So I finally got off the fence about upgrading my stock exhaust - thanks Chuck and Jon B. for all your help with it!
Of course being an audio geek I "needed" to record, measure, and assess the difference between stock and Corsa Track 3" in terms of sound levels.
First, the setup:
3 mics fed through a PreSonus DigiMAX LT into an Alesis HD24 @48khz/24bit.
All recording levels set during "sound check" with stock exhaust and left exactly the same for the later Corsa recording.
...I thought I left enough of a cushion for the increased volume on the Corsa, turns out I still clipped the recording deck on WOT with the Corsa, so those sound clips sound like fuzz, but the recording is measurable at everything below WOT.
The mini rack on the garage floor:
Mics
Rode NT1-A placed on shockmount 3' from the ground, 5' away from the right-rear wheel, capsule parallel to the ground.
Matched Pair of Earthworks QTC-30s on stand in passenger seat, spaced slightly wider than human ears
Results:
I will follow with the audio clips as soon as I come up with a good way to share them... Might just mean cutting together a video - In the meantime here's some hard data:
The Corsa is certainly putting out a higher SPL at every RPM, from idle through redline, but in many cases it doesn't feel like it's that much louder. The Corsa kicks out a HUGE jump in frequencies below 50hz, even as low as 20hz (which is the fq at which we no longer "hear" it, just feel it). At 31hz for example the Corsa kicks out almost 20 db more than stock at idle. The increase in low frequency pushed the recording level up by almost 10 db overall, but in some fq ranges the difference is much less pronounced. For example at 100 and 200 hz the db level is almost exactly the same for Corsa or Stock. Sound in that mid-bass range around 200 hz is far more intrusive than a nice 30hz rumble, so parity between Corsa and Stock at those fqs is a big plus, and helps explain why the car doesn't seem that much louder. As for the tone "quality" I love it! (of course that's subjective but worth mentioning, more growl/bite from the Corsa makes
)
Here's a spectral analysis of the sound, Viper at idle, from the mic positioned outside
STOCK GEN III EXHAUST - outside mic
CORSA TRACK 3" CAT-BACK (stock headers and cats) - outside mic
And here's the spectral analysis at idle, mics positioned inside passenger seat, in this case with top and windows open - when I get the closed up clips matched and exported I'll post those graphs as well.
STOCK GEN III EXHAUST - inside passenger seat mics
CORSA TRACK 3" CAT-BACK (stock headers and cats) - inside passenger seat mics
Before jumping in, I also watched this vid from the SoCal Club, which is excellent and covers some different territory - http://forums.viperclub.org/srt10-s...video-viper-dyno-day-exhaust-sound-tests.html
Of course being an audio geek I "needed" to record, measure, and assess the difference between stock and Corsa Track 3" in terms of sound levels.
First, the setup:
3 mics fed through a PreSonus DigiMAX LT into an Alesis HD24 @48khz/24bit.
All recording levels set during "sound check" with stock exhaust and left exactly the same for the later Corsa recording.
...I thought I left enough of a cushion for the increased volume on the Corsa, turns out I still clipped the recording deck on WOT with the Corsa, so those sound clips sound like fuzz, but the recording is measurable at everything below WOT.
The mini rack on the garage floor:
You must be registered for see images attach
Mics
Rode NT1-A placed on shockmount 3' from the ground, 5' away from the right-rear wheel, capsule parallel to the ground.
You must be registered for see images attach
Matched Pair of Earthworks QTC-30s on stand in passenger seat, spaced slightly wider than human ears
You must be registered for see images attach
You must be registered for see images attach
Results:
I will follow with the audio clips as soon as I come up with a good way to share them... Might just mean cutting together a video - In the meantime here's some hard data:
The Corsa is certainly putting out a higher SPL at every RPM, from idle through redline, but in many cases it doesn't feel like it's that much louder. The Corsa kicks out a HUGE jump in frequencies below 50hz, even as low as 20hz (which is the fq at which we no longer "hear" it, just feel it). At 31hz for example the Corsa kicks out almost 20 db more than stock at idle. The increase in low frequency pushed the recording level up by almost 10 db overall, but in some fq ranges the difference is much less pronounced. For example at 100 and 200 hz the db level is almost exactly the same for Corsa or Stock. Sound in that mid-bass range around 200 hz is far more intrusive than a nice 30hz rumble, so parity between Corsa and Stock at those fqs is a big plus, and helps explain why the car doesn't seem that much louder. As for the tone "quality" I love it! (of course that's subjective but worth mentioning, more growl/bite from the Corsa makes
)Here's a spectral analysis of the sound, Viper at idle, from the mic positioned outside
STOCK GEN III EXHAUST - outside mic
You must be registered for see images attach
CORSA TRACK 3" CAT-BACK (stock headers and cats) - outside mic
You must be registered for see images attach
And here's the spectral analysis at idle, mics positioned inside passenger seat, in this case with top and windows open - when I get the closed up clips matched and exported I'll post those graphs as well.
STOCK GEN III EXHAUST - inside passenger seat mics
You must be registered for see images attach
CORSA TRACK 3" CAT-BACK (stock headers and cats) - inside passenger seat mics
You must be registered for see images attach
Before jumping in, I also watched this vid from the SoCal Club, which is excellent and covers some different territory - http://forums.viperclub.org/srt10-s...video-viper-dyno-day-exhaust-sound-tests.html
.
That's awesome! Thanks so much for doing this. As a fellow audio geek also looking into an exhaust upgrade, I really appreciate the time you took to do this. Good man! 
