#1
I have a celestion heritage 30 16 ohm in a homemade 1x12 cab and when I measured the impedance it said 6 ohms. I'm pretty sure I hooked up the multimeter right and there was nothing else hooked up to the speaker. Can someone tell me what's going on?


Thanks
Quote by timbit2006
Probably right around $3000 Canadian(We have to pay a lot more for some stupid reason...).

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so true
#2
Does it not sound right, or are you just measuring the impedance for the sake of measuring it?
#3
a 16 ohm speaker should rear 12/13ohms on the meter....6 would be about right for an 8 ohm speaker so are you sure it is 16??
#4
I played it through my solid state head and it sounded good and strong, but that doesn't mean too much. It says 16 ohms and the guy I bought it off of said it was 16 ohms. I tried adjusting my multimeter and it went from 0-6 ohms maxed out both ways. I figured I would test it out to make sure I was right before testing it on my $1000 dollar tube head and I'm glad I did!
Quote by timbit2006
Probably right around $3000 Canadian(We have to pay a lot more for some stupid reason...).

Quote by RealGuitarHero
Because of the French.


so true
#5
A multimeter only measures DC resistance. Impedance is the sum of resistance and any inductive and capacitive reactance (which only affect AC). That is why the meter is reading so low.
#6
If it says 16 ohms on the label it most likely is. My multimeter reads impedance accurately enough when measuring resistance but I suppose that's an exception.

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#7
I've always wondered why the DCR is always practically the same as the rated Z. My theory (that I literally just thought of) is that with modern, more powerful magnets, coils can be wound with fewer turns and with smaller (higher resistance) wire thus coil reactance can be pretty much negligible and the DCR of the wire itself makes up most of the impedance. But I'm probably wrong.
#8
Connect a speaker cable to the wires of the speakers then measure the resistance. You get a different result from doing this to just using the lugs on the speaker.
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#9
Quote by Invader Jim
A multimeter only measures DC resistance. Impedance is the sum of resistance and any inductive and capacitive reactance (which only affect AC). That is why the meter is reading so low.


Does that mean the resistance is double what the meter says and is actually close to 16 ohms? I'm brand new to all this stuff. Thanks!
Quote by timbit2006
Probably right around $3000 Canadian(We have to pay a lot more for some stupid reason...).

Quote by RealGuitarHero
Because of the French.


so true
#10
Well the difference may not be that drastic but from what I've seen the impedance is usually just a bit higher than the actual coil resistance (bit it is always higher). For example, a lot of old table radio schematics note the speaker coil resistance as 3.2 ohms for a 4 ohm impedance. Therefore the reactance makes up only .8 ohms of the entire impedance.
#11
So to be clear my speaker is 16 ohms and is safe to use on my tube head?
Quote by timbit2006
Probably right around $3000 Canadian(We have to pay a lot more for some stupid reason...).

Quote by RealGuitarHero
Because of the French.


so true
#13
Something isn't right here, either you have an 8ohm speaker, there may be a short in the coil or the measurement is wrong. Your meter has a battery in it, if the battery is flat then the meter will read low. If you are using an old meter with a moving pointer it may not be accurate at low readings.

The impedance of a speaker comprises of two parts; the resistance of the coil, which is fixed and what you are trying to measure and the inductance of the coil, which depends upon frequency. The inductance rises with frequency in a predictable way and depends upon the coil construction and the pole piece in the magnet, since most speakers are similar this occurs in a similar way in most speakers. At the resonant frequency of the speaker the cone moves more than it should do and this induces a voltage in the coil that makes the impedance rise in this area.

For most of the middle frequencies the impedance of the speaker is just a touch over the DC resistance you are measuring, only rising at real lows and the top end.

Either you measurement is wrong or this is an 8ohm speaker.

Using the wrong ouput tap on your valve amp probably won't cause you too many problems other than a slight loss of power but if you mix this speaker with any others assume it is 8 ohms. If it is a 16 ohm speaker the resistance will be 12 ohms give or take a couple of ohms.