Q Acoustics also has whitepapers for both the
300 and the
500, including a frequency response graph for the latter.
I'd personally go with the 300. Imo the Concept 500 does not reach low enough to be worth the extra price and visual impact. As good as the the frequency response and dispersion may be, the bass is too anemic. Q acoustics rates the Concept 500 down to 41Hz -6dB, but looking at the graph in its own whitepaper, it's more like 46Hz.
That's pretty unacceptable in my book for a pair of $6,000 bookshelf speakers weighing 92lb apiece. For comparison, the KEF R3, a bookshelf model a third of the price and many times smaller and lighter, is rated down to 38Hz -6dB. That figure is accurate or maybe even a little conservative based on KEF's graph:
The Sierra 2EX beats the Concept 500 too:
As does the Buchardt S400:
The one thing maybe helping the Concept 500 is that it's port is low to the ground, so you might get a bit more reinforcement from that design. But overall it still very much seems like you'd need a subwoofer if you care about full range sound. And if you need a subwoofer anyway, why not get the smaller speaker?
I also personally do not consider 4500 and 6000 to be close in price. That extra $1500 could get you a pretty awesome sub that would almost certainly outweigh any benefit of owning the 500 and balance out its advantage in efficiency.
Granted, I'm pretty biased against most floorstanding speakers. If it can't at least reach ~30hz -6dB anechoically then I'm not interested
On a more subjective note, I think the Concept 300 on their stand are some of the most beautiful speakers I've seen. I heard the Concept 300 last year and at the time thought they were some of the best speakers I'd ever heard. But that wasn't in my home, and I've since heard many more speakers, so who knows how I'd feel in an A/B test at home. But in terms of first impressions, it hit the sweet spot. Haven't had the chance to hear the 500s though.
Side note: The Concept 300 whitepaper also explains the benefits of its stand over other designs. Seems reasonable enough, though whether its improvements are actually audible is another matter. Anecdotally, I've noticed a cleaner impulse response when covering my speaker stand with a weighted blanket during gated measurements, but haven't looked too much into it and I doubt it'd make much of an audible improvement. Is there any serious research into the effectiveness of different stand types out there?
