SPL, Loudness, and Dynamics
The May 2018 issue of HiFi News had just arrived at the local library. I was shocked to read that HiFi News had just absorbed Stereophile. Well, I suppose that is good, two of the better HiFi magazines (Ken Kessler notwithstanding). But that is not what I want to talk about.
In the issue there is an excellent article by Keith Howard (as usual) on how loudspeakers struggle to reproduce musical peaks. He cites the research of Marshall Chasin, which is basically the benchmark. The table below is from Chasin:
Basically there are several points to note:
- By Peak Level it is meant the instantaneous oscilloscope peak, which can be very short (milliseconds), not the much slower averaging response you see on the average VU meter.
- Basically nearly all loudspeakers fail BADLY trying to reproduce such peaks. EXCEPT horns! This is incontrovertible, as Keith Howard had made dynamic simulations.
- Aside from horns, only Line Source Loudspeakers need apply. The Infinity IRS V (more info here) is cited as an example (others would be Carver, McIntosh etc). Indeed, I have heard these, and can attest they are great. Note that for a stereo pair, there are 108 driver units, and 4000 watts of built in power amp for the woofers. By my calculation, the surface area of each woofer column is equivalent to a 30" driver.
Horn Colorations? I reckon the horn's ability to play loud and sound dynamic, and real, is tied to its ability to reproduce peaks. This is why horn lovers, including myself, find the horn's realism unrivaled. Keith Howard freely admits horns can achieve these peaks naturally, but he pointed out the horn colorations. Now, this so-called cupped-hand phenomenon is commonly quoted, and indeed can be heard in badly implemented horn systems. However, in a well implemented horn system, such as Eric's, or the many I heard in NYC, including mine, I almost never hear such undesirable sounds.
Horn is the ONLY way to go, if you have the space!