body-thumping low-end is often used to dramatic effect, with explosions and spacecraft flying overhead – even though in space, as the line goes, no-one can hear you scream – but can play a major part in the reproduction of music, too.

Subwoofers for music are nothing new, but they’re generally misunderstood, not least due to that association with action movies. I remember a long and fascinating discussion I had over dinner after a Gramophone Awards ceremony with Richard Lord, the late founder of subwoofer specialist REL, which centred on the role of subwoofers in music reproduction. Richard built some truly huge subwoofers alongside more modest models, all designed with the accent on music – but then his first-ever design, even before he started the company bearing his initials, was a massive affair, built into the seating of a bay window in his home. And from the start, the intent of the company was simple: to build the world’s finest subwoofers, all underpinned by his persuasive descriptions of the emotionality of bass, or at least what deep bass does for music and film sound in terms those that love it might understand.

REL continues to make subwoofers getting on for a decade after Richard passed away, but it’s now been joined by a phalanx of companies offering designs echoing his aims, rather than the ‘maximum impact’ models available from the USA around the time he was introducing his first models. And on the REL website you can find an excellent speaker-matching tool to help you choose the right subwoofer for your system: you just put the make and model of speaker into a form at rel.net/pages/speaker-pairings, and it will give you models suggested from its range after allowing you to filter for the kind of use you’re planning – music/home cinema/both – and room size.

Another tool on the site allows you to visualise how a subwoofer will slot into your system and room, which is as crucial to the performance as the set‑up of the subwoofer’s electronics (just about every consumer subwoofer has its own amplification and crossover system built‑in).

So, can you use a subwoofer with your system? The answer is almost always yes: many amplifiers now have a dedicated subwoofer output, or preamplifier outputs, and any outputs of this type, controlled by the volume setting, will be fine to feed a subwoofer. Alternatively, many subwoofers offer so-called ‘high-level’ inputs, which can be fed using a parallel pair of speaker cables run from the same amplifier terminals as your main speaker wires. Richard Lord used to be a firm advocate of this latter connection, saying it produced results much more coherent with the main speakers’ output, but then dedicated ‘low level’ outputs have come on a long way in recent times.

So which subwoofer should you choose? Tempting though it is to go for the largest one you can afford and accommodate in your room, that might not always be the best approach: if you’re underpinning a small pair of bookshelf speakers in a modestly-sized room a relatively compact sub, such as REL’s TZero MkIII or the Bowers & Wilkins ASW610, would be more than sufficient. Each is a very compact cube you can hide away almost anywhere in the room – as you’ll be setting up the sub’s frequency range and volume so that the bass is ‘just there’, rather than being from a discernible source.

In fact, that’s the guideline for set-up of a subwoofer: adjust the high-frequency roll-off of the sub so that it just overlaps the lower frequency extension of your main speaker, and then adjust the output level so the subwoofer just disappears, and you’ll be in the right ballpark. After that, just tweak by ear over a period of listening.

And if you want more room-filling power, there’s no shortage of larger models available, such as the REL 212/Sx, with twin 30cm drivers, and rear- and downward-firing passive radiators, plus a 1kW amplifier, or KEF’s mighty Reference 8b model. But there is an alternative if these speakers are starting to get imposing in the room: you could always use two compact subwoofers – one for each channel – and hide them away to much the same effect.

What will a subwoofer bring? Well, better, more controllable bass comes hand-in-hand with greater low-frequency extensions, but there’s also a subjective effect: every time I’ve added a subwoofer into an existing system, even one already offering a wide frequency range, I’ve found the midrange and even the treble seems to take on greater purity and greater openness. Try it, and I think you’ll be hooked.