The Weight of Sound

There’s likely an extremely scientific explanation to whether sound actually has a weight or not as it rattles the air around our ear drums, but that’s not really up for discussion here..

My title pun is based more around being careful with a selection of equipment chosen specifically to fit in a car that’s balance/torsional strength and weight is absolutely key to its performance. We’ve managed to install a 7 speaker upgrade system including an amplifier, processor, 6 speakers and a subwoofer with adding no more than 15kg to this stunning 991-911 Porsche Gt3 of Samuel De Haan.



All equipment offset to the passenger side to counter driver weight and spread out evenly from the floor pan to the rear deck area should make sure as little disruption possible. Sam actually drives this car the way it should be, having already tracked the car multiple times. He enjoy’s decent sound on the long drives between racing and also the occasional daily drive so the plan was set.. Minimum weight, everything must be able to return to stock, maximum sound/pound ratio.


Equipment chosen for the job – Click for links


Hertz Mille Legend 7″ midbass

Hertz Mille 3″ midrange

Hertz Mille tweeters

Hertz Mille 8″ Subwoofer

Hertz HDP5 5ch Amplifier

Audison Bit Ten D Processor

Audison Connections Cabling


With the existing (and quite shocking) 3 way set removed we set about making some new ply baffles, used the existing fixing points an placed some very strategic deadening on the aluminium/plastic door panels, measuring just where the panel was peaking when agitated allowed us to use the minimum amount of skinz 3mm panel deadener to bring the excitable door panels resonating frequency down to a level we were much happier with.


The Hertz Mille Legend 7″ midbass and 3″ midrange were mounted in the same locations as the stock drivers only on much stronger baffles, ensuring little to none of the speakers energy being wasted. If we had it our way, Porsche would have mounted this a little way further up in the car, closer to the dash mounted tweeter. I suppose like most, it’s a GT3, the fact you can’t spec them with any stereo options means they aren’t focussing much in this direction.



The subwoofer, A new Hertz Mille Legend 8″ was chosen for multiple reasons. Weight, Physical size and its enclosure requirements meant we could keep its weight down again..




The subwoofer box was made from ply in a stack design, routed and laminated together, this was then completely sealed with PVA and bonded with a thick fibreglass bottom shell we moulded from the cars rear passenger seating (in the loosest sense of the word) area. This together made .6cuft for the 8″ driver to play very happily from the 600 Watts on tap. A level of build fitting for the prestige of the car.







The processor was mounted to the floor underneath the factory carpet under the passenger seat and the amplifier directly behind it in the rear leg area. The processor was fed a full range signal from the factory nav head unit, de-equalised and then sent out via RCA to the amplifier. This then feeds the subwoofer and front speakers in a “passive-active” formation with the midbass active and mid and tweeter sharing a passive crossover. With the system running this way every part of the factory functionality has been retained.

With all of the fabrication done, the wiring complete is was time to test the system, get the car back together and get it back over to its owner..





The system with minimal tuning sounds fantastic, high end speakers, small sealed subwoofer and plenty of power in a small cabin all work in unison to create realistic strong sound. Given the distance between the midrange and tweeter the stage is pleasingly high. For those with toes curled in their suede sparco boots muttering about racing car’s never needing stereos If he wants to listen to the car, he can turn it all off…




It’s been a pleasure installing this system into this car, Sam’s happy, we’re happy.. Chek out the rest of Sam Rutters images from the hand over day –


















As always, thank you!! All products available and SHARES/LIKES on social media are gratefully encouraged.


Shakey – Studio Incar