Hard Audio - Ceramic Speakers

@exfoliate

Dr. Toole has a wealth of knowledge and far more experience than most experts. I trust what he says to be true. I think frequency response is primary but I can’t believe he would say that this is all that matters. After frequency response and harmonic distortion measurements then even dispersion response and finally waterfall is very important. Stereophile show off -axis dispersion and waterfall plots on most speaker tests.

Furthermore, we know that concert hall reverberation and room RT60 are very important to our enjoyment of music. Sabin studied this extensively. Anyone who says spurious artifacts and poorly damped resonances (easily visible in a waterfall plot) aren’t important is ignoring a very important aspect of SOTA design.

One interesting fact about any unusual bumps in the frequency response is that they are often an indication of some undesirable resonance that will be even more evident in a waterfall plot and visible in the impedance curve too. So flat frequency response is indeed the most important indicator of a good speaker - even transducers should have a flat smooth response across their useful bandwidth and any unusual wiggles usually indicate trouble.

@shadorne

What he has said is, if two speakers have the same response but one speaker has a rise of x db at a particular frequency caused by ringing, and the other is completely free from such artifacts, all you have to do is remove that 3db of output via EQ, and the two speakers will sound exactly the same, and that no one can hear the independent effects of time domain ringing outside FR in a double blind test.

If harmonics and ringing are inaudible from the fundamental frequency then a sufficiently advanced room correction software should be able to make any speakers sound exactly the same on-axis.

Dr. Toole has said that EQ can help for room effects, but it can't fix a poorly designed speaker.  Frequency response is important, but you can't just look at on-axis.  A smooth and predictable off-axis response that mirrors on on-axis response (though with a more downward slope as you move further off axis due to directivity of the tweeters) is just as important as a smooth on-axis response, and EQ often doesn't fix problems in off-axis response.  

So, proper EQ can help make a good speaker sound even better in a room, it can't fix a speaker with fundamental design flaws.

As far as the various levels of Revel speakers go, while all are designed to exhibit the best on and off-axis response as possible at their various price points, there are benefits moving up the line. 

Moving from Concerta2 to Performa3 (and now Performa3 Be) to Ultima2 you get greater bass extension, greater power handling, greater dynamic range capability, less dynamic compression, less distortion at extreme dynamic levels, etc (plus of course the intangibles like more nicely finished cabinets and such).

Playing material without much bass content at a lower volume the Concerta2 F35 should sound remarkably like the Ultima2 Salon2.   Change the material to something with deep bass content and a very wide dynamic range played at reference levels and the differences will become apparent.  

The new drivers in the Performa3 Be offer more dynamic headroom, lower distortion at extreme volume levels, and stronger motor structure/better cooling to decrease dynamic compression.

AFAIK, damping the FR damps the ringing as well. Something about this is how minimum-phase devices work.

It’s not intuitive. We believe that a passive or active EQ would affect the frequency but not time domain, but I’ve read otherwise.

In rooms, the same principle works, with some help from bass traps. 

Best,

E

In theory, with everything equal and no other speaker distortion mechanisms then Dr Toole may be correct: pure ringing at the fundamental can be removed with a notch filter it. However, in practice speakers are not perfectly linear and have limited operating range and other forms of distortion - so the speakers won’t sound the same -  so in practice it is far better to have a speaker with a flat response to begin with then to compensate using electronics. 

The kind of ringing that is of most concern is that from wobbling modes from energy within the cone diaphragm itself. This sounds splashy or dirty and is not necessarily harmonically related to the music.