I've never heard the grand reference, but I've heard the concert grand a couple times. Easily one of the best speakers ever produced. They make music enjoyable and mesmerizing. Having said that, I've also heard a few of Carl's other speakers down the reference line. When I first met Carl (he was demoing a CG at CES a couple years ago), he told me that the prospective owner should choose the proper speaker in his reference line based upon room size/volume. My initial impression was "the big speaker has to sound better!" After all, this is what most of us have heard with our own ears. However, after knowing Carl a lot better over the years, I can say he doesn't sugar coat or exaggerate. Earlier this year at CES, I heard his new studio grand. To my shock, the studio grand sounded a whole lot better than the CG in the same demo room (which was quite large). My initial impression was that the room would be way too large for the studio grand to fill properly. I thought the room size would be more aptly suited for the CG. I was totally shocked to hear a speaker at 1/10 of the cost of the CG just do everything better, musically speaking. I even had to mention that to Carl once the demo died down (after most people left). He also agreed. The CG was actually a bit constricted even in that relatively large room size, whereas the studio grands grew to fill the room (my guess is the studio grand was designed for a room size much smaller, which made the feat even more amazing). This had me rethink my whole "bigger is better" paradigm. In truth, many speaker manufacturers "lower line" speakers provide sound that is a shell of what can be heard from their top of the line series. As evidenced by the components used in all of Carl's reference line speakers, the midrange drivers on up is usually identical. Same crossover design approach. Same cabinet design approach. So one would hope they all sound quite similar. In this specific demo, of course the studio grand couldnt match the CG in bass output, but this is to be expected. Although the studio had a nice, tight bass in general. I'd say a nice music sub would fix this. Anyways, the point here is, pick the speaker that fits your room size and/or budget the best, and enjoy the same NOLA quality sound from any of them.
One other thing Carl mentioned during this specific demo, which caught my attention. He stated it is a common myth that people believe all the spaciousness, and overall sound stage size advantage gained from the NOLAs is a "gimmick", artificially created by a dipole speaker design. To debunk this typical myth, Carl played a recording that obviously had little to no depth or width in the recording , and the speakers responded by crashing the sound stage size into nothing. Of course, this proved the point. I've also seen this effect on my own baby grand ref 2. The NOLAs only play the sound stage that has been recorded, without any exaggeration. Although I would say being dipole the sound does feel more spacious, I also don't think there is any artificial increase in the stage size due to being a dipole. The "ease" in my mind could be attributed to lower distortion coupled with a clean crossover design.
Most people posting here already know what type of sound quality to expect from a NOLA ref speaker. But in case they don't, I think the best way to sum this up is in the first email I sent to Carl after receiving, and setting up my baby grands. I could still say that all the enthusiasm and hype I felt on the first day has not waned until now (over a year later). I still go home to enjoy a great musical experience. The stage is satisfying. Sounds emerge from nothingness when the recording warrants. The performance is out in front of me, where it should be, not sitting in my lap. For example, on a live CD, when the audience cheers or claps, I hear those claps flank my side, as if I'm sitting maybe 10 rows away. The imaging is not specific to a certain width or depth, but it is 3D. Sounds emerge from every quadrant of space bounded by the space between speakers, behind the speakers, in front of the speakers, above the speakers, and even in some cases, seem to startle me from almost behind me. This kind of reproduction would make people wonder why multi-channel sound is in existence, when high quality 2 channel stereo is more than capable.
Anyways, here is what I wrote Carl after receiving my speakers and after my first day with them:
I think you're speakers are going to make me go deaf, Carl! I notice the volume keeps moving up! The presentation is super relaxed and smooth, but not rolled off or anything. Actually, quite detailed (more than I'm used to). I can't say if my ears "heard" distortion before, but since I have no "tenseness" while turning the volume up, I can say that my ears can tell when there is distortion, whether my brain knows it or not. I had the speakers in a 7.5ft triangle, firing straight ahead, which happens to be the "comfortable" size and spacing for my room, however I kept feeling the sound stage was constrained to the left and right (beyond the speakers), compared to my other speakers in a similar location. I ended up pushing the BGII's to 9.5ft apart, with my seating position about 9ft away from the drivers. I think this is possible because of the dipole minimizing side reflections, and because I have 4" thick Roxul panels on the side walls to absorb those waves that would otherwise cause confusion. After I spread the speakers to 9.5ft apart, wow, things changed quickly. The sound stage opened up dramatically left to right, with the same solid center fill. I guess these babies need a little more than 7ft to breathe. The depth (behind the speaker plane) is simply untouchable by any non-open baffle speaker I've ever heard. My other speakers had a more "you are standing right in front of the performance, on stage" kind of presentation, whereas the BGIIs put me clearly in the middle of the stadium, sitting in the audience for the event. The stage is much farther back, and spreads all around, just like it would at a real live event. I guess this is how it should sound (we are the audience, not on the stage..).
There is more detail and speed in the midrange, which is the biggest improvement from my Andra IIs from a pure nuts and bolts point of view. Of course, the detail and speed are still so silky smooth and natural. One thing I noticed is CDs that I once thought were recorded very poorly (irritating), although still noticeably compressed and non-ideal, are now very listenable. The BGII's make me dig through my entire CD collection and pop in CDs that I thought were irritating to listen to. And even with these non-ideal CDs, the volume keeps going up! I don't know how you did that Carl. More speed, more detail, more cohesiveness.. more of everything to make bad recordings sound "good". Amazing. Just pure music. I don't need to dissect each frequency band to talk about what I hear. I hear music, and it sounds right, end of story.
The synergy with my Berning 200W monoblocks is pretty good Carl. If you have not tried one of Berning's latest designs with your speakers, please do yourself a favor and try it out. See what you think. I think these amps fit your design methodology well (they are fast because of the lack of a traditional output transformer at audio frequencies). The amps complement the speed of your drivers. You may want to use a warmer tube preamp though, since most would characterize the Berning sound as "lean" or "cool". I don't see it that way. I feel they are neutral and correct (not extra warmed up like most tube components are).
I could write more and more, but I think I've covered the highlights. These speakers are definitely keepers. Until I go deaf! The louder I turn them up, the more they make me feel like I'm in the club or venue. I never truly experienced this before. Now I can safely say that I have better sound in my home, than many audio booths at the shows I visit. Finally!!!!!
Keep up the good work. You've got golden ears. Music is addicting. I've been listening almost all day, and still craving more. Geez.
I think part of the reason the music is so effortless from these speakers (in addition to Carl's design approach to minimize driver mass, enhance speed, lower driver distortion, etc) is the design of the crossover. I don't sense any anomaly in the crossover points (in terms of frequency peaks or troughs). The overall staging and imaging resolution are probably attributed to a crossover that exhibits minimal group delay as well. Carl clearly knows what he is doing in all respects of speaker design. Some speakers may be more dynamic (like certain horn speakers), and other speakers may do bass better, etc, but I have yet to hear a speaker (or speaker line) do overall music as much justice. Just sit back, close your eyes, listen to music. Don't dissect what the speaker is doing. I never do. Oh, just to make it clear, my amps are Berning Quadrature Z monos, and I've also employed the use of a pair of NOLA Thunderbolt 3 subs. I find they add more substance in the lowest octave (20-40Hz), but I could say most people wouldn't really care. I feel it helps the overall presentation this way. It was my way of cheating and trying to emulate a concert grand
And, in parting, I would like to say Carl is pretty approachable and accessible. He works very hard during his show demos to educate and bring music to the people (as evidenced by his offerings over the price range). He's also very available over email to answer any questions and to help you get the most of your investment. Carl asked me a favor to help spread my experiences with his speakers on this forum, and I kindly obliged. I felt it was the least I could do for all of the help and guidance he has provided, in addition to thank him for designing speaker systems that deliver music. His designs need to be heard. Too bad most of the publicity goes to other speaker manufacturers.