How to calculate S/N ratio

[synthius]

Hey guys,
I was wondering if anybody knows how to calculate S/N ratio of an audio amplifier. I have attached the FFT analysis of one channel at 45 watts. Is there someone out there who can tell me how to calculate the signal to noise ratio of this channel.

**broken link removed**

Thanks

 

[Analog]

Hey guys,
I was wondering if anybody knows how to calculate S/N ratio of an audio amplifier. I have attached the FFT analysis of one channel at 45 watts. Is there someone out there who can tell me how to calculate the signal to noise ratio of this channel.

**broken link removed**

Thanks

answer here: **broken link removed**

 

[synthius]

I read through that page and can't really extract how to get S/N ratio from my FFT post. Could you give me some sort of equation or solve it for me. I don't' have a lot of time to waste on S/N ratio, have a presentation tomorrow.

thanks for the help though

 

[audioguru]

The max signal is +25.7dB.
The first wave of noise is at 90dB below it and many waves of noise are at 95dB below it.

So the signal to noise ratio is 95.7dB.

 

[synthius]

The max signal is +25.7dB.
The first wave of noise is at 90dB below it and many waves of noise are at 95dB below it.

So the signal to noise ratio is 95.7dB.

audioguru, I've only been on this forum for a few days but I've noticed you are very helpful. I was hoping you would come across this post.

Thanks alot