The speakers are of my own design modeled after the Infinity Reference Standard 1B. The old IRS models had an appeal to me from their birth and my versions indeed do them justice.
The 12 midrange drivers were originally from Monsoon PC speakers. I had to completely rebuild each one of them since the magnets had all but disintegrated. With a lot of patience and some magnets from Bruce Thigpen [he licensed the driver design to Monsoon], they were completely restored and their sensitivity improved.
The tweeter is a Mundorf AMT and the super tweeters are Monacor RBT-95. Panel layout took fourteen iterations in various lengths and widths before finalizing the design. A friend built the final panels after I was happy with the driver layout.
The woofers started out as a cardioid design with some tips from a local manufacturer but the baffle step issues just could not be resolved passively. Weird phase issues ensued so the design evolved into a slot-loaded rear port. I still have to rebuild the prototype cabinets but they sound pretty good as they are waiting for me to finish other aspect of the system with a higher priority.
The crossover networks are all phase-coherent Bessel fourth order using OCC wiring and of course quality components with the super tweeter network using all Teflon capacitors. Each network pass band is confined to its own external PC board so with a 4-way system, each speaker has four outboard crossover boards.
Both speakers use hand-made star-quad wiring, one speaker wire to each crossover network board, and one speaker wire from the crossover network board to the speaker panel. Each network board uses non-magnetic stainless-steel 1/4" bolts, nuts, and washers with solid copper terminals and more OCC wiring.
All panel wiring in this speaker is hand-made OCC star-quad and attenuators are all of 0.01% or better T-pad designs. This permits maximum power transfer and matching from the output impedance of the amplifier to the input impedance of each driver. If one measures the impedance plots for each driver through these T-pads, the impedance does not vary and is precisely what the crossover network expects to see. As one could expect, this takes a while to achieve since off-the-shelf resistor values may not be what is needed and series-parallel arrangements are required.
As a side note, I have found that the best sounding resistors used in the attenuator circuits are of the Nichicon chassis-mount non-inductive variety. I've also used heat sinks on these resistors to maintain better resistance stability.