[cpalcott]

I have 2nd gen Magnepan MMGs in Magnestand style wood frames. I'm using Ant-Cables Level 3 (4 twisted 12awg conductors) from an NAD C390DD integrated (Hypex Ncore).

Here's what I'm thinking...

High Pass: (16uf total value)
(2) Solen 7.5uf capacitors
(1) Jantzen Z-Superior 1uf bypass capacitor

Low Pass:
(1) Solen 2.0 MH Air Core Inductor
(1) Vishay 25uf shunt capacitor

Choke Tweak? Conjugate (Zobel/RC) Network (Econotweaks Detail Magnifier or DIY)? Both? Neither? Thoughts?

[Davey]

What is your objective??

FYI, a second-generation MMG has a single inductor and single capacitor in the network.  Your thinking describes a topology much closer to the earlier generation.
Are you sure your speakers are not an earlier version?

A conjugate usually indicates an LCR network at the crossover input for leveling the impedance sweep.  You should not need one unless your amplifier has significant output impedance......which yours doesn't.
The switching frequency of the Ncore amp should not cause the MMG tweeters any problem at all......or vice-versa.  I would suggest not using the choke tweak.

Cheers,

Dave.

[cpalcott]

Hello Davey and thanks for the reply. It definitely is a 2nd gen mmg, and came with a single cap and single inductor as you described. These cap/inductor values are ones you had suggested on a number of threads. I was just thinking I might be able to squeeze out a little more warmth by using multiple capacitors to reach the suggested 16uf with a higher quality bypass cap of sorts to impart it's flavor on the rest of the caps. I've read about this approach, but have no experience with it so I can't say if t has any merit. Not sure if the shunt cap on the inductor would do any good at all, but I thought it might be worth a try. I guess I'm really trying to make the 2nd gens sound more like the 1st gens I used to have. Glad to hear the choke and conjugate network are not necessary with my amp!

[Davey]

I don't believe I suggested a shunt capacitor for the woofer network, but the other (basic) values are good.....IMO.
I also strongly recommend a series resistor on the MMG tweeter.  The top end is much too hot without it.....IMO.

For info, this is a photo of the latest MMG crossover that I used:
The inductor is a 2.0mH Solen.
The capacitor is six 2.7uF Panasonic polys in parallel.
The tweeter series resistor is 1.5 ohms.

That setup works just fine.....IMO.

Dave.

[neolith]

The first gen MMG had a 4 ohm tweeter while the 2nd gen tweeter is 2.6 ohms. You can confirm if you have a multimeter.  As you note the 2nd gen has 1st order LP and HP filters while the 1st gen is 2nd order LP and 1st order HP. Putting the 1st gen crossover into the 2nd gen speaker will not give you the right sound.
Can I sell you on biamping with a PLLXO? The cost of the crossover will be less than a dozen donuts (gourmet, of course) and a suitable used 2nd amp will probably be in the range of your contemplated new crossover. Much more to be had, going this route.

[Davey]

For reference, the current version (2nd generation) MMG has a tweeter that measures 3.6 ohms and the woofer measures 4.8 ohms.

The tweeter is a flat line and resistive across its entire range.
The woofer is mainly resistive also, but inductance starts to raise the impedance value at high frequencies.  It's 7.6 ohms at 20khz and rises from there.

Since fairly good results can be obtained with a simple network on these, it's my opinion that a line-level crossover has a limited (relatively speaking) potential for improvement on the MMG.  If a person has easy/cheap access to a second amplifier, it's worth doing, but it's not a show-stopping difference.   IF the same simple transfer function is maintained.

Dave.