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Old 12-16-2004, 07:55 AM   #51
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Cut the guy some slack Adrian. While engineering terms are engineering terms, 10dB higher or lower is twice as loud or quieter to the human ear. Don't get me started on what a 250dB active sonar transmission does to whales.
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Old 12-16-2004, 08:06 AM   #52
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Quote:
Originally Posted by Unabomber
Don't get me started on what a 250dB active sonar transmission does to whales.
Awwww. That'd be really cool to hear about too.

I was just giving you guys a hard time anyway. Never take things too seriously! Aaaalways look on the bright side of life ... da na, da na da na da na ...
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Old 12-16-2004, 05:39 PM   #53
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http://hyperphysics.phy-astr.gsu.edu...und/db.html#c1

"Another consideration which prompts the use of powers of 10 for sound measurement is the rule of thumb for loudness: it takes about 10 times the intensity to sound twice as loud."

So there...
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Old 12-16-2004, 05:46 PM   #54
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Quote:
Originally Posted by LotusDrift
Sounds like a good test.




my next liscence plate is going to own *snickers*


Wow. My exhaust was up there at the 3krpm point! W00t W00t. Now, who wants to pay my exhaust ticket???

Last edited by D_Block; 12-16-2004 at 05:52 PM.
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Old 12-16-2004, 05:47 PM   #55
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Touche! I sense an e-dork fight ruining this thread.
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Old 12-16-2004, 06:29 PM   #56
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Quote:
Originally Posted by GravelRash
One note that I remember from some C&D(?) sound testing a few years back: the background for your "sound stage" can make a huge difference in the readings. E.g., car sitting on dirt with an open grassy field behind it would produce much lower readings than having the car sitting on concrete, in front of a concrete wall.
this is true, I would assume he is testing on asphalt or concrete (shouldn't make a difference) with no other cars/people, walls, etc in the immediate area. the lower the frequency tested the greater these distances need to be.
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Old 12-16-2004, 06:30 PM   #57
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I will run my own test tomorrow when i finally go from stock exhaust to an APS 3" catless TBE and vishnu up.
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Old 12-22-2004, 04:58 PM   #58
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Quote:
Originally Posted by Unabomber
Testing policy:
a. All measurement are and will be taken with an Exetech digital dB meter with an accuracy of plus or minus 2db using the same settings at the same distance.
b. All idle measurements are taken at warm idle, NOT cold (higher RPM) idle, and then 3000RPM.
c. All measurements are taken 6" from the tailpipe.
d. All measurements are averaged, not peak high or peak low as the exhaust dB can vary 5-10dB due to the boxer motor characteristics.
Ever consider doing the testing in a truly STANDARD fashion, such as the procedure laid out by the Society of Automotive Engineers in their spec for automotive exhaust noise testing?

SAE J1169

I'm surprised that you didn't search before you started doing this.
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Old 12-22-2004, 05:40 PM   #59
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I thought about it, but since my meter doesn't comply with ANS S1.4-1971 standards, there wouldn't be point would there? Aside from that nonesense, I correlated my data to match the results that Turbo Magazine got with their testing so that I could have more exhaust data.

If you are trying to view the data over the next day or three, my host got borked due a ton of people downloading a certain WRX video. I hope everything minus the video will be back online very soon.

Last edited by Unabomber; 12-22-2004 at 05:46 PM.
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Old 12-22-2004, 05:48 PM   #60
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Just a point of clarification relating to the "NOTES" section d. "3bB is equal to twice the loudness, so an exhaust at idle with 93dB is twice as loud as an exhaust at 90dB."

In point of fact, an increase of 10dB is required to obtain a "perceived" doubling of loudness. Much of this misconception has occured due to the fact the the energy required to increase the sound level will need to double for every 3dB increase. This holds true from approximately 40hz on up through the range of human hearing. As frequencies decrease, less energy is required to obtain a "perceived" doubling of loudness.
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Old 01-02-2005, 08:13 PM   #61
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Bump for two new exhausts. I did a CES full TBE on an STi and just a Greddy catback on an 05 WRX.
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Old 01-16-2005, 09:09 PM   #62
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Added another Prodrive and Blitz dB tests to the spreadsheet.
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Old 01-17-2005, 12:55 AM   #63
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will this be sticky or will it take 10 years like everything else?
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Old 01-17-2005, 01:03 AM   #64
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It's referenced in my Exhaust FAQ. Since I'm a mod now, I can sticky it. I probably will later on down the road when I refurb the 2.0 stickys.
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Old 01-17-2005, 02:07 AM   #65
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Quote:
Originally Posted by Unabomber
It's referenced in my Exhaust FAQ. Since I'm a mod now, I can sticky it. I probably will later on down the road when I refurb the 2.0 stickys.
you are hardcore. you have helped the masses, may god have a special place in heaven for you.
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Old 02-06-2005, 09:54 AM   #66
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Another update with 8 exhausts/cars tested. I got to test a Borla Hush finally. Still not as quiet as my Prodrive.
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Old 03-01-2005, 03:19 PM   #67
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Pardon me for asking, but I'm trying to make sense of the results.

There are two listings for the the Greddy Evo catback with everything else stock.

Line 16: 2002 WRX: idle 94, 3000rpm 92.
Line 52: 2005 WRX: idle 94, 3000rpm 102!!

Did something big change from 2002 to 2005 or is this a mistake???

Otherwise very useful info.

Anyone care to guess what a Helix UP, Bosal DP and Bosal ST Catback would rate on there? I'm looking for something that isn't as noisey @3000rpm as my current setup.
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Old 03-01-2005, 09:59 PM   #68
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BTW, what is with the shipping & handling charge on the PayPal donation link? Am I going to be sent something?
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Old 03-01-2005, 10:14 PM   #69
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As to the Greddy ECO test, I cannot say. I assume the #16 one was brand spanking new. The #52 one was a used one. I'd hypothesize that the older an exhaust is, the worse it gets in quieting sound.

As to the paypal link, I don't send anything and don't know why it has S&H charges. Perhaps I was drinking when I filled it out. Send if you want, but so far, I've made a whopping $1. I only put up the link as a joke mainly.
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Old 03-01-2005, 10:20 PM   #70
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any chance of getting some data on Perrin exhaust? i've got catback right now on my 04 wrx, be happy to help you out if u ever in san diego area
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Old 03-02-2005, 02:20 AM   #71
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Quote:
Originally Posted by Unabomber
As to the Greddy ECO test, I cannot say. I assume the #16 one was brand spanking new. The #52 one was a used one. I'd hypothesize that the older an exhaust is, the worse it gets in quieting sound.
Gets coated with carbon. My friends and I regularly wash our mufflers inside. I know I know ... corrosion. But what's the point in even having it if it doesn't muffle?

Here are two other concepts straight out of "The Scientific Design of Exhaust and Intake Systems" that might help you reach muffling goals:

1: Tri-Y headers, the technical name for which is "interference" headers, have a SIGNIFICANT muffling effect. The GP-Moto headers make a Stage II WRX with Stromung catback almost as quiet as a stock STi!

2: A "muffler to nowhere", which is a resonator pipe attached in parrallel to your exhaust which has no outlet can actually muffle sound significantly! Some mufflers for Rotary engines have them built into the muffler.

Just food for thought!

Adrian~
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Old 03-02-2005, 11:54 AM   #72
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As per Paypal:
Item Amount:
$1.00 USD
Shipping:
$0.04 USD
Handling:
$0.00 USD
Quantity:
1
Item Title:
Helpin' a brother pay for his meter
Date:
Mar. 1, 2005
Time:
18:57:23 PST
Status:
Completed

And then they take $0.30 out of that for themselves.

Well, here is another drop in the bucket. Maybe if you make a covert trip up to NoVa, Darrin and I can get a chance to talk to you and play with the DB meeter (I'll make sure he chips in some as well).
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Old 03-20-2005, 07:16 PM   #73
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Added 3 more entries from testing today in San Diego, an APS, a Helix, and a Stromung.
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Old 03-20-2005, 11:29 PM   #74
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Hey Ron -
In your exhaust testing travels, did you ever take note of which muffler sections are straight -through and which are chambered?
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Old 03-21-2005, 12:13 AM   #75
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Quote:
Originally Posted by Unabomber
Cut the guy some slack Adrian. While engineering terms are engineering terms, 10dB higher or lower is twice as loud or quieter to the human ear. Don't get me started on what a 250dB active sonar transmission does to whales.
actually 6 dB spl is twice as loud.
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