I've built and listened to many speakers over the years, but have recently come up with a design that is really very good. It is based on a Jordan JX92S transmission line by Carolina Audio ( http://www.carolinaaudio.com/ ; Ronnie is a very nice guy to deal with) and an ESg2 ribbon distributed by E-speakers.com ( http://www.e-speakers.com/ ; Andre is also very helpful). The speaker fulfills many criteria that I had: use minimal number of drivers of high quality, shielded drivers for potential home theater, no MTM or dipole configerations, time/phase aligned, 1st order x/o, play loud, have great detail and imaging, have flat frequency and impedance plots, and not be too large.
The speakers fit all of these criteria and sound wonderful with all types of music. (Although be aware that the Jordans definitely require some serious break-in time.) The JX92S + ESg2 are flat from 50 Hz to 20+ kHz (limit of my measuring system) within 2 dB. (The ribbons are flat to 30 or 40 kHz.) With a pair of subs (12" BagEnd x/o at 100 Hz, 1st order passive going into my main amps for the JX92S), the system is flat to 25 Hz, being -3 dB in my room at 20 Hz. I've played them at 100 dB continuous, measured from the listening position 2 meters from the speakers and they sounded very smooth and dynamic (powered with 350 W/8 ohm monoblocks). In fact, they are so good, I'm selling my Quad 988 that I compared them to when I built them.
The crossover is very simple, but only arrived at after many weeks of measurements and listening tests using impulse, freq resp, and in room warble testing. While the JX92S appears flat on the manufacturer's graphs, I believe the upper frequencies are only flat due to cone breakup distortions adding to the signal. Removing them using the x/o described below, helped improve them. The freq response is also flat to 45 degrees off axis. Since this is not a dipole room interaction is minimized. Imaging is superb. The speakers can be aimed to cross in front of you for a wide sweet spot extending from speaker to speaker, or aimed to cross outside your head for better depth and a wider soundstage while making the sweet spot narrower.
The x/o uses a 1.5 mH inductor in series with the JX92S (I tried series x/o but I could not get it to measure or sound proper). Also, a Zobel consisting of a 4.7 microfarad capacitor in series with a 6 ohm resistor is used on the Jordan. The ribbon is crossed over with a Auricap ( http://www.audience-av.com/passive.htm ): 3 microfarad/200V with an L-pad of 5 ohms in series and 3 ohms in parallel with the 8 ohm ribbon. This creates 8.5 dB of attenuation with a tweeter impedance of 7.2 ohms. The overall speaker impedance is about 5.5 ohms and is ruler flat from 100 Hz to 20 kHz.
The ESg2 ribbon is recessed on top of the cabinet by about 18 mm to time align it with the Jordan. The whole package is about 42 inches tall, 7 inches wide and 9 inches deep, so the speakers are not intrusive (not counting of course the subs). The Jordans are about 36 inches from the floor, so head level falls between the Jordan and ribbons, depending upon your sofa/chair height.
I think this about covers everything. Good luck if you give them a try.
Regards, Robert
The speakers fit all of these criteria and sound wonderful with all types of music. (Although be aware that the Jordans definitely require some serious break-in time.) The JX92S + ESg2 are flat from 50 Hz to 20+ kHz (limit of my measuring system) within 2 dB. (The ribbons are flat to 30 or 40 kHz.) With a pair of subs (12" BagEnd x/o at 100 Hz, 1st order passive going into my main amps for the JX92S), the system is flat to 25 Hz, being -3 dB in my room at 20 Hz. I've played them at 100 dB continuous, measured from the listening position 2 meters from the speakers and they sounded very smooth and dynamic (powered with 350 W/8 ohm monoblocks). In fact, they are so good, I'm selling my Quad 988 that I compared them to when I built them.
The crossover is very simple, but only arrived at after many weeks of measurements and listening tests using impulse, freq resp, and in room warble testing. While the JX92S appears flat on the manufacturer's graphs, I believe the upper frequencies are only flat due to cone breakup distortions adding to the signal. Removing them using the x/o described below, helped improve them. The freq response is also flat to 45 degrees off axis. Since this is not a dipole room interaction is minimized. Imaging is superb. The speakers can be aimed to cross in front of you for a wide sweet spot extending from speaker to speaker, or aimed to cross outside your head for better depth and a wider soundstage while making the sweet spot narrower.
The x/o uses a 1.5 mH inductor in series with the JX92S (I tried series x/o but I could not get it to measure or sound proper). Also, a Zobel consisting of a 4.7 microfarad capacitor in series with a 6 ohm resistor is used on the Jordan. The ribbon is crossed over with a Auricap ( http://www.audience-av.com/passive.htm ): 3 microfarad/200V with an L-pad of 5 ohms in series and 3 ohms in parallel with the 8 ohm ribbon. This creates 8.5 dB of attenuation with a tweeter impedance of 7.2 ohms. The overall speaker impedance is about 5.5 ohms and is ruler flat from 100 Hz to 20 kHz.
The ESg2 ribbon is recessed on top of the cabinet by about 18 mm to time align it with the Jordan. The whole package is about 42 inches tall, 7 inches wide and 9 inches deep, so the speakers are not intrusive (not counting of course the subs). The Jordans are about 36 inches from the floor, so head level falls between the Jordan and ribbons, depending upon your sofa/chair height.
I think this about covers everything. Good luck if you give them a try.
Regards, Robert