Compact desktop speakers can work wonders for a PC, bringing to life the sound of games, videos and even web video-calling. But the laws of physics will insist that little speakers only give small-scale sound.
There are ways you can cheat those laws of nature a little, using digital signal processing (DSP) and psychoacoustic trickery to extract a quart from the proverbial pint pot.
These DSP sleights of hand also help ensure that turning the volume up doesn’t make the music clip or distort. But listen carefully and you can hear the dynamic limiting and compression at work. Or the artificial highlighting of acoustic reverberation, for example.
With small drivers, long cone excursion is required to move as much air, and distortion is almost inescapably higher. In short, there’s no substitute for large, efficient speaker drivers to give a smooth, relaxed sound.
Filling that need for larger PC stereo speakers is the Teufel Concept D500. The main speakers are certainly large by desktop standards, standing almost a foot tall (285mm) on their angled bracket stands. With their 75mm mid-bass drivers, these speakers cones are bigger than many ‘full-range’ PC speakers.
But there’s more – a lot more – in the shape of the accompanying sub-woofer. And unlike just about every ‘sub-woofer’ that is bundled with PC speakers, this one actually warrants the name. That is, it seems quite capable of reproducing low frequencies that approach the sub-bass level.
First the main speakers: these are classic passive two-way designs, with a separate 20mm fabric dome tweeter. That tweeter gains a little horn-loading to improve efficiency, with a gently flared front plate that radiates out to the same diameter as the main drivers.
The satellites are built around a plastic cabinet and have screw-down binding posts on the rear that can accept bare wires, and maybe 4mm speaker plugs if inserted into the clamping holes.
The sub-woofer unit is a relatively huge affair, standing as tall as a PC workstation. It has two front-facing bass drivers, aluminium-coned and 120mm diameter. The 32-litre cabinet includes a reflex port that vents below, and four screw-on cones that serve as feet and raise the box from the floor.
On the back is a single pair of phono sockets for audio input, and two pairs of binding posts to connect the satellite speakers. All amplification resides inside the bass box: Teufel quotes 200W amplifier for the bass unit, and another 35W per stereo channel for the satellites.
Do note that these figures may be somewhat optimistic. In the case of the main speakers’ amplifier, we find a one-chip amp solution whose designer cites only 25W per channel, and that with a gross 10% distortion figure.
That level of distortion is all-too audible, which is why high-fidelity equipment typically quotes power ratings with a 1% distortion threshold. Using that scheme, this amplifier is closer to 20W per channel.
For the bass speakers, the Teufel Concept D500 uses a 200W Class D mono amplifier.
We tested the Teufel Concept D500 system from the headphone output of a laptop and an iPhone, as well as at a higher quality using an ADL GT40 USB DAC from Sound Fowndations, fed a variety of CD files and high-resolution 24/96 audio.
With that size of bass cabinet it’s little surprise that the system is capable of moving air quite effortlessly. Moreover, it does so cleanly and tightly – that is to say, with an excellent sense of slam, clearly audible and perceptible on bass drums, for instance. This is no dub reggae soundsystem, only majoring on quantity over quality.
Play some bass-light material, and the system remains mercifully free of unwanted thickness and weight. But extension is plentifully available when called upon, fleshing out the sound in a thoroughly realistic way.
That tuning is impressive for electronic and rock music, bringing big scale to the music. And that’s with the bass turned down really quite low on the 2m wired remote control – two dials are offered on this plug-in box, with a ring of blue LEDs to show the setting.
The remote’s lower dial is a volume control, the upper for bass level adjustment. In our tests, we never needed more than two of these bass LEDs lit, corresponding to around the 8 o’clock position.
It’s worth noting that the volume dial, if pressed, can also put the system into sleep mode. Almost too easily in fact, as we discovered initially when just trying to turn this volume knob.
You can also sleep the system using an odd-looking protuberance on the front of the sub-woofer, a coat-hook Standby button.
But the relaxed and large-scale sound of the Teufel Concept D 500 also brings to life acoustic and classical material, preserving some of the natural wide dynamic range of good recordings.
The intimate plucked sound of quattro from the Penguin Café Orchestra had some delicacy and pureness, with a levelness approaching that of our reference BBC monitors, while full-blown orchestral pieces such as Beethoven’s choral symphony remained intact and free of undue bluster. Midband coloration from the plastic-bodied satellite cabinets was suitably low.
If we wanted to break into particulars, there was a touch too much reediness to orchestral strings, sounding rather like the beginnings of break-up at the top of the mid-bass drivers’ passband. Once heard, this edginess was apparent across most music, a coloration that robbed the system of true high-fidelity status.
The handover between mid and high-frequency drivers was relatively smooth otherwise, and vocals projected well, perhaps more so than with more classically tuned reference monitors.