oops! I didn't look close enough. Thanks!
In other news, I'm discovering that there is no simple way to add two dB values without first converting them to power.
In other news, I'm discovering that there is no simple way to add two dB values without first converting them to power.
dB
Hi,
yes there is:
When looking at outputs from a group of filters you can do it like this
dBtot = dBa +dBb + dBc + .....
Try searching the web for "bodeplot"
When you have the "s" functions you can
dBtot = dB(H1(s)*H2(s)*H3(s)*......)
\Jens
Hi,
yes there is:
When looking at outputs from a group of filters you can do it like this
dBtot = dBa +dBb + dBc + .....
Try searching the web for "bodeplot"
When you have the "s" functions you can
dBtot = dB(H1(s)*H2(s)*H3(s)*......)
\Jens
Jim85IROC said:In other news, I'm discovering that there is no simple way to add two dB values without first converting them to power.
Well, actually dB’s are logarithmic values. When you add dB values you are multiplying in reality.
😉
Here's the equation I used for the summed signal:
sigT=10*LOG((((10^(Sig1/10))+(10^(sig2/10)))^0.5)/0.000016666)
I used .000016666 as the reference power level based on the dBm scale that assumes 1mW and a 600 ohm impedance.
Right now the curve looks good, but it's a few dB above the other plots. I think once I bring phase into the equation it should be fairly accurate.
sigT=10*LOG((((10^(Sig1/10))+(10^(sig2/10)))^0.5)/0.000016666)
I used .000016666 as the reference power level based on the dBm scale that assumes 1mW and a 600 ohm impedance.
Right now the curve looks good, but it's a few dB above the other plots. I think once I bring phase into the equation it should be fairly accurate.
Incase anybody is interrested, here's the spreadsheet so far:
http://www.sover.net/~lirace/Jim/crossover_slopes-A1.xls
It's very crude at the moment, and not altogether real accurate, but the idea is there. It's a somewhat different approach from the other stuff I've seen in that you can tinker quickly and easily just by independantly changing crossover slopes & frequencies of each individual driver. Once I get those slopes accurate, I'm going to have it calculate component values from it. But... I have a long way to go before those plots are accurate.
Anyway, enjoy. If anybody has any suggestions, feel free to give them. Just keep in mind that this is just a toy right now... it's not a tool yet.
http://www.sover.net/~lirace/Jim/crossover_slopes-A1.xls
It's very crude at the moment, and not altogether real accurate, but the idea is there. It's a somewhat different approach from the other stuff I've seen in that you can tinker quickly and easily just by independantly changing crossover slopes & frequencies of each individual driver. Once I get those slopes accurate, I'm going to have it calculate component values from it. But... I have a long way to go before those plots are accurate.
Anyway, enjoy. If anybody has any suggestions, feel free to give them. Just keep in mind that this is just a toy right now... it's not a tool yet.
Transferfunctions
Hi,
Thats right
To calc. dB you must use 20*log(|H(s)|), s=j*2*pi*F
The transfer function (in this case) it the frequency dependant gain.
\Jens
Hi,
Thats right
To calc. dB you must use 20*log(|H(s)|), s=j*2*pi*F
The transfer function (in this case) it the frequency dependant gain.
\Jens
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