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Old 29th May 2015, 06:15 PM   #1
WrineX is offline WrineX  Netherlands
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Default Oke rubenoid impdance measurement. some help needed

Hi im not really into impdance measurements (reading them) i tested a coil in a magnet motor. and i wondered if maybe there is a clue in why it has a huge drop at around 13-14 Khz, so far i dont see anything weird in the measurements. any one a clue ?
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Old 29th May 2015, 06:27 PM   #2
WrineX is offline WrineX  Netherlands
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Pardon me impedance!!!
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Old 1st June 2015, 02:15 PM   #3
Davey is offline Davey  United States
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I would test a resistor for a baseline evaluation of your measurement setup.

Dave.
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Old 1st June 2015, 04:06 PM   #4
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Hello my friend,

I posted this answer on the other thread of ours..

Believe it or not the the bigger you go with the cylinders, ex Janus 50, 70 the more you accentuate the high frecvency response and flatten the rest.. A bigger influence factor is the contact between the coil and the membranes. The more weight you add to the cylinders you lose efficency.
To lose more of your impedance peaks, you have to make an overhung coil structure.. If it is underhung, and the magnetic gap isnt large enought and the mebranes arent stiff enought to keep the coil in the gap, the coil goes out of the gap, gets hot and the impedance goes higher at that time...
The solution is a clever overhung design with a bigger gauge or continue in undergung design by using a smaller diameter wire and tighten the elastics that centeres the coil in the gap so that the coil remains in the gap all the time.
Look at the elastics from the two pictures bellow:
Click the image to open in full size.
Click the image to open in full size.

This elastic smart "trick" will keep the coil centered in the gap, linearise the impedance, and get rid of some nasty resonances. The elastic is tighten in two points on the chasis here and one point on the cylinders...

And now look at the picture bellow :
Click the image to open in full size.

As you can see the elastic is tighten in one point not in two points (like in the two pictures above) on the chasis and lets the coil move freely in the gap.. If in this third pic the magnets arent strong enought or if it isnt overhung design it will have impedance peaks just like you have.

Please keep this in mind.

Cheers
Sergiu
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Old 1st June 2015, 04:41 PM   #5
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The original thread is located hear.
A DIY Ribbon Speaker of a different Kind
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Old 3rd June 2015, 04:12 PM   #6
WrineX is offline WrineX  Netherlands
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Quote:
Originally Posted by Davey View Post
I would test a resistor for a baseline evaluation of your measurement setup.

Dave.
i did that with the resistor used to calibrate the setup , but nevermind an ADmin may close this thread. sorry for making a mess
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