Peavey Black Widow Impedance?

[Old Fart]

What is the impedance of a 15" Peavey Black Widow? It's not printed on the speaker frame.

 

[Old Fart]

It measures 5.4 ohms. I guess that means it's an "8 ohm" speaker. Right?

 

[someparts]

Either 4 or 8 - but yeah that 5.4 should be an 8 ohm version.

 

[will33]

Yeah, that's an 8 ohm.

For future reference, if it has the model number still on it, it's the number after the dash.

Example:

1505-4 = 4ohm.
1505-8 = 8ohm.

 

[JTE]

BW come in different impedances, so there's no single one. And the basket comes with a sticker that tells you the model and the impedance as will33 said. Note that they also make different kinds of speakers within the 15" BW range. Different characteristics for different applications, so just getting a replacement 15" BW basket may not work well in your particular application.

John

 

[Aluminium Beard]

I'm confused. If it measures 5.4, how can it be 8 ohm and not 4?

 

[1n3]

I'm confused. If it measures 5.4, how can it be 8 ohm and not 4?

Speaker impedance varies with frequency; the 4 or 8 ohm rating is an average value. Multimeters use DC, so can only measure DC resistance. Inductance, capacitance, and cone resonance (all factors affecting an audio signal) are not seen with a DC measurement, so the number is lower. With a DC resistance of 5.4 Ohms, it can't be a 4 Ohm speaker.

 

[Aluminium Beard]

Speaker impedance varies with frequency; the 4 or 8 ohm rating is an average value. Multimeters use DC, so can only measure DC resistance. Inductance, capacitance, and cone resonance (all factors affecting an audio signal) are not seen with a DC measurement, so the number is lower. With a DC resistance of 5.4 Ohms, it can't be a 4 Ohm speaker.

I get it now, thanks.

 

[nashvillebill]

There is a difference between DC resistance and impedance. Impedance reflects the device's reaction to alternating current, so it is a product of DC resistance plus inductance plus capacitance. The end result of the impedance calculation varies according to frequency of the signal being input.

Here's an example [Invalid or Expired Link Removed] This is a Jensen C12N, a classic guitar amp speaker. Look at the chart on the bottom. There's two curves, so don't get confused. The upper curve with all the jiggles is the frequency response (the output volume versus frequency). The bottom curve is the impedance. Notice it curves and spikes abruptly, then goes back down then climbs back up.

So when manufacturers give an impedance rating, it's a nominal number. Usually the lowest number on the curve.

 

[Vince Klortho]

Right, nominal is the word used most often. It is definitely not an average.

 

[1n3]

Right, nominal is the word used most often. It is definitely not an average.

True. I considered "nominal", or putting "average" in quotes, but was trying to simplify.