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» Termpro Audio Forum » Component Specific Topics » Subs and Enclosures » long vs short coil

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Author Topic: long vs short coil
msholit
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going to recone a couple subs, i can choose between a short and a long coil, the original is the short one.

short one:

75mm width
40mm height
3.6 ohms

long one:

75mm width
50mm height
4 ohms

would there be any benefit to using a long coil?

i may be wrong but im thinking, the longer coil is less efficient than a shorter one... but may be able to handle more heat.

im trying to keep things as efficient as possible.

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GA Loan
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not sure but, i think you may have issues with the coil & former bottoming out on the back plate if you use a longer coil than original. maybe talk to jacob fuller(sundown audio) or jd w/t3 audio or some other sub builders. scott w/ fi audio maybe able to help.
good luck with the build

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sundownz
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Indeed, you need to be careful about using a coil too long for the motor as it may bottom out if the motor does not have excess mechanical clearance.

You must also be aware of the vertical centering of the coil in the gap when changing the winding height, it will be different than the OEM spec.

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- Jacob Fuller
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msholit
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checked for clearance, theres enough room...

i also have the choice of a dvc 2ohm coil, but the space between the top plate and the windings is really tight...how does the space between the plate and the coil effect the performance?

i have 6 subs, but am trying to decide whether to go with 3(recoiled) or 6 (oem spec)

thanx!

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sundownz
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If the space from the TP to the coil is too tight the coil could rock a bit and hit the TP at high excursion.

Generally ~1 mm is enough to prevent this, many subs use more than that -- a TC-9 motor I have here has ~2 mm with an 8-layer coil in it.

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- Jacob Fuller
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D-Bass
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are you talking 40-50mm bobbin length, or wind-height?
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msholit
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winding height

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SOUND XTREME
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depends on alot of different factors. What motor is it? are you going fo spl or SQ? What kind of coils are they (AL or copper)?what size spiders? how much power??
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msholit
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just need to know the trade offs between a short and long coil, when used with the same motor.

1.motor consist of double stacked strontium magnets, 40mm height (total), 7.25" wide

2.toplate is 10mm

3.backplate has about 20mm after the bottom of the magnet.(thickness of back plate taken into account)

so around 30mm of travel in each direction.

top of pole piece extends past top plate 8mm, and is beveled.

spider landing is 7.5"

come to think of it i should probably stick with the short coils...

my amps are old school orion 2150sx's...3 of them.

thanx

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msholit
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oh and the coils are round copper

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D-Bass
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Which motor topology? overhung, underhung, xbl2, any of the others that are out there? any tapering?
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msholit
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just regular over hung, like the majority of subs out there, no tapering...

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MR.T3
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Mo wire in gap, mo better.
If the design allows for it.

What will the use of the speakers be for?

SPL, Daily, etc?

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Johnathan Demuth- OWNER
T3 Industries Inc.
T3 Audio Technologies L.L.C.
T3 Elite L.L.C.
D.A.V. Engineering L.L.C.

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www.myspace.com/t3audio
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msholit
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just for regular ground pounding ...

would it be at all possible to stack on another top plate and extend the pole piece, or would i have to stack it and charge the entire assembly again?

is this even possible, without making it sound like garbage?

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