Hard Audio - Ceramic Speakers

@shadorne

Regarding your views on hard drivers & ringing, what do you think of the Floyd Toole school of thought on this? On AVS he routinely cites his research (which is from the 80s), claiming no one can hear ringing and FR represents the full picture.

If you take Toole’s beliefs to their logical conclusion, the company he is with (Revel) is wasting their time as their entry level Concerta line has just as good FR measurements as Performa or Ultima, and things like using Ceramic drivers like on the Performa3 have no performance gain to using a driver that rings like aluminum or titanium, and by offering these things at a higher price they are merely selling to the market.

I asked Floyd why a company like Sennheiser would create something like Helmholtz Radiator to suppress time domain ringing when they could have simply changed the FR response of the driver, and he gave the impression that it’s done merely for marketing and FR response is all that matters.

IMO Toole’s beliefs on this seem weird considering we’ve known for decades people can pass double blind tests when comparing amps that used and didn’t use excessive negative feedback (and caused a spike in IMD distortion) even with ruler flat FR.

@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