Truck Tuba Car Sound Quality Questions

For livingroom sound better than in a theatre.
Message
Author
User avatar
Bill Fitzmaurice
Site Admin
Posts: 26786
Joined: Tue May 02, 2006 5:59 pm

Re: Truck Tuba Car Sound Quality Questions

#31 Post by Bill Fitzmaurice » Sat Feb 09, 2019 11:42 am

hotbutta wrote:
Sat Feb 09, 2019 10:41 am
There are guys doing 160db+ on tones and 157 average on music. Measured on the windshield.
Once again, no, they're not. At the maximum possible sensitivity for any system, 120dB/watt, it would take 100,000 watts to reach 160dB. They're fooling the meter. It's just like if I take my BMW, which has a constant dashboard read out of gas mileage, out on the road and take a picture of my dashboard showing me doing 80MPH at 100 plus miles to the gallon. I see that reading on a regular basis :hyper: ...going down a 25% grade hill. :roll:

hotbutta
Posts: 44
Joined: Wed Dec 22, 2010 12:53 pm

Re: Truck Tuba Car Sound Quality Questions

#32 Post by hotbutta » Sat Feb 09, 2019 11:49 am

They can fool that meter, but they are also fooling your diaphragm into thinking there is an elephant sitting on your chest.

And if that down hill was 100 miles long, your BMW will use less than 1 gallon. That's no fooling

User avatar
Bill Fitzmaurice
Site Admin
Posts: 26786
Joined: Tue May 02, 2006 5:59 pm

Re: Truck Tuba Car Sound Quality Questions

#33 Post by Bill Fitzmaurice » Sat Feb 09, 2019 12:38 pm

hotbutta wrote:
Sat Feb 09, 2019 11:49 am
They can fool that meter, but they are also fooling your diaphragm into thinking there is an elephant sitting on your chest.
Not even close. Maybe a Great Dane. None of those people in the videos experienced 150dB, as that would cause eardrums to instantly burst. What actually does reach 160dB is a rocket launch. Spectators at the Kennedy Space Center are kept several miles away to prevent hearing damage, and even at that distance it's still mighty loud.

SethRocksYou
Posts: 304
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: Truck Tuba Car Sound Quality Questions

#34 Post by SethRocksYou » Sat Feb 09, 2019 12:42 pm

Bill Fitzmaurice wrote:
Sat Feb 09, 2019 11:42 am
...maximum possible sensitivity for any system, 120dB/watt...
That's an interesting little factoid I'd never heard before. Science, being science, it makes sense that there's a maximum theoretical, SPL per measure of power at 100% efficiency.

It's just something that's never crossed my mind. Thanks for that little tidbit.

Now, does that include "cabin gain" too?

ACUA
Posts: 344
Joined: Sun Sep 25, 2016 6:21 pm

Re: Truck Tuba Car Sound Quality Questions

#35 Post by ACUA » Sat Feb 09, 2019 1:06 pm

No one sits in the 160-181db spl vehicle chambers while they are running. I order to do that the chamber is sealed and they are doing those numbers one upwards of 100,000 watts power consumption those systems use cap/batt banks that sustain short power bursts at that level it is a stupid the rigs never play music and the vehicles likely don’t drive either more cement than car for real. The meter may be tricked but it’s a standardize measuring system and the records stand just waiting to be broken
Advanced concepts underground audio

ACUA
Posts: 344
Joined: Sun Sep 25, 2016 6:21 pm

Re: Truck Tuba Car Sound Quality Questionsu

#36 Post by ACUA » Sat Feb 09, 2019 1:45 pm

The lower the frequency the higher spl the ear can tolerate. It can take a lot of sub 40hz!!! You don’t get hair trick sir movement until around 140dbspl on 50hz and down. The fun zone is 26-34 hz at 140dbspl I have never seen it done on anything short of +4kw average vehicle at like 60-70% efficiency on 500sqin cone area
Advanced concepts underground audio

User avatar
Bill Fitzmaurice
Site Admin
Posts: 26786
Joined: Tue May 02, 2006 5:59 pm

Re: Truck Tuba Car Sound Quality Questions

#37 Post by Bill Fitzmaurice » Sat Feb 09, 2019 2:52 pm

The maximum efficiency of a group of direct radiators is 25%.
http://www.xlrtechs.com/dbkeele.com/PDF ... eakers.pdf

hotbutta
Posts: 44
Joined: Wed Dec 22, 2010 12:53 pm

Re: Truck Tuba Car Sound Quality Questions

#38 Post by hotbutta » Sat Feb 09, 2019 4:08 pm

Almost everything I knew about auto sound has been wiped out in half a thread.
I still want to do hair tricks though...

SethRocksYou
Posts: 304
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: Truck Tuba Car Sound Quality Questions

#39 Post by SethRocksYou » Sat Feb 09, 2019 7:33 pm

Bill Fitzmaurice wrote:
Sat Feb 09, 2019 2:52 pm
The maximum efficiency of a group of direct radiators is 25%.
http://www.xlrtechs.com/dbkeele.com/PDF ... eakers.pdf
Even more interesting! So, the maximum possible sensitivity for any system is 120dB/watt at one meter, half space, and assumes at 25% maximum eficiency? (Statement question :) )

SethRocksYou
Posts: 304
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: Truck Tuba Car Sound Quality Questions

#40 Post by SethRocksYou » Sat Feb 09, 2019 7:45 pm

Bill Fitzmaurice wrote:
Sat Feb 09, 2019 11:42 am
At the maximum possible sensitivity for any system, 120dB/watt, it would take 100,000 watts to reach 160dB.
100Kw @ halfspace, 1m? Wouldn't that work out to be closer to 10Kw in car? ... purely mathematically speaking

ACUA
Posts: 344
Joined: Sun Sep 25, 2016 6:21 pm

Re: Truck Tuba Car Sound Quality Questions

#41 Post by ACUA » Sun Feb 10, 2019 9:47 am

Bill Fitzmaurice wrote:
Sat Feb 09, 2019 2:52 pm
The maximum efficiency of a group of direct radiators is 25%.
http://www.xlrtechs.com/dbkeele.com/PDF ... eakers.pdf
I can not read this. I don’t have the intellect or the degree to back it. I tried and the content highly interested me it’s going to add a dimension of understanding that I will value but I will have to chew on it a while.

I see Bill’s point I ran some numbers and I can’t see how 180.1 dB is actually achieved as it’s been recorded As the standing record. Seems silly now but knowing that sound is logarithmic and trying to approach 180 dB is near impossible.
I do know that there is a lot of time and effort placed into that potentially fake industry. I don’t know what true spl level it takes to achieve hair raising velocity but I find it cool the current accepted method of measure suggests it’s in the 140dbspl range but if that is false good luck talking the masses into it.

I turned on my bfm rig last night and played some music and realized that the sounds I was hearing suggests that there is sound engineering put into the equipment and it works can’t discredit any of that.

I would love to see some horn loaded configurations give the current dB drags a good run for their money kind of shake up. I have four t45 24” wide singularly loaded lab12s that I would love to see walled off in a van. I would love to see what they can do there!!!
Advanced concepts underground audio

User avatar
Bill Fitzmaurice
Site Admin
Posts: 26786
Joined: Tue May 02, 2006 5:59 pm

Re: Truck Tuba Car Sound Quality Questions

#42 Post by Bill Fitzmaurice » Sun Feb 10, 2019 11:15 am

Keele's math is beyond my understanding as well, but it can be simply explained. When you double driver count the broadband power conversion efficiency is doubled. Sounds good, but power conversion from electrical to acoustical watts of the average driver in a direct radiating enclosure is only about 1%. Two drivers 2%, four drivers 4%, eight drivers 8%, it takes a lot of drivers to get a high conversion ratio. Even so if that's the only factor to be considered with enough drivers you'd exceed 100% conversion, and you don't have to be Einstein to know that's not possible. The other factor is the K frequency, simply put where the forces working against additional efficiency dominate. With every doubling of driver count that frequency goes down by a factor of 0.7. You can see how that works in this chart of multiple T24s:

Image

The flat section to the right of the chart keeps moving lower in frequency with each doubling of cab count. With enough cabs that flat section will extend all the way to the lowest frequency.
Anticipating the next question, a horn may have efficiency in the 5 to 10% range. A large group of horns will max out in the vicinity of 50% efficiency.

Post Reply