What did you do to your 4th gen. Legacy today? Vol - 10

I haven't driven it yet. This project has always been on my to-do but it's gone up the list since I installed the STI exhaust, I'm getting a loud highway drone now. The biggest investment is time as the weight of one Safe 'n Sound bale is approx. 40 lbs and I haven't even used 1/4 of it. One hundred sq. ft. roll of 1lb MLV is... 100 lbs, which I expect to have to go through by the time everything is done.

 

Sorry I haven't answered your question. From what I read on DIYMobileAudio forums, insulating the doors makes a significant difference. Too late for me to do a before and after decibel measurement but I can still do a midway through complete job comparison. I'm not confident sound deadening will sufficiently address the drone. I have a Toyota tuned mass damper waiting to be installed and I'm researching quarter-wave/J-pipes as well as your typical resonator.

Edited August 3, 2020 by Enlight

For drone, those J-pipes/Helmholtz resonators really work well if sized correctly.

 

On my WRX, I have it fully sound deadened, and it made the drone a more pleasing sound, but if measured by a db meter, I doubt it would register an amplitude difference. I did the doors, floor, trunk, and used roofing tar in the wheelwells. It made the car feel like a higher quality car, the doors close more solidly, the stereo sounds better, and the NVH changed to a more "solid" type of sound, versus the rattle-y, pingy sound Subarus usually exhibit. For that, it was worth it, but specifically for drone, a Helmholtz resonator is better for that.

Pics of the carnage?

 

These are just what i had on my phone. I will get some better ones tonight.

Edited August 3, 2020 by Oreellyfool
Add pics

It has the right diameter to be M12; and if I set my M10x1.0 tap on it, the threads line up; but I don't have an M12x1.0, nor can I find one locally. It's not a common size as far as I can tell, seems that usually 1.0 threads usually stop at M10. But M10 is too small and 1.25 threads are too coarse, so I'm fairly certain it's M12x1.0

 

I've tried to see if it might be a BSPT/BPT, but I can't find a size that aligns with the measurements I've taken. Kinda wish it was, would be easier to find an adapter I think.

 

 

Found this, https://www.speedwaymotors.com/Earls-AT9919BFEERL-Straight-Male-AN-4-to-12mm-x-1-0-Black,393698.html?sku=425AT9919BFEERL&msclkid=7a5c0104f7e8148acff55e2ca32d31f1&utm_source=bing&utm_medium=cpc&utm_campaign=SMI%20-%20Shopping%20(CSE)%20(Bing)&utm_term=4577129468977155&utm_content=All%20Products%20II%20(Feb28_2020)

 

May be that site might have what your looking for.

For drone' date=' those J-pipes/Helmholtz resonators really work well if sized correctly. [/quote']

 

Have you made a Helmholtz resonator before? I'm having trouble committing to welding a J-pipe because I'm not sure how much to trust the math I see online. They instruct us to measure the frequency we want cancel, but do we measure the frequency from the cabin or at the exhaust? Shouldn't we be measuring for the frequency inside the pipe where we plan on installing the J-pipe? I'm sure I'm over-complicating this, but seeing as there's little adjustment that can be done after installing I'd welcome an engineer clearing up any misunderstandings I have.

 

That being said, a company called Solo Performance includes adjustable J-pipes for their exhaust offerings and are also open to selling them separately, as reported on some domestic forums.

 

While doing research I also found that Lexus, Ford, and BMW use mass dampers to eliminate exhaust vibration. Of course these are tuned for their specific exhausts, but I was able to pick up a Lexus damper for $25 shipped on eBay and I can manipulate its placement along the exhaust to see if I can tune out drone. This solution is easier to make work within space restrictions. Lexus issued a service bulletin to install these dampers to address complaints RX400 owners had of drone.

 

 

 

[ame=http://www.youtube.com/watch?v=FPT9dPE4oRs]Using tuned mass dampers to reduce vibration - YouTube[/ame]

Edited August 3, 2020 by Enlight

No I haven't installed a Helmholtz resonator on an exhaust from scratch. My experience is on another car (Infiniti G37, which is known for being droney with aftermarket exhausts). I tried a few different exhausts, and while they sounded different depending on the mufflers used, they all droned in the same range. The drone was a car thing, the sound quality was unique to the exhaust brand. When I finally tried an exhaust with the Helmholtz resonators, it was perfect - all of the exhaust sound when you were on it, and none of the drone. Actually, it was really quiet when I wasn't heavy on the gas. Now, I understand that it's a different car, but the "Wookie howl" that the VQ is known for is about as droney as the EJ with an aftermarket exhaust. So, different car, but similar starting point, and similar objective.

 

Interestingly, the Infiniti's stock exhaust also has a few mass dampers welded to it. It might do *something*, but I've never played with mass dampers before. Just thinking about it, I would expect that mass dampers would affect a more narrow band of frequencies compared to a Helmholtz resonator. The theories behind them are that the mass damper changes the resonant frequency of the pipe (amplification device) so it doesn't create an additive effect of certain frequencies; the Helmholtz resonator creates an opposite wave that cancels out certain (low frequency) waves, effectively killing them. The reason why I would think the resonator would be more effective is because it manipulates the source of the sound, not the amplification device. And if you change the frequency response of the source, you would also be changing the levels of harmonics that are included in the other frequencies, so a cancellation wave to the source would cover more of the audible spectrum.

 

I am an audio engineer, so this theorizing is rooted in *some* form of real knowledge. But that said, I haven't seen any research on mass dampers on exhaust systems.

 

But keep us posted with how the mass dampers work out. We're all Subaru owners here, so it's safe to assume that we're all annoyed with the drone.

Left the Honda Accord at exwifes garage and have the subie this week since my daughter said take the Subaru daddy because the Honda is too quiet and slow. Gotta love when the 4 year old requests the fast car lol. Subaru it is! Smiles all week and EWG all week on E85 wheeee

 

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Have you made a Helmholtz resonator before? I'm having trouble committing to welding a J-pipe because I'm not sure how much to trust the math I see online. They instruct us to measure the frequency we want cancel, but do we measure the frequency from the cabin or at the exhaust?

 

The frequency you want is the frequency of the drone (pitch of the loudest part of the exhaust tone at the RPMs you're getting drone), it will be pretty much the same anywhere it's measured. Not sure how you'd actually measure this, though you'd probably be able to get close enough with just an audio recording.

I am an audio engineer, so this theorizing is rooted in *some* form of real knowledge. But that said, I haven't seen any research on mass dampers on exhaust systems.

 

But keep us posted with how the mass dampers work out. We're all Subaru owners here, so it's safe to assume that we're all annoyed with the drone.

 

Nice! Good to have a audio engineer in here. Everything you said about the Helmholtz Resonator makes sense. If I decide to go that route I will share my results, I'm surprised no one else has undertaken/shared yet. Do you think location of the resonator matters (upstream/downstream)?

 

The frequency you want is the frequency of the drone (pitch of the loudest part of the exhaust tone at the RPMs you're getting drone), it will be pretty much the same anywhere it's measured. Not sure how you'd actually measure this, though you'd probably be able to get close enough with just an audio recording.

 

I have an app called Vibration Isolator Pro that will measure the dB and frequencies of sound being emitted, others have had sufficient success without professional audio equipment. The frequency should be the same anywhere measured - got it. Thank you.

Nice! Good to have a audio engineer in here. Everything you said about the Helmholtz Resonator makes sense. If I decide to go that route I will share my results, I'm surprised no one else has undertaken/shared yet. Do you think location of the resonator matters (upstream/downstream)?

 

I have an app called Vibration Isolator Pro that will measure the dB and frequencies of sound being emitted, others have had sufficient success without professional audio equipment. The frequency should be the same anywhere measured - got it. Thank you.

 

Keep in mind, your exhaust tone is a spectrum, not just a single frequency. Look at a recording in the frequency spectrum and look at about what frequency the largest peak is where you're hearing your drone, that's the frequency you'll want to use for your resonator calculations.

It sounds like the augers that you buy amd insert into the midpipe work well but at a cost of decreased flow.

Weeeeelp wife needed a daily so we found her a beautiful OBXT with a knocking motor. Car ran so idea was to baby it to the shop since the motor's trashed anyways. Forgot that she's never driven an automatic with a manual mode, so it promptly got piss revved in 1st until the motor seized. Purdy, though

 

 

Nice ride

Did you say partout?

Yeah, just the motor's included in the partout though

Started getting a random front-end grinding noise. Sounds like it's the driver-side Timken bearing (passenger Timken went out a while back). I'm most surprised how suddenly the sound came on. Drove it in some rainy weather Saturday, parked it and drove it again Sunday without hearing a thing. Left for work Monday and could hear it right away above 5-10MPH. Gonna confirm it's the bearing and swap it out with a legit OEM I have laying around. These have gotten down to a 20 minute job for me at this point.

I installed my new headunit on my car yesterday, looks hella clean and fits a lot better than that Joying pos I had in there before and routed a usb cable to the center console for AndroidAuto or USB music. Also why did Subaru make it so difficult to change the cabin filter in our car? seems like too many things to remove for something that needs to be replaced frequently

Later model 4th gens have an access panel that easily removes behind the glove box. The early models required full removal of glove box and back panel. Upgrade to 2007+ trim behind the glove box and problem solved!

Good to know, thanks. I prolly wont swap the trim unless I get a crazy deal on it but damn annoying

Later model 4th gens have an access panel that easily removes behind the glove box. The early models required full removal of glove box and back panel. Upgrade to 2007+ trim behind the glove box and problem solved!

 

 

Well shit. Maybe I'll change mine then lol. I've been avoiding it cuz I kept hearing it was a nightmare but I've got an 08.

 

 

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Cabin filters get nasty.

Well shit. Maybe I'll change mine then lol. I've been avoiding it cuz I kept hearing it was a nightmare but I've got an 08.

 

 

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This made me laugh harder than it should. I, too, put mine off bc of how involved I understood it to be. Got around to it after 30K+ miles. Shame on me. Now I could do it in 10mins.

yes, I bought that fancy cabin filter from Rock Auto ---> Carbon Filter Particulate Filter; Activated Carbon, was only $10 but man was it a pain to change. My old filter was nasty and I could smell the air in the cabin kinda musty. If you havent changed it in a while, make sure you check the hamster wheel and to make sure nothing is living in there lol.

yes, I bought that fancy cabin filter from Rock Auto ---> Carbon Filter Particulate Filter; Activated Carbon, was only $10 but man was it a pain to change. My old filter was nasty and I could smell the air in the cabin kinda musty. If you havent changed it in a while, make sure you check the hamster wheel and to make sure nothing is living in there lol.

 

 

The biggest problem I have is that I have nearly no sense of smell. I forgot a clean work shirt the other day and pulled a dirty one out of my bag and made my lady check if it was OK to wear. I thought she was gonna gag.

 

Which means I just need to do it before my move lol. I'll add it to the list.

 

 

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FWIW, early 05's don't have the cabin filter. Thank God for that. The thing is uses anyways.

 

Every car I've owned before the 05 didn't have them. How did mankind survive without them.

 

They are useless. leave it out. When the weather is nice and your driving roll down the windows and let the fresh air in.

 

When at work or home on nice day's I leave the windows down or open a little so the fresh air blows through the car and dry's it out.

 

 

In fact, I just went out and opened all the windows in the 4 vehicles in the driveway. Let them air out after yesterdays storm Isaias.

 

We lost power at 4:49PM, the Generac generator has been running since then.

Edited August 5, 2020 by Max Capacity