Well, color me surprised (pun intended) in this
review in Stereophile of the Acora SRB. Made with top notch drivers and granite.
Before anyone gets hot, I want to make it clear that this post is not about whether neutral speakers are good. This is about sincere admiration for a manufacturer using a crossover to eek out a very unique and colorful performance and target specific users instead of making a speaker for all users. My hats off to them, with zero sarcasm.
There's two things going on here which I think are instructive. First, based on the drivers, final frequency response, and the impedance profiles we can infer that there's some additional EQ going on to create the W shaped curve. Dynaudio has also produced some very well received speakers with such a curve.
The other part which is mirrored in the review is the ability of the speaker to be discerning of amplifiers. Based on this statement in the measurements:
the "equivalent peak dissipation resistance" (EPDR,
footnote 1) is close to 4 ohms for much of the audioband and drops to
2.54 ohms between 120Hz and 130Hz.
While some makers stress this range deliberately, sometimes this is just an accident of a driver in a ported enclosure which is what I think happens here, but still we should discuss the effects. A lot of modest amps, and even some beefy ones, tend to sag when you do this, so your nominally 6 Ohm speaker suddenly can show you WHY a Krell/Boulder monoblock MUST be purchased. Along with the house curve these both combine to the sense of having a magnifying glass on the music.
Again, here is a master class in leveraging the hell out of your crossover to make a special speaker, in addition to the drool worthy granite enclosure with barely a resonance anywhere. Anyone who wants to sell speakers for a living (instead of just be an armchair critic like myself) really should take note of how well the crossover choices and impedance are mirroring the perceptions of the reviewer.
Something else to look at is the absolutely perfect matching of the drivers in the step response.
I have no personal comment on whether this is a good or bad speaker, but any buyer should make sure they listen at their preferred volumes. I would not make these choices, which is probably why I have to devote myself to work which will actually pay me. It may be further instructive to see how the Crystal Cable Minissimo Diamond speaker fared at Stereophile by comparison.
Best,
Erik
