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?
With those two speakers running paralleled,the combined resistance is about 3.4 ohms.That is hard for an amp to drive. 8+8 ohms =4ohms.4+4 = 2 ohms.8+6= 3.4286 ohms.
there are a number of speaker selectors (niles comes to mind) you can attach to the amp which provide for impedance matching--i.e. you can match the resistance of your speakers to the selector so the amp doesn't get overloaded. the added advantage, obviously, is you can choose to use either one or both pairs of speakers by simply pushing a button on the selector. hope that works for you.
I found this on the net.One last thing,0 ohms is a direct short.LINK>>[]
A much better solution would be to get a second power-amp or a high-end home-theater power amp (i.e. McIntosh MC7205), and run each speaker of its own amplifier channel. Simply split the preamp signal with Y-cables on the amplifier inputs.

Also, if the second/new power amp has input gain controls, you can adjust the front/rear loudspeaker balance to your liking, with no performance side-effects.
Hifitime - Yes, in parallel that looks bad.

I suppose that amps with an A+B selector option have a different wiring than parallel. I do not notice any change in volume in set A or B when I switch from A or B to A+B, so I suppose there is some degree of separation of the output stages. Mine is an old Japanese amp for which I have no specs.

Would you, or anyone out there, know whether it is true that driving 4 speakers from an amp designed with that option actually causes excess wear on and eventual damage to the amp, as some sales guys (in an amp department - maybe not without motive) told me?
Heat does shorten transistors life.Running two 8 ohm speakers is about the limits of most amps(4 ohms total).All the amps I've owned do parallel the speakers through the speaker switches.Some budget receivers run them in series,but that ruins the sound because both speakers would be using the others crossover along with its own.The 8+6 ohm speaker combo is over doing it in my opinion.The other peoples ideas sound better if you like the amp and want it keep on going.
Thank you all for the facts n ideas. It sure cut out a lot of time for me. I'm still thinking about my next move.
I am running 18 separate speakers, that are "passive",
with 3 Amplifiers driving them ALL.

Respect "Ohms Law!" and you can safely run in "series",

several speakers without presenting a low impedance that

is hard on the amplifier.

In addition, I implement 2 Velodyne subwoofers.

An 18" and a 15" one in front, one in the rear.

I implement front speakers, and side speakers, along

with rear center speakers.

Stereo ONLY, simply put, just 2 separate systems working

together to fill the room EVENLY with sound.

I have done speakers in both parallel and series, for over

30 years without ANY incidents at ALL.

PS Audio GCA 500, and a GCA-250 do the lions share,

while a Pro Hafler 300 wpc. @8ohms and 500wpc. @4ohms

for the side speakers.

NO sound processors are used, just PURE 2 channel sound

that is IMHO, the finest "Surround" Sound I have heard

so far.

Every speaker adds +3db. so you can see that this is an

easy way to squash the -10db. that most people have,

from their listening spot.

My idea was simple, 1 speaker must play very Loud to try

and fill a given room.

Placing speakers, in key locations where the hearing, is

able to pick up sound literally "ALL Around".

So I have plenty of "Headroom", and there is NO need to

ever increase the Volume, since the moment the "play"

button is engaged, it is as if a metamorphosis of the

Audio kind takes place.

Never be afraid to think outside the box.

Some of my Best ideas, have spawned out of the box.

Love Your Music!
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: ( You can find the manual for the DH-220 here: (
Re connecting speakers in series:

1)To the extent that the speakers which are connected in series do not have identical impedance vs. frequency characteristics, frequency response irregularities will be introduced into each speaker. That is because the voltage applied by the amplifier across the series connected speaker string will divide up between the speakers differently at different frequencies, if the speaker impedances have different proportions to each other at different frequencies. Avoiding that effect will typically mean that the speakers should be identical models.

2)Even if the series connected speakers are identical models, bass damping will be degraded. That is because the source impedance driving each speaker will be the sum of the impedance of the other speaker and the power amp's output impedance, instead of just the power amp's output impedance.

-- Al
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.

-- 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>[]
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.

-- 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. @

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.

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.
Thank you Renjy651 for that last comment. I can't agree more.

I was very happy to learn that the L 505u can play A+B. People in a shop here said it couldn't. After reading your post I found it can from the Luxman site, and now I have a new possible amp goal in mind. I hope to find some way to listen to it at home.

Tonight I'll go and listen to a used pair of Sonus Faber Concertos (original type, not Homes) at a local shop. I'll be bringing my Luxman 507 and my own CD player (Ah! Njoe Tjoeb 96/24 w/Siemens 7308 gold pin tubes).

The intention is to have nice sounds in my computer room. I almost bought Adam 7 powered speakers, but was talked out of it. I have no idea yet whether the Sonus Fabers might match nicely with my Yamahas (totally opposite approches to sound reproduction, but sometimes such differences synergize), but if I buy these SFs I'll certainly experiment with that.

I love the sound of SF speakers, and I'm thinking it would be nice to have three very different-sounding pairs at home: My Yamaha NS100x's, modified B&W 805Ns, and Sonus fabers. This should cover the spectrum of my own tastes with differing types of music and recording quality.
Just an update in case anyone is interested
I listened to the Concertos and didn't like them much at all. The bass was weak and muffled, they didn't image well, lacked detail, and were very much "in the box." The had a lot of cosmetic damage as well. I compared them to some Quad 12L's, which were in mint condition and at half the price of the Concertos. Originally, i just wanted to use the Quads as a comparator, but I wound-up buying them as a temporary fix until I find something better. Since then I've come to like the Quads more and more, though best within a certain range of genres. I still think of them as temporaries, and I'm looking for some SF Minimas to try next.

In the meantime I bought the very first Japanese version (different mains power) iDecco in Japan, directly from the distributor before they reached the market here. This is an amazingly good unit. I'm using this mainly to listen to flac files streamed from my iMac to my Quads, and it sounds warm and extremely detailed.

I also picked-up a second set of NS-1000x's, a rare walnut set in the best condition I've ever seen these speakers in. I'm thinking of keeping this set for replacement parts, so that I'll always have NS-1000x's in good shape around. The full set here in Japan costs about as much as two used so-so conditioned beryllium tweeters do overseas.
AL - I would never connect speakers in series but I believe DF doesn't suffer - at least with woofers in series within the same box. It appears that each woofer sees impedance of the other woofer in series (JBL wrote paper on that - that is incorrect) but in reality EMFs are in opposite phase and cancel. If amp's output impedance is zero - it looks like two woofers are connected in parallel in opposite polarities (EMFs cancel). Connecting woofers in series makes sense only when they are identical (for cancellation). Connecting speakers boxes in series will be a mess.

More info here:

or here:
Jim -- Thanks for the update. Enjoy!

Kijanki -- That's an interesting thought, which I hadn't previously seen stated.

A series connection, whether of two woofers within an enclosure, or of two series connected speakers, would have to be done such that the plus (or red) terminal of one woofer or speaker is connected to the minus (or black) terminal of the other woofer (or speaker). Otherwise the two drivers would operate out of phase and cancel acoustically.

Given that arrangement, the voltages corresponding to the back-emf of each driver would add together, resulting in double the voltage assuming the drivers are identical. And the papers you referenced appear to say that the doubled voltage compensates for the doubled total impedance, resulting in the same current and hence the same dissipation of energy from each woofer (or speaker) that would occur with a single woofer (or speaker) connected to the same amplifier.

That seems to make sense. Thanks!

In any event, we (you, me, Rodman, HifiTime) are all in agreement that for other reasons series connection of speakers, especially if they are not identical, is a no-no.

Best regards,
-- Al

Thanks Kijanki . . . A good explanitation of why it can be appropriate to wire speakers in series under certain circumstances. It should be noted the main assumptions/limitations . .

First, it makes the loudspeaker performance more variable with manufacturing tolerances, so in i.e. the D'Appolito array mentioned the effective tolerance for the drivers themselves must be better than for the parallel connection to get the same average results. And for a professional sound reinforcement application, there's one-quarter the statistical redundancy in the event of driver damage.

Second, it assumes that the driving source (amplifier) have essentially a zero output impedance. Although one wouldn't expect to see an SET or OTL amp for this kind of application, series volume controls should definitely be avoided, especially because they introduce enough frequency-response variations of their own.

So for something like putting four pairs of identical outdoor speakers on a single receiver ... The series/parallel scheme works great, provided they're hooked directly to the (typical solid-state) amplifier.
Kirkus - I remember seeing large bass guitar stacks that had a lot of small (about 10") speakers (10-12). They must have been connected serial/parallel to obtain any drivable impedance.

I've read on this forum that before SS popularity speakers/drivers had very high impedance (16 or even 32ohm). Maybe it was to match better with tube gear but it could be for other reasons. Lower impedance allows to squeeze more power from SS amps.
Kirkus - I remember seeing large bass guitar stacks that had a lot of small (about 10") speakers (10-12). They must have been connected serial/parallel to obtain any drivable impedance.
Actually, just about every instrument cabinet I can think of is parallel connected . . .the classic Ampeg SVT bass cabinet used eight 10" 32 ohm speakers, and I think the modern versions do as well. In Fenders, many of the differences between the (ostensibily very similar) amplifiers used in heads and combos were different output transformers . . . i.e. a Super Reverb combo had 4 8-ohm speakers, and the amp had an OPT designed for a 2-ohm load.
I have had fantastic success in running speakers in series.

I have a set of Klipsch 5.2 with a 12, 10, and a medium size horn.

Loving the nice low end response, the 5.2 lacks the mids and the sensitivity in the highs that I get from a set of 3.2's which have a 10, 8 and a smaller horn.

The 3.2's have very nice mids, decent highs, but lack body on the low end.

I simply stacked the 3.2's ontop of the 5.2's running off an old Scott Tube amp, and I am now getting the best of both worlds.

So any theory about destroying your sound by running two sets of speakers in series is not an absolute universal concept. It's working fantastically for me.