6.5 ohm woofer drive replacement?

Guest

Hi guys.can someone please tell me if this 6.5ohm woofer driver is good to replace a 8ohm woofer driver,thanks and have a merry christmas.

vtech · Joined: 08 May 2006 Posts: 1264 Location: USA

Depends on your Amplifier drive capability; while it is not too far off, it may be too much of a load on the amp and you have to make sure not to crank it up too much?

Guest · Posted: Wed Dec 07, 2011 1:41 am Post subject:

Thanks. it's for a subwoofer box that has an amp of max 200w max output and i 'll be using a receiver of 100w per chan.

Guest · Posted: Wed Dec 07, 2011 11:43 pm Post subject:

vtech · Joined: 08 May 2006 Posts: 1264 Location: USA

Remember;

When talking about "impedance", it is actually the resistance of the speaker to the AC signal--NOT DC (as a simple resistor).
In order to measure the actual impedance of a driver, you'd need to have a rather complex setup with a variable sinewave generator to get various readings at different frequency spectrums and average the result(not something for the average user).
You can however use a multimeter (like a fluke) to get an idea by means of a simple DC measurement. As a rule of thumb, the dc reading of the meter will be about 2/3 to 3/4 of the actual impedance. Therefore, what you have is very close to the 8 ohms speaker.
As far as the polarity, there should be some sort of an indication/marking on the speaker but if there isn't any, it is easy to find out;
Speaker is constructed of a stationary magnet surrounded by a moving coil which is attached to a cone. So why not get a standard 1.5v battery and momentarily touch the leads as you pay close attention to the cone movement(depending on the thickness of the paper you may have to use more than one battery)--& no it won't damage the speaker.
When the cone moves outward, positive of the battery IS the positive terminal of the speaker & vise versa.
Cool

Guest · Posted: Thu Dec 08, 2011 11:41 pm Post subject:

vtech · Joined: 08 May 2006 Posts: 1264 Location: USA

No, no.. let me clarify,
You use the fluke ONLY to measure the resistance of the speaker by itself without being connected to the amp. This will give an idea of what the actual impedance is (something that you have already done & came up w 6.5ohms which is close to 8 ohms)

Guest · Posted: Fri Dec 09, 2011 8:27 am Post subject: Woofer replacement

When measured with an Ohm meter 6.5 Ohms is the DC resistance of the speaker. This places it safely within the 8 Ohm impedance range.

As already said by others the impedance of an speaker is the resistance to an AC signal, which in accordance with the frequency generates a variable back EMF thus adding to the DC resistance. The impedance of a speaker is normally measured with a 1 KHz sinewave.

What you must also look at is the RMS output of the amplifier and the power handling capability of the new speaker. If the power handling capability of the speaker is the the same or higher than the output of the Amplifier, Good, if lower distortion and a blow up can be expected. So in this case never "crank" it up.
If the impedance of the speaker is lower than that indicated on the amplifier then the current draw will be excessive and it will blow either the speaker of both the amplifier and speaker. Some systems work on anything from 2 to 15 Ohm so it would be best to check the manual.