We wanted to learn more about the process of developing loudspeakers at the builders of in-wall and on-wall loudspeakers, so we set out to peer over shoulders at the R&D department at ArtSound.

Walking into the R&D department we see electronic gear and test equipment right, left and centre. Indicator lamps flicker and circuit diagrams hang on the walls. Sitting at the end of this genuine audio-lab are Axel and Bart, the two acoustics experts at ArtSound. They’ve managed to make time for us between designing and testing loudspeakers and we take our seats at the table.

What steps can we roughly define in the design process for a loudspeaker?

Well, first of all we look at the market. We look at what the needs are and what application the speaker will be used for later. You have, for example, loudspeakers that wind up in bars or restaurants, and speakers that get built into your living room or kitchen. It goes without saying that both loudspeakers need a different design approach.

One key aspect in all developments is the price-quality ratio. Do we want to build a high-end or basic series for instance? After all, both types use different components…

Then we lay all the pieces of the puzzle down and make an initial concept drawing with specially designed modeling software. In this phase we test our model against the market and present it to a few selected customers. Based on their feedback, we may still make a few changes.

After modeling the concept we do the mechanical 3D design. In that phase we define the size of all the components and choose the materials to be used. We draw up the precise blueprint of the end-product. For the dimensions we base ourselves on the Thiele-Small parameters we obtain as the result of our computer simulations and years of experience.

We send our 3D model to the prototype supplier. Based on this “recipe” he puts the first prototype together for us. That first prototype consists of the frame, the terminals and the mounted drivers. The drivers in turn are completely built to spec for us: we choose the cone, the magnet, the suspension and the spider for the driver.

So what are the next steps in the development process?

At this stage of the design, you know, there is still no question of a physical filter. A filter in a loudspeaker splits the incoming signal down into two or three signals, depending on whether it involves a 2-way or 3-way speaker. A good filter produces a high-quality sound with clear detail reproduction and a robust bass. But we don’t want to make 200 prototypes of the filter, so we have a much more efficient approach.

We simulate the filter digitally, so we can adjust the filter as we go and then listen to the results straightaway. We set up the filter without having to solder components. In this phase we have direct control over all possible filter parameters.

An example: Here you have a CD player; it sends the sound signal to a digital signal processor (DSP). Software on a laptop drives the DSP. We set the frequency range per driver, because each driver is “specialised” in a closely defined frequency range.

Once this virtual filter has been applied, the signal leaves the DSP along three separate cables. Each of these three signals takes one driver for its account: the bass, the mid-range and the tweeter. This is where the sound so typical of ArtSound is created. If we’re happy with the result, we make a first analogue filter.

What are you up to here?

Like I just said, we’re now making the digital filter analogue. So we’re moving from a digital virtual filter to a physical version that we put together with separate electronic components.

This transition phase is really difficult and critical, because a digital filter reacts differently from a “real” analogue filter. Then the filter is drawn in a PCB design. That design goes to a specialised supplier and he sends the first prototype of the filter back to us.

What’s this on the table?

What you see here is such a prototype of the filter. If the filter prototype is OK, we have a prototype of the loudspeaker built this time with the drivers and the filter mounted together in one whole. So a complete loudspeaker like you might buy it in the shop. After rigorous testing and our final approval, the production can start.

What model is being born here, when will it be on the shelves?

Here we’re testing the filter for the IntiiMi high-end. We’re building a complete series with 7 models. The process from idea to ready-to-sell loudspeaker takes more or less a whole year. This series is our best series to date. The one you see here is a 3-way speaker.

3-way?

3-way means there are three drivers in this loudspeaker. We’re going to split the incoming signal coming from the amplifier to the driver which reproduces that frequency range best. One driver for the low tones, one driver for the mid-range tones and one for the high tones (the tweeter).

By splitting the signal and sending it to a “specialised” driver you get a more detailed reproduction of the sound. The filter is crucial here; it delegates the signals to the drivers.

What were the most difficult points in the design process for these in-wall speakers?

Defining what materials we’re going to use is fairly difficult. This model is a 3-way speaker. Making the filter for 3-way models is really difficult, and building a realistic test environment is anything but a matter of course.

Designing and testing an on-wall loudspeaker is fairly straightforward. In acoustic terms, you only have to consider one defining environmental factor: the wooden cabinet. But the background for an in-wall speaker can be practically anything: insulation material, wood, concrete and so forth. That doesn’t make testing it any easier.

What makes this series of in-wall speakers so special?

The loudspeakers have the aesthetic properties of the other flat series, which means the frame protrudes barely 4 mm from the wall and is 1 mm wide. But the basket (= suspension) and all components are of superior quality, which makes this series our best ever!

The filter helps define the soul of the speaker, hence the sound. What sound are you going for?

We want a detailed sound, but not a tiring one. You need to be able to listen to it all day long. The bass has to be there, but controlled yet robust. There has to be a decent bass foundation. We’re aiming for a British sound.

The presence of the voice is really important in the mid-range. Our high range is clear but by no means aggressive. Glitteringly clear high tones, and all three have to merge harmoniously into one another.

Can you tell us a little more about your career in the audio sector?

Axel: As a child I was already fascinated by loudspeakers. I built my first speaker when I was 6 and connected it to my cassette player because I found the standard sound too thin. I haven’t stopped since. During my schooldays other kids gave talks about beetles or their cat; mine were all about building loudspeakers. Before working with loudspeakers at House of Music I spent around ten years selling pro audio projects, but in private I was tinkering with loudspeakers every day, building them but also as a collector of vintage loudspeakers.

Building a loudspeaker is like building a violin. Whenever the final result reaches the depths of your soul and a lovely piece of music or a voice moves you, then the world around you simply stands still.

Bart: I’ve been working for more than 20 years now in the audio industry, of which 7 years for House of Music.  I’ve always been passionate about loudspeakers; they form the final link in a complete audio chain. If that link is imperfect, then the entire sound installation is imperfect. You might have an amplifier of huge quality, but the speaker finally defines the quality of your system. All the more reason why, beside my electronic developments, I enjoy getting the best out of a loudspeaker.

Gentlemen, thank you for the interview.

You’re welcome.