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[Sin x/x]

Since every audio signal has a frequency band with and a s/n ratio, whats the s/n ratio of speaker systems and how do you measure it?

[johnR]

I take it you're referring to the modulation noise caused by the magnetic flux jumping between domains (aka Barkhausen noise) in the magnet material here. Could be tricky to measure as it's program dependent.

[johnR]

Other sources of noise like mechanical resonances and turbulence in reflex ports are program dependent too. Making any meaningful measurements of all these would be very difficult.

[zmix]

Sin x/x wrote on Sat, 28 July 2007 03:43

Since every audio signal has a frequency band with and a s/n ratio, whats the s/n ratio of speaker systems and how do you measure it?

The parameter is called "efficiency"...  it's a measure of how much signal produces how much noise...

[Sin x/x]

zmix wrote on Wed, 01 August 2007 08:09

Sin x/x wrote on Sat, 28 July 2007 03:43 Since every audio signal has a frequency band with and a s/n ratio, whats the s/n ratio of speaker systems and how do you measure it? The parameter is called "efficiency"...  it's a measure of how much signal produces how much noise...

I don't understand what "efficiency" has to do with noise.

"efficiency" is the difference of how much energy goes in and how much energy comes out.

[Sin x/x]

The spectrum of the noise must be important to, but even more difficult to measure.

Anyone have an idea?

Or is it a meaningless thing and I should not think about this?
It seems important for AD/DA converters, summing mixers etc...

[johnR]

This is starting to look familiar. andshesbuyingastairway, is this you?

[Sin x/x]

johnR wrote on Fri, 03 August 2007 17:18

This is starting to look familiar. andshesbuyingastairway, is this you?

No. And I don't lurk at any other pro audio forums.

I have never heard a discussion about this subject, hence my question.

If there are other discussions on the net about this, please kick my butt into the right direction.

[johnR]

Sorry, sinx/x. I shouldn't have jumped to that conclusion.

Noise in speakers is something most people don't think about.
I mentioned a few of the possible causes, but those are hard (if not impossible) to measure, and they only occur when a signal is present. They do affect a speaker's resolution though, so it is important to consider them. Quite a few speaker manufacturers would be resistant to the idea of resolution being quantified by measurement, because it would show how bad their speakers are.

Here's a forum thread on Barkhausen noise:
http://www.diyaudio.com/forums/showthread/t-5857.html
Unfortunately the link to John Watkinson's original article is broken, but some Googling might find it.

If I was being pedantic I'd also mention thermal noise caused by the resistance of the voice coil, but that is so small you can forget about it.

(BTW zmix was joking).

[Sin x/x]

Thanks JohnR!

[franman]

seems to me (not being a speaker designer... Lars??) that s/n isn't really defined for a pure loudspeaker. It's a transducer and will great distortion, but not noise.

Amplifiers in powered loudspeakers will certainly have a s/n but it's not like a line level piece of gear that will add noise to the signal chain. It's the final piece of gear and it's 'self-noise' is insignificant if it's not readily audible at the listening position...

Does any of that make sense?? I have no idea not being a speaker designer (Lars??_)

[Rivendell61]

johnR wrote on Sat, 04 August 2007 05:00

Here's a forum thread on Barkhausen noise: http://www.diyaudio.com/forums/showthread/t-5857.html Unfortunately the link to John Watkinson's original article is broken, but some Googling might find it.

Try this link for the Watkinson paper:
http://www.celticaudio.co.uk/articles/science.pdf


Mark