I've only seen it used exactly by people "who know better", Linkwitz being one example.Mr Evil said:"Linear distortion" is just bandwidth limiting and phase shift. Other than the technically incorrect names, the definitions on that site seem correct - real (non-linear) distortion adds new frequency components; "linear distortion" only alters amplitude and phase.
Still, it is a very commonly used term, even by people who should know better!
This is exactly most succint way to express all sorts of linear _changes_ to the signal that you would otherwise need zillions of terms for.
Linear basically means that there is no information added or removed. Only manipulated.
Distortion is it as soon as output signal is not exactly proportional replica of input. Remaining question is only if its linear or non-linear.
It is most commonly used in context of frequency response as you seem to imply, but that is an error. Linear distortion is not limited to FR.
Linear distortion examples are:
equalization, any filtering, resonance, acoustics, bandwidth limiting, phase shifts, group delay, polar response, baffle step, etc etc. Energy storage, echo and reverb is linear distortion aswell. Its a class of distortions, not any specific one of these.
A fairly wide range of B&C drivers is included in my newest Partsexpress catalog. The catalog seems to include more "pro" drivers with every new issue. There seem to be very few diy plans available using these drivers for home system? Know of any?
Just a couple of questions from a very non-technical guy after reading this entire thread...
Why are Seas, Vifa, Eton, ScanSpeak, Peerless, and other "home-fi" speakers necessarily less sensitive than pro sound drivers? Why is this engineered into the design? ... at what tradeoff? ... why not just make them more sensitive?
Is the general conclusion that larger cabinets must be used with pro drivers more or less a rule? Does this correspond at all directly with the increased sensitivity of the driver?
Perhaps someone could compare, for instance, the B&C 8PS21 8" woofer with another 8" incher from among the brands listed above.
Why the almost exclusive use of cloth accordion surrounds on pro drivers vs rolled rubber on "home fi"? Is this a function of lower xmax in the pro stuff placing less extension demand? Or is it economics? Why is cloth accordion (almost) non-existent in "home fi"?
And just one more thing while I'm here (sorry!) Paper cones? It always just seemed counter-intuitive to me. A pro sound driver subjected to massive pounding from the voice coil, club smoke, occasional outdoor environments, etc, etc. Are the properties of paper really that critically irreproducible by other means (plastics or metal) that it still dominates in pro sound drivers?
Just a couple of questions from a very non-technical guy after reading this entire thread...
Why are Seas, Vifa, Eton, ScanSpeak, Peerless, and other "home-fi" speakers necessarily less sensitive than pro sound drivers? Why is this engineered into the design? ... at what tradeoff? ... why not just make them more sensitive?
Is the general conclusion that larger cabinets must be used with pro drivers more or less a rule? Does this correspond at all directly with the increased sensitivity of the driver?
Perhaps someone could compare, for instance, the B&C 8PS21 8" woofer with another 8" incher from among the brands listed above.
Why the almost exclusive use of cloth accordion surrounds on pro drivers vs rolled rubber on "home fi"? Is this a function of lower xmax in the pro stuff placing less extension demand? Or is it economics? Why is cloth accordion (almost) non-existent in "home fi"?
And just one more thing while I'm here (sorry!) Paper cones? It always just seemed counter-intuitive to me. A pro sound driver subjected to massive pounding from the voice coil, club smoke, occasional outdoor environments, etc, etc. Are the properties of paper really that critically irreproducible by other means (plastics or metal) that it still dominates in pro sound drivers?
Pretty much - yes. High sensitivity means powerful motor structures (STRONG magnets, not BIG, small voice coil gap etc) and light cones. But strong motors and light cones means low Qts and high Fs and thus limited bass response.
If Bill Fitzmaurice chimes in he could probably give you a more complete answer.
Correlated with the Q above. If you look at pro sound 8''s you have to realize that these were almost always designed to be midranges and some are more or less optimized for front horn loading too.
Since pro drivers (for the reasons stated above) almost always are tuned higher they need a stiffer suspension. One problem with foam surround is that it tends to tear down with time, hard use and (probably the worst enemy) UV light exposure.
One exception here is the excellent JBL 2235H, a 15'' driver for bass/sub use in studio monitors and such.
This is something I also have been scratching my head for!
One really would suspect that something better than paper would be available 35 years after man walked on the moon!
But maybe it is a cost/performance tradeoff where more "exotic" materials simply are not worth the extra cost and trouble. I don't know. Some of the JBL pro drivers use a special paper composition with a few more "high-tech" ingredients. But me too would really like a complete answer to this question!
Cheers
/Magnus
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