I have recently bought a pair from a kind gentleman who sent them to me their huge size notwithstanding. The original crossovers (schematics is somewhere on this site) were a bit tired sounding and gave too much mids for my taste. I researched the cornucopia of different filter networks for the combination of drivers which is huge (new “improved” Falcon and Wilmslow crossovers, old “improved” Falcon crossovers, the elusive Falcon “AusKEF” crossover (found only two blurry photos on the web, no circuit), Radford crossover, IMF crossover, Cambridge R50 crossover and more).
I did not want to spend much money on new crossovers and I wanted to keep the position of them on the front baffle – very handy for easy swapping of components. I did a lot of tests and finally settled for the circuit below. It incorporates the original aB circuit from the 104aB (not the “simplified” one which some of the Falcon crossovers use). The speakers sound fantastic now. I have a pair of KEF reference 105’s as a, well, reference. Strengths of the Concertos are a sweet, sweet midrange, a tuneful, deep and fast bass, and a treble that is never sharp. Imaging is very good (though not as spectacular as with the 105’s, but that would be hard to do).
I was even thinking of designing a circuit board to swap in the place of the old one, but I am short of time. I reused the original inductors apart from the one in the treble circuit, which needed a higher value. I turned the crossovers 180 degrees to accommodate the bigger components (there are also some elements on the solder side). I had to rotate the connector in order to do that. Now the Concertos are outstanding. They have this rare “rightness” about them. I tested them with my usual fleet of amps, among them a Kenwood KA-6000, Sansui TR-707, NAD 3140, Musical Fidelity B1, and Onix OA46 (all restored-recapped-upgraded).
See the circuit for the particular caps I used. The crossover is very sensitive of the type of cap. I tried various combinations (polyester, polypropylene, “raw” foil, “smooth” foil, aka LL, low loss). The caps in parallel to the drivers were – against some opinions I had found – MORE sensitive to the type and quality of the caps used there, particularly in the mid circuit. What is in the schematics now is what sounded most sensible after weeks of trials. I don’t have measurement equipment, but, as I said, the (serviced) served 105’s as a reference.
It was also VERY important to clean the connectors to the crossover, giving immediate audible results. I assume many reports of the Concertos performing sub-par have to do with dirty contacts here.
(PS Sorry, couldn't manage to upload the photo upright although it is taken and saved that way on my computer.)
I did not want to spend much money on new crossovers and I wanted to keep the position of them on the front baffle – very handy for easy swapping of components. I did a lot of tests and finally settled for the circuit below. It incorporates the original aB circuit from the 104aB (not the “simplified” one which some of the Falcon crossovers use). The speakers sound fantastic now. I have a pair of KEF reference 105’s as a, well, reference. Strengths of the Concertos are a sweet, sweet midrange, a tuneful, deep and fast bass, and a treble that is never sharp. Imaging is very good (though not as spectacular as with the 105’s, but that would be hard to do).
I was even thinking of designing a circuit board to swap in the place of the old one, but I am short of time. I reused the original inductors apart from the one in the treble circuit, which needed a higher value. I turned the crossovers 180 degrees to accommodate the bigger components (there are also some elements on the solder side). I had to rotate the connector in order to do that. Now the Concertos are outstanding. They have this rare “rightness” about them. I tested them with my usual fleet of amps, among them a Kenwood KA-6000, Sansui TR-707, NAD 3140, Musical Fidelity B1, and Onix OA46 (all restored-recapped-upgraded).
See the circuit for the particular caps I used. The crossover is very sensitive of the type of cap. I tried various combinations (polyester, polypropylene, “raw” foil, “smooth” foil, aka LL, low loss). The caps in parallel to the drivers were – against some opinions I had found – MORE sensitive to the type and quality of the caps used there, particularly in the mid circuit. What is in the schematics now is what sounded most sensible after weeks of trials. I don’t have measurement equipment, but, as I said, the (serviced) served 105’s as a reference.
It was also VERY important to clean the connectors to the crossover, giving immediate audible results. I assume many reports of the Concertos performing sub-par have to do with dirty contacts here.
(PS Sorry, couldn't manage to upload the photo upright although it is taken and saved that way on my computer.)
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