GR-Research Line Force First Transparent Speakers?

The drivers have gone up in price because of the cost of neodymium magnets (vast majority from china). They are what makes these little planar magnetics so efficient. To make a real line source with the Neo Tens, crossed at the 160 Hz he mentions, the speakers will need to be at least 8 feet tall. The tweeter section can be shorter but you would need enough of them to match output and impedance. I can imagine these being a great speaker. As compared to my favorite ESLs the only downside I can think of is having to use a crossover in the midrange. From what I have seen so far dispersion characteristics may not be as controlled as a Sound Lab style ESL. They would be a much easier load than ESLs and way more efficient. Doing them in kit form would be an easy build but you are looking at around $3000 in drivers alone and you have not gotten into the bass yet. 160 Hz is a bit high for a subwoofer crossover and these subwoofers need to be line source to match the rest of the loudspeaker. So, you would need to either build two floor to ceiling enclosures with four drivers in each or do what I do which is to arrange the subs along the base of the front wall making a horizontal line source. 
I would think a practiced DIYer could do the whole affair for $8000 which is not bad considering what you get. I would tri amp the whole affair and use digital crossovers. But, will they image? The big downside would be resale value. If you wind up not liking them you are going to lose a lot of money. I have no doubt that they can be made to sound excellent and probably made to image well but there is no way to know that for sure.

@douglas_schroeder , comparing any speaker to Tektons is a real insult. I am sure these GR speakers would handily out perform Tektons but then I don't know of many that wouldn't. 

I've been waiting to finish building these speakers for two years. I ordered enough Bohlender-Graebener NEO10 drivers from Parts Express before they became unavailable. But the company building the cabinets for me ran into Covid supply chain issues with the special composite material the cabinets are made from. I finally got the cabinets a few weeks ago and got them built up.

They only have about 25 hours on them so far, but they sound glorious. I can't wait until the crossovers are fully broken in. 

The Line Forces are being driven by DIY 300B Parallel SET monoblocks with WE new-issue tubes. The servo-controlled open-baffle woofers (three 12" drivers/channel) handle from about 170Hz and are powered by Rythmik 370W class A/B amps. 

Awesome @jaytor! I’m green with envy :-( . And I’m only a half hour or so away from you ;-) . I know of a few guys who replaced the magnetic-planar midrange driver in their Tympani T-IVa loudspeakers (which I own) with six or seven NEO-8’s. The NEO-8’s fit right in the slot the stock Magnepan driver sits in, and the owners feel the NEO-8’s provide a significant improvement to the T-IVa. But 12 or 14 NEO-8’s (when available) cost more than I paid for my T-IVa’s!

You still have your GR Research NX-Otica’s, I presume? With the OB/Dipole subs, of course. Glutton ;-) . I’ve been telling everyone about the sub for years, but you can only lead a horse to water. I suppose many are afraid of doing a simple DIY build of the H-frame the sub kit gets installed in, but anyone who did Jr. High or High School wood shop is up to the task. If I can do it, just about anyone can! I went with a W-frame (rather than an H-), and two of the 8 ohm drivers (rather than three of the 16 ohm).

@bdp24 - Thanks. I might have mentioned that I owned Tympani IVs in the mid 80's. I used Entec subwoofers (one of the first servo controlled designs), but I was never able to get these to fully integrate. I imagine that your OB subs work MUCH better. 

I'd be happy to have you over for an audition once my Line Forces are broken-in (probably a couple months for these crossover caps). 

I've always been intrigued by the Infinity IRS and Genesis One, but didn't have the budget or space for them. When I heard about the Line Forces, the idea of building a modern (and more compact) interpretation of these designs with more advanced and efficient drivers was exciting. 

It took a while to work out the details since these speakers weren't in production, but I've finally been able to complete them. Unlike the IRS and Genesis One, these are quite efficient at 98db/w, and easy to drive (impedance never drops below 5ohms), so they are a good match for low-power SET amps. 

These drivers are very clean and dynamic. The well-reviewed PS-Audio FR-30 uses similar planar drivers, but using a large number of them all but eliminates thermal compression, improves efficiency, and further reduces distortion. It also allows the drivers to play lower.