Magneplanar -- I'm doing the SMG crossover upgrades

[Feanor]

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Feanor,
I'm sorry I can't answer your questions about lowering the high pass and making it 2nd order. I don't have that kind of technical knowledge (I'm pretty sure yours exceeds mine in this area).

Basically I simply "cut and pasted" the new capacitors and inductors into place and copied the original wiring schematic. I used a 7mfd + 7mfd + 8mfd capacitor array which replaced the 10 + 6.8 + 5.1 original array. Oddly, there was no 0.1mfd bypass cap that I could see. This bypass cap is on the schematic (I have the same one you do), but darned if I saw it anywhere. On the inductor side, I just snipped the wires from the original inductor and left it sitting in place. There's no way the new inductor was going to fit in the same space. I did not change 25.0 mfd bypass on the inductor side.

I gritted my teeth when I cut the sock, but it turned out to be very easy. I cut along the bottom edge of the crossover compartment and then up the sides to the top edge. I rolled up this "flap" (kinda like a rolled up awning) and pinned it along the top edge of the compartment.

My biggest fear was the soldering part. As feared, I did a messy job but everything seems secure, if not aesthetically first class. I will see if I can get a couple of pictures.

tx,
Bill

ps. Yes, I definitely think the effort was worth it.

Bill, your comments are very helpful indeed, and do encourage me to try this.

In particular I'm interested to hear the you cut the sock rather than trying to remove it as some people suggest; I think I'd user your approach. Your pictures are great, BTY, and answer the question whether you used the original cable connectors and fuse, (yes), unlike squeegy who is providing new connectors on account of his completely external crossover box.

From what I know, the most critical upgrades would the high-pass capacitors, but clearly a better low-pass inductor couldn't hurt. The 0.1µF capacitor would have almost no effect on the crossover point; I think the theory is that these low value capacitors in parallel with higher value ones provide better transient response. However I'm not sure whether this effect is proven or significant.

I doubt I'd try it, but as a matter of interest, a 2nd order high-pass would involve some increase in the capacitance (to lower the crossover point a bit) and inductor in parallel with the tweeter itself (to increase the crossover slope from 6 to 12 dB per octave). Note a 2nd order crossover induces 180 degress of phase shift so it would be necessary reverse the polarity of the tweeter -- from the diagram, it looks like the standard crossover has the tweeter opposite phase so you'd be bringing it back into phase.

Right now I user bi-wiring so I bypass the jumpers; also, I user a part of Hi-Fy Tuning fuse in place of the stock ones. These fuse are $60 a pair and make a slight, positive difference -- you'd no doubt get more improvement by simply bypassing the fuses.