Shavano Music Online

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 spread-sheet. 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 pre-wired 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:

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:

The option that can be driven at 4 ohms is the best choice

Suggestions

Most speaker cabinets for Pro-Audio 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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