Soarer Central: Archive through November 09, 2006

Soarer Central General Soarer Chat Apex Exhaust Valve Controller Archive through November 09, 2006

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Andrew Nguyen
Tinkerer
Vic
Find out next year

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Wednesday, November 08, 2006 - 02:53 am, by: Andrew Nguyen (Nuggz)

just wondering if anyone has tried one of these

http://cgi.ebay.com.au/Apex-Exhaust-Valve-Controller-ECV-on-and-off-yourself_W0QQitemZ130025198735QQ ihZ003QQcategoryZ32624QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

it say's it lowers the sound by a max of 10dB
which isn't much for $350 odd

just wondering if anyone has had any experience with it

Sean Fair
Tinkerer
Alberta
GTT-L

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Wednesday, November 08, 2006 - 04:11 am, by: Sean Fair (Sean_fair)

Well, considering a 10 dB reduction works out to halving the sound pressure level, then I think that's a good reduction

Scott Ferguson
TryHard
Alberta
Soarer GTT-L

Posts: 304
Reg: 07-2006

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Wednesday, November 08, 2006 - 04:24 am, by: Scott Ferguson (Scott_ferguson)

Similar product taken in a different direction

http://www.quicktimeperformance.com/QTEC/

The Apexi works by increasing or decreasing flow through the exhaust system. The QTEC uses a Y-Pipe to allow for a straight pipe exhaust. Or else close to make the exhaust flow through the exhaust system.

I'll be putting mine in sometime soon. I hope.

Lars Olsson
TryHard
NSW
30 V8

Posts: 158
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Wednesday, November 08, 2006 - 10:37 am, by: Lars Olsson (Lars)

Wouldnt you have to reset the ecu every time you open of close the valve. As mentioned by others ( had the same with mine)when you replace the standard system for a more free flowing one the car feels gutless untill you reset. Please note this is just a question and not a statement

Maurice Diggler
TryHard
Victoria
Twin Turbo

Posts: 482
Reg: 06-2006

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Wednesday, November 08, 2006 - 05:03 pm, by: Maurice Diggler (Mau_rice)

Lars, it depends why you want this installed on your car.

For me, it would be just for booze buses or 'Random' breath tests. The cop lights flash, and you car goes back to being quiet. Then hit it back to normal when they send you on your way.

Adam Barry
DieHard
WA
UZZ30

Posts: 514
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Thursday, November 09, 2006 - 02:03 pm, by: Adam Barry (Acdchook)

Andrew Nguyen wrote on Wednesday, November 08, 2006 - 02:53 am:
it say's it lowers the sound by a max of 10dB
which isn't much for $350 odd

An increase of 3dB is roughly 2x sound intensity. So a decrease of 10dB means you'd be less than 1/8th as loud. That's pretty quiet.

Peter Nitschke
JunkFilterer
South Australia
GT4.0 V8

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Thursday, November 09, 2006 - 03:43 pm, by: Peter Nitschke (Pen)

Wrong. A rise of 10 dB in sound level corresponds approximately to a doubling of subjective loudness. That is, a sound of 85 dB is twice as loud as a sound of 75 dB which is twice as loud as a sound of 65 dB and so on. That is, the sound of 85 dB is 400% times the loudness of a sound of 65 dB.

However, to achieve an increase of 3dB in an audio system, requires a doubling of input power. To achieve a doubling of perceived level in an audio system (10dB), requires 10x as much input power. So you need 100watts to be twice as loud as 10watts assuming all else to be equal.

Adam Barry
DieHard
WA
UZZ30

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Thursday, November 09, 2006 - 04:38 pm, by: Adam Barry (Acdchook)

Well mathematically, 3dB is roughly a doubling in intensity, as in if a sound source is producing twice as much sound energy, the dB measured at a given point should increase by 3.

Peter Nitschke
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South Australia
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Thursday, November 09, 2006 - 04:48 pm, by: Peter Nitschke (Pen)

Perhaps it might if you could concentrate the sound into a single coherent beam such as a laser, but in the real world it doesn't work that way.

Simon Triantafillou
DieHard
NSW
Soarer Turbo

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Thursday, November 09, 2006 - 05:00 pm, by: Simon Triantafillou (Soarer)

I have one of these valves. Measured the difference opened and closed with RTA approved hardware and within regulation limits (engine at certain rpm, testing device at certain distance and angle).

It decreased my noise levels by 11dB, so the product works exactly as specified.

Peter Nitschke
JunkFilterer
South Australia
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Thursday, November 09, 2006 - 05:06 pm, by: Peter Nitschke (Pen)

How much difference did you hear?

About 1/2 the original volume or about 1/8th?

Rehan Bandara
Tinkerer
NSW
TT

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Thursday, November 09, 2006 - 05:27 pm, by: Rehan Bandara (Parsec)

10db is quite a bit more than doubling the intensity.

there is a bit of confusion of terminology here, so i'm going to attempt to clear it up. all logs referred to are base 10.

sound power level is defined as 10log(r) where r is the ratio of some quantity that defines the "loudness" of the sound.

If this quantity is power, then the ratio is simple, its the sound power divided by a reference sound power (usually 10^-12W)

similarly, if the quantity is intensity, because sound power is proportional to intensity, the ratio is the intensity divided by a reference intensity.

now, if we talk of sound pressure level, the sound power level is proportional to the square of the SPL, divided by the square of a reference SPL. Going back to some simple highschool maths, logm^p = plogm

so if you substitute this into the 10log(r) relation, you get 20log(r). this is where the 6db comes from.

so, in conclusion, a doubling of sound pressure level results in a sound power level increase of 6dB. A doubling in intensity or sound power results in a sound power increase of 3dB.

This ebay sale is ambiguous, as it says it reduces the "loudness" by 10dB. I think it's pretty safe to assume that this is some sort of linear power descriptor though.

so the definitive answer is, a decrease of 10dB is equivalent to a 10 fold reduction in sound power (1/10th), as peter previously mentioned.

Rehan Bandara
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NSW
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Thursday, November 09, 2006 - 05:31 pm, by: Rehan Bandara (Parsec)

if anyone wants more info, i'm happy to provide it. that was the abridged version.

i forgot to mention that sound power level, sound pressure level and intensity are three distinctly different descriptors of sound, hence the confusion.

Adam Barry
DieHard
WA
UZZ30

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Thursday, November 09, 2006 - 05:36 pm, by: Adam Barry (Acdchook)

Ok, I've looked this up in my old physics handbook. The loudness increases by 10dB for each order of magnitude increase (10x) in intensity. An increase of 20dB is equal to an 100x increase in sound intensity. That doesn't necessarily mean it will sound like that much of an increase to the human ear, but I think that has more to do with the way the brain deals with relative volume.

I just plugged in the numbers for a 50W vs a 100W point source, and the increase in loudness at 1m distance is 3.01dB +/- .01 for rounding error.

Peter Nitschke
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South Australia
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Thursday, November 09, 2006 - 05:38 pm, by: Peter Nitschke (Pen)

I didn't say that.

I said that the perceived difference to the ear of a 10dB change in volume is roughly half/double depending which way you go.

According to what has been said, if the car started at 95dB and you managed to reduce it to 85dB (10dB difference), then it would only be 1/8th or 1/10th (depending how you read some of the previous posts) as loud as it was originally, ie about as loud as a mosquito on a quiet night.

It would in fact, be only 1/2 as loud as the original.

Keep in mind, we are talking about how the ear perceives it, ie how loud it is, not how much sound energy is involved - though that is a related side issue.

Peter Nitschke
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Thursday, November 09, 2006 - 05:40 pm, by: Peter Nitschke (Pen)

Adam, exactly what I said. Double the input power = 3dB increase, but that isn't twice as loud.

Adam Barry
DieHard
WA
UZZ30

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Thursday, November 09, 2006 - 05:43 pm, by: Adam Barry (Acdchook)

Rehan Bandara wrote on Thursday, November 09, 2006 - 05:31 pm:
i forgot to mention that sound power level, sound pressure level and intensity are three distinctly different descriptors of sound, hence the confusion.

The POWER produced by the source over the AREA of the spherical surface at a given distance from the sound source equals the INTENSITY (I) in W/m^2.
The SOUND LEVEL (dB) is 10log(I/Io), where Io is the reference intensity of 10^-12 W/m^2, which is the threshold of human hearing. So 0dB is the threshold of hearing, and every 10dB increase is an order of magnitude increase in both intensity and power.