building my first crossover

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C

Curmudgeon

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Joined 2005
The inductance varies with the square of the number of turns so you would strip about 10%, rather than 20%.

Verify with the calculator. Also as was indicated above, if you use the pi*d calculation for turn length, you need to measure the diameter at the middle of the buildup, to get the average turn length. The calculator is more accurate of course.
 
J

jaygeorge1979

Member
Joined 2005
the calculator idea sounded fun and everything, but i found something more convenient in the electrical engineering lab....found the toy they use to measure caps/inductors well down into the MICRO farad/henry ranges...boy that was fun...i just hooked it up, uncoiled it till i got to .08mH, cut it, retaped it, and im done :) thanks all

sadly, i didnt write down how many coils i undid...i just did it until it said 80 microhenries...wish i woulda wrote down the # of coils...
 
owdi

owdi

Member
Joined 2003
What did the coil measure before you started unwinding?

what do u mean break the speakers in first? are you gonna hook up the filter without adjusting the inductance first? see how it sounds? or run the speaker without the filter for a lil while first...
Click to expand...

Exactly. I ran test tones through the speakers for about 40 hours to loosen the spider and surround. The fs dropped from around 125hz to 105hz. It will drop more over time, hopefully close to the manufacturer specified 80hz.

Be sure to take some pics after your done, and post your listening impressions.

Dan
 
Cloth Ears

Cloth Ears

Member
Joined 2001
owdi said:
Cloth Ears - .19 seems high. I got my estimate of .15 from looking at the air core inductors at partsexpress, where the 18 awg was .13 and the 20awg was .19. I know the shape of the coil matters, but I doubt madisound would waste copper.
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Probably is high - but I was just using the link that jaygeorge1979 mentioned in post #2 to work out the values.

But it looks like he got the value he was after anyway...
 
J

jaygeorge1979

Member
Joined 2005
owdi said:
What did the coil measure before you started unwinding?

Exactly. I ran test tones through the speakers for about 40 hours to loosen the spider and surround. The fs dropped from around 125hz to 105hz. It will drop more over time, hopefully close to the manufacturer specified 80hz.

Be sure to take some pics after your done, and post your listening impressions.

Dan
Click to expand...

i had two .1mH coils.....one measured .102mH and one measured .099 mH...not too shabby, madisound :)

you want pics of my speakers once they are built, or pictures of my crossovers? or my inductors :)
 
C

chubby chaser

Member
Joined 2007
It will be very hard for you to tell the difference, since you have to listen for something very specific. Using test tones you may be able to get close, but there's no substitute for electrical and acoustic measurements.

I'm in the middle of a B3S project myself, and I haven't unwound my .1 mh coils yet. I'm waiting to break in the speakers and complete the enclosures before I tweak the filter. If you like, I can post/email how many turns I unwind, although I'm using slightly different coils from Parts Express.

Dan

OWDI So how many turns did u unwind??? What type of coil??
 
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