eq. or parametric analizer

[jlaudiomark]

I have a great system in my car but i can't find a 15 or 20 band analizer so i can see in real time the frequency high and low points. Its just a way that tells me how good the disc is so i can adjust my head unit to the best listening sound.Also im looking for a db meter with digital display that goes to 150 and plugs in my lighter. There are a few out there but only go to 120 or128 db. Thanks mark

[audioguru]

Hi Mark,
Welcome to our forum.
Does the sound system in your car produce 150dB? Kinda loud isn't it?
Let's see. Most speakers produce a sound pressure of 90db/1W/1m. So with 10W would produce 100dB. 100W for 110dB, 1,000W for 120dB, 10KW for 130dB, ......, you're talking about a megawatt, you know.
Sound confined in a car behaves differently from in an auditorium or open-air stadium. It has nowhere to go so gets concentrated. So instead of a megawatt to produce 150dB you probably need only (!) 100KW.
Maybe you have your ears and sound level meter up close to the speakers so you don't need anywhere near that much power.

Hello, can you hear me? Please be careful with your hearing. Continuous sound at only 90dB can damage it permanently!

120dB of sound level is considered the threshold of pain. 150dB? OUCH!
Air at sea level has a pressure of about 15 pounds per square inch. With close to 150dB of sound, the air pressure waves would be at its limit of 30 pounds of compression and a total vacuum when the wave swings back.

I wonder why you need a graphical frequency/sound level display so that you can adjust the EQ for each CD. Musical sounds have harmonics that extend to the 12KHZ-20KHZ limit of your hearing but the highest harmonics are very low in level. If you boost them, they would sound very unnatual.

[MP]

Mark,
Welcome to the forum. Please ignore the offensive ridicule by audioguru.
This type of equipment is usually connected to the output of the pre-amp to save a lot of expensive circuitry. The values are calculated and thus you have the levels at the power out. Such a circuit as you have described would be very expensive to produce (and unnecessary).

MP

[audioguru]

My statements are true and accurate, not offensive and certainly not ridicule.
Do you know how loud a sound pressure level of 150dB is?

[ante]

There are competitions in car audio, and what it all comes down to is how many dB you can produce in a car. The competitors are standing outside and away from the car with the remote control and some measuring equipment is rigged inside. I have been to this kind of event once and I remember the windows popping out of a BMW 530 at 133dB!! Even outside the cars you needed ear protectors to stand it! Is this insane of what?? I think the record that day was 137dB in a Chevy C30 van. :o :o :o

[audioguru]

Hi Ante,
I was looking and looking to find what is the absolute maximum achievable sound pressure in air at sea-level and at 25 degrees C. That is when the air compresses to double atmospheric pressure for half-cycle and total vacuum on the other. I could't find it in the maze of kpascals, newtons, psi and stuff. Please see if you can find it.
I did find that 150dB is measured 30m from a jet engine (it didn't say which one) at full power!

I also attended a car max sound level competition. I stayed far away because I treasure my hearing, but felt the ground vibrate. I didn't see any windows blow out but many amps and speakers blew-up! One car had 16 batteries. Those guys are crazy. ;D

[ante]

Hey, this is an interesting page: http://www.lowertheboom.org/trice/dbdragracing.htm :o :o :o

Insane? 8)

[audioguru]

Hi Ante,
Thanks for the excellent article. "Instant death", "180dB". Insane, alright! :o