Installation loudspeakers typically require long runs of cables, snaking through wall cavities, piercing beams through specially drilled holes, from amplifiers or other sources. But how about ceiling speakers that require nothing more than a power point? That’s what the resi-linx Blue Series Premium RL-BT500 Bluetooth In-ceiling amplified speakers offer. Stephen Dawson explains.

The name gives away what’s happening here. This system is a pair of two way installation loudspeakers with a built in amplifier and Bluetooth connectivity. No need for an external amplifier. No need for those snaking cables. If there’s a power point somewhere up there, you’re right to go.

Down in the room proper, you do need some equipment, but not much – any old Bluetooth-enabled tablet, phone or portable music player (e.g. iPod Nano or iPod Touch) will do the trick.

The Blue Series Premium RL-BT500 Bluetooth in-ceiling amplified speakers should be broadly compatible with pretty much everything, supporting Bluetooth 2.1+EDR (Enhanced Data Rate) and A2DP (Advanced Audio Distribution Profile), which is needed for streaming music. No special codec support is specified (such as the newest and coolest one, apt-X), but the standard SBC (Low Complexity Sub-Band Coding) codec definitely provides compatibility with all stereo Bluetooth devices and should provide adequate fidelity for ceiling speakers.

Each package comes with a pair of speakers, one passive, the other with the amplifier and Bluetooth receiver attached. The speakers are two way units, featuring a 25mm dome tweeter, capable of being swivelled so that it better radiates towards particular listening areas, and a nominally 165mm woven Kevlar bass/midrange. These each pack 20 ounce – that is, a weight of more than half a kilogram – magnets.

The drivers are covered by removable metal grilles – and removal is required to provide access to the four screws that tighten the clamps which hold each speaker in place. Each speaker extends only 78mm into the cavity, measured from the front of the wall or ceiling.

The amplifier module had me puzzled. Occupying two semicircular circuit boards, it had none of the hefty components that you’d expect from a 15W per channel amplifier. Indeed, simply by subtracting the weight of the passive speaker from the active one we can determine that the amplifier section and the Bluetooth receiver (and the cable for connecting the amp to the passive section of the speaker to which it is attached) comes to just 54g!

It’s clear from inspection that the amplifier chip is sealed within a blob of resin. Two or three square centimetres of exposed circuit board seem to act as a heat sink. The small size of both the amp and its heat sink, given up to 30W of output, suggests that its design makes use of the high efficiency of Class D amplification. It would probably be wise, if you’re ceiling mounting these units, to fashion some kind of cover to sit above this unit to ensure that dust can’t settle on it, reducing the effectiveness of any cooling.

The crossovers of both units are quite substantial, with four good-sized inductors, large capacitors and a couple of 5W rated resistors. Connections to the passive sections of the speakers are made via good sized gold-plated spring clips. The amplifier output to the speaker to which it is attached is via a plug. The other one, for connecting to the other speaker (you have to supply the wire) has small screw clamps.

Physically the speakers will install into a wall from the front with no intervention at the rear. The clamps swivel both to lock the unit in when turned one way, and to release it when turned the other. But you’ll have to make sure a speaker cable extends from one to the other, of course, and put the power supply up there. This is an 18V unit, which looks like a laptop supply, and it has quite a long cable. You will need, of course, to find a power point to plug it into.

In Use
I installed the speakers into my test box – it’s 1,200mm by 600mm by 300mm, largely sealed except for a substantial cable access hole at the rear – for testing. Having fed the power cable in, I was able to do the complete installation (and, later, removal) from the front.

No testing enclosure can be fully representative of what environment an installation speaker might find itself in. Often a ceiling installation is effectively an infinite baffle, with virtually no acoustic suspension since the ceiling volume is so large. A wall installation, though, is likely to result in some resistance to the speaker cone movement, thanks to the smaller volume of contained air.

Both environments almost certainly have the baffle constructed of plaster and cardboard – aka Gyprock – which is far from an ideal material for holding a speaker solidly. My box is 12mm chipboard, so not a great deal sturdier than Gyprock.

Use is straightforward. You go to the setup screen of your Bluetooth-enabled music player. I used an iPod Touch for this purpose. The Bluetooth selection panel instantly found the unit’s name. When I selected it a PIN (‘0000’) was required and a couple of seconds later it was right to go.

An immediately obvious problem is: what do you do if you want multiple pairs of these speakers throughout your home? resi-linx provides a Windows software tool that allows you to change the Bluetooth ID of each receiver (there’s a Mini USB socket on the amp board).

Only one Bluetooth device at a time can be paired with the speakers. If you want to change, you make sure the first device is completely switched off and then just pair a new one. This will replace the previous device.

There are no controls on the speakers, of course, so everything is run from your player. It’s there where you set volume levels and so on.

The left channel proved to be delivered by the active unit, while the right channel’s sound was delivered by the passive speaker. Normally I’d suggest that having ceiling speakers deliver left and right channel sound separately, rather than mixing it down to mono, isn’t a good idea. Ceiling speakers aren’t generally used in the traditional hi-fi equilateral triangle configuration, with the listener at one of the points.

But with these speakers you can swivel the tweeters towards the preferred seating position, so perhaps you can use them as stereo speakers.

Listening
These speakers sounded remarkably good mounted in my test box. They were lively and with a good tone.

The tone had a slight bias towards the upper bass and lower midrange, making them an easy listen, yet still retained enough of the upper frequencies for a good bite with cymbals.

With complex music – say, tracks from the group mewithoutyou – there was a small amount of confusion, or loss of precision, as the volume advanced to the maximum level, the various elements of the mix being even more difficult to isolate in my mind than usual. There was also a hint of harmonic distortion in the upper midrange – the harmonics associated with the voice of such singers as Damien Rice.

The essential character remained through a range of artists, a slightly laid-back tonal balance, with good dynamics and drums punching through the mix quite nicely.

The designers have judged the sensitivity of the speakers quite nicely, allowing them to hit pretty much their maximum clean output when the volume of the iPod Touch was advance to the highest level. Hotel California by The Eagles was, at max volume on the iPod, peaking in the high 90s of decibels at a range of about a metre and a half. Not head-banging party levels to be sure, but more than enough to get the blood rushing with most music.

The Eagles, Dire Straits and Deep Purple all produced a surprising amount of bass, at surprisingly deep levels. There was good, grinding reproduction of the bass guitar, and even a reasonable hint of what was happening with the bass drum.

Here’s the thing: I doubt very much that you’re going to find a standalone Bluetooth speaker for a comparable price that will deliver sound as good as these speakers. Their downside is of course that they are fixed in one place.

I did a quick frequency response measurement. It turns out that the restrained tonal balance was due mostly to a 6-9dB reduction in output in the octave between 3,000Hz and 6,000Hz. The measured output was pretty bumpy, with a peak at 12,000Hz and good output to around 17,000Hz. At the bottom end the average output fell by about three decibels below 200Hz, but then was maintained at around that level to a remarkable 52Hz. There were a couple of strong peaks in the bass – at 53Hz and 70Hz – which I suspect were resonances in the enclosure.

If you’re sitting near a wall that 3dB fall off will be counteracted by room effects.

Conclusion
What a good idea the resi-linx RL-BT500 speakers are. I wouldn’t be inclined to use them as my main system. But for day to day music in a room in which I’m pottering around, these are lively, listenable and reasonably loud, all for rather good price.