Chained speakers signal connected in series

Interesting - I spent a little time to sketch the schematic. Granted the amplifier output will see 2 inductors in series, the crossover frequency of the driver is based on the L and C values. That ratio does not change whether the speakers are connected in series or parallel. My vote is that it does not change the crossover frequency. As far as the series or parallel connection of the speakers to the amplifier, the series connection does make it typically easier for the amp to drive the load. But this is only true up to about 70% of the maximum voltage capability of the amplifier. A parallel connection of the speakers will yield a 3dB increase in SPL, if your amplifier can handle the load resistance and deliver enough current. I preferred to connect them in parallel. That being said, I frown on multiple drivers in series OR parallel, especially in the midrange and tweeter frequencies. Whether they are point source of line source drivers, the sound will lose detail and become fractured and unclear. Happy listening!

Good summary.

A 6db first order XO in series, the SECOND speaker drivers will get what is left over after being filtered by the inductor. IF the XO is built in parallel
NOT series.  Parallel the speakers would NOT change the Crossover points. In series it would.. 

To keep the XOs points all the SAME. Paralleled XOs and Paralleled Speaker connections. 

In series WILL change the XO point. I'm not sure how much but a little grade school math will get you close. It would be LOWER.

I'm not sure you could hear anything BUT a bass signal out of the second speaker box in series. Parallel and use a stout class d, that will work.. :-)

That wiring set up is exactly how you wire a MB and Sub in series by just adding an additional resistor between the two. The first would be at 280 and down, THEN between drivers ad a second resistor to drop to the 80-120 db first order. It's part of a Quasi 2nd order paralleled passive XO, I actually use.. Sure helps out a tube amp IF it has to do bass duty, TOO.
Shares the load more evenly. LOL It's HEAVY all the time..:-)

It's a great design for planars too.. Fast, transparent and VERY revealing.. What  you're feeding the drivers is exactly what your gonna hear.. SO a high floor noise, bad source or funky sounding (BRIGHT) SS STUFF is still gonna sound BAD.. High E speakers 90+. One ribbon I use is 103 db and 100 watts RMS. 10 watts your ears are bleeding..
1-40khz. I can point that thing and break glass. I'm pretty sure..

Regards

oldhvymec - You are funny, thanks. I'm going to actually do some "grade school" math on a 2nd order low-pass filter. I will connect them in series first, then in parallel and the numbers should speak the truth, unless my math is bad. I will share the numbers once I'm done! Your analogy of a 103dB speaker also got a chuckle out of me. 103dB @ 1watt,1meter distance is not that loud, really. Break glass you're flat out wrong, even 1000watts, that only 133dB. Jet engines at a distance of more than 100 feet are 140dB, that doesn't break glass. 123dB @ 100watts is loud, but rock concert levels and threshold of pain are about 130dB. While I don't listen to music at those levels now, I wish I NEVER did... 

I did some testing this morning by connecting and disconnecting the speakers from the amps. The speakers connected in series (two speakers per channel chained) sound different from what they sound when they are connected separately (single speaker per channel). Interesting, that while both speakers in series produce a duller sound, one of the speakers degrades the sound more than another. Unless it is OK to connect them in parallel I would have to loose one pair from the system as it appears a single speaker per channel sounds way better.