I used my Altec 604e with the original N-1500 crossover.
After 10 years I bought an autotransformer DIY crossover from Germany. I liked it more than the original one. As I understand lately the schematics of this new crossover wasn’t good but better parts quality made speakers sound more transparent despite losing some neutrality.
Then I upgraded it with Duelund RS, Jupiter VT and Duelund Cu-Sn bypass that made the sound even better - more resolution, tone and clarity.
When I bought a measurement mic MiniDSP I found some significant issues with this crossover schematics that caused serious dips in frequency response.
So I decided to build the original N-1500 with better parts. I used old N-1500 inductors with Duelund RS, Jupiter VT, Jensen Aluminium foil, Duelund Bypass (Cu-Sn and Silver) that I already used in German crossover plus constant Duelund Cast resistors (that I used instead of variable resistor in original N1500). So I get even better and more neutral sound with much better midrange and bass. In the end I exchanged the inductor to Jantzen copper foil Wax Coil inductor that improved dynamic and bass even more.
I never tried the famous Mastering LAB crossover that should improve bass extension of price of sensitivity and smooth high frequency frequency response. I don’t think it will sound better than my current crossover that use much better quality parts than Mastering LAB does.
