
Speaker Wiring; Impedance Calculator Information

12/98  Jens Moller 
http://www.colomar.com/Shavano/impedance_info_help.html
This application allows you to model a combination of Series, Parallel or
Series/Parallel networks simply by entering the impedance values into a
sort of spreadsheet. The main goal is to make sure that you don't overload
a power amplifier as you add more speakers to the system.
Each data entry box represents either a separate speaker driver, or a
prewired speaker cabinet. You only need to know the impedance of the
speaker or cabinet to calculate the effective load. Any spaces left blank
are ignored.
Examples
The programs logic is such that if there are no entries on a row, the entire
row is ignored. If you only enter a single value for a row, that value is used
for the whole row. If you enter 2 values for a row, it knows that you have
entered 2 values. Leave blank any areas where you don't have a speaker or
cabinet.
If you enter data on more than one row, the rows are placed in parallel with
each other, and from there the program calculates the total load of the
speakers/cabinets in the configuration you have devised.
Example 1: 4 10 inch speakers mounted in a single cabinet.
The speakers used are all 4 ohm speakers. To find out what the possible
impedances are, you can:
 Put all 4 in series with each other in Row 1. This will give you a 16
ohm load when wired this way.
 Put all 4 on parallel with each other by placing a single entry into each
of the available 4 rows. This will give you a 1
ohm load when wired this way.
 Put 2 speakers in Row 1, and 2 speakers in Row 2  this will give you
a combination of series/parallel. This will give you a 4
ohm load when wired this way.
 Put 3 speakers in Row 1 and 1 speaker in Row 2  the
equivalent of a 12 ohm speaker in parallel with a 4 ohm speaker
This will give you a 3 ohm load when wired this way.
 Put 2 speakers in Row 1, 1 speaker in Row 2 and one speaker
in Row 3. This will give you a 1.6
ohm load when wired this way.
If your amplifier will drive a 4 ohm load, the best pick is the one
that generates a 4 ohm load. If your amplifier will drive an 8 ohm
load, and there is no 8 ohm match with all for speakers, you can use
the next value impedance greater than the limit on your amplifier. In this
case 16 ohms.
Example 2: 6 speaker cabinets.
You have 6 PA cabinets to be wired to a monophonic PA system. This means
that you need to hook all 6 cabinets up to the same audio power amplifier.
This audio power amplifier can drive 4 ohms.
You have 4 cabinets that are rated at 8 ohms and 2 cabinets that are rated at
16 ohms. Normally you split up the sets so that each side of the stage has the
same configuration. This would mean 2 of the 8 ohm cabinets and 1 of the
16 ohm cabinets on each side of the stage.
To find out what the possible
impedances are, you can:
 Put all 4 8 ohm cabinets in series with each other in Row 1 and put the
16 ohm cabinets in series in Row 2. This will give you a 16
ohm load when wired this way.
 Put 2 8 ohm cabinets in series in Row 1, 1 16 ohm cabinet in Row 2,
2 8 ohm cabinets in series in
Row 3 and 1 16 ohm cabinet in Row 4.
This will give you a 4 ohm load
ohm load when wired this way.
 Put 1 8 ohm cabinet and 1 16 ohm Row 1, 1 8 ohm cabinet in Row 2
1 8 ohm cabinet and 1 16 ohm Row 3 and 1 8 ohm cabinet in Row 4  this will give you
This will give you a 3 ohm load when wired this way.
The option that can be driven at 4 ohms is the best choice
Suggestions
Most speaker cabinets for ProAudio are 4, 8 or 16 ohms. This allows you to
mix and match more effectively. It is dangerous to make cabinets that are
less than 4 ohms  mostly because it is very easy to damage a power amplifier
that sees this load and can't drive it. The odds are good that you will
damage something that can cost a lot to repair.
Try to keep any cabinets that you make one of these values and do you best
to match your power amplifiers load capability to any speaker loads
you create.
Some power amplifiers can drive a 2 ohm load safely  never assume you have
one of these unless it say so somewhere on the amplifier or on the
documentation that came with the gear. If in doubt, assume 8 ohm loading
capability and do not create a load less than that.
This CGI application is running under Irix (Silicon Graphics V 6.x Unix)
on a Web Server running Apache.
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Questions? Comments?
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