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Running 4 speakers from a 2-channel amp

I love the sound of 4 speakers playing at once around me. I've got a simple old SS amp, Luxman L507 (mid-1970's) that runs 4 speakers at once. I'm running a pair of Yamaha NS-1000x (6 Ohm) as mains, and a tweaked set of B&W 805Ns (8 Ohm) as B's.

I'm talking here about 2-channel sound, 4 speakers, not 4-channel surround sound.

I've been looking for a higher-end amp, but find almost all are two-channels only, with ports for only two speakers.

Some great old Luxman tube amps offer 4 channels, but only one pair at a time is available on the selector ("A or B," not "A and B"). One shop told me they could have one modified for me to be able to play 4 speakers, at only a small cost.

Another shop told me that playing 4 speakers at once, even on my current old Luxman, which has the "A and B" option, overburdens the amp and shortens it's life.

I wonder - can't we wire-up 4 speakers, say two on each side in parallel, like in so many car stereo setups?

Am I really limited to only 2 speakers with a 2-channel amp?
jimthewebguy

Showing 3 responses by rodman99999

rodman99999
5,983 posts
 
Find a used David Hafler DH-200, DH-220 or DH-500. All can drive a two Ohm load with ease, utilizing MOS-FETs for output devices(not prone to thermal runaway). An operating 200 or 220 should be fairly inexpensive, and appear often on eBay. ie: (http://cgi.ebay.com/Hafler-Dh-200-Amplifier-Clean-Cheap-No-Reserve-1-Wow_W0QQitemZ390151415488QQcmdZViewItemQQptZVintage_Electronics_R2?hash=item5ad6d626c0) You can find the manual for the DH-220 here: (http://www.hafler.com/techsupport/pdf/DH-220_amp_man.pdf)
rodman99999
5,983 posts
 
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.
rodman99999
5,983 posts
 
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.
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