Elevation effects SPL, but how? - Tech Stuff Tuesday
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- Опубліковано 15 вер 2024
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Sean, the audio brand Fusion had an extreme vehicle back in the mid 2000’s, it burped a 176.1 at world finals in the states, left the comp and was loaded onto a ship and sent back to fusion New Zealand. Upon unloading of the van it was put on charge, we then burped it as per everything the same as at world finals and would only produce a 173.4, so the van was down 2.7db simply from now being on the other side of the world.
With extreme vehicles, there is more to it. I've been involved with a few 180+ vehicles and you'd be amazed at how much the environment changes the score. One instance in particular, for every 5 degrees temperature change the frequency had to be changed by 1 hz either up or down. If the frequency didn't change, there was over 1 dB loss per frequency. Humidity was another factor as well. Regardless of what was going on outside, if the correct temperature and humidity was maintained inside and the correct frequency was played for that temperature and humidity, it would do the same predictable number every time.
It would be interesting to see barometer readings at the different elevations and then moisture (humidity) content with a psychrometer. You would need to measure temperature as well.
There are charts you can look at for psychrometer vs temperature which could give you an idea of the weight of air which the speakers are pushing. Then you have to make sense of it all. Interesting though, I liked the test.
You may or may not want to look into the following SMD product flaw I have encountered.. I cannot get 2/0 SHCA (Sky High Car Audio) wire lugs to fit on any of my 3 types of SMD fuse holders despite Steve using them in his recent build vids. IMO the fuse holders need revised (made longer). I recently made 2 short vids attempting to explain this but you're much better at this YT production thing than I am plus I thought you'd like to be the one to point out SMD product flaw(s). ;-) DETAILS: SHCA fuses don't fit longways in between two SHCA ANL wire lugs lined up tip-to-tip on the fuse holders including the SMD XL fuse holders. I cannot speak for the XL2 fuse holders because I don't own one but I get the feeling those won't fit either. Besides that, the SHCA ANL fuse hits the SHCA 2/0 lug's tip regardless if you place the fuse on top or on the bottom of the lugs. It sounds like a lot to understand but it's actually quite simple to see what the problem is as soon as someone attempts to lock in two SHCA 2/0 wire terminal lugs (I use tinned copper) with an ANL fuse in between them (longways)(not next to one another)(Meaning, if you added an SMD fuse holder to one power wire) Feel free to just watch my TWO vids on this topic to see what I mean >> ua-cam.com/video/0aQutRpsKn4/v-deo.html
I don't think we learned anything useful from these tests but you are a super audio nerd if you're doing SPL tests in a rental car when you're on vacation. I think people who don't seriously compete can't really grasp the lengths some of us go through to chase those elusive tenths. Cool video, thanks for your efforts.
I think there was more to take from it than you think, at the very least you can see there is a somewhat unpredictable correlation. Meaning, you can't blanket statement "less altitude is louder".
@@EMFAudio
I had very much expected a more linear trend so I'd say it is unclear what this tells us. I'd certainly like to see the test repeated in different vehicles to try to find any paterns.
Awesome to see you personally did the test and demonstrate the truth behind SPL and elevation.
👍🏻☺️👍🏻
Sean, I have also personally done tests parked on a boat ramp at sea level high tide vs low tide, here is a big difference simply from the tides, I would have to find notes but from memory at low tide it was .4db louder then at high tide
Tides is an interesting aspect I'd like more detailed information on.
Frequency changes at different altitudes.
Mine changed 1-2hz from 3000 ft to sea level.
I didn't have time to change port length, so I changed the cars resonant frequency 🤐.
Manged to backup my incoming SPL. I'm sure I could have made it louder, but I had pneumonia and almost died....
Dope... great info
I know humility plays a big part in spl as In Australia we can go from 95% down to 5% in a matter of an hr and I notice up to 0.5db difference
Maybe u can buy a “air con” and “humidifier” and test differences between hot vs cold and low vs high humility and mix the 2 aswell
Because the speed of sound is affected by these so it definitely can lead to spl differences
Those differences are well documented, that's why we tried to maintain temperature as closely as possible. Humidity is something we couldn't regulate.
EMF But for another test u could do in the garage with the crx is do in-depth testing with hot vs cold and humidity differences towards spl
That would make a great video
Like the barometric pressure at those different places
What if I told you below sea level to over 5,000 ft was around 20 miles to do the whole range?
@@EMFAudio What I meant is if you would take a barometer and check the difference between those locations at different altitudes, we could calculate how different atmospheric pressures affect the wave's kinetic energie in the air!
Did you verify the voltage of the vehicle was the same on all tests , I had vehicles that the voltage would vary 1 volt or more , this could affect the results
We're talking about a vehicle trying to produce about 40 watts, it's going to do that regardless of voltage.
Humidity levels ? ... Would be nice to have those numbers with all those stats ...
Why ALTITUDE or ELEVATION has no effect on SPL---- No matter how high you get! Altitude is a measurement that describes a position above or below sea level. Sound does not care what elevation it is produced at. What CAN effect SPL or sound waves in general is Air Density, or Atmospheric Density, commonly measured with a Barometer. Sound generally moves faster through denser materials and slower the less dense. So take a barometer to the spl competitions and adjust accordingly. Temperature also affects atmospheric pressure, it has no effect on altitude. Great scenery tho
You did not account for humidity level for differents elevation.
The speculation regards only elevation, that was the continuous variable.
If me and my brother ever take our 160db truck to another grand junction show we can test from 5000 ft to 10000 ft
Just kidding, I didn't realize that the esienhower tunnel was at 11000 feet. Only problem with taking the truck from Denver to grand junction is how hard it is on the truck. It doesn't like driving up that hill
I bet! I was at 9,900 in that truck and you could definitely tell, without a ton of added weight.
I would love to see a video with a full blown spl set up , where everything else is the same 👍🏻
That is a harder task, but I'd like to do that some day.
I'm wondering if the meter needs to be recalibrated at different elevations
That would literally be altering the meter to get the desired results. Calibration has set parameters that don't' change.
Interesting info. Never really considered it a factor with SPL. I know it is a factor with vehicle performance/tuning.
Rocky mountain bass test vs Death valley?
If the testing was done windows up I would have done even higher elevation, all the way up to 10,000. Between the snow and 18 degrees, I wasn't gonna sit there and test and try to modulate temperature inside.
Could barometric pressure be a factor ?
I believe it is.
I had heard about that👍
affects**
Not effects 😅😅😬
Why have you disabled likes/dislikes count? Repellent...
Why would it matter if I did? Average on the channel is over 94% BTW.
Have a garage full off subwoofers. Uses cars stock speakers.... cringe
Know what makes me cringe? When people comment without watching the beginning of videos that explain what's going on in the video.