This file has been on my desktop ever since I came to grips with the reality of losing the 1812s.Wayne wrote' "That G3Si ribbon looks very good, but the midhorn does not have response high enough to reach it. The 2123 as a direct radiator would do nicely paired with it though. That would make a very sweet sounding speaker, I'll bet.
Here's what I would do: I'd run the 2226 and the 2123 as direct radiators. Put the 2226 in 2.5ft3 cabinet tuned to 40Hz and put the 2123 in a sealed box larger than 0.2ft3. Mount them both on the same baffle, one on top of the other. Then place the ribbon above that.
With the midrange cabinet inside the main cabinet, you have a pretty nice external box size. It will end up being 3.5ft3 to 5.0ft3 outside, something like that. I think this is a real good speaker size range, because it is large enough to look substantial without being overwhelmingly large. It also makes it easy to put the mid and tweeter high enough to be over the furnature, great for seated listening.
The lower crossover point isn't critical, because wavelengths are long. The 2123 is going to have natural rolloff at 200Hz, so use that to set your woofer crossover point. I'd wouldn't even use a capacitor on the 2123, and for the woofer, I'd just use a 6.0mH coil in series and that's it. I've done a lot of speakers just like this and it sounds fantastic.
You could also go second-order on the woofer to match the rolloff of the sealed box mid, using a 12.0mH coil and a 47uF capacitor on the woofer and adding a Zobel. But I'd go with the simple first-order in this situation because it sounds great and the parts count is low.
The mid/tweeter crossover is going to be more tricky, both because wavelengths are shorter and also because most ribbon tweeters are fragile if you hit them with low frequencies. They're excellent, but you mustn't send them low frequencies. That is something they have in common with compression drivers - Not a lot of wiggle room. So my first thought is a second or third-order for the mid/tweeter crossover. I can't be more specific because I've used compresion horns and slot tweeters more than ribbons, and I've never used the Aurum Cantus G3Si. But I think this is probably where I'd start and see how it sounds."
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That's exactly what I did except for using the Fountek CD2 instead of the more expensive Aurum Cantus. John Kalinowski recommended it.
The BatSpeakers could be the basis for a 13 Pi!
Borrowed a pair of Delta 10's from the One Speakerman. With just a coil; way too bright. I put back the attenuation from the 2123: 15ohm R parallel and 10hm R series. Tamed the Delta right in line.
Tone, imaging and dynamics are great. The ribbon passed the Alison Krause test with high marks and the 2.5mV cartridge really appreciates the extra 3dB over the 1812's. (Did I tell you I don't even play CDs while I cook anymore.)
With the Delta available at $150 and all those 2226s floatin' around, the BatSpeakers become affordable and available. I'm sure the Vifa would do but the Fountek ribbon isn't that expensive compared to the JBL woofer. Total driver cost $700 for stereo.
This system obviously sounds quite a bit different from the 1812. There's less low-level detail and the bass is diminished from the
physical presence of the 2241. But it sounds familiar to someone who's "owned" the 1812s for over 8 months.
I'm listening to Emmy Lou Harris' Blue Kentucky Girl now and Dire Strait's Brothers In Arms before that and loving it!