You can easily test a speaker if there is no receiver to play them. With a 9v battery briefly touch the speaker inputs with the battery. You should hear a small pop and the woofers should move in or out together. You might want to ask the owner before whipping out the battery and test the speaker.
Speaker polarity is determined when connecting the wires between the amplifier and the speaker. When the positive amplifier terminal is connected to the positive speaker terminal and the negative amplifier terminal is connected to the negative speaker terminal, the speaker will be in correct polarity.
Attach the multimeter to each terminal of the speaker where the wires attach. If the multimeter reads 1.0 ohms, the speaker is working. If it displays a reading of infinite ohms, the speaker has been blown.
Multiply the voltage by the amperage to find the wattage.
Turn the test tone off, shut your amplifier down, and remove your multimeter’s probes. Then, multiply your voltage and amperage together to find the amplifier’s wattage.
Physically inspect the speaker.
A blown speaker can have damage that can be heard with some mechanical movement. If you gently tap on the cone of the speaker it should have a firm drum like sound. If you hear a rattling sound (like a loose snare drum), this is an indicator of a bad speaker.
For a 4 ohm speaker, it should read between 2 and 4 ohms on a meter. For a 8 ohm speaker, it should read between 4 and 8 ohms on a meter. For a 16 ohm speaker, it should read between 8 and 16 ohms on a meter.
about 30 volts
The voltage on a speaker wire depends on amplifier power; for a 100-watt-per-channel amplifier, the voltage will be about 30 volts RMS. At such voltage, a 1 percent loss will occur at 3,000 ohms or less of capacitive reactance.
Connect the red probe from your multimeter to the positive side and the black probe to the negative side. Read the impedance on the multimeter and round the number up. For example, if the multimeter reads 3 ohms, it’s a 4-ohm speaker. If it reads 14 ohms, it’s a 16-ohm speaker.
The most common aural indication of a blown speaker is an unpleasant buzzing or scratching sound, by itself or roughly at the pitch of the note the speaker is attempting to reproduce. Or there could be no sound at all.
To tell if the speaker is blown or not without taking it apart is really easy. All you have to do is take a 9 volt battery and touch it to the wires. If it makes scratching noises its good. If it makes no sound at all its blown.
As long as the speakers aren’t mirror-image pair, it should not matter which speaker you use for the left or right, or whether you decide to switch them from one side to the other.
With a 4 ohm speaker, the maximum output power will be 200 watts. With a 16 ohm speaker, the maximum output power will be 50 watts.
For example, if the amplifier is producing 20 Volts at the output terminals, Ohms law (R=V/I) tells us that there are 50 watts being fed into an 8 Ohm speaker (watts equal voltage squared divided by impedance).
Multiply the number of volts by the number of amps to determine how many watts the speaker uses. If the speaker operates at 110 VAC, at 2 amps, the speaker’s wattage is 220 watts.
To measure distortion for the lower part of the spectrum, do a near-field measurement (place the microphone as close as possible to the speaker). Depending on how big the speaker is, this will be accurate up to a certain frequency. But most of time, take this measurement for frequencies of 250 Hz and below.
Too much bass can cause the speaker cones to move excessively beyond its limits — a situation known as over excursion. Over time the cones will deform and eventually break. Also, an extremely loud bass can easily damage midrange speakers because they are not designed to play low frequencies.
There is a variety of issues that can occur with speaker voice coils, and sometimes it is possible to repair them. … Occasionally on smaller speakers with no adjustments it can be possible to repair them by easing them back into the centre. Gently hold the cone – remember it is made of paper and can damage easily.
Your 16 ohm speakers will have one quite predictable effect – if the amplifier is rated at say 100W into 8 ohms, it will only deliver approximately 50W into 16 ohms.
When a speaker is labeled 8 ohms, it is actually a nominal reading. … You will find that a 8 ohm speaker will be between 5.1 and 8 ohms, 16 ohm speaker will be between 11 and 16 ohms, and a 4 ohm speaker will be between 2.1 and 4 ohms.
Speakers are essentially large coils of wire, and when they “blow”, it’s generally that the coil is taking too much current and isn’t being cooled enough, and is damaged. If the speaker is completely destroyed, this may be that the wire in the coil is broken or shorted, so that it doesn’t operate.
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