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Magnepan MG-12 Crossover upgrade
Magnepan MG-12 Crossover upgrade
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Old 28th May 2011, 04:47 PM   #11
gootee is offline gootee  United States
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I would have to guess that Andyr knows what he's talking about. He's spent a LOT of time experimenting with his maggies. His posts on the Planar Speaker Asylum are a good testimonial for his knowledge and experience.

I ordered the 16 ga because I wasn't certain what effect they would have and didn't want to spend the money for the 12 ga until I saw what the difference might be with the 16 ga, compared to the stock inductors, and also because people said that even the 16 ga made a big improvement. In retrospect, I probably should have ordered the 12 ga right off the bat.

The DCR (DC Resistance) of the 16ga ERSE 2.7 mH FoilQ air core inductor is rated at 0.669 Ohms while the 12 ga is 0.365 Ohms (according to Madisound, at least). I don't know the DCR of the stock iron-core 2.7 uH inductor in the MG12. But I have heard that it might be around 0.3 Ohms (derived from DCRs of available similar iron-core inductors). I will measure mine, once I get them disassembled, and report back.

A higher inductor DCR in the MG12 crossover would tend to give less bass, and would also change the crossover frequency. But the air core should make the bass "better", since it wouldn't have the hysteresis or saturation effects of an iron-core inductor.

I think that, in the end, we will want to match the DCR of the stock iron-core inductor, as closely as possible, if we don't want to change the crossover point and don't want to attenuate the bass at all because of a higher DCR. That would mean that the Erse 12 ga should be used instead of the 16 ga.

That being said, the text at the following "MG12 crossover upgrade" link ( magnapan3 ) claims that with the 16 ga Erse air core inductors, the bass is much better. But he also upgraded the caps (but to approximately the same values as the stock ones). Here is a quote: " ...the caps will have to break in again, perhaps another 100 hours or so, but you will notice an immediate improvement. On my speakers, the midrange is stunningly smooth and clear, and the bass seems to go much lower with more slam. The bass keeps improving during the break-in process. I turned off my subwoofer weeks ago, and don't miss it at all". (His comment about the bass improving during the break-in process might point toward the bass improvement he's hearing being related more to the capacitors.)

One would also need to be very careful to ensure that the conditions for comparison were exactly the same. For example, I recently moved my MG12s just slightly (about 18 inches or so away from center, with slightly-increased toe-in to compensate), in order to place a pair of Vandersteen 2Ce speakers in listening position. When I reconnected the MG12s, after a week or so of listening to the Vandys, without moving any of them, I was absolutely stunned by the improved bass response of the MG12s. I thought I had tried them "everywhere" in this room, but moving them slightly changed everything! I actually think they might have a little TOO MUCH bass, this way!! They have very-significant bass "SLAM", now, which I never really experienced with them, before. And very low sustained bass notes are incredibly strong, yet everything is still perfecly clean and clear, and seems properly proportioned. The mids and highs seem better, too. So it looks like "room placement is everything"! (Or, maybe it's the fact that the Vandys are still nestled up against the inboard edges of the MG12s? I guess I'll have to experiment some more...)

It might be interesting to temporarily wire all of the old and new crossover components in parallel, with a switch for each pair of components (old vs new), so the effect of changing each component could be judged, or measured.

Cheers,

Tom

Last edited by gootee; 28th May 2011 at 05:15 PM.
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Old 28th May 2011, 05:21 PM   #12
gootee is offline gootee  United States
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Just FYI: The Erse 12 gauge 2.7 mH FoilQ air core inductors are $73.30 each, at madisound.com, versus $33.50 each for the 16 gauge.

And a small correction: I think that the stock inductor in the MG12 is 2.8 mH, not 2.7 as I stated. Oh, I did also put uH when I meant mH. Sorry about the errors.

Last edited by gootee; 28th May 2011 at 05:31 PM.
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Old 1st June 2011, 02:33 PM   #13
waynebosz is offline waynebosz  United States
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Default 12ga vs. 16ga. inductor

I will be keeping my ERSE 16 ga. 2.7mH FoilQ inductors for my MG12 crossover upgrade project when considering the remarkable price difference.
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Old 2nd June 2011, 03:48 AM   #14
gootee is offline gootee  United States
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I would probably consider going to a different type, with a DCR that more-closely matches that of the original inductor. They can be much cheaper, and are still better than the original.
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Old 2nd June 2011, 03:20 PM   #15
waynebosz is offline waynebosz  United States
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Default Maggie MG12 Inductors

Wow! I pondered this issue all evening and made a critical decision to return my 16ga for 12ga to bust the bank. Which inductor would be a better match for the 2.8mH inductor already in place? I'm totally baffled now, but if I can correctly match and also save a considerable amount of duckets - please help!

Again, thank you for your reply.
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Old 3rd June 2011, 08:57 AM   #16
andyr is offline andyr  Australia
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Quote:
Originally Posted by gootee View Post
I would have to guess that Andyr knows what he's talking about. He's spent a LOT of time experimenting with his maggies. His posts on the Planar Speaker Asylum are a good testimonial for his knowledge and experience.

Cheers,

Tom
Thanks for your kind words, Tom, but unfortunately I am a bit lacking when it comes to passive XO components (having gone analogue-active, many years ago).

But harking back to Waynebosz's last post, I would suggest that whatever 2.8mH 12g ribbon coil you can get hold of, would be fine. (15 years ago, when I rebuilt my external IIIa XOs, I used 12g Solo (now Alpha-Core) ribbon coils but Michael Percy seems to be winding his stock down, today. So they are no longer to be had. )

From my experience with active, I don't agree with the "you should match the DCR of the stock coils" theory. IMO, the less DCR there is between the amp and the driver, the more dynamic the bass will be. (So active is the optimum, if you like dynamic bass. )

Sure, getting a 12dB ribbon coil with a DCR of 0.3 ohms (vs. the 0.36 ohms of the stock coil) will:
a) raise the low end of the bass slightly, vs. the treble, and
b) change the bass roll-off frequency, slightly

... but IMO these are minor, compared to the improvement in bass slam.

Regards,

Andy
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Old 3rd June 2011, 04:32 PM   #17
waynebosz is offline waynebosz  United States
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Default 12ga vs. 16ga. inductor

It's that "SLAM" bass that I will be anticipating to experience.

Best,

Wayne
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Old 3rd June 2011, 08:04 PM   #18
gootee is offline gootee  United States
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Here's a 2.7 mH 14ga with 0.370 Ohms DCR, for $50: https://www.madisound.com/store/prod...products_id=41

I don't remember seeing that one when I was ordering or I probably would have gotten it instead of the Erse!

And here's a 2.75 mH 14ga one that's wire instead of foil, with DCR of 0.390, for $34:

https://www.madisound.com/store/prod...roducts_id=896

And here's the 2.7 mH "Sledgehammer" with wire and a steel laminate core and a DCR of only 0.168 Ohms, for $15.10:

https://www.madisound.com/store/prod...roducts_id=864

Edit: Here's another source of inductors/coils: http://www.northcreekmusic.com/COILS.html

I guess I really need to measure the DCR of the stock coils, before I can decide what DCR to go after. But the price of the "sledghammer" coils is so low I'll probably also buy a pair of them, just to try them out.

Here's a discussion about the effects of using a different DCR than the stock crossover:

Audio Asylum Thread Printer

And here's another good discussion (but note that his initial negative findings about the effect of the coil were later found to be due to a loose connection):

Audio Asylum Thread Printer

Whoa! In the article linked below, which is about upgrading the MG1.6, it says this: "...Magnepan's explicit recommendation not to replace the stock inductor by an air core foil type". (But the link that is said to explain more about that is dead.)

Paco's 1.6 Modifications

I guess I'll try the Sledgehammers first?

Last edited by gootee; 3rd June 2011 at 08:12 PM.
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Old 3rd June 2011, 09:26 PM   #19
andyr is offline andyr  Australia
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Quote:
Originally Posted by gootee View Post
And here's the 2.7 mH "Sledgehammer" with wire and a steel laminate core and a DCR of only 0.168 Ohms, for $15.10:

I guess I'll try the Sledgehammers first?
Yes, the steel laminate core enables you to use a smaller length of wire to get the same mH rating ... but IMO, air-core gives better SQ. The DCR of a 12g ribbon coil will be more than the Sledgehammer but will be less than the DCR of the stock coil.

For bass LP filter purposes, there are also the North Creek 12g wire coils.

Regards,

Andy
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Old 3rd June 2011, 09:28 PM   #20
gootee is offline gootee  United States
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I noticed that the 2.7 mH Sledgehammer is out of stock at madisound.com, but parts-express.com has the similar-looking Erse SuperQ coils. But they only carry the 16ga, apparently, for $18.98. And they don't appear to list the DCR. At ERSE - Super Q , they show the DCR as 0.163 Ohms and sell it for $16.58.

However, at ERSE - Super Q they have a 14ga version with a DCR of 0.118 Ohms, for $19.91. I guess I'll try those, in addition to the foil air core coils that I already have, and might also try some wire air cores (maybe I'll try winding my own). Wow, the 12ga North Creek ones would cost $120 each. Ouch.

Oops, it looks like erseaudio.com is "temporarily out of stock" on both the 14ga and 16ga 2.7 mH SuperQ coils.

I think maybe I'll just do the capacitor upgrades first, and see what effect that has, and do the inductors at a later date.

Last edited by gootee; 3rd June 2011 at 09:39 PM.
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