ampage
Tube Amps / Music Electronics
For current discussions, please visit Music Electronics Forum.

ampage archive

Vintage threads from the first ten years

Search for:  Mode:  

Math?


 :
5/28/1998 7:59 AM
D Barber
Math?
this is an exerp from FAT SCREAMER I dont know how to put it in italics but here it is...and resistor determine the frequency roll-off.  
1/6.28*.047uf*4.7Kohms=720 hz>.............. drive set on min....1+51k/4.7k=11.8  
drive set on max....1+(51K + 500K)/4.7k=118>........ I am a math retard but I do own a calculator now if I could only understand the equations that Jason posted about the rolloffs and gain. I tried to duplicate the math and could not get the same answers,(i must be doing something wrong)what does (/) mean, what does (*) mean. Better yet if someone would type this out without symbols like...1 divided by 6.28 multiplied by .047uf (i dont have a uf button on my calculator what if i want to use a 22uf) Multiplied by 4.7......you get the idea. I work by experimenting by ear but I would love to have the math to document my work and catalog results scientificly. Once again I would appreciate any help I can get on this.
 
Today
ampage
archive
And now, a word from our sponsors:


 
5/28/1998 9:05 AM
jason

The formula is 2, times pi, times cap value(in farads), times resistor value(in ohms). Then take the recipricol of that (divide it into 1).  
 
The .047uf cap should be inserted into the formula like this
.000000047  
(if you want to use 22uf
.000022, just take the caps uf value and move the decimal 6 places to the left)  
 
The resitor should be inserted into the formula like this 4700  
 
/ divide  
* multiply  
 
maybe I should have used some brackets in the formula (remember to do what is in the brackets first)  
 
You should end up with  
1/(2*pi*.047uf*4.7k)  
 
now let's simplify it some  
 
1/(2*pi*.000000047*4700)  
(remember to do what is in the brackets first)  
 
1/(.001387252)  
 
and finally  
 
720  
 
I'm no math teacher by any means...I hope this helps some.  
 
Read the technology of the tube screamer over at GEO.  
 
 
jason
 
5/28/1998 7:59 PM
D Barber

Lord I knew I should not have eaten so many paint chips! Where do I find a calculator that will take .000000047 or smaller er uh umm bigger? whats a recipricol again?.........actually I kind of understand better (ooh man my head hurts) thank you for helping me, I'll go back to my abacus or some verisimilitude of one. All for these vociferous boxes.........
 
5/29/1998 6:09 AM
GFR

If you have a calculator with scientific notation, this is how you do it:  
 
 
p : exp-12 (pico)  
n : exp-9 (nano)  
u : exp-6 (micro)  
m : exp-3 (mili)  
k : exp+3 (kilo)  
M : exp+6 (mega)  
 
 
so for example:  
120pF is 120exp-12 (120x10-12)  
100nF is 100exp-9 (100x10-9)  
.047uF is 0.047exp-6 (0.047x10-6)  
35mA is 35exp-3 (35x10-3)  
82k is 82exp+3 (82x10+3)  
2.2M is 2.2exp+6 (2.2x10+6)  
 
GFR
 
5/29/1998 6:54 AM
jason

your calculator may also have a reciprical button on it. It usually looks like this...  
1/x  
In fact, the calculator that came in windows 95 has a reciprical button on it and exponent key. If you have windows 95 pull up the calculator program(under accessories), go to veiw and select scientific. Then use the chart GFR provided in his post and you should be good to go.  
 
Good luck,  
jason
 

  Page 1 of 1