Chevrolet Volt Audio Build — OEM Rework

The brief

Commission № 001 is a 2012 Chevrolet Volt, made quieter and entirely reworked beneath the trim. Vehicle: Chevrolet Volt. Level: Stage 3 — a quiet car made quieter, and, beneath, entirely reworked. The build was carried out in Kraków, in the same workshop behind every Jullia commission, using the same restraint that guides the atelier's car audio and home audio work alike.

The starting point and the problems

Out of the box, the car's audio system sounded better than average for its class, but it had a number of serious shortcomings:

Sound. The bass was surprisingly good for a car of this class, and the soundstage was focused and neutral, with clear dynamic potential.

Main faults. Turning the volume up made listening uncomfortable: distortion crept in, and the door panels began to vibrate and resonate.

Work carried out

Bass amplifier upgrade. The low-frequency amplifier was reworked using Jullia Audio's own know-how, keeping the original amplifier chip.

Power filtering. Filtering was added to the head unit's power supply circuit.

Signal path. The signal path between the DAC and the amplifier was reworked.

DAC power. The DAC's power supply was reworked and every power circuit of the digital section refined.

Crossovers. New crossovers for the tweeters were calculated and built.

Acoustic treatment. The doors were sound-deadened and the “Helmholtz resonator” effect eliminated.

Note: the main audio path was left in its original form.

The result

Dynamics and bass. The sound changed completely: the bass became fast, dense and tight, with no excess boom. It feels as if a proper, high-quality subwoofer were in the car.

Space and stage. The soundstage widened considerably and now fills the whole cabin evenly, for a sense of complete immersion in the music.

Comfort. The sound became soft and natural, so long listening no longer tires.

Detail. Instruments gained a live, natural voice. The finest details emerged: fingers on strings, keys being pressed, and the kick drum is felt with the whole body inside the cabin.

To hear this build in person, request a listening, or see the Mercedes GL 550 build for a second look at the same rework philosophy applied to a very different car.