Speaker Resistance
Speaker Resistance
(OP)
Got into an argument the other night about speaker resistance and what it really means.
I was fighting that this was an impedance that takes into account both the resistance and inductive properties of the speaker, basically the Z at a certian frequency.
The other guy was saying this was a purly resistive measurement that he could take with his multimeter.
Anyone care to clarify,
Thanks
Dob
I was fighting that this was an impedance that takes into account both the resistance and inductive properties of the speaker, basically the Z at a certian frequency.
The other guy was saying this was a purly resistive measurement that he could take with his multimeter.
Anyone care to clarify,
Thanks
Dob





RE: Speaker Resistance
RE: Speaker Resistance
Also, A speaker will generally say 4 ohms or 8 ohms or 6.5 ohms or something like that but you will almost never measure this rated resistance or impendance with an ohmmeter.
Go to Parts Express. There's lots of technical info with speaker impendace curves connected to their different drivers. If nothing else, look up the large Dayton woofers because I know they have lots of info attached to them. you'll find some impendance vs frequency curves for the
RE: Speaker Resistance
RE: Speaker Resistance
OperaHouse,
I am not OLD and I think magnapans are a great modern invention! Also, competing against a Pearson with home made toroids and matching networks to make nice pulse shapes was great fun when a few decades ago when I got to do that sort of thing. Thanks for bringing back the memories.
RE: Speaker Resistance
In operation these things are inductive/resistance so you ARE talking "impedance".
RE: Speaker Resistance
Which complicates things a little more... impedancewise.
RE: Speaker Resistance
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One day my ship will come in.
But with my luck, I'll be at the airport!
RE: Speaker Resistance
A proper analogue style Marconi LCR bridge came up with some fairly peculiar readings, didn't want to balance particularly, but there was a null of sorts at about 20uH.
The AC across the speaker was enough to produce quite a reasonable volume at 1kHz.
Twiddling the D control produced a better balance, but it was still weird.
Trying to measure the resistance on AC was pretty odd too..
RE: Speaker Resistance
RE: Speaker Resistance
Speakers are constructed with coils & permanent magnet. Coils have resistance component, inductance & small capacitive reactance. Combined, they are called impedance.
If the speaker specs is 4-ohm speaker, that value is resistance value. This has to match with the output amplifier for maximum transfer.
RE: Speaker Resistance
Inductive and capacitive reactances are measured in Ohms, and when they are combined with resistance to form a complex impedance, the resulting impedance is also measured in Ohms.
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One day my ship will come in.
But with my luck, I'll be at the airport!
RE: Speaker Resistance
To pick up on your point "If the speaker specs is 4-ohm speaker, that value is resistance value. This has to match with the output amplifier for maximum transfer" - with modern solid state amplifiers the output impedance is extremely low compared to the impedance of the speaker. The amplifier may state "xx Watts ouput power into z Ohms", but this is more a case of ensuring that there is sufficient voltage swing to provide the rated power, whilst at the same time keeping the load current (and hence output stage device current) within design limits.
RE: Speaker Resistance
Exactly right! Impedance matching is not typically used in audio amplifiers; the output Z might be a small fraction of an ohm (the lower the better). Google 'damping factor' if you're interested. The concept is that the amplifier can control the speaker cone more like a piston, and less like a pendulum.
The DC resistance of a speaker is almost a non-issue in the real world. Who listens to DC ???? Real world data would start at around 20 Hz (YMMV). If your amplifier is putting out any DC, that is normally a Very Bad Thing.
RE: Speaker Resistance
As your bass drivers discover in short order...
RE: Speaker Resistance
TTFN
RE: Speaker Resistance
RE: Speaker Resistance