Thanks for the info and the encouragement, guys! It very nice.
OK, going to start talking crossovers. This is just the beginning. Crossovers can make or break a speaker. They are a full 1/3 of the speaker - drivers, box, crossover. All equally important. Many speakers do not live up to their full potential because of poor crossover design. There has been a lot of progress in the past decade on computer crossover design, but it only helps, it does not do the whole job - at least not well. It takes a lot of experience, time and effort to design a great crossover. I'm a novice, but learning.
So here we go!
My A7-500s came with the stock N-501-8 crossover. This is the 500Hz crossover for 8 ohm drivers. I have attached a schematic that I drew from the actual part. I measured all values. The inductors measure 2.7mH outside the crossover, but probably rise to ~3mH when mounted in the steel frame. I have called them 3mH. Also included is a photo of the insides. The caps are marked 28uF 125V and measure spot on. L-Pad is 24R & 5.6R Just a basic 2nd order crossover with L-Pad. No Zobel, no traps, no EQ.
The values for a nominal 500Hz, 2nd order Butterworth filter are 28uF + 3.6mH. So the N-501 has slightly smaller inductors than "textbook." The problem is, although the drivers are nominally 8 ohms, they are not 8 ohms at the crossover frequencies. (See impedance graphs in the next post.) So the frequencies are shifted a bit. Simulations show the 416-8A electrically crosses a bit higher, the 511/802 combo pretty close to 500Hz. Electrically speaking. I will try to measure both the electrical filter function and the acoustic points for further reference.
Here is the schematic I drew from the actual crossover and pix of the guts. Nice big L-Pad!
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