Help interpreting 2nd/3rd Harmonic values on WE datasheet
#1 Help interpreting 2nd/3rd Harmonic values on WE datasheet
I stumbled across a WE datasheet for the 300B which included a table of operating points showing 2nd and 3rd harmonics, expressed in dB. Screenshot attached.
Now I'm reasonably competent with maths, but will readily accept to dB being a weakness of mine. As a measurement it's a ratio, right ? So in this instance it must be expressing 2nd and 3rd harmonics as a ratio of the output ? So higher figures represent lower levels of harmonics ?
Now I'm reasonably competent with maths, but will readily accept to dB being a weakness of mine. As a measurement it's a ratio, right ? So in this instance it must be expressing 2nd and 3rd harmonics as a ratio of the output ? So higher figures represent lower levels of harmonics ?
#2 Re: Help interpreting 2nd/3rd Harmonic values on WE datasheet
Yes, so for example 40dB is 1%, 20dB is 10%
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
#4 Re: Help interpreting 2nd/3rd Harmonic values on WE datasheet
So if we call the dB value above x
y = -x/20
z = 10^y
Percent = z * 100
So, x = 40 in your list,
y = -40/20
y = -2
z = 10^-2
z = 0.01
Perc = 0.01 * 100
Perc = 1.0%
Or take 48dB
y = -48/20
y = -2.4
z = 10^-2.4
z = 0.003981
perc = 0.003981*100
perc = 0.4%
y = -x/20
z = 10^y
Percent = z * 100
So, x = 40 in your list,
y = -40/20
y = -2
z = 10^-2
z = 0.01
Perc = 0.01 * 100
Perc = 1.0%
Or take 48dB
y = -48/20
y = -2.4
z = 10^-2.4
z = 0.003981
perc = 0.003981*100
perc = 0.4%
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
#5 Re: Help interpreting 2nd/3rd Harmonic values on WE datasheet
if it's of any benefit I used to use the calculator from:
http://www.sengpielaudio.com/calculator-db-volt.htm
as shown in this doc:
http://www.vitalstates.org/diy/amplifie ... rement.pdf
part 5 shows the calcs
http://www.sengpielaudio.com/calculator-db-volt.htm
as shown in this doc:
http://www.vitalstates.org/diy/amplifie ... rement.pdf
part 5 shows the calcs
There's nowhere you can be that isn't where you're meant to be
#6 Re: Help interpreting 2nd/3rd Harmonic values on WE datasheet
TBH, I just use a scientific calculator on my phone to do the conversion I posted. Yet another thing that phones have taken over.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
#7 Re: Help interpreting 2nd/3rd Harmonic values on WE datasheet
's'funny...I don't have a phone and for some reason I keep thinking there are others like me, that don't have one.....
I know I'm mistaken but I still keep thinking that there are others.
There's nowhere you can be that isn't where you're meant to be
#8 Re: Help interpreting 2nd/3rd Harmonic values on WE datasheet
You have a good point, but you did post a solution that requires access to a computer connected to the internet...s'funny...I don't have a phone and for some reason I keep thinking there are others like me, that don't have one.....
My original solution can be done with a slide rule or set of log tables.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
#9 Re: Help interpreting 2nd/3rd Harmonic values on WE datasheet
Many many thanks. I use a calculator called HandyCalc on Android and it allows me to create functions which are really quick and easy. I'll create one for this.
#10 Re: Help interpreting 2nd/3rd Harmonic values on WE datasheet
bah humbug!
I was all set to try it on my trusty castell 1/60 when I realised it doesn't have the LL scale, which is needed for the expo....
not all slide rules are created equal...
I'm not even going to look for my 4 fig tables...you got me!
There's nowhere you can be that isn't where you're meant to be
- IslandPink
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#11 Re: Help interpreting 2nd/3rd Harmonic values on WE datasheet
I don't have an I-phone. Just a simple one for sending a few texts.
"Once you find out ... the Circumstances ; then you can go out"
- pre65
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#12 Re: Help interpreting 2nd/3rd Harmonic values on WE datasheet
Me too.IslandPink wrote: ↑Tue Aug 20, 2019 6:31 pmI don't have an I-phone. Just a simple one for sending a few texts.
Infact mine is a Doro old gits phone.
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)