air core inductor vs. iron core inductor - diyAudio
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Old 6th May 2007, 11:02 PM   #1
WBS is offline WBS  Tibet
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Default air core inductor vs. iron core inductor

While I have one of my MMGs apart to replace a torn panel, I'm wondering if I should replace the 2.2mH iron core inductor with a heavier gage air core inductor of the same value.

Would there be any sonic benefit in doing so? It is attached to one side of the midbass panel. A 12uF polypro is between the other side of the midbass and the tweet panel.

Any thoughts?
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Old 6th May 2007, 11:40 PM   #2
BudP is offline BudP  United States
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WBS,

The only iron core inductor better than the hockey puck air cores or film / foil air cores are the non saturable reactors of the type pioneered by Peerless for Altec ever so many years ago. These are not easy to find and if you want to explore them PM me, I can help you locate some.

Bud
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Old 7th May 2007, 03:47 AM   #3
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Quote:
Originally posted by BudP
WBS,

The only iron core inductor better than the hockey puck air cores or film / foil air cores are the non saturable reactors of the type pioneered by Peerless for Altec ever so many years ago. These are not easy to find and if you want to explore them PM me, I can help you locate some.

Bud
Hi BudP,

The schematic for the version of MMG model I have is posted here:
http://www.integracoustics.com/MUG/M...0XO%20Diag.gif

After reading a post from a guy who recommended winding your own air core inductor, I found an air core inductor calculator here:
http://colomar.com/Shavano/inductor_info.html

My stock MMGs sound pretty good. I'm just wondering if I can improve the sound noticeably by winding and substituting an air core inductor using heavier gage wire for the puny one that is there. I'm hoping that bass response might improve and tighten up as a result. I figure Magnepan used the cheapest parts available in order to keep the cost down on its loss leader speakers.

The inductor shown in the picture you attached to your post would be too big. There is only a fairly small, flat space available in these planars.

Thanks for your ideas!
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Old 7th May 2007, 04:49 AM   #4
BudP is offline BudP  United States
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Replacing the inductor to increase bass might not be a worth while idea.

Is this a model that uses a regular cone woofer for bottom end? If so, reducing the DCR will help with slightly more power to the woofer but an air core is not going to help that driver match the clarity of the Planar driver.

You could learn how to apply the EnABL process to the woofer and have it match the planar speed and clarity exactly. If this interests you go find the EnABL + Mamaboni thread over in the Loudspeakers Loudspeakers forum and begin reading.

The Mamboni process will help enormously and is much more intuitive than the EnABL process. They will provide you with similar results. Using both is possible but it may end up putting your planar in the shade for clarity and musicality. Can't hurt to read about it, anyway.

Bud
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Old 7th May 2007, 02:31 PM   #5
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MMGs are entry level maggies. They have only one panel each with a bass/mid circuit and a pseudo ribbon tweeter circuit. No cone woofer at all.

Thanks for the tips Bud. I'll check them out for more info.
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Old 7th May 2007, 11:02 PM   #6
lne937s is offline lne937s  United States
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I have a pair of MMG's on which I have replaced the crossover.

The Iron core inductors they use are not the greatest (~ .45 ohm DCR) - I would try a heavier guage laminate core like the Erse (~.18 ohms DCR) they have at PartsExpress. For low passes coils at those frequencies, I tend to follow the low DCR camp.

I also changed all the values and went with a 2nd order low pass:
30uf high pass cap
33uf low pass shunt
2.5mh inductor

I believe the lower crossover point helps them image better. The tweeters on newer MMG's are essentially the same as MG12's, so they can handle the lower frequency. External crossovers are a must, as the upgraded parts will not fit.

I used ASC x386s caps on the high pass from Allied Electonics, bypassed with vishay roederstein on the high pass. I am in the process of replacing the low pass with x386s also....

for the money, I don't think you will do much better...
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