Ai Design Blog
An audio system worthy of a supercar
For a good client with a McLaren 720S Spider, we had done an earlier audio upgrade. But when he decided to dial it way up, we needed to rethink that entire system design. The prior system featured an 8” subwoofer in the passenger footwell, an amazing front stage integration of some ScanSpeak drivers in the doors, and a very cool set of preamp volume controls integrated into the center console. At the time, the focus was to maximize an upgrade without too heavy a hand on modifying certain structures in the cockpit.
Our thinking on the second-round upgrade came down to retaining that front stage, those pre-amp controls, and the subwoofer enclosure at the footwell – but not the woofer. The next big step—essential to the goal of meeting the client’s vision for the system—was about finding available real estate for a subwoofer with prodigious output inside a chassis where packaging had already been considered down to the last detail. As with many systems, the size and output level of the subwoofer sets the magnitude of it all. Once we have that figured we can design back from it.
above: Creating the void in the 720S bulkhead
Ultimately, we chose the service area behind the seats as the subwoofer location. This cavity sits underneath the envelope that houses the convertible top mechanism, which includes all manner of OEM electrical gear. This area was configured from McLaren as a service point. Arduously, we carefully re-oriented the bulk of what was there to shift space and create a void on the passenger side for the new subwoofer cabinet.
above: The subwoofer box in place.
We then fabricated a composite wood and fiberglass enclosure that fit to every irregular plane and surface in that cavity. This box was able to yield precisely the optimal air space required for the JL Audio woofer we wanted to use –the esteemed JL Audio 10W3 which is a house favorite. Through this, we still retained the complete serviceability of the OEM electricals!
To finish off the subwoofer, we designed and handcrafted a speaker grill that would fit the aesthetics of car, and built it into a new panel covered in the matching material as the rest of the bulkhead.
above: The new speaker grill for the subwoofer
left: The front tub removed from the frunk.
With the subwoofer design in the bag, we then turned our attention to the best location to house the amplifier and processing gear. No small feat. We selected the frunk (front trunk), as a suitable location for this relatively bulky gear, despite the frunk consisting of what is essentially a large removable plastic bucket.
This is a major service point that had to remain removable during dealer servicing. This serviceability was maintained with some clever packaging of our own, while paying close attention to preserving zero water intrusion. Tricky area for this…
above: We built a removable rack in the frunk to house the audio components, including three JL Audio amps and an Audiotec Fischer Helix DSP
Next, our pre-existing footwell subwoofer was lightly converted to run a different speaker driver, one better suited to utilize as a dedicated mid-bass driver. This capability within the system design, of a mid-bass driver in a dedicated cabinet enclosure, is the sort of thing that really adds to the attack and definition of the lower bass at the rear.
The two biggest challenges addressed – a prodigious subwoofer and a home for the great increase in amplification – coupled with an amazing front stage which could now reach its full potential, the client’s mandate for a truly impactful system was reached. The new level of performance shone through even with the top down, and running at highway speeds. Generating enough sound pressure to overcome the competing noises when the top is down on a performance chassis like this is quite tricky, something we need to design-around at the outset.
The client is thrilled with the result!
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