Running 4 speakers from a 2-channel amp

Besides what Almarg mentioned about running speakers in series,the highs and mids will suffer too.The highs and mids will all be traveling through the other speakers low frequency choke and other parts of the crossover that otherwise would never,and was never meant to by the speakers designers.

The highs and mids will all be traveling through the other speakers low frequency choke.

With much respect, HifiTime, I don't think that is true. I believe that at any given frequency the signal will follow the same path or paths through each speaker that it would follow if the speaker were connected to the amp by itself.

High frequencies, for instance, will be blocked by a choke in series with the woofer just as they would be if the speaker were connected directly to the amp. They will follow a path through the high-pass part of the crossover, and the high frequency driver, and from there continue to the other speaker.

An unrelated further thought, about having more than one speaker per channel: If each channel is being reproduced by two speakers, and the two speakers are producing comparable volumes at the listener's ears but are located at significantly different distances from the listener's ears, what are called comb filtering effects will occur, which will degrade the sound. That occurs when the same sound arrives at the listener's ears at multiple arrival times. How significant that effect will be is obviously dependent on many variables, including the listener, but I would expect it to be significant for many listeners under many circumstances. And it applies whether the speakers are connected in parallel or in series. Something to consider.

Regards,
-- Al

re: Series connection- Anytime components are added to a signal path, the signal is degraded. Introducing the reactance(and Back EMF) of the drivers of the systems to the signal path WILL CERTAINLY cause distortions. Whether they bother the listener or not will depend on how discerning they are. Further- raising the impedance that the output of a typical solid state amp sees, above 8 Ohms, can cut it's power significantly.

Re;Series Hi Al,
In the 70' or 80's,a friend called me over upset about his stereo and asked me to come over,and I did.When I got there he showed me the new second pair of Infinity's(I believe)that he bought.He said he hooked them up together and must of blown something out.I told him I thought they were 4Ω ohm and his receiver couldn't drive two pairs most likely.The dealer told him it will work,and he had it playing at low volume when I arrived.He said the tweeters must have blown.I told him to turn the volume down and switch to one pair.When he did and turned it back up his eyes lit up.The highs were back.When switching both on you could here the volume drop.Right then I told him his receiver must be running them in series,and it sure enough was.On these crossover diagrams,figure 5 or 6 the highs that get though the choke coil are getting shorted out by C2 and C3 in these diagrams at least to my eyes.
Regards LINK>[http://www.termpro.com/articles/xover2.html]

Hello Mr H- The highs that pass through the inductor of a second, third or higher order filter, will be selectively shunted to ground via a cap, to increase the roll off to the woofer(and midrange, if applicable). The highs will be passed through the tweeter section of the crossover however, and still continue to the next system in the series. Of course, much of the energy in that frequency range will have been expended, in reproducing the highs/creating heat in that first system. Depending on the complexity, efficiency and reactance of the first system in a series circuit, there exists a large possibility/likelihood for seriously degraded sound, as your friend learned.