calc resonant freq simplified... :) for the SPL guys

Postby SR » July 10th, 2009, 11:29 pm

Take a 10 inch subwoofer in a sealed enclosure and position it in the center of the interior of your vehicle
Attach it to your amp and set your volume level at a "medium to high" level
Play a pink noise track through the system
Measure the frequency response with a meter (we recommend the AudioControl

)
This will give you a frequency range where the vehicle resonates
Using the IdBL CD, start playing test tones through the system at the same volume level as the pink noise, from 5 cycles back in the range to 5 cycles over the range
The resonant frequency of the vehicle will deliver the highest SPL measurement
Build your enclosure to perform at that frequency, based on the subwoofer specs

The 10 inch sub in a sealed enclosure will be relatively neutral and not affect the resonant freq. of the vehicle. This will give you a fairly accurate measurement without having to use any expensive testing systems.

Courtesy of Moe Sabourin Iasca

hope this helps those looking to build for spl

3stagevtec · Postby **3stagevtec** » July 11th, 2009, 1:43 am

what would really help the SPL industry imo is having cheaper SPL meters on the market. they don't need to be as accurate as the termlab / audiocontrol.. but just consistent enough to allow easy at home testing by the average competitor...

after you find the resonant frequency of your vehicle, a good recommendation is to build and tune your enclosures about 5Hz below that frequency.. from there you can easily fine tune your enclosure to give it's best performance by simple port and volume modifications..

3stagevtec · Postby **3stagevtec** » July 11th, 2009, 2:47 am

Postby SR » July 11th, 2009, 6:49 am

there are cheaper meters but so far non will read over 130db without going seriously inaccurate

i know that AC can make a smaller light spl meter however due to patents held for the existing chassis as well as the large stock that they have on it we dont see that changing anytime soon

ideally the AC meter does not need the built in battery or the 30 band display as it can just use an LCD numeric display with a smaller power supply and cct board just for SPL

however the 3055 and 3056 meters can do soo much more in the audio analasys the spl side is just the basic function of what the meter can do

pink noise and rta helps determine where your peak freq's are

MonsterPower · Postby **MonsterPower** » July 12th, 2009, 9:49 am

termlab basic meter starts at $799usd ... much cheaper than most amps out there ..

3stagevtec · Postby **3stagevtec** » July 12th, 2009, 12:41 pm

^ + shipping + VAT and Customs...

nareshseep · Postby **nareshseep** » July 13th, 2009, 11:21 am

can a 12" sub be used?

3stagevtec · Postby **3stagevtec** » July 13th, 2009, 1:13 pm

nareshseep wrote:can a 12" sub be used?

yes, but the bigger the sub / box the more it might affect your car's resonant freq.. you need a very small (physically) sub / box to not affect the internal volume etc inside your car by much..

shameer · Postby **shameer** » July 14th, 2009, 11:05 pm

3stagevtec wrote:<off topic>

<embed src="http://www.youtube.com/v/Pjy59QsLF2U&hl=en&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed>

</off topic>

aye alyuh know dat was me on the mic........lol R U READY,.....lol

altec · Postby **altec** » July 15th, 2009, 5:05 am

what could the radio shack meter be used for except spl? I have one for about 5-6 years going nothing, could it be used to tune systems for sq?

djlegac · Postby **djlegac** » July 15th, 2009, 8:27 am

damn i love stetsom!!!!!!

3stagevtec · Postby **3stagevtec** » July 15th, 2009, 8:34 am

altec wrote:what could the radio shack meter be used for except spl? I have one for about 5-6 years going nothing, could it be used to tune systems for sq?

i believe so, but it depends on how linear they are at recording full range sound.. it could be used with various test tones to 'RTA' your system..

for SPL use, they not very accurate as SR said..

Shameer :shock:

Postby SR » July 15th, 2009, 8:51 am

shameer wrote:
3stagevtec wrote:<off topic>

<embed src="http://www.youtube.com/v/Pjy59QsLF2U&hl=en&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed>

</off topic>

aye alyuh know dat was me on the mic........lol R U READY,.....lol

roflmao

Shameer was on the mic
Daleland was by the desk and Fawwaz was wandering around the lanes somwhere

IASCA CARIBBEAN JUDGES WERE PRESENT :twisted: