[Royster]

I'm new to this group so thanks in advance for your patience and I'm sure this topic has been beaten to death. I really like my MMGs but heaven help me...I have the need to mod. After getting to the crossover I notice I have a 14 mf cap, a 100 mf cap and a inductor of unknown value (2.2 mh?). None of the pictures, drawings or schematics I have seen online show a 100mf cap. I understand I need to replace the 14 mf cap and the inductor with better parts. Question #1 what is the 100 mf cap for? Question 2, how do I figure out what the value is for the inductor? Question 3, any suggestions on the 14 mf cap? I really do appreciate any help you can give me.

[Davey]

The later MMG's utilize a single capacitor (12uF) and a single inductor (2.2mH.)  You may have an earlier set, but I'm not sure what a 100 microfarad capacitor would be doing in there.  Maybe somebody has modified these speakers?

Just so you/we don't get confused, change your labeling since "mf" would normally refer to millifarad, and not microfarad.

http://www.integracoustics.com/MUG/MUG/tweaks/MMG%20XO%20Diag.gif

Anyways, just changing the components to better "quality" is a complete waste of time.....in my opinion. 

Your best best is to remove the whole crossover and convert the system to a bi-amp setup with line-level crossover.

Cheers,

Dave.

[rlee8394]

Not knowing how the 100uF cap is connected, if it is in series with the 14uF, that would equate to a 12.28uF cap, depending on the true value of each.

Ron

[Royster]

Thanks for the responses. I misspoke, it's not a 14 but a 12uF cap. According to Magnepan my speakers are barely a year old although I did buy them used. The 12 & the 100 are wired in series and appear to be factory installed. The 100 is an electrolytic & the 12 is film. I'm just gonna rip it all out and replace with a good 12uF cap and an air core 2.2mH coil and call it a day. I will probably sprinkle some fairy dust in there before I button it up.

[Davey]

I'm not buying that a 12uF and 100uF capacitor are wired in series and factory installed.  Your speakers have been modified in some way.....and by someone who didn't have a clue what they were doing. 

However, your plan of replacing everything with a 12uF and coil should be fine.  Use a coil that has fairly low DCR if you want to duplicate the insertion loss of the factory coil.  Otherwise you will alter the high/low balance of the speakers.

Cheers,

Dave.

[SteveFord]

Davey,
There are now 4 different versions of the MMG if you include the Super version.
Are there schematics available for all four?

[Davey]

Steve,

I haven't seen any of those schematics, but even still, it makes no sense at all to wire two disparate value capacitors like that in series.  (All kinds of issues when you do that.)
I'm assuming that they actually are in series.    It's possible that Royster is not evaluating/viewing the wiring configuration correctly.

Cheers,

Dave.

[Royster]

Dave, you are right, I may not be viewing and/or explaining this correctly. I'll draw the circuit out.

[Davey]

Yeah, good idea.  Post a photo.

A 100uf capacitor is a very large value for most speakers.  It would be physically large too.

It's possible somebody wired a large capacitor like that in series with the whole speaker to create a low-frequency high-pass network for better integration to a subwoofer setup.  That's my guess.

Dave.

[Royster]

Thanks Dave, when you say using a coil with a fairly low DRC, what do you mean by fairly low?

[kevin360]

Yeah, good idea.  Post a photo.

A 100uf capacitor is a very large value for most speakers.  It would be physically large too.

It's possible somebody wired a large capacitor like that in series with the whole speaker to create a low-frequency high-pass network for better integration to a subwoofer setup.  That's my guess.

Dave.

I actually did something like that a long time ago. They were called Maggie Mates. I gave them to someone on that other forum. They did the job they were designed to do - relieve my MMGs of some bass. Here's a photo of them. By this time (3rd mod, according to the name of the photo), I had completely eliminated the connector plate, but I still had lots more fun ahead of me.

[Davey]

Thanks Dave, when you say using a coil with a fairly low DRC, what do you mean by fairly low?

The stock 2.2mH coil in the MMG's is 0.6 ohms DCR.  So, you'd want to be in that neighborhood.

Dave.

[Davey]

After some thought (always dangerous when I do that) 100uF seems like too low a value to provide a suitable integration to a subwoofer.  (-3db at 400Hz.)  Maybe this was some sort of attempt at a three-way system?

Regardless, it seems the intention is to remove everything anyways, so I suppose it doesn't matter much what the mysterious 100uF capacitor was used for.

Dave.

[Royster]

The fairy dust must have worked! I took the 100uF caps out and now I have new speakers! The midrange is beautiful whereas before it was very congested. The soundstage has snapped into focus. The balance is great. Thanks for your help. I can't wait to hear them after I've treated my cables with unicorn urine.

[kevin360]

That's good news, but did you snap a photo before changing anything? I imagine that a number of us would like to see such a picture.

Be careful with the unicorn urine - only takes a drop or two. 

[dpump]

I replaced my cap with a Dayton Audio#027-246 and the inductor with an Erse#266-906, both from Parts Express. Also bypassed the attenuator jumper and fuse. I  heard some improvement. Sound Anchor stands also make an improvement, but may not be worth it new. I got my stands used for a good price. Of course, as was stated above, biamping with an outboard electronic crossover would be the best, but not very cost efficient.