Speaker Ohms Question
- Thread starter Wolfe64
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Yup but...
Sure you can. If the receiver is solid state, it will produce a little more power into 6 ohms that it will into 8 ohms. If the receiver is tube or has separate 4, 8, and 16 ohm outputs (unlikely but possible) hook it to the 4 ohm outputs.
Speakers (with very very few exceptions) present a reactive load, not a resistive load to the amp. The ohm rating of a speaker is kind of a gentleman's agreement that the speaker is around 8 ohms some of the time. In actuality, an 8 ohm speaker probably runs between 5 and 50 ohms depending on the frequency. The 6 ohm will be a little less maybe depending on how it was rated.
That said, here's the "but". I would not run a second pair of speakers on the receiver at the same time. If you hook up a second pair, just don't play them at the same time.
Sure you can. If the receiver is solid state, it will produce a little more power into 6 ohms that it will into 8 ohms. If the receiver is tube or has separate 4, 8, and 16 ohm outputs (unlikely but possible) hook it to the 4 ohm outputs.
Speakers (with very very few exceptions) present a reactive load, not a resistive load to the amp. The ohm rating of a speaker is kind of a gentleman's agreement that the speaker is around 8 ohms some of the time. In actuality, an 8 ohm speaker probably runs between 5 and 50 ohms depending on the frequency. The 6 ohm will be a little less maybe depending on how it was rated.
That said, here's the "but". I would not run a second pair of speakers on the receiver at the same time. If you hook up a second pair, just don't play them at the same time.
Good advice...but I have always thought about speakers as being both resistive (varying with frequency of the signal) and reactive (having capacitance and inductance, which are the forces causing resistance to vary by frequency). I don't think there is any point at which a speaker id ever a purely reactive load
The standard for nominal impedance ratings says that actual impedance should not drop more than 25% below rated impedance...but as you point out, some manufacturers don't adhere to this standard.
To the OP...just about all amps/receivers (solid state and tube) can handle 8 ohm speakers (or higher). However, as impedance drops, the amp must be able to produce more current. This is a function of the amp's power supply...and the power supply is the most expensive part of an amp. So, as you might imagine, many amps are designed to produce the current required for 8 ohm speakers, but not for the more demanding loads of 4 ohm speakers.
Six ohm speakers fall in between (obviously)...but should be ok with an amp rated only for 8 ohm speakers, especially if you don't push it too hard. And as Bill said, if your amp can drive two pairs of speakers simultaneously (and if the speaker terminals are wired in parallel, which is most commonly the case), make sure both pairs are rated at 8 ohms.
- Two pairs of 8 ohm speakers = 4 ohm load on the amp
- Pair of 8 ohm and pair of 6 ohm speakers = 3.4 ohm load on the amp
- Two pairs of 6 ohm speakers = 3 ohm load on the amp
Consumer-grade amps can handle, at best, a 4 ohm load...and many (most) can handle only 8 ohm loads (or higher)
Right you are, KCBluesman
Absolutely correct. One point that should be made is that as the frequency goes down, the woofer approaches its resonant frequency at which time the woofer's impedance rises dramatically. Since most of the energy is in this frequency range, the rising impedance lowers the current draw lowering the load on the amp.
Most of the reactive load comes from the crossover, not the drivers. That's why drivers that require no crossover are almost (but not exactly) resistive; think piezo tweeters and Magnepan woofer panels that are driven full range..
Absolutely correct. One point that should be made is that as the frequency goes down, the woofer approaches its resonant frequency at which time the woofer's impedance rises dramatically. Since most of the energy is in this frequency range, the rising impedance lowers the current draw lowering the load on the amp.
Most of the reactive load comes from the crossover, not the drivers. That's why drivers that require no crossover are almost (but not exactly) resistive; think piezo tweeters and Magnepan woofer panels that are driven full range..
True...but impedance also drops rapidly (with traditional dynamic speakers) as frequency rises beyond resonance, bottoming out around 200Hz or so. There's still a lot of energy in the signal at this level, with correspondingly high demands on the power supply and the outputs....especially if the load is capacitively reactive at this point.