Originally Posted by Jeff Smith
I have always wondered this, but now I may need to put it to a real application. I want to put background music in my yard. 4 speakers would be "OK", 6 would be almost perfect, 8 would be maybe more than I need.
I'm trying to learn the science here and apply it to how it would make the system sound.
I know running 2 8 ohm speakers in parallel makes them a 4 ohm load. running them in series makes the amp see 16 ohms. Then if you want 4 speakers on the same channel, you can series 2 pair to 16 ohms, then parallel the 2 16 ohm pairs to get back to 8 ohms.
But will any of that actually make the music play louder with good quality
The general rule is that running more speakers in parallel will make things louder until you create a low impedance load that the amp can't handle.
Most receivers will drive 4 ohm loads no matter what their spec sheets say, particularly if you don't push the levels too high.
Loads under 4 ohms are a different matter, and really should only be used with pro audio amps and the few heavy duty consumer amps that are designed to go that route.
more than the other or is it more about protecting the amp?
Modern amps are supposed to protect themselves. For example, I'm informed that some Sony amps will actually check out their speaker loads during power up, and flash a warning if the speaker loads are too much for it to comfortably handle.
More typically, excessively low speaker impedance loads will cause the power amp to actually put out less power before distorting, which is counter-productive.
I have an old Sound Craftsman Pro Power 10 amp in great condition (not used much at any laod or volume at all). It has 4 channels 200wats each at 8 ohms, 400 at 4 ohms, and I read somewhere (not in the manual, on another forum) that it is stable at 2 ohms.
If its in good shape and meets original spec, that all might be true.
What exactly happens to the real world sound (volume and quality...if anything) if I were to go from 2 8 ohm speakers per channel, parallelled to 4 ohms...to 4 speakers per channel set up as above as a "series-parallel combo" to end up with 8 ohms to the amp?
Hooking identical speakers in series creates a higher impedance load and will actually cut maximum loudness, all other things being equal. The power will be equally divided between the speakers, which will make life easier for them.
Hooking dissimilar speakers in series creates a higher impedance load and will also actually cut maximum loudness, all other things being equal. Unfortunately, the power will not be equally divided between the speakers, and can easily create a mess where the speakers just don't sound as good as they could.
Which setup would play louder, or perhaps it better asked, which would allow you to occasionally crank it up for a party (still for ambiance, not for dancing...just louder enough to be heard above a large number of people who could still converse?
I'm not inexperienced enough to venture out and predict how things will work when you start cranking your stereo up at a party. If alcoholic beverages are served, then I'm running the other way really fast! I've seen a lot of equipment damaged that way. Your gun, your bullets, your toes! OTOH, your situation might be a picture of moderation, and no innocent audio gear may be harmed in the execution of your party.
What I will predict is that hooking speakers in parallel is a proven working methodology for making things louder, at least until you start breaking things.
I cant imagine you could do this adding of speakers forever with more and more speakers, it seems eventually there wouldn't be enough "oomph" in the amp to power multiples of this (say 16, 24, 32 speakers).
You got that right!
assume the speakers are all the same for now.
I doubt that you'll have any problems as long as you use the speakers and amps within their capabilities. To me that means that you will not create any effective loads for an amplifier channel that is less than 4 ohms.
It also means that no amplifier will ever be run into audible distortion in the judgement of a sober, experienced audiophile.
Put more simply, do 2 pairs in parallel play louder with the same quality at 4 ohms than a single pair a 8 ohms?
As a rule, yes. Again this assumes that no amplifier will ever be run into audible distortion in the judgement of a sober, experienced audiophile.
How about 3 pairs in parallel at 2.66 ohms? same question, is it a lot louder because of more watts, or less so because there is more speaker cone mass to move?
I would hesitate to try this with an el-cheapo receiver, but that heavy duty old SoundCraftsman might be up for it. Just blow the dust out of the heat sinks, keep it in a cool, well-ventilated place and put your hands on the heatsinks every once in a while.
Now, if you were talking about a modern Crown or QSC amp, or even one of the Berhinger EP-series power amps, I'd say go for it.
And do impedance matching speaker selectors like Niles and Russound decrease the overall volume available, or is it a moot point?
They tend to err on the side of conservatism, which means that you might get louder results with wire strippers and wirenuts as your splitter devices.
I do know that in the past, I have had the Russound controlling 3 pairs of 8 ohm Polks on 2 amp channels - with the other 2 channels powering 2 16" woofer, horn mid, and tweeters (big grey felt carpet covered "band" speakers by Cerwin Vega - dont know the ohms), and I could blow away the homes across the water. The band speakers weren't great quality, but loud and usefull in my younger, stupid days. The point is the amp seems strong, and I want to do the right thing by planning this in advance.
Sounds like nothing bad happens, so maybe you could stage a repeat engagement without breaking anything. But you're on your own!