Answers to Ron's queries:
what is your current thinking as to who will make the cabinet for you and who will make the cross-over and who will assemble the drivers and cross-over into a finished loudspeaker? Cabinet plans are available, you can get any local carpenter to make it for you. For crossovers there are two possibilities - I have not written yet about the second one.
Do you also subscribe to the view that only a 15 inch woofer is worthwhile? I find that a little hard to understand, because it seems very possible that a number of smaller, theoretically faster drivers could provide the same "oomph" and low frequency output of a single 15 " woofer, but with greater speed and, perhaps, delicacy? Horn guys will tell you there is something called QTS in the parameters used to measure drivers, which shows how much the driver needs to move to produce bass. Drivers like Altec 515, made for horn loading, are require to move much less than a driver used in a cone which has higher QTS. In closed cones, smaller drivers moving slowly will produce more bass. Because the cone is closed, they can afford to be smaller. The more towards open baffle you go, you will need to have bigger and greater number of drivers to produce the same bass, but here they will need to be faster. Altec drivers are as fast as they come, and their strength is the midbass - for tone, oomph, speed, delicacy. That's why I fixed Altec for midbass and am quite willing to rotate higher mids and tweeter. The only driver I will consider here over the Altec is an 18 inch which Silvercore used, which he and his friends had made, and there are similar alternatives from JBL. Otherwise you cannot get this level of bass at 110 db, 8 ohm impedance, drivable by under 5 watts
Why isn't there a concern that original vintage Altec paper woofer drivers get dried out and brittle over time? For their mids drivers, replacing the diaphragm is recommended. For their woofers, Allnico magnet loss is more of a concern but if in doubt GPA can remag it for you.
I, too, like the "bottom up" tonal balance and heft where the bass and mid-bass provide a solid and rich-sounding foundation which supports the entire orchestra. I heard that from the Tannoy Westminster, and I really liked it. ("The center of gravity of the frequency balance of the speakers is in the lower frequencies.") I want to achieve that effect with planars. With planars Apogees do that. I lost my interest in Apogees when I saw the the Silvercore dual woofer FLH made Henk's Grands sound relatively puny in the midbass. And they did with the most linearity and flow and tone. Later, I saw that at a much lower price and size and fit for any living room, Tannoys gave me a similar satisfaction with their midbass oomph and midrange. The Tannoys are good, and easier. The Altecs if done right are superlative. Tannoys to me is the most practical solution for an audiophile, it makes everyone happy for all music, good WAF, good resale, fit and play. If you want to exceed, and play audiophilia like a competitive sport with Mike, Tang, G, DIY extremists like Leif, without having to spend that time and money, and without DIYing yourself, assemble yourself a dual woofer FLH. Otherwise stay with Tannoy. The dual woofer FLH will have much more detail and extension and transparency than Tannoy, can be more tuned, and can run on lower wattage SETs. On audiophile rating scale, much better. On satisfaction scale, very similar
What driver are you planning to use for the middle frequencies and high frequencies? The Markus Klug wood replica of the metal Altec multicell horn? You are confusing drivers and horns. Drivers like I mentioned in my write-up, choice between Altec, Beryllium drivers like TAD and Radian, and if one wanted a lower crossover point, Vitavox S2 or AER. This will also depend a bit on music tastes and preference. Horns - Markus Glug's Altec multicell replica for Altecs, other choice is Autotech JMLC (circular horn). There are also radial horns but I haven't heard one I have liked yet, and smaller circular horns called tractrix which are only required if you are crossing over muc lower. For multicells one needs space from sidewalls. All these can be rotated pretty easily once the speaker is ready very much like a cartridge, just easier and cheaper.
Why don't these vintage dual woofer designs (or modern iterations thereof) place the midrange and treble driver in the middle of the cabinet, instead of on top of the cabinet? The Rey audio designs of TAD speakers are MTM though closed box. I haven't heard one, can be done
How would you rate and compare Altec multicell horn + Altec woofers on vocals and "girl with guitar" versus Apogee Full Range or Grand, and versus Analysis Audio Omega? Already compared it to Grands and electrostats. Beryllium drivers are more like electrostats, on the higher mids. Altec is also very good but this is where preferences of transparency to recordings and see through transparency will come into play.
Have you had occasion to listen to planers at one or more points during this FLH inquiry and Altec search process? Do you not miss at all the open-ness and sonic spaciousness of planars? I have heard Apogees and Logans since I heard the silvercore and the Berlin JBL, not since the Altecs. No I don't miss that as these are very open and spacious. In fact horns Universum is extremely electrostatlike, better, where it loses out to dual woofer FLH and to Apogees is the midbass below.
In the course of your travels did you come across anybody who uses a plasma super tweeter on top of his FLH speakers? No. That said I prefer the mids and highs of TADs and Radians much more to the Acapella (similar high frequency transparent sound) as well as AER. Tweeter should be selected upon what mids driver is selected, and sometimes can be a smaller compression driver of the same family
Where does YG driven by your favorite Audionet amplifier rank in your current loudspeaker pantheon? I think we have had this discussion 50 times or more, but my frustration shows because you will never accept the importance of digital, else you would have worded the question differently. To have a lower sensitivity system, I will set it around Lampi. Which means a Pacific 242 with the audionets (because I heard this and it was the best source I heard, better than all analog and orginals), with a speaker that is capable of being driven by the audionets. YG is a top choice for that. This could be better than the dual woofer FLH, for completely different reason, because the Lampi 242 properly tuned creates the best dynamics, dynamic range, nuance and grip that I have experienced in audio. It is not at all surprising that all those who own Lampi and stellar analog set ups are listening 80 to 90% to their digital. And this is not for convenience. The only issue with this is that I cannot afford the audionet, so I have to find a cheaper alternative that I do not have, or tune my Lampi 242 similarly with a SET amp on the FLH.