To speed up the breaking in period, the easiest method is to connect the speaker to a filament transformer. Having said that, let's look at the precautions you need to take. Since you will be driving the speaker with a steady state signal, you don't want to drive it at its rated power or it will quickly burn up the voice coil.

1/3 of the speaker's power rating is a safe figure to use. Let's say you have a 50 watt speaker and it is 8 Ohm. 1/3 of the power is about 17 watts, and at 8 Ohm, that is around 11.5 volts. Using a 12.6 volt transformer will put 20 watts into the speaker.

But just to be safe, you might want to go with a 6.3 volt filament voltage, which will put about 5 watts into your speaker. Another option is to use a Variac into the primary side of the 12.6 volt filament transformer and dial in the voltage you want on the secondary. That way, you can dial in the 11.5 volts we originally calculated at the 1/3 power level.

It is suggested that this operation be performed in a garage or closet, because listening to the loud 60hz hum from the speaker will grate on your nerves very quickly. Also, if you leave the speaker out of the cabinet, the rear radiation of the speaker will cancel a lot of the front radiation and reduce the noise. You need to lay the speaker face up though, so the cone can move as much as possible since the whole idea of this operation is to loosen up the cone and spider. Laying the speaker face down would trap air between the cone and the surface of the table and restrict cone movement. You're going to be surprised how much the cone moves and how loud the speaker is, even at 1/3 power.

Here's how to determining the correct voltage to use in case you have a different wattage and impedance rating than our example above:

1. Take the power rating of the speaker and divide it by 3.
2. Take that number and multiply it by the speaker's Ohm rating (4, 8, or 16)
3. Use your calculator to find the square root of that number.
4. The result is the voltage you need to use to drive the speaker at 1/3 its rated power.

Break-in voltage Calculator:

Enter your speaker's impedance and power rating and then click on "Calculate Break-in Voltage". The correct break-in voltage will appear in the Break-in Voltage box.