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Calculating Final Impedance

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Old Feb 9, 2007 | 12:56 PM
  #1  
maltesechicken's Avatar
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2000 Watt CAFz'r
 
Joined: Jan 2001
Posts: 2,026
Calculating Final Impedance

When connecting Speakers in Parallel (All positive voice coil wires connected together to the positive on the amp & all negative voice coil wires connected to the negative on them amp) Follow this formula:
Y= Number of voice coils
X= Impedance of each coil

Take the impedance of each coil (X)
Turn it into a fraction (X/1)
Then reciprocate the fraction (1/X)
Take all of the fractions and add them together (Y/X)
Then reciprocate the facrtion again (X/Y) THis is your final load.

A Practical examples:
6 coils @ 4 ohms each.
4
4/1
1/4
1/4 + 1/4 + 1/4 + 1/4 + 1/4 + 1/4= 6/4
4/6 = 0.6666 ohms

3 coils @ 6 ohms each
6
6/1
1/6
1/6 + 1/6 + 1/6 = 3/6
6/3 = 2 ohms

When connecting the speakers in series (+ from Amp to Coil + Coil - to next coil + ect until the last coil negative returns to the amp)
Very simple. Add all of the voice coil impedance values together.

Using Series and Parallel together. There is no set formula that can be applied here because several combinations can produce different results.

Example:
3 Dual 4 ohm Voice Coil Speakers (6 coils at 4ohms each)
Series first: (4 + 4) (4 + 4) (4 + 4)
Parallel next: (8) (8) (8)
8/1
1/8
1/8 + 1/8 + 1/8 = 3/8
8/3 = 2.666

or
Series first (4 + 4 + 4) (4 + 4 + 4)
Parallel Next: (12) (12)
12/1
1/12
1/12 + 1/12 = 2/12
12/2 = 6 ohms

Or
Parallel first (3 pairs):
4/1
1/4
1/4 + 1/4 = 2/4
4/2 = 2
Series next: 2 + 2 + 2 = 6


It is important to note that each sub needs to be treated equally when combining series and parallel. If the wiring is imbalanced on any individual sub, the output will be adversely affected - The coils on one sub cannot be wired in series and while the coils on another are wired in parallel. This will cause a massive power imbalance between subs. In the above three examples, the subs were treated equally.

These generic formulas can be adapted to fit any application.
Old Feb 9, 2007 | 01:11 PM
  #2  
92zed34's Avatar
500 Watt CAFz'r
iTrader: (4)
 
Joined: Dec 2004
Posts: 812
thats a lot of math lol. I use this Woofer Enclosures - Fraction to Decimal - Parallel - Series - Port Length and Volume Calculators

The links for those with minimal math skillz like me.....
Old Feb 9, 2007 | 03:25 PM
  #3  
tonez735's Avatar
50 Watt CAFz'r
iTrader: (1)
 
Joined: Aug 2006
Posts: 374
That's a wicked link man.

thanks!!! just figured out my enclosure size in minutes!!!
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