As a mechanical engineer, gear-head and fellow tinkerer, I appreciate a video explaining the science rather than the typical exhaust comparison. Well done 👏!

Just wanted to add my experience. I was a certified Vibration analyst for NASA. One of the issues discovered about vibration or "Drone" was that it is all about "Frequency Resonance". Where did the Frequency/Drone occur? Without any testing or frequency readings on your vehicle, "Just add Mass". Example - find some lead sheeting or heavier sheet metal and wrap it around the muffler and secure. By adding enough "Mass" to the muffler it will change the frequency of the vibration inside the muffler, thus moving the frequency to another level. It might take some playing with the amount of mass but it worked on many of the vibration frequencies" affecting critical NASA equipment. Just food for thought.

I'm a mechanical engineer and a car lover as well, and man this was a really awesome explanation. Very easily relatable to principles studied and also very enlightening. Keep putting out these videos 👊🏿

I’m watching this to fix my droning, but something you said just flipped a switch in my head. You solved my problem with my tweeter sound reflections. Thank you sir

Great video Alex. I appreciate the work that you put in to help folks understand what's actually happening with you install one of these pipes.

Man this video is so clear and simple ! You have done a great work thank you !

Super useful video, I knew the concept but the actual science was magic to me, now I understand it and will use this to solve a very bad droning issue with an exhaust I built for a customer of mine. Thanks for making this easy to understand!

Finally somebody brakes it down with some science!!! Good info

Hi Alex your info was spot on as I had a really annoying drone from a internet bought muffler delete on a RAM truck. Sick sound tho. At 130hz and about 1800 revs at 100kph the engine would switch to eco mode (shuts down 4 cylinders) and literally vibrated the crap out of the vehicle. It was really easy to work out the frequency that was causing the issue as when the drone was at its worst 130Hz reached max amplitude and stayed constant rather than fluctuating. I used the calculations on your spreadsheet to work out 87cm was what I needed. Worked unbelievable.

Nice video! Thank you for taking the time to make video and for explaining how the drone sound can be eliminated.

I was looking at this as an option for my focus st with a Magnaflow exhaust, thanks for this great explanation!

Well done, sir. This has large applications in recording studios as well for similar reasons, to remove unwanted frequencies. Your explanation is much better described than many, if not all , of the other videos on the subject. The fundamentals of this are the same as used in pipe construction for pipe organs. But when you really want to get down to building an HR this video really shines for it's simplicity and details of measurements. Kudos.

Awesome video💯 you were great at explaining this issue. Now I understand this is the best way to cancel my drone and still get to enjoy my exhaust system. 👍🏾👍🏾

Would liked to have seen your spectroid graph with the piece installed and compared the graphs.

Holy crap i cant believe you did this. I've thought about doing this for so long and here the info is available to me thanks!

This was well done mate. I'm 56 and been messing with cars my whole life. This is a great explanation with both science theory and practical stuff relayed in a down-to-earth fashion. Top marks!

Thank you Alex for your spreadsheet, I fixed my done on my Acura MDX with Magnaflow mufflers,

Thank you for taking the time to make this video! A+ for you!

This is great! Thanks for taking the time to explain this, well done.

Well done! Great to see its effective even when you've rolled the pipe up!

Best video I've seen yet in regards to drone. The spreadsheet is perfect. Going to use this in the future

God i love it when nerds are car guys! Thank you for educating me on this. I just picked up a 23 passport and im looking forward to modding it.

Well done, all makes sense and easy to follow video....it’s a credit too you mate!

Very informative video ! I've been searching for a while this simple explanation and you dit it ! Many thanks !

lol..... I love how all the videos from 2020 are forever gonna have covid easter eggs.... I had to do a double take on the masks hanging from the rear view mirror for a second "wait... what??"

Here some answers to common questions I’ve seen. 1. I confirmed with some mechanical engineers that this modification should not affect air flow or back pressure at all. 2. While diameter of the pipe is not critical, I assume a larger diameter will create a greater cancellation effect. I used 1.5" OD vibrant tubing. 3. If you have a frequency range, make your calculation for the highest amplitude frequency measured in the app. 4. If your car has dual exhaust, (i.e. you calculate 36" for your V8 truck), you need to put 36" pipes on both sides of the exhaust.

Thanks for building the math tables, Sir. I was trying to work all this out several years ago via internet research and it was a dead end of lore and third party anecdotes. There's still some nuance and elbow room here in design, but you can at least get a good start an zero in on length with these tables.

Thank you for the detailed explanation AND the time stamps :)))

This is a great explanation, good job! I actually just did one of these for my Golf R, only I had room to do a straight pipe down the length of the car. So I cut the pipe and used a slightly smaller end pipe with a band clamp so I could experiment with different lengths. What I found is that these rough calculations can get you in the ball park, but after a bunch a trial and error I found certain lengths are far more effective over a broader range of frequencies, and it was not very close to what I had calculated. My car was droning a lot from 2800 to almost 4000 RPM (50-130 Hz) , there wasn't one particular frequency that really stood out. So with experimentation I found a length that worked best and gave the sound I preferred. I used the same spectrum analyzer app, it works okay but I did notice that in some cases my hearing perception did not always match what the app was showing me. So I used it, but ultimately went with what sounded best to my ear. In my application 41" to 42" seemed to work best.

Great video, very helpful and informative. Also, you can shift, also props for that lol.

Nice to see a young man using his head. Excellent. Taught me a lot.

Amazing video. I just bought Honda sx8 VTEC. I am going to make a custom full system exhaust. Usually, these 1.5 vtecs sound like a fart can exhaust. I'll use a stock resonator and this j pipe method to eliminate that fart can sound. Thank you so much.

Great video. Smart young man you are. I've got horrible resonance/droning on my car. Up on the lift, the y pipe is vibrating so hard. Moves like a .25 inch back and forth. It's a custom stainless setup I built. It sounds great, but the vibration noise that is heard from inside the car makes it sound as if its laying against the frame. It's not a hurt your ear drone, just annoying. Again, great vid bud. Good luck at honda.

OMG that sounds so much better‼ Now I need to do this to our supercharged 2.7L Tacoma. I may be back asking questions ⁉ Thanks So Much!

Nice explination your diagram and concepts were well done, thanks

THANK YOU!! I'm a mech. engineering student and I wanted to use proper math and science to eliminate the 2000 rpm drone on my Mustang. I feel so much more confident in designing a branch resonator now.

Bro your cars idling was shaking my entire room through my bass LMAOOOOO. Dope video dude you did it perfectly right I hope this gets a ton of view. Great explanation and good sound clips all backed up with science!

As a mechanical engineer, I couldn't leave without letting you know I am a mechanical engineer. Nice video by the way.

thanks for this, it will help me a lot in designing the exhaust muffler for my motorcycle

Perfect explain! Perfect video! Thank you very very much!

Thumb up! Finally there is someone who actually knows math to look at the problem.

Awesome video, glad others are interested in the acoustics of exhaust. Great explanation for a traveling wave (like 1 dimensional in a way). Here’s some thoughts I had, maybe someone could shed some light on them Many exhaust companies don’t add a long pipe, but a chamber. This is my initial guess on variation in diameter and it’s effects- If you look at the exhaust like pulses of a certain volume, you can probably create a relationship between diameter and length. The relationship would be linear in terms of volume, but to the second power in terms of pipe radius. I would also guess that a flat end really nails down one frequency, I wonder if a domed end would give a smoother curve to the frequencies you cancel out.

sick job mate ! my ears will thank you forever ! try this as soon as possible !

I'm glad someone did an actual video explaining this. My designs use larger rear chambers to shorten the length, but either way, this is the way to tune your exhaust drone. One more tip is that it's often cleaner in terms of the cancellation including harmonics to place the resonator closer to the engine.

Friggin fantastic! I appreciate all you did here.

Learned a lot very interesting thank you bro

Very well done Alex!

Well done. Thanks for the great information.

Thanks for the spreadsheet!

so nice, better then my school teachers, tks!!! you could add in the video, if you still have the car, the app working and showing the cancel of frequencies.

Amazing video, thank you for producing this.

Great video Alex..thank you!.. just one question.. can you share the before and after screenshots of the Spectroid.. I’d like to see the difference it made to the measured data. Thanks.

Best explanation. Thanks!

Great video and thank you for the scientific approach. This makes sense but does the diameter of the J pipe have an effect on sound. I have a length of pipe that is not the same diameter as my exhaust, would this still work? Thanks for any help.

Very well done. I had to replace my JeepWJ muffler and pipes, and with that went a little more aggressive which has produced the drone effect. I will be utilizing this method to address,. You stated this solution addressed 2000 -3000 RPM? So the length of the pipe will address droning in that 1000 RPM range?

Great stuff! I have a severe drone on my truck that i will try this on. My truck has 4" pipe... how important is pipe size for this fix? I was thinking of using 2.5" pipe but maybe that wouldn't be as effective??? Thanks Much for your hard work on this!

Nice video. Can you make measurement after you added your J pipe? Thx.

Awesome video! Thanks for the speadsheet and the explanation of how to calculate your own J-Pipe length. 👍🏻 Question... I see a lot of J-Pipes on the market that are a LOT shorter than yours, how is this possible? Thanks.

Bro this is awesome!

Awesome video man. Im still searching for someone to show me how to calculate an actual chamber vs. tubing. Some of us dont have room for TWO 34” pipes on a dual exhaust car! Lol again, propps on the video

Great explanation and video! How do I choose the diameter of the J Pipe, I've seen other guys using a slightly smaller diameter pipe than their exhaust.

Thanks for this video, I've been dealing with a drone at idle that carries through walls and indoors. Found it was worst at around 64hz and my exhaust temp seemed to be pretty cool compared to yours at a max of 114C (granted air was pretty cool, about -4C). According to your spreadsheet I should need about a 60" pipe. I'm gonna go talk to a muffler shop tomorrow. Fingers crossed.

Use your calculations and it's dead on. No more drone, I am loving it.

very nice job!

Amazing vid!

Great video !! So if I have room to add a straight pipe at a direct 90 to the exhaust that's better vs the actual "J" shape ?

Great video!! What’s the best place to install a j pipe on on an exhaust or does it matter where it’s placed ?

Very informative. Take my like!

Awesome video.

Awesome explanation! I kinda knew that it cancelled the sound out. But I wanted to make sure! I understood everything you said and I love the before and after of driving in the car, cold starts and warm starts! You covered it all! Now I just have to J-Pipe my 2005 Volvo XC90s custom quad pipe exhaust. Sounds MINT and mean. I just hate how much freakin drone it has. Its easily as bad as yours in the civic or worse! Its horrible

good work, I'd love to see the spectrum analysis afterwards

Sorry I missed how you calculated the diameter for the J pipe? Cheers, great vid!

Great video! 👍🏻

Sounds nice!

No spectrum analyzer comparison on final test drive, compared to first test drive?? With ear buds in, sounds almost identical in that rpm range. In my opinion. But the analyzer comparison would show the changes. Great video. Very cool!

just finished mine using this guidance and it works perfect !! just before the last muffler and completely eliminated a heavy drone measured at 110hz frequency, the question is , what happens if I make another 1/4 wave resonator to further clean up the tone. , upstream, lets say right after the cat to cancel out another frequency, around 175hz, would they shifted waves from the 1st one interfere with the other?

great video..

Hi Alex, hats off to you! Great video! Sub'd & Liked - trying to reduce freeway cruising drone on a straight pipe Ram 1500 ECODIESEL. Hope to use all of your knowledge, thank you again.

Good job. 😍.

Hey Alex, should the speed of sound be calculated for air or would speed of sound in CO2 be more accurate? And should the length be “straight section + 1/2*pi*(bend radius+1/2 pipe diameter”?

Very interesting, kind of led up to it to let me figure it out myself. Awesome! By the way, when sound bounces off a wall, doesn't that create a standing wave?

Nice explained, I am surpriced that the pipe needs to be so long

Exhaust sounds through KZfaq video are sus so really even with headphones the car sounded poor ,however your presentation of the information you facilitate was excellent. I’ll have to take your word on the sounds. Well done 👍

Great presentation. Thank you! Question: if the J pipe length calculation is 30 inches on a dual exhaust system, do you add two 30in J-pipes or two 15in J-pipes?

Thanks for sharing!

Hi. Thank you for this video. I have been looking for a solution to my catback drone problem for some time and I also didn't like the idea of replacing the mufflers. Finally I found something, that can be easily calculated, and then got here with your video, but I have a question for you. Does the spreadsheet work for a cars That have 2 exhaust pipes? Like most of V-engines? I have a V6 which is going with 2 independent pipes that got toogether in the last muffler. I am planing to mount resonator chambers just before the last muffler starts, so it means i should do 2 of them for each side of the engine and each pipe? Should I divide the lenght to 2?

Why attach to end and not at the mid pipe? Wouldn’t that allow for less bends in the piping ?

Like many have already said, wonderful job on this video. My degree is mechanical engineering and your explanations of the engineering and science involved were done at an ideal depth of explanation, perfect for those not having technical degrees and also informative for those that do. Well done. My question involves the Excel spreadsheet you used / developed for this project. In the video you stated you will post the link to the spreadsheet, but I've not been able to find the link. I'd much rather be lazy and use your spreadsheet than create one of my own! Is that link available? Thanks.

Awesome video, does the size of the piping matter?

Thanks Alex, just what I was looking for and exclent explanations. But one question, I see that some companies use an closed mufler on the J pipe. Is that to widen up the range of HZ or to shorten down the pipe lengh? Do you have any idea for that? and if, how to calculate that? I got a Volvo S60 2,5T 5cylinder with a 3" vibrant system, but the drone is quite noticable at 68-79HZ. When I have a solution on the J pipe I will come back with the info on the final design. But hope you have a comment on the mufler typed J pipe. BR John

Cool video. I can't help but commenting on thinking it was hilarious when you honked at that person and drove around them. Good stuff though, very helpful.

Needed this data to eliminate the drone in my AWE dual exhaust system. They say their resonators completely eliminate drone, but did not on my '18 Tacoma between 2k and 2500 rpms., even after 1,700 miles they said it needs to break in. My nephew is an audio engineer, so ran this by him and he agreed Alex is right on it. The AWE system is true duals all the way through, so must install two J-pipes. $$$$!!! Will post results after the modification done. Thank you, Alex, for an excellent video with good camera angles, audio, lighting, etc.

If my car has no stock mid resonators would you recommend adding some actual resonators before attempting to put a j pipe into the setup?

thanks so much for your effort of explaining this. I have a question however, does it not matter where in your exhaust you put the pipe? like wether you put it right before your muffler or after the headers? maybe that would change how long the pipe needs to be, so you can run a shorter one for weight and space reasons?

With a baffle cone at the end of the J Pipe, we must be able to increase the noise reduction range, right ? (Like a two stroke engine tuned pipe.)

Hello Alex, congrats of your detailed explanation of all maths behind the drone and J-pipe. I got one doubt about the J-pipe diameter. Does it need to be the same of the exhaust or could it be narrower?

Great video. I have a question that I'm pretty sure I know the answer too, but I want confirmation. If you have a true dual exhaust setup, you would need the J pipe on each side correct? I have a Porsche Boxster and the exhaust sides don't meet until the muffler.

Hi, how would u design a phase shifter to cancle out the lower resonance modes of living rooms, like between 20...120Hz..? Thx a Lot

Excellent video. I have a question: most illustrations show the J-pipe before the muffler. From what I have read, it seems like it does NOT matter if the J-pipe is before or after the muffler. Is that accurate? I do not have space for the J pipe until after the muffler, so that's why I am asking.

Thanks for the great video! I remember seeing somewhere that the lack of a solid surface at the opening of the heimholtz resonator would generate less friction for the air molecules near it, and would increase flow rate slightly - I am guessing that the reasoning behind this is similar to the fact that a golfball with a dimpled surface has less aerodynamic friction than a golfball with a smooth surface. Perhaps it is negligible, since there is only one opening for the heimholtz resonator in your case? What if there were multiple heimholtz resonators? Or better yet, what if the inside of the exhaust piping was dimpled? Would that affect flow rate then? Also, if the flow rate is increased un-uniformly (only at one side of the piping where it has the opening to the heimholtz resonator), then does it create turbulence within the flow past the heimholtz resonator opening? Or is it negligible again, since there's only 1 heimholtz resonator?