Portable Audio

Focal XS 2.1 iPod Amplified Speaker Dock

ARTICLE INDEX

Design

Gerard Chretien, the general manager at Focal, took some time with me to discuss his approach to design and the development. The XS 2.1 has its roots in the Solo 6 Be powered studio monitors. The Solos have garnered quite a reputation in the pro-audio field, notably with mastering engineer Dave Kutch who has worked with artists Natasha Bedingfield, Erykah Badu and Alicia Keys to name a few. During the development of the Solos Gerard was approached by one of the engineers on the project for a set of critical ears. While Gerard never indicated to me why he connected the Solos to his iMac in the first place, ultimately that was how he tested the Solos.

During this time Gerard realized what many of us have; the computer can provide a good delivery mechanism for both music and video. A question naturally arose following up his listening experience with the Solos and his iMac, "Why can't multimedia speakers sound this good?" This lead to Gerard issuing a challenge to his team, design a multimedia speaker that replicated the sound of the Solos, but at a multimedia speaker price point. Note the challenge was to design multimedia speakers, and not an iPod dock. The dock was originally included to facilitate charging and simplify setup, as opposed to being an integral part of the overall design.

The challenge Gerard presented was significant given the constraints and the available technology. While near field audio is well defined, largely by studio systems, the design concepts are not always transferred appropriately for consumer products. One of the major issues that arise for near field systems is surface boundary effects. Conventional home audio is commonly designed with the assumption that the user will seek to minimize (or optimize) the effect of boundary surfaces. i.e. move the speaker adequately away from the wall. Near field audio necessarily assumes close proximity of boundary surfaces to the listener. The constraint comes from the speakers resting on a surface at which the listener is seated. The most common near field audio example of which is the sound engineer at the mixing console.

The average computer setup closely approximates a studio setup with regards to speaker location, and boundary conditions relative to the listener. Given the cost constraints, and initial design decision to have a sub/sat system, the XS deals with the surface boundary by elevating the speaker on the integrated stands. It might seem like a long explanation for a rather inane design feature, but it only serves to emphasize Focal's attention to the design. In a multimedia context, the added height also serves to align the audio and video. Focal even went so far as to coin the term Visual Sound Coincidence or VSC.

Although the relative proportions of the satellites and stand are such that they don't seem very large, I was struck at first by the relative size of the speakers. This leads to another constraint that Gerard placed upon his design team. The satellites have a low enough frequency range as to limit localization of the woofer module. There is definitely something to be said for well integrated sub/sats as compared to hearing all the bass coming from under your desk. The curved satellite cabinets, while visually appealing also help diffract the sound coming off the back of the drivers.

The final driver design and configuration was arrived at after nearly twenty different prototypes. The final design has a slight emphasis to brighten the 2-4 kHz range; this is intended to compensate for some of the degradation in compressed music. Gerard emphasized to me that the sound is achieved through acoustic design and not digital processing of the signal. Cost constraints limited the range of materials available for the driver, this lead to lower design pressure limits within the cabinet. So while the speaker grilles are permanently affixed, it would be safe to assume the tweeters are most certainly not made of beryllium as in some of Focal's other products.

The subwoofer module is vented, with a downward firing 6" woofer. The amplifiers are all housed within the woofer module. The amplifier is a traditional Class A/B design, with a large transformer. The integrated dock also houses an auxiliary 1/8" stereo analog input, a USB digital audio input, and an IR receiver for the included remote. The XS uses a Burr-Brown DAC for the USB signal. I was curious as to why Focal did not pull the digital signal from the iPod. Apple does not permit digital output from the iPod in its dock design guidelines and will not grant the "Made for iPod" designation for docks with digital outputs. Depending upon the model of iPod, the quality of the DACs can vary quite significantly. Following the original design intention of the XS, however, the USB digital input will always provide the highest quality signal to the amplifier. I will say, however, with my 4th generation iPod, it was too close for me to call between the Wolfson in the iPod and Burr-Brown in the XS.

Focal XS 2.1 iPod Dock

Focal XS 2.1 iPod Dock