Building the PERFECT, DRONE-FREE EXHAUST with simple maths | J-Pipe Resonators (Helmholtz resonator)

This is my longest video yet, and also my longest to make. I've spent the past 5 months refining the exhaust on my Passat CC to get the perfect sound, and I can finally call it 'done'. Feeling underwhelmed by vague quotes and uncertain advice from various exhaust shops, I decided to design my own exhaust system to fine tune my car's sound and cancel out drone using J-Pipe Resonators.

J-Pipes, also called Helmholtz resonators, are designed to be exactly 1/4 the length drone's sound waves, meaning that when the sound wave travels to the end of the pipe and back, it's 50% offset with the sound waves coming from the engine. This means they cancel out when re-joining the exhaust system, virtually eliminating the drone. It's basically an analogue version of the technology used in noise cancelling headphones, and is used by AMG in their factory exhaust systems.

I hope this video is informative and helps anyone looking to build their own exhaust system. I had to do a bit of digging around to find everything I needed when creating mine, so I thought I'd compile it into one video. As always, if you have any questions, leave them below!

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www.briskwear.com

0:00 Intro
1:15 Initial calculation
4:59 Build
12:46 First road test
15:09 Resonator before / after
15:17 Revised calculation
17:35 Modification
18:36 Final test and conclusion