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Ohms ? What are they

AudioGMan said:
Are the Advents rated 8 ohm or 6 ohm nominal impedance?
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They are rated 8Ω, but per @spark1 (post 3):
The Advents, if rated via IEC standards, would be 6 ohm speakers. A pair of 6 ohm speakers = 3 ohm load. Most consumer amps, including yours, are at best rated for a 4 ohm load. The harder your drive them (the louder), the more stress you are putting on the amp. Your Sansui will probably acquit itself quite decently against this challenge, but just keep in mind that you are asking it to perform at/slightly beyond its limits.
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ric27 said:
What I have been trying to get at through this thread is, am I getting more out of my amp. using the stacked in parallel vs connecting two sets of speakers to amp output and running a+b?
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The most concise answer to this question is NO! The connections are exactly the same electrically wise. Although some amplifiers run 2 pairs of speakers in series when A+B is selected, yours connects them in parallel.
 
There is an easy way to find out if your amplifier connects speaker pairs in parallel or series.
Connect speakers to the A speaker connections only. Run amplifier with A and B speakers selected. If your amplifier has a series connection, you'll get no sound.
 
If all your were trying to understand throughout this thread is whether or not there is any difference between doubling up vs using A+B, I totally missed the mark and introduced all sorts of confusion and complication into the thread. Sorry.

JoeESP9 is absolutely correct. There is no difference.

Not sure how I concluded that you were asking about power, loudness and impedance differences between running one and two pairs of speakers.
 
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ric27 said:
No doubt I am confused and confusing.

I think what I am wanting to know is the performance of the speakers in terms of SPL and how that relates to 4 ohm and 8 ohm set up I have described at the volume levels I am listening at.
I think you answered my question when you posted " As you move closer to maximum output, the amp is less and less able to do so. At max output, power is only 40% higher into the doubled load (which is actually pretty good performance, relative to many other receivers)"

So my thought was that at lower volumes the amp could be producing the gains nearer the 3db, more so than at what could be expected higher volume levels. But then that was poo pooed in a post later by another member which did confuse me.
Ric
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If someone crapped on my answer, they were wrong :)...although I didn't notice anyone doing so.
 
Spark1, your info has been very helpful. You were certainly correct a few post back when you said I was confusing things. I am very interested in what is going electronically from the source, to the pre-amp, to the power-amp and to speaker. So I asked a lot of dumb questions. Thanks for you patients.
 
If I missed it somewhere mentioned already. The lower the ohms the closer to a short. So 0 ohms is the two speaker wires touching. If you Sansui is able to handle a 4 ohm load then you should be fine.
 
Language can really also get the way, because resistance and power or force are used in dealing with weight, as in "the less resistance (gravitational) the less power is required to lift", which is very intuitive knowledge.
In electrical terms, power (wattage) is current flow demand (amps) x differential energy provided (volts).

watts = amps x volts

Resistance is measured as ohms (not the same thing at all as weight).
With gravity, the less weight lifted, the less power required.
With electricity, the less resistance offered, the more amperage or less voltage required. With a constant voltage, the lower the resistance offered, the more power (watts) required. Why?

ohms = volts/amps

With a lower ohm speaker and the same voltage, we need more amps. Amps are provided by actual electrical particles moving through the resistor, which means the more there are, the hotter the resistor gets. We need a better build on the speaker spider. So with higher amps x volts we get higher watts. The output of the amplifier must therefore provide more watts.
If we lowered the voltage instead of increasing the amps, we'd get the ohm level desired but less wattage would be required, and we are after wattage for those hungry speakers. Just don't let friends near the volume control on an overpowered amplifier or they will fry your speakers in a split second.
Overdriving an underpowered amplifier will cause it to generate uneven electrical pulses that can damage speakers as well as the amp itself.
 
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Resistance refers to a DC source. Impedance refers to an AC source which in this case is variable from below 20 HZ to over 20,000 Hz. Impedance has a resistance component and a reactive (capacitive or inductive) component. Depending on the those two additional components they can be much more demanding of an amplifier. So just because the impedance meter says the resistance is 5 ohms at 50 hz , it will also tell you about the reactive component at 50 HZ which can be much more demanding of the amplifier. So always make sure the amplifier you choose has a large safe operating area. If not the life of the amp will be reduced significantly earning itself a bad reputation. Leaving you very frustrated. Its one thing for an amp to sound good, but it should do so for a very lengthy amount of time. 20 years!
 
twiiii said:
Resistance refers to a DC source. Impedance refers to an AC source which in this case is variable from below 20 HZ to over 20,000 Hz. Impedance has a resistance component and a reactive (capacitive or inductive) component. Depending on the those two additional components they can be much more demanding of an amplifier. So just because the impedance meter says the resistance is 5 ohms at 50 hz , it will also tell you about the reactive component at 50 HZ which can be much more demanding of the amplifier. So always make sure the amplifier you choose has a large safe operating area. If not the life of the amp will be reduced significantly earning itself a bad reputation. Leaving you very frustrated. Its one thing for an amp to sound good, but it should do so for a very lengthy amount of time. 20 years!
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I see that language problem cropping up again in the Wikipedia article on impedance:

"In addition to resistance as seen in DC circuits, impedance in AC circuits includes the effects of the induction of voltages in conductors by the magnetic fields (inductance), and the electrostatic storage of charge induced by voltages between conductors (capacitance). The impedance caused by these two effects is collectively referred to as reactance and forms the imaginary part of complex impedance whereas resistance forms the real part. "

In electricity, there is actually nothing imaginary at all about the imaginary number calculations... that's just a bad choice of words inherited from centuries of usage. But, who'd recall that unless they remembered high school math like the exam was this afternoon instead of fifty years ago?

And back to your point... speakers are indeed only ever delivered AC current from the amplifier. An alternating magnetic field produces alternating movement of the spider coil and the speaker moves in and out just like the microphone that recorded the sound in the first place.

I always thought anybody who could look at a circuit board and understand what was happening inside was a genius. Still do.
 
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