For those wanting a one-box solution for listening to music using Apple AirPlay®, the A5 and A7 are exciting additions to our product portfolio, but it is all too easy to forget how our experience and expertise in making traditional core hi-fi speakers has influenced their design in a way that makes them stand out from the crowd – by simply sounding better. Senior Product Manager Mike Gough explains.
Let’s put functionality aside for a moment and remember that any product that renders sound is subject to a common set of acoustic challenges. The techniques that make a regular passive hi-fi speaker sound better are just as relevant when it comes to products like A5, A7, Zeppelin Air, etc. that are designed for different, specialist applications.
So we’re going to look at a couple of technologies you’ll find in these new products. They originated in speakers costing thousands of pounds/dollars/euros, but have been applied with equal effect here.
Look at the back of either the A5 or A7 and you will see a hole that terminates in a flared shape covered with dimples. There are two on the back of the Zeppelin Air and you will see similar on our other speakers including our flagship range 800 Series Diamond speakers. These holes are properly called ports and their purpose is to reinforce the level of bass.
They only do their work over a limited range of bass frequencies, but within that range, air pumps back and forth along the attached tube that extends into the enclosure and radiates sound that adds to the sound that the drivers themselves are producing. The idea is that the drivers do less work and so have less distortion. This sounds very positive, but there is a downside. Air rushing through tubes can make other noises too. It’s often called chuffing (after the old steam locomotives) and is caused by turbulence in the airflow, mainly generated at each end of the tube.
The aim, therefore, is to reduce the turbulence so you don’t hear it above the music. That’s why the outlet of our ports is not only flared, but is also covered in tiny dimples. It’s no coincidence that the dimples look like those on a golf ball. The same technique is being used to smooth the airflow. In the case of the ball, it flies much further than one with a smooth one would. With the port, we’re simply out to reduce extraneous noise and we apply the design to both ends of the tube, not just the end you can see. We call it Flowport™.
Now look at some similar products from other manufacturers. Some may not have a port at all. That’s fine and certainly gets round the turbulence problem, but for a similar sized product, they won’t sound as full bodied and the balance will be a little on the thin side. Others may have a port, but it will probably have plain ends with sharp corners. There may be some token curving at the ends, but it probably won’t be as gradual as ours and it certainly won’t have the dense dimpling pattern, because we have a patent on it.
Now the acid test. Do some comparative listening, paying attention to the bass line. Turn up the volume until you begin to hear turbulence noise from the port. Size for size, our product will be playing louder.
We now turn to another technique that you’ll find in almost every product we make. This one you can’t see because it’s on the inside, but it makes a difference to the sound, so we use it. The difference is rather more subtle than Flowport, but is there none the less. On the back of each tweeter is a tube filled with sound absorbing material. We refer to this as a Nautilus™ tube, because the technique first saw the light of day on that extremely expensive speaker.
All drivers produce as much sound from the back of the radiating diaphragm as they do at the front and, whilst you listen to the sound from the front, you need to absorb the sound from the back. If you don’t, it reflects back through the diaphragm and interferes with the front sound. It arrives a bit later and at worst sounds like some low-level reverb. At best is just fuzzes the sound a bit; things are not quite as clear as they should be.
With cone drivers, the rear sound energy is absorbed by wadding inside the main enclosure. Tweeters, on the other hand, are sealed units, so we provide them with their own little enclosure, and it turns out that a tapering tube works the best at these high frequencies. Nobody else does this either and, for this design, we were granted a Queen’s Award for Enterprise in Innovation, which is one of the UK’s most prestigious business awards.
So, just two of the many techniques we apply to make our products simply sound better. In this particular case, it means better sounding AirPlay® speakers.