I own a pair of Super Alnico Monitors as well as a pair of wide-baffle Super 3's with RS5 drivers. I love both of them in different ways. I also managed to luck into a second pair of RS5 drivers. I had thoughts of a 1.5 way or omni implementation for the two sets of RS5's. However, over time I have managed to amass more equipment than I can use at one time. This both requires me to make choices (I have two rooms in which I can set up systems: the living room which also houses a HT system, and a small dedicated listening room which will only have one system).
The listening room setup currently has the Super Alnico speakers driver by an Inspire PSE amp (20 wpc KT77/KT88) and preamp. The ultimate speakers in this room will be Altec 414A/Altec 802D/Altec 32A speakers similar to the Shindo Petite Latour (
https://pitchperfectaudio.wordpress.com/2012/12/10/precious-petite/). In gathering parts for these speakers (drivers, horns, and crossover components that include custom-wound autoformers from Germany), I somehow managed to accumulate two pairs of Altec 414A's and one pair of 414-8C's along with a pair of Altec 614 cabinets. This changed my plans: The living room system can now accommodate the 614 cabinets and 414-8C drivers alongside the HT system in a built-in layout. The whole thing is getting a cool 1960's vibe (if you ignore the 65" 4k TV and Xbox One S).
Altec 414's will pretty much run with no crossover, rolling off naturally at 6dB/octave above 3-4khz. An accepted arrangement is to bring a HF driver in at 6-8khz at 6dB per octave. The listening room system will have 414A's (99dB) and 802D's (104 dB). However, I don't have a HF driver for the 414-8C's (96 dB) that will live in the living room. Not wanting to invest in another Altec HF horn system (hundreds of dollars), I started looking at other drivers such as the Heil AMT or horn loaded tweeters that would be good down to 3khz. It then occurred to me that I had an "extra" pair of RS5 drivers (94.5dB) laying around.
In the 1.5 way RS5 implementation, the driver is run full range (no crossover) and a second RS5 is brought in with a single inductor as a midbass driver. The RS5 treble response is in my opinion the better of the two Omega drivers I have experienced. Rather than use this pair of RS5's as full range drivers, why not use them as 5" "tweeters", filling in above the 96dB 414-8C? A single 3.3uF capacitor would roll off at 6dB/octave below 6kHz, complimenting the natural rolloff of the Altec. High quality cone tweeters are not unheard of: the JBL LE26 paper cone tweeter gives an honest 96 dB in this range, and in my opinion does not go as high as the RS5.
I don't think 1 or 1.5 less efficiency than the Altec is the end of the world - most music is happening below 3kHz anyway. And with all due respect to Louis, the alnico Altec 414 ("A" version specifically) is regarded as one of the best midrange drivers ever made, bettered only by a handful of considerably more expensive drivers (including the WE/Altec 755A and 728, both running 5-15 times the price of a 414A), with an effective cone mass of 32 grams for a 12" driver and a powerful Alnico motor.
I'll keep everyone in the loop with my experiences. I welcome any suggestions for the best way to mount the "tweeter" (I'm thinking maybe a miniature open baffle tweeter pod, perhaps with something to absorb the rear wave.
