Can Someone Help Me With A Formula

[tunescool]

i used to be an installer in the early 90s

i cant remember how to do the formula

calculate for gain in DB at fc

9.3339 is my Qtc

can someone breakdown doing all the math

and tell me what 20log is

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[Papermaker85 5,000+ posts]

do your functions first. do your exponents tops should be QTC^4 is 7590.1887

QTC^2+ 87.122

87.122-.25

the formula looks to be flawed because QTC^4/QTC^2 is QTC^2 lol

20log10 is another way to say Db/voltage

Im sure the EEs here are more familiar with calculating sound pressure.

ill give it a shot though.

i get 9.3473 not sure if that's correct..

 

[tunescool]

i followed what you had, found a calculator

for all the division inside i get

87.3721

i wouldnt know where 20log comes from

in my notes i have

Qtc to the power of 4 divided by Qtc to the power of 2 - .25 = √ log x 20

87.3721 = √ log x 20

i have nothing written down about log, i dont know what it is

 

[Papermaker85 5,000+ posts]

honestly don't know.
this sounds like a problem for @Souldrop

 

[The_Quiet_One 10+ year member]

A log operation is just the inverse of raising a number to a power. Your formula is essentially 10^(x)=(sqrt(Q^4/(Q^2-0.25))^20)) : solve for x

Spitballing it should be somewhere around 19.

if you need/want more explanation reply to me or mention me and I'll try and answer more thoroughly tomorrow when I'm not headed to bed. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif If you're wondering where that formula comes from I'm going to have to do some digging. I don't think I've ever ran across that formula, but acoustics is one many areas in which I consider myslf weak. *shrug*