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PostPosted: January 2nd, 2019, 11:56 pm 
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It just dawned on me! The word I was trying to remember regarding this whole coil issue was Hysteresis.

By definition:

When a ferromagnetic material is magnetized in one direction, it will not relax back to zero magnetization when the imposed magnetizing field is removed. It must be driven back to zero by a field in the opposite direction. If an alternating magnetic field is applied to the material, its magnetization will trace out a loop called a hysteresis loop. The lack of retraceability of the magnetization curve is the property called hysteresis and it is related to the existence of magnetic domains in the material. Once the magnetic domains are reoriented, it takes some energy to turn them back again. This property of ferrromagnetic materials is useful as a magnetic "memory". Some compositions of ferromagnetic materials will retain an imposed magnetization indefinitely and are useful as "permanent magnets". The magnetic memory aspects of iron and chromium oxides make them useful in audio tape recording and for the magnetic storage of data on computer disks.

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PostPosted: January 3rd, 2019, 9:44 am 
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Two items. First the valve stems were not only good but were also approved for TPMS which is the high frequency link that transmits tire pressure to the car's on board monitor. Some valve stem inserts must interfere with those RF signals. When you don't have to spend more for one valve stem in time and money than for 100 who cares how many you will use. In the case of the female terminals you will need a total of twelve so buying them locally will cost far more than on line. Please do whatever works for you. It was just a suggestion. It seems lately that trying to offer suggestions on this forum only brings a hail of negativity. Too bad.

Second, another way to look at bad placement of inductor coils is to think of them as primaries and secondaries of a transformer. The changing fields as the current changes through the coils act like the field in a transformer that couples them together. Tight coupling is good for a transformer but bad in a crossover.


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PostPosted: January 3rd, 2019, 9:59 am 
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SoundMods wrote:
It just dawned on me! The word I was trying to remember regarding this whole coil issue was Hysteresis.

By definition:

When a ferromagnetic material is magnetized in one direction, it will not relax back to zero magnetization when the imposed magnetizing field is removed. It must be driven back to zero by a field in the opposite direction. If an alternating magnetic field is applied to the material, its magnetization will trace out a loop called a hysteresis loop. The lack of retraceability of the magnetization curve is the property called hysteresis and it is related to the existence of magnetic domains in the material. Once the magnetic domains are reoriented, it takes some energy to turn them back again. This property of ferrromagnetic materials is useful as a magnetic "memory". Some compositions of ferromagnetic materials will retain an imposed magnetization indefinitely and are useful as "permanent magnets". The magnetic memory aspects of iron and chromium oxides make them useful in audio tape recording and for the magnetic storage of data on computer disks.


That is one of the reasons where in most situations an air core inductor is superior to one using a magnetic core. Air has no hysteresis. If the inductance value needed is so large that an air core inductor is impractical then using a premium magnetic core inductor such as the ERSE SuperQ series that I used in the eggs will help. The core is made of many very thin sheets of magnetic material which reduces eddy currents in the material compared to a solid slug and extends frequency response. Also, air will not saturate like a magnetic core when subjected to very large signals. It is always a trade off.


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PostPosted: January 3rd, 2019, 11:32 am 
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tomp wrote:
SoundMods wrote:
It just dawned on me! The word I was trying to remember regarding this whole coil issue was Hysteresis.


That is one of the reasons where in most situations an air core inductor is superior to one using a magnetic core. Air has no hysteresis. If the inductance value needed is so large that an air core inductor is impractical then using a premium magnetic core inductor such as the ERSE SuperQ series that I used in the eggs will help. The core is made of many very thin sheets of magnetic material which reduces eddy currents in the material compared to a solid slug and extends frequency response. Also, air will not saturate like a magnetic core when subjected to very large signals. It is always a trade off.


[color=#BF0000]When I was first working on my Altecs I figured why not go first class. I was able to obtain a nice pair of ribbon inductors for the low pass function. When I measured them agains the laminated-core inductors that Altec used they didn't measure as well -- the DCR especially was much higher than the laminated core inductors. So the ribbon inductors were relegated to the parts bin.

As it turns out -- Wilson Audio used to use air-core wire inductors and two years ago went to laminated core inductors. COOL! I never regretted my decision and I expect they haven't either.

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PostPosted: January 3rd, 2019, 12:38 pm 
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Tom
Walt
Shashi

Please stop. Take the theoretical and esoteric discussions to their own threads.

Steve is trying to attack his first build. He's flailing a bit, looking for help.

This one-upmanship is not helping to clarify the project build for him.

Steve doesn't need 100 Faston connectors, nor the finest air core inductors.

If the inductors are simply at opposite corners of an 8" board he'll be fine.

Let it be.


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PostPosted: January 3rd, 2019, 1:04 pm 
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Stuart Polansky wrote:
Tom
Walt
Shashi

Please stop. Take the theoretical and esoteric discussions to their own threads.

Steve is trying to attack his first build. He's flailing a bit, looking for help.

This one-upmanship is not helping to clarify the project build for him.

Steve doesn't need 100 Faston connectors, nor the finest air core inductors.

If the inductors are simply at opposite corners of an 8" board he'll be fine.

Let it be.



YUP! You're right.

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PostPosted: January 4th, 2019, 6:44 pm 
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Parts are delivered!

But, I can't pick them up until tomorrow or Monday.


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PostPosted: January 4th, 2019, 7:10 pm 
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:character-oldtimer: Patience Grasshopper.


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PostPosted: January 5th, 2019, 6:28 pm 
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Would a 5 inch x 7 inch thin piece of wood plaque be enough for it?

Found it at Walmart.


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PostPosted: January 5th, 2019, 8:23 pm 
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Depends upon where you are planning to mount to crossover.
5"x7" is too big to mount behind the drivers as it will not pass thru the driver mounting holes.

If you want to mount on the rear outside face of the cabinet, size is not an issue.

If not, draw out the component layout to scale on a square ruled pager and see if it fits in the bottom inside of the cabinet.

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