With the advent of Dolby Atmos – and Dolby Surround – in-ceiling loudspeakers have taken on a new role in home theatre. Stephen Dawson looks at a new offering from industry stalwart TruAudio.

Previously they might have acted as replacements for surround speakers or surround back speakers so as to keep things relatively inconspicuous in a shared space. But now Dolby Atmos offers four explicit channels for which ceiling speakers are best suited. Using ear level speakers is faking it.

And it’s not just Atmos. Arguably – and I’m happy to argue the case – Dolby Surround is even more important, at least for the next few years. It is proving astonishingly effective at extracting height information from 5.1, and even from 2.0, audio tracks, delivering a more rounded surround effect for older material. If you have an Atmos-capable receiver, you also have a Dolby Surround receiver. And you’re not taking full advantage of it without ceiling speakers.

The Equipment

The TruAudio GC-6 speakers may well be just what’s needed. For Dolby Atmos/Surround you will need two or four depending upon your receiver’s capabilities.

These are two way in-ceiling speakers, with a 165mm bass/midrange driver and 25mm tweeter. The tweeter uses a titanium dome, fronted by a somewhat unusual spiral wave guide. These can be swivelled through ten to fifteen degrees to direct the high frequencies more closely at the listening position.

The bass/midrange driver features a copper-coloured woven carbon fibre cone which would look rather attractive in loudspeakers where the drivers might be used without being covered by a grille.

But these speakers are part of TruAudio’s ‘Ghost’ series, which means that they are relatively invisible if installed correctly, which includes using the grille. They sensibly feature the standard kind of grille which low visibility speakers employ: a white perforated metal circle that completely covers the whole speaker assembly and is held in place magnetically, yet is only about 2mm thick.

The grille diameter is 229mm. The depth of the speakers is 104mm. The cones of the speakers are largely covered at the rear by a perforated metal basket, although some ceiling dust and fibres may make its way through to rest on the cone. The substantial and well constructed crossover network coils and resisters are exposed, though, so it would be wise to put a protective plate above the speakers. That aside, they can be installed and removed without entering the ceiling space, thanks to the rotating lugs that drag into place as their screws are tightened, and move away as they are loosened.

Each speaker has a three position level trim switch for both the bass/midrange and tweeter, accessible from the front but normally hidden under the grille.

The speakers are rather weighty at 2.15kg each, thanks in large part to their solid construction and hefty magnets.

Listening

I installed a pair of the speakers in my chipboard test box. The conditions of a ceiling speaker are hard to predict. Generally you expect an open rear with no acoustic suspension whatsoever, nor any particular tuning, nor a speaker baffle specifically designed for rigidity. My test box is large enough to result in little restriction on cone movement, while ensuring that bass won’t be attenuated by an insufficiently large baffle. But at best it can only approximate any specific installation environment.

Initially I was quite a while dissatisfied with the sound. The reason was simple: I’d centred both the driver level trim switches for both speakers, as is my normal practice. That turned out to be wrong. The sound was somewhat harsh, light in the bass and all too prone to confusion at higher levels.

Then I smartened up and started playing with those trim switches. First I flicked the woofer one to the ‘0’ level, which is to say up by 3dB. That made a big difference to the balance, but still left that sense of confusion. So the next step was to slide the tweeter’s trim switch to the -6dB position. And that did the trick. The balance – after the few minutes needed to allow my hearing to recalibrate – was close to right, and the sound was much cleaner and more precise. High volume levels became possible without excessive harshness. There remained a bias towards to the upper midrange, but with the harshness eliminated this tended to make the sound bright, forward and attractive.

There wasn’t much in the deep bass, but the upper bass’ balance was good. Black Sabbath’s first album was delivered with enough of the ominous bass to satisfy, and Ozzy’s voice was perhaps a touch too clear despite it normally being somewhat recessed in the mix.

Switching to solo instrumental – classical guitar – there was still a general sense of upper midrange forwardness, but fine precision and control and good imaging. The air around the instrument was excellent.

The speakers were clearly comfortable with plenty of power. At times I drove them very hard indeed with a home theatre receiver capable of a genuine 150W into 8Ω. They retained their composure and clarity despite this.

Of course this is an unfair test. In-ceiling speakers are supposed to provide support sound – height or surround – to the main speakers of a system and I was using them alone as a stereo pair. Their delivery on this front makes it clear that they’ll be absolutely happy in their intended role.

Measurements confirmed that the most even overall balance was to set the switches to maximum output for the bass/midrange driver, and minimum for the tweeter. Even with that setting there was a slight prominence at 2,400Hz.

In a sense, the frequency response within the effective bandwidth of an installation loudspeaker doesn’t really matter very much these days, and least in any but a very low end system. Any mid-range or higher home theatre receiver is going to EQ the speaker for you to provide the necessary balance and of course to align them with other speakers in the system. Setting the switches to the positions suggested provides a good baseline from which the receiver’s EQ can nudge them into the correct alignment.

But what does matter is the bandwidth – the range of frequencies which the speaker can clearly output at reasonable levels. All my measurements showed clearly that at the treble end, these speakers comfortably extended out to at least 20,000Hz. Certainly no problems there.

The claim that the speakers go down to 35Hz within a +/-3dB band is a bold one, though. That’s the kind of bass performance that you’d expect in a fairly competent floorstanding loudspeaker, with a carefully tuned bass reflex enclosure. My listening did not suggest the presence of such deep bass at those levels. My response measurements, conducted at one metre, didn’t either. They had the output disappearing rapidly below about 60Hz.

But measuring bass output is notoriously difficult, because of room effects. So I did a close microphone measurement, with the head of the microphone about two centimetres from the cone of the woofer. This showed a peak output at 110Hz, with 80Hz about 3dB down and 56Hz a further 3dB down. At 35Hz the output was down by around 18dB, which means if it is effectively contributing nothing to the sound.

The specifications don’t indicate the crossover frequency between the bass/midrange and the tweeter. My measurements suggested that it’s at 2,000Hz.

Conclusion

So the TruAudio GC-6 in-ceiling speakers do their job very well, and will easily cope with the demands of the new surround sound systems. Just don’t be misled by that 35Hz claim. Let your subwoofer carry the load for anything below 60Hz.