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
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.
Hmm, actually HifiTime's statement about highs passing through the woofer crossover is more correct than I initially thought.

If speaker A is series connected to speaker B, the high frequency energy that manages to get through the inductor that is in series with the woofer of speaker A will not be shunted to ground via a cap, it will be shunted to speaker B through the cap. Where some fraction of that shunted signal will be reproduced in its full glory by the mid or high frequency driver of speaker B, complete with whatever distortions, phase effects, etc., were imposed on it by that inductor and capacitor in the woofer section of speaker A.

Figure 5 of the article HifiTime linked to in his previous post is helpful in visualizing this.

In any event, all three of us are in agreement on the bottom line -- for any of several reasons series connection is not a recipe for quality sound.

Regards,
-- Al
Thanks all you ppl for this insightful thread. I had initially thought it a simpler question...
The Bottom Line:

1.Respect Ohms Law!

2.Use a "real" power amplifier{one that Doubles Down)

3.Use accurate, sensitive, speakers that are 95db. min. @
8ohm.

4.Use quality cable at EVERY connection!

5.Respect Ohms Law!

Do the above, and I assure You, the sound you HEAR!

Will blow away what a single pair of ANY speaker!

Not the Infinity I.R.S. or the sister companies speakers,

that are 7' FEET TALL!

I am talking about smaller speakers that have a single

woofer, instead of 4 or 6 woofers in one cabinet, like

those "Super Speakers".

This is the whole IDEA! To create that same "SLAM!"

and "IMPACT!" that those 7' FOOT and taller speakers

are able to attain.

I assure You, few people have heard, and "FELT" what

an "array" of drivers can do with "UNLIMITED POWER!"

"SOUND" can be a very powerful, and devastating Force,

if ample speakers with Unlimited Power, are mated.

EVERY Hi-FI Person in Sales, ALL have told me, "You can't

do that?" But I do, and I HAVE, for 30 years+ without

ANY problems EVER!

They don't want you to achieve what they "can't SELL!"

LIES! LIES! LIES! ALL the B.S. saying "cancellation" and

all sorts of stupid "excuses", NONE of which, is TRUE!

When in doubt, TEST EVERYTHING!

Don't believe me, do it for yourself, THEN...

Insert "FOOT!" into mouth!

2 channel Stereo, 1 in front and 1 in the rear, with front

and rear center speakers, and side speakers.

Looped from 1 pre-amp to the 2nd, so volume is set for

front and rear to blend into a "Natural Surround" Sound.

I LOVE MUSIC!
Jimthewebguy -

Only very high-end integrated amps offer two pairs of speakers. The Luxman L505U offers two pairs of speakers, which allows you to utilize A+B. This is achieved through employing Takasina capacitors, which are custom-made capacitors that Luxman uses in all of its amplifiers. These capacitors are used in parellel circuitry - and thereby permits the bi-wiring of a single-set of speakers.

I completely agree with Bjpd57a1. Without two pairs of speakers, even the highest-quality amps cannot achieve the highest levels of quality that quadrophonic systems can. However many high-end companies (such as Bryston and Krell) do not offer two pairs of speakers because it entails extra production costs (due to the added circuitry). When you use A+B, make sure that the speakers are 8-ohms.

Jimthewebguy, you used your old Luxman L507 with four speakers without problems. I used my old Luxman1120 for 29 years without any problem. There is no sound that can beat a four-speaker system.