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> OFFICIAL AMP SOUND LIMIT EXPLANATION, To End All The Misinformation
Littlezeke77
post Dec 23 2016, 08:14 PM
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Hello All,

I apologize, I have been away from the forums for the last 2 months, and it appears my official information has been missed biggrin.gif . As the outgoing Site Liaison (thanks Jim Boller for taking over my 3rd SC position!) whom just spoke with our AMP General Manager today, I can give you all the OFFICIAL AMP Sound Policy. So here it is:

In order to run on either the AMP Road Course or the Driving Pad, and to get your little AMP sticker, your car must run an AMP sound check and be under 96db (yes, it used to be 94db until recently). The County Sound Limit for the Driving Pad (where we run our autocrosses) is still 92db. If your car breaks the county limit of 92db while racing, then unfortunately we, SCCA AZ Solo, must end your day, no if's and's or but's. I will not get into our contractual agreement with AMP regarding the amount of sound violations we get per event, or the fines we must pay. All that matters is that you all know that 92db is still the magic number, and if the County Meter flags you for going above 92db while you're racing on the Driving Pad, then your day is unfortunately done. I do believe this should clarify everything and end all misinformation.

(All Measurements are "A-Weighted", dbA, Fast Response)


--------------------
Derek Bellamy
Assistant Director & Treasurer
1992 "Bass Boat Sparkly Red" Miata (STS)
2005 Scion tC (STF)
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Evo James
post Dec 27 2016, 07:00 PM
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QUOTE (Littlezeke77 @ Dec 23 2016, 09:14 PM) *
Hello All,

I apologize, I have been away from the forums for the last 2 months, and it appears my official information has been missed biggrin.gif . As the outgoing Site Liaison (thanks Jim Boller for taking over my 3rd SC position!) whom just spoke with our AMP General Manager today, I can give you all the OFFICIAL AMP Sound Policy. So here it is:

In order to run on either the AMP Road Course or the Driving Pad, and to get your little AMP sticker, your car must run an AMP sound check and be under 96db (yes, it used to be 94db until recently). The County Sound Limit for the Driving Pad (where we run our autocrosses) is still 92db. If your car breaks the county limit of 92db while racing, then unfortunately we, SCCA AZ Solo, must end your day, no if's and's or but's. I will not get into our contractual agreement with AMP regarding the amount of sound violations we get per event, or the fines we must pay. All that matters is that you all know that 92db is still the magic number, and if the County Meter flags you for going above 92db while you're racing on the Driving Pad, then your day is unfortunately done. I do believe this should clarify everything and end all misinformation.



What if you pass the 96 limit but don't pass the 92 limit? Do you still get a refund for the day? You would never know if you will pass on the pad until you try it.


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James Hodges
2008 Evo X
2014 Camaro Z/28
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renfield90
post Dec 27 2016, 08:01 PM
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No repair attempts?

No hopping into someone else's car?

Policy for repeat offenders or if AZ Solo has too many violations?


--------------------
Manfred Reysser
2001 Celica GT - gone to the clearing at the end of the path
2013 FR-S

"As long as my car goes I drive it. I like racing to the limit, first and last." - Gilles Villeneuve
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hatrick6
post Dec 28 2016, 10:47 AM
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QUOTE (Evo James @ Dec 27 2016, 07:00 PM) *
What if you pass the 96 limit but don't pass the 92 limit? Do you still get a refund for the day? You would never know if you will pass on the pad until you try it.


Derek will correct me if I am wrong here, but the 96db limit is done at 50ft, while the 92db limit is done at 150ft. The super powers that work more with physics than I do have deem that 96db@50ft approx. ='s 92db at 150ft

QUOTE (renfield90 @ Dec 27 2016, 08:01 PM) *
No repair attempts?

No hopping into someone else's car?

Policy for repeat offenders or if AZ Solo has too many violations?


repair attempt's no, as we cannot have that car blow a 2nd violation on that same day, but yes you can hop in another competitor's car for the day We have to end the CAR's day, not the driver.


--------------------
"Maybe I should just buy a 240 and become a mad tyte drifter." - Hitler
Josh Johnston
AZ Region Director
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renfield90
post Dec 28 2016, 11:21 AM
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Another question: the first time or two we ran at AMP with the sound restrictions, we had our own sound meter set up earlier in the course to catch loud people and red flag them before they got near the county meter. Is that something we could start doing again that could help?

Another thought: why not test everyone at 92, and make the exclusion area smaller? As it is 150ft is kinda big, but doesn't take into account the additional buffer a course design must account for (i.e. the course should avoid giving drivers the opportunity to go WOT with their exhaust pointed at the meter, the course should avoid maneuvers near the exclusion area that could cause a car to spin into there, etc.).


--------------------
Manfred Reysser
2001 Celica GT - gone to the clearing at the end of the path
2013 FR-S

"As long as my car goes I drive it. I like racing to the limit, first and last." - Gilles Villeneuve
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SEymann
post Dec 28 2016, 03:00 PM
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QUOTE (renfield90 @ Dec 28 2016, 11:21 AM) *
Another thought: why not test everyone at 92, and make the exclusion area smaller?


It was AMP's choice to not have 2 testing standards. Up to us to do what is necessary to maintain 92dB on the pad.


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Steve Eymann
Turning money into noise
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SMeyers
post Dec 28 2016, 04:17 PM
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QUOTE (renfield90 @ Dec 28 2016, 11:21 AM) *
Another question: the first time or two we ran at AMP with the sound restrictions, we had our own sound meter set up earlier in the course to catch loud people and red flag them before they got near the county meter. Is that something we could start doing again that could help?

Why do we not do this anymore? I know that doing so may or may not catch a problem early, as some noises are "activity specific", but it might help.

Or, did it prove ineffective in practice?


--------------------
Scott Meyers
2006 Mazda3S "STS" .......(Really just a Miata with four doors and a trunk......)
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dysmike
post Dec 28 2016, 04:31 PM
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QUOTE (renfield90 @ Dec 28 2016, 11:21 AM) *
(i.e. the course should avoid giving drivers the opportunity to go WOT with their exhaust pointed at the meter, the course should avoid maneuvers near the exclusion area that could cause a car to spin into there, etc.).


Yea, I figured it was tires as well as exhaust.


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mike stenson
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Jim Boller
post Dec 28 2016, 06:34 PM
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I think I said something before on this but a spin/ tires is what made us blow sound the last time we did. Luckily it wasn't a big deal but most course set up' are off camber in the area of the meter and even seasoned people spin there. Not sure what the answer is but wanted to throw that out.


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Jim Boller
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Wicked991
post Dec 28 2016, 06:36 PM
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QUOTE (SMeyers @ Dec 28 2016, 04:17 PM) *
QUOTE (renfield90 @ Dec 28 2016, 11:21 AM) *
Another question: the first time or two we ran at AMP with the sound restrictions, we had our own sound meter set up earlier in the course to catch loud people and red flag them before they got near the county meter. Is that something we could start doing again that could help?

Why do we not do this anymore? I know that doing so may or may not catch a problem early, as some noises are "activity specific", but it might help.

Or, did it prove ineffective in practice?


my recollection is that in practice we were red flagging cars that were not tripping the county meter. Not aware that the exclusion zone is causing any significant course design constraints. Also appreciate that AMP raised the sticker db point to 96 db in part on the assumption that car clubs would continue to respect the current exclusion zone.


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Kim Kemper
Dark Side Racing
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Littlezeke77
post Jan 3 2017, 03:55 AM
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QUOTE (renfield90 @ Dec 28 2016, 11:21 AM) *
Another question: the first time or two we ran at AMP with the sound restrictions, we had our own sound meter set up earlier in the course to catch loud people and red flag them before they got near the county meter. Is that something we could start doing again that could help?


We found it caused more problems than it was worth. We needed an extra worker position, that worker position location needed to be before the car reached the county meter AND be at a location where the car was close to WOT for max db's. We were also slightly leery about someone needing to be staring down at a sound meter, instead of head up on a swivel while cars were on track. In the end, we wound up having more false alarms than anything else, which in turn caused a whole bunch of pointless red flags as well.

QUOTE (renfield90 @ Dec 28 2016, 11:21 AM) *
Another thought: why not test everyone at 92, and make the exclusion area smaller? As it is 150ft is kinda big, but doesn't take into account the additional buffer a course design must account for (i.e. the course should avoid giving drivers the opportunity to go WOT with their exhaust pointed at the meter, the course should avoid maneuvers near the exclusion area that could cause a car to spin into there, etc.).


IIRC the 150ft exclusion zone is more so what AMP likes to keep on the Driving Pad at all times regardless. It's just another layer of protection to try to not ping the county meter. As Josh mentioned above, AMP feels that roughly 96db@50ft = 92db@150ft. But yes, you're correct in the sense that it can be a pain to work around when it comes to the course design. Fortunately, Dave Hurt the new Chief Course Designer is very familiar with the challenges of working around it.

In the end, we have only blown the County Meter a handful of times in the 21 events we've had there since 2013, so our current procedures are obviously working just fine. In general, racing sites are becoming harder and harder to come by. Since AMP loves us, and we want to keep them and the county happy, we're going to continue to do what they ask of us, and what has worked in the past.

As I mentioned before, all that matters is that you all know that 92db is still the magic number, and if the County Meter flags you for going above 92db while you're racing on the Driving Pad, then your day is unfortunately done.


--------------------
Derek Bellamy
Assistant Director & Treasurer
1992 "Bass Boat Sparkly Red" Miata (STS)
2005 Scion tC (STF)
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renfield90
post Jan 3 2017, 09:30 AM
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I guess as long as AMP is happy, we're fine. I just worry a bit given this is our only site.


--------------------
Manfred Reysser
2001 Celica GT - gone to the clearing at the end of the path
2013 FR-S

"As long as my car goes I drive it. I like racing to the limit, first and last." - Gilles Villeneuve
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Chuckster
post Jan 3 2017, 04:15 PM
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The equation for comparing sound levels in dB at different distances is 20 log (D1/D2) where D1 is one distance and D2 is the other.
20log(150/50)=9.54 dB difference.

That means that to meet a 92 dB maximum at 150 ft, one must be at or below 101.54 dB at 50 ft.

Someone may have used the incorrect formula 10log (D1/D2).
The reason that it is really 20log and not 10log is that sound level varies as an inverse square law response.
This is an extremely common mistake that people make with both sound and radio signals.

Here is a site with nice graphics and an online calculator.
http://hyperphysics.phy-astr.gsu.edu/hbase...ic/isprob2.html
Start with entering 101.54 dB and then plug in these numbers for meters 15.24 and 45.72 to get 50 and 150 ft. for the distances.
The resulting lower sound level at the second (greater) distance (150 ft.) will be 92 dB.

Now, if someone has determined that they wish to add a safety margin for errors in measurement or other variables, that is another matter.
3 dB margin would mean that people must be at or below 98.54 dB at 50 ft. to meet 92 dB at 150 ft.
6 dB margin would mean testing for 95.54 dB at 50 ft.

-Chuck


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SEymann
post Jan 4 2017, 07:27 AM
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While Chuck is right on the calculation, the 150' was more empirically derived. When the official test is done, the meter is 50' from the side of the car. As the car gets farther away, the exhaust is pointed more directly at the meter, but the distance overcomes it. On the skidpad, depending on the course, it would be easier to have a course where the exhaust is pointed more directly at the meter. We came up with 100', but decided to add an extra 50' just in case. This has turned out to be a correct decision as tire noise from a skidding car (which is not tested) has been more of a problem than exhaust noise.


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Steve Eymann
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Littlezeke77
post Jan 7 2017, 03:35 AM
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Added (All Measurements are "A-Weighted", dbA, Fast Response) to the original post for clarity sake...


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Derek Bellamy
Assistant Director & Treasurer
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Chuckster
post Jan 7 2017, 12:12 PM
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Steve, to protect AMP best, perhaps you should not be so strict on exhaust and possibly make some correction there, but now add the apparently more critical test by skidding the car.

There is a saying on conservatism: There's the 'ol belt plus suspenders backup, but you are totally going overboard if you add rubber underwear too.

Then again, 'ol farts like me may actually need the rubber underwear more than the suspenders. rolleyes.gif


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kvenisn
post Jan 7 2017, 02:38 PM
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By my count, we have had 3 or 4 incidents of tripping the AMP sound limit on the skidpad. Two were due to tire noise and 1 (or 2) were due to a backfire. AMP track management has been more then fair with us during these incidents and I am confident we have a excellent system in place to protect both our ability to run at AMP and AMP's ability to continue to hold events. In addition, we work very closely with AMP on this issue and are quick to make any needed adjustments and to maintain AMP's confidence in us and out system.

I do not want to delve into specifics here on the forum but would be happy to discuss any thoughts or concerns with anyone in person at the event tomorrow.



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Kevin Venisnik
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EricSS
post Jan 7 2017, 05:51 PM
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What are the chances of the 2016 Camaro SS with the dual mode exhaust passing sound limited on track mode? Or will I have to drive it in stealth mode? Thanks.


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Eric Swannie
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EricSS
post Jan 8 2017, 04:51 PM
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In answer to my question above, yes, the Gen 6 Camaro SS did Pass AMP sound limits with the dual mode exhaust in track mode. 👍🏼


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Eric Swannie
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Evo James
post Jan 8 2017, 05:48 PM
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QUOTE (EricSS @ Jan 8 2017, 05:51 PM) *
In answer to my question above, yes, the Gen 6 Camaro SS did Pass AMP sound limits with the dual mode exhaust in track mode. 👍🏼


Eric, it was nice meeting you today and glad you didn;t have sound tech issues. I look forward to seeing the SS out there next.
James


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