I just completed upgrading my old Mission Argonaut speakers. The new sound is great. The Argonauts are a two-way sealed tower with Mission "Super Elliptic Impedance Transformed" tweeters and a pair of Mission 8" woofers.
I mailed one of the old crossover networks to Danny Ritchie of GR-Research
. Danny is a professional speaker designer for several speaker makers as well as running his own shop. The best thing would have been to get one of my speakers to him in Texas and have him design new crossovers, but that wasn't worth the freight cost to me. Danny measured the values of the parts I mailed to him, evaluated the old parts, and gave me some options for upgrading, including some cost/benefit choices. The original resistors were suitable for re-use, and we used new inductors and capacitors.
For the tweeters we used an Alpha-Core air-core copper foil inductor
and Sonicap capacitor
with a Sonicap Gen II 0.1uf bypass cap. The woofers got the Alpha-Core inductor with an Erse cap
and Sonicap bypass.
I also added Danny's No-Rez
damping material, removed some of the original poly stuffing, and replaced magnetic nuts and washers on the binding posts with nonmagnetic parts.
My Mrs., no audiophile, got to A-B test the speakers after I had one done. She called the original speaker muddy sounding. After both were done, she said that they now sounded very good. The only thing she said before was, "can you turn them down?"
I'm very pleased with the results. The sound is clear, clean, accurate, and musical. The raspy sound of a saxophone is as clear as the sweet sound of a violin.