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Playing 4 speakers at once

Discussion in 'Audio Hardware' started by dennis1077, Dec 24, 2018.

  1. dennis1077

    dennis1077 Forum Resident Thread Starter

    My receiver has connections for two speaker sets. Until now, I've only hooked up one set of speakers.

    I'm considering hooking up my old speakers and playing 4 speakers at the same time. Ever cautious, I consulted the receiver manual. Here's what Onkyo advises:

    "When you connect speakers to both SPEAKERS A and SPEAKERS B terminal posts and output sound from both speaker sets simultaneously, use speakers whose impedance is 8 to 16 OHM. Set the speaker impedance setting on the receiver to 4 OHM."

    This ruins all my fun. One speaker set is 8 ohm but the other is 6.

    Let's say I throw caution to the wind and proceed. Is it possible to damage my equipment by driving 4 speakers at once....particularly when those speakers are rated at different OHMs?
    rodentdog likes this.
  2. Helom

    Helom Forum member

    Don't worry about it. Watch the video in the link below and leave your receiver set at 8 ohms. Forget that switch is even there.

    Setting the A/V Receiver Impedance Selector Switch
    BrentB and quicksrt like this.
  3. SandAndGlass

    SandAndGlass Twilight Forum Resident

    Go with @Helom 's advise. The switch set to 4-Ohms will not improve your sound and will likely do the opposite.

    On a tube amplifier, you would have a separate 4-Ohm tap and a separate 8-Ohm tap of the output transformer. On a tube amp, the same amount of power is delivered to the speaker whether it is a 4 or an 8 Ohm speaker.

    SS amps work differently, as there is no output transformer's (except on McIntosh amps).

    Basically, in theory, Say that you have an amp that can deliver 100-Watts, using an 8-Ohm speaker (on each channel).

    The way you amp operates, is the when you are connecting a second speaker, both -Ohm speaker's are now operating in parallel.

    If you operate the two 8-Ohm speaker's in parallel to each other, they will look like a single 4-Ohm speaker, to the amp.

    What that means, electrically, according to Ohm's Law, is that when you cut the resistance in half, than twice the amount of current will flow through the circuit.

    So, instead of your amp delivering 100-Watts to the speaker, it will be delivering 200-Watts, to the two 8-Ohm speakers, which are running in parallel.

    When the resistance is cut in half, the current that is flowing through the circuit doubles and the amp (in theory) produces twice as much power.

    If you were to connect two 4-Ohm speakers to the amp, the amp will be seeing them as a single 2-Ohm speaker.

    The current flowing, will now be twice the amount of current that was flowing when you connected the two 8-Ohm speakers, which resulted in a 4-Ohm load.

    So, going from a the amount of current that would be flowing with a single 8-Ohm speaker connected, with two 4-Ohm speaker's connected, now there will be 4-times as much current flowing as there would have been with the single 8-Ohm speaker, because you would now be presenting a 2-Ohm load to the amp.

    Going from 8-Ohms to 4-Ohms, the current is doubled and the going from 4-Ohms to 2-Ohms, the current is doubled again.

    You don't have to connect up two speakers that are of the same Ohm's, having different Ohm rating doesn't make any difference. What does make a difference, is that if you connect an 8-Ohm speaker in parallel with a 6-Ohm speaker, the resulting load will be 3.42-Ohms.

    This is only slightly less than 4-Ohms and should not make that much of a difference, in the real world.


    Parallel resistance is calculated by the formula 1/R1 + 1/R2 + 1/R3... = 1/RT (which is the Total Resistance), where "R" is the individual resistance.

    Since you have only two speaker's, you have R1 and R2. With R1 being 8-Ohms and R2 being 6-Ohms.

    When you divide 8 (Ohms) into 1, you get .125. When you divide 6 (Ohms) into 1, you get .167.

    When you add these two numbers together, you get .292 which is 1/RT which is 1/.292

    RT is 1/.292 (1 divided by .292) or 3.42-Ohms.

    This is why the Ohms of any two speaker's individually is not important. What is important is what the total Ohms are when they are together in parallel.

    Note: Than when you read that a speaker is rated at say 8-Ohms, it means 8-Nominal Ohms. This is because your speaker is an inductor, which is just a fancy way way of saying a coil of wire (which is what the voice coil of a speaker essentially is).

    There is AC electricity going to your speaker. In an AC circuit, the speaker's inductance (which is like an AC resistance), will vary with the frequency.

    At different frequencies, your speaker's resistance (impedance), will vary with the frequency. So when they say your speaker is 8-Ohms, that is sort of an average impedance for your speaker.
  4. F1nut

    F1nut Forum Resident

    The Mars Hotel
    You'll never get double the wattage or current from a $250.00, 50wpc stereo receiver that weighs 16lbs.

    In fact, what happens when you use the 4 ohm switch is it restricts current to save the receiver from cooking itself because it doesn't have the power supply to safely drive 4 ohm nominal loads, which is what you'll have (actually closer to 3.5 ohms) by running both sets of your speakers. Either use the 4 ohm setting or just run one set of speakers. If you had planned to run both sets in the same room it was a bad idea anyway.

    One last comment, your receiver is not rated to drive 4 ohm nominal loads, it is only rated as 4 ohm capable because of the reason I stated above.
  5. head_unit

    head_unit Forum Resident

    Los Angeles CA USA
    If you are thinking to run 4 speakers in one room, well, that will make more and different sound but certainly not more accurate. And I'd set the receiver to 4 ohms as it reduces the output rail. It doesn't really matter, let me quote you "Head_Unit’s Rules Of Protection":
    1) If when things start to sound distorted or odd you TURN IT DOWN, you are unlikely to ever break anything.
    2) If you constantly "turn it up to 11" you will break something.
    NOTE: the size and power ratings and impedance ratings of the speakers and amp do not affect rules 1 and 2. (In any case, specs for amps are often not thorough and for speakers pretty meaningless).
    The Pinhead, The FRiNgE and Helom like this.
  6. SandAndGlass

    SandAndGlass Twilight Forum Resident

    This is important, which is why I used the words, "in theory" in connection with Ohm's Law and current.

    I have a 72-lb. power amp, with a large power supply and a lot of aluminum to dissipate heat.

    It is rated at 250-Watts @ 8-Ohms and 400-Watts at 4-Ohms. This is because even as large as this power amplifier is, it is not designed to deliver 500-Watts of power, which is what it would theoretically be at 4-Ohms, according to "theory".

    If we were to run the amp into 2-Ohms (which would be a very bad idea), in theory, the amp would be delivering 1,000-Watts. In actuality, this is something that the amp would not be able to do (or do for long).

    AS F1nut points out, your "tiny" little receiver, simply is not capable of delivering much more than 50-WPC, into it's 8-Ohm rated load.

    As @Helom pointed out in the the link that he provided, all the switch does is to cut the voltage to the rails, effectively reducing that available power even more, to begin with.

    More important than that switch, is head_unit's rules, which I have quoted below.

    These are essentially my rules too. These are rules that you should always be following, regardless of the amp, the speakers you are using or the impedance.

    Most amps, as specially the inexpensive low powered amps, will crap out and start to distort before even reaching full power.

    This is as specially true, if you are playing something that has a lot of bass in it, as bass takes up way more of the amp's power, than does the midrange or the treble.

    When you reach the point of distortion, your beautiful curved sine wave hits the ceiling, which is the point that your amp can no longer produce the additional power ti complete the top (an bottom) parts if the sign wave and that sign wave becomes a square wave.

    Think of a sign wave as an upside down "U". draw three upside down "U's". One smaller one, the next one twice the size of the first one and the third one, three times the size as the first one.

    This represents (sort of), the top part of a sign wave. As you turn up the power on your amplifier, the amplitude (size) of the height of the sign wave gets larger. As you continue to turn up the amp, the amplitude of the sign wave, gets even larger still. This is in a perfect world.

    Now, take and draw a horizontal line from the very top of the sign wave in the middle, to the right and cut through the sign wave, which is the larger sign wave on the right.

    Now if you erase (or simple cross out) the top part of the sign wave on the right, the top of the sign wave is now "flat" and is no longer curved.

    This is what happens, when your amplifier, runs out of steam and does not have enough power to complete the top part of the curve. It hits a "ceiling" where it can not produce the power necessary to complete the sign wave.

    This is what happens when an amplifier is driven into "clipping". The tops (and bottoms) of the sign wave have been clipped off, hence the term "clipping". Instead of a nice perfect sign wave, the wave now looks more squared off and this is what we call a square wave.

    Your sign wave is now, no longer perfect and has now become distorted, like in the diagram below.


    Under normal conditions, we don't normally notice distortion, until that distortion, becomes more than 1%.

    Then, the more distortion of the original signal, the more it begins to sound like "crap".

    So, as head_unit suggests, never turn you amp up to "11" as it will more than likely be driven into distortion at this point.

    And two, when the volume is turned up to the point that it starts to sound bad, your amp is clipping and is being driven into distortion.

    Which means, turn your volume down. When this happens, always turn your volume down.

    Note: What is bad for your ears, is also bad for your speaker(s).

    F1nut and I disagree on this.

    Often times, as specially when you have two speakers, as specially when you have only two "small" speakers in a room that is much larger, then the sound from you speakers, is insufficient to fill the room.

    Turning the volume up, only serves to make the sound that is coming out of those two small speakers louder, not more room filling.

    If you put a second pair of speakers in the room, preferably in the opposite side of the room, along the rear wall, facing out into the room, you will project more sound out into the room and project that sound more evenly into the room.

    At the same overall volume level, your sound is now filling your room more evenly. This is like being in a car that has four speakers, a pair in front and a pair in the rear.

    While the "perfect place" would be in the dead center of the car's interior, the sound is now more evenly dispersed and no passenger is sitting next to a speaker that is significantly louder than the speaker which is next to where another passenger is sitting.

    Having more than a single pair of speakers in a room, just happens to be one of those "audiophile" no-no's (which is something akin to a Bozo no-no).

    Meaning, that it doesn't have any real meaning. It is your stereo, listen to it any way it pleases you.

    I had three separate stereo's in my listening room, before I retired, earlier this month.

    Because I have a home theater too, I have one amp and a pair of speaker's in the front and another amp and pair of speakers in the rear. I also have a third pair of speakers between them, which sit at a right angle to the front and rear pair.

    I can run one pair, two pair, or all three pair at the same time, which often I do.

    Please feel free to click on my avatar and visit my equipment page. When you scroll down past my equipment listing, I have put together a tour of the system room, complete with photos and descriptions.

    If you are interested in connecting a second pair of speakers in your listening room, you may find the "tour" interesting.
    Last edited: Dec 25, 2018
  7. quicksrt

    quicksrt Senior Member

    City of Angels
    Don't listen to anyone saying four speakers (one in each corner) is a bad idea or that it's less accurate.

    In fact you will have a wider "sweet spot" with more areas of the room "on axis" which means nicer performance out of what you have in more areas of the room.

    I've been doing four speakers for 35 years and hope I never go back. It really fills the room up with sound just like it would if the artist, band, or ensemble were playing in the room. It's very real sounding and the on-axis listening means you can climb into the recording mix, and hear details like room size, and things not always noticed before.
    sberger, zebop, bdfin and 8 others like this.
  8. BIGGER Dave

    BIGGER Dave Forum Resident

    This makes me think I can put to use those Harbeth P3ESR that I retired when I upgraded to the M30.1 model!

    A while back, probably in the 70’s or 80’s, I remember reading articles in various Stereo mags, about hooking up rear speakers in an unconventional way. If I remember correctly, you use the secondary set of Speaker Outputs on your receiver, and string the rear speakers in series. This method used three wires. If I recall correctly, it went this way:

    * Connect the first wire to one of the negative terminals of the secondary Speaker Outputs on the receiver
    * Connect the other end of that wire to the negative of one of the speakers
    * Connect a second wire from the positive of that speaker to the negative of the other speaker
    * Connect a third wire from the positive of that other speaker to the other negative on the Secondary Output on the receiver
    * (nothing is connected to the positive connections of the secondary Speaker Outputs)

    Does any of this sound familiar? Maybe this was all a dream?
    Last edited: Dec 25, 2018
    SandAndGlass likes this.
  9. SandAndGlass

    SandAndGlass Twilight Forum Resident

    There are different ways of doing it.When you do the phasing thing, you have to be careful with your amplifier.

    The way I do things is that I never mess with or process the original stereo signal in any way.
    Three systems, all with a straight stereo signal.

    The first and the second system is the front mains and the reach HT channel towers.

    The power amplifier that I use for the rears has to stereo inputs. One is for the right rear HT channel and one is for the left rear HT channel.

    For stereo, I use the 2nd input pair on the rear power amp. But I reverse the input RCA's.

    This way stereo preamp is sending the left front stereo speaker a signal and that same preamp signal is being sent to the right rear speaker.


    The stereo preamp is sending the right front stereo speaker the other signal and that same preamp signal is being sent to the left rear speaker.

    So it is the left front and the right rear and the right front and the left rear. The speakers are crossed over, rather than the left being all on one side and the right being all on the other side.

    I this achieves a better balance in the mix this way.

    I started doing this, back when I was sixteen and was playing around with a 2nd set of speakers that I had.

    I keep all speaker's wired in-phase.

    Here is an overall view of the room. The sweet spot for the front mains for both HT and stereo is on the teal sofa.


    Here would be the right rear HT speaker, which is the left rear stereo speaker.


    Here would be the left rear HT speaker, which is the right rear stereo speaker.


    Both rear speakers are up on on top of a credenza so that they can project sound towards the center of the room more effectively.

    Below is the third system and the photo was taken from a seated position on the tan sofa, the is shown in the first photo.

    Third system is a pair of vintage, restored, Altec Lansing A7, Voice of the Theater speakers. The third system is powered by all tube amplification, past the DAC (if using a digital source).


    When using this third system as my main system, I can bring up the volume level of the the two systems in the room.

    The two front mains are to the left of this seated position and the two rear towers are to the right of this position.

    The room is about 450 sq. ft. and the other two systems provide sound to fill the rest of the room.

    The volume of all three systems can be adjusted separately, controlling the sound signature balance in the room.

    There are two sub woofer's in the room one is at the front and the other is at the rear. The 15" horn loaded sub is to the side of the left A7 cabinet. It os powered by a 1,600-Watt Crown XTi-2000 amp. It can produce a sustained SPL of 133 dB, continuous program material. The rear sub is a Polk DSW PRO 660, wireless 12", 400-Watt sub.

    Note: I have two different pairs of front main's speaker's. The LSiM707's (the inside pair) are the front mains that I mentioned above. The Zu, Omen Definition's are actually driven by a separate amplifier and are a 4th system.
    sberger, The Pinhead and Tullman like this.
  10. rodentdog

    rodentdog Forum Resident

    I run two sets of speakers A+B and have for over 25 years. Sounds great. I have a big room with tall ceilings. Two speakers won't cut it to fill the room with sound. I do have a RX-Z9, a beast of a receiver (170 watts/channel x 7, weighs 60 lbs.).
    dennis1077, ronm and SandAndGlass like this.
  11. E.Baba

    E.Baba Forum Resident

    I've used 4 speakers run from modest output old NAD. It was built with A+B Speakers switch.
    Your Onkyo manual seems to effectively be saying "You can do it but be careful ".
    Check that it's not getting hotter than normal.
    Mister Charlie and SandAndGlass like this.
  12. Hymie the Robot

    Hymie the Robot Forum Resident

    My old NAD receiver couldn't handle my Polk SDA bookshelf speakers, one pair. Added a NAD power amp to the receiver preout, and all was well. My first impedance lesson.
    KT88 and SandAndGlass like this.
  13. SandAndGlass

    SandAndGlass Twilight Forum Resident

    Where you get into trouble is usually with very "entry" level receiver's.

    When I was first setting things up, back in 2011, 2012. I had a pair of Polk Montior 60 Series II speaker's that I was using for the rear speaker's.

    I bought a $99 receiver from Amazon that was a stereo 100-Watt per-channel receiver.

    It did have a speaker A & B switch to connect two sets of speakers. Since I was using it only to power two 8-Ohm speaker's, that I was using in the rear, this feature meant nothing to me.

    What got me thinking about it, was, If I had the stereo turned up real loud and the rear's just barely clipped, the protection circuit would kick in.

    Now when this happens on a typical receiver, the protection circuit will cut in temporarily, when clipping occurs, the music will cut out for a couple of seconds and then it will resume playing again, when not driven into clipping.

    This receiver of mine would cut out, with just a single brief transient.

    Not just that, but the entire receiver would turn completely off, which was completely annoying.

    Since it was this extremely sensitive to clipping, more so than any other piece of gear that I have ever owned, I became curious about how it could handle two sets of speaker's?

    In digging through the manual, buried deep inside, in small print was a warning, "When connecting more than one pair of speakers at a time, make sure that both pairs of speakers are 16-Ohms".

    Now who owns 16-Ohm speaker's. Most of those are used professionally, with a longer wire run.

    Home speakers that someone would buy to run with an inexpensive amp, would not likely be 16-Ohm speaker's, they would be standard 8-Ohm speaker's.

    What they were really saying is that the cheap stereo receiver, could only run 8-Ohm speakers.

    Two 16-Ohm speaker's running in parallel would be an 8-Ohm load.

    I thought that this was very deceptive. This information was not written anywhere on the outside of the box and I really had to dig to find it, and I was specifically looking for it.
    The Pinhead likes this.
  14. F1nut

    F1nut Forum Resident

    The Mars Hotel
    Yet at any audio shop, audio show or serious audiophile's house they use only 2 front speakers and for a damn good reason.
    marcb, KT88, The FRiNgE and 1 other person like this.
  15. Hymie the Robot

    Hymie the Robot Forum Resident

    I rarely upmix two channel to four speakers but rooms and tastes vary.
  16. Tullman

    Tullman Senior Member

    Boston MA
    My garage system has 3 sets of bookshelf speakers...cough cough... overkill. I use 3 separate cheapo used power amps to drive them. This way I don't have to worry about over driving just one amp.
  17. 911s55

    911s55 Forum Resident

    Wa state
    2 channel stereo, 2 speakers in front of your ears. If you want ambient sound throughout there are lot's of options, if your amps can handle the load.
  18. Tullman

    Tullman Senior Member

    Boston MA
    Or....two sets of speakers in front of your ears.:agree::cool:
    The FRiNgE and SandAndGlass like this.
  19. Bingo Bongo

    Bingo Bongo Music gives me Eargasms

    I've done it with my old Marantz component amp in the 80's and never even worried about it. It was great for loud music, but not an improvement in any way!

    Even hooked up my 8 ohm speakers to my old van stereo without issue. Great Bass, but wasn't the loudest.
  20. SandAndGlass

    SandAndGlass Twilight Forum Resident

    True, but in the real world of commercial audio where they have world class live entertainer's they do not.

    There is a lot that you can do in audio that you cannot do with two speaker's.

    I have several sets of two speaker's, many different SS and tube amplifier's.

    Every home that I have ever been in, has only two sets of speakers (except for home audio distribution systems).

    Every stereo store that I have ever visited demonstrates their gear with two speakers (except for HT surround sound systems).

    I am currently sixty four. If I thought that a 2-speaker set up sounded better to me, than I certainly would not have gone to the time, trouble and expense to set up the system and improve it the way that I have done.

    At the end, I had four separate systems in the room and I could run any single system with a single pair of speaker's any time I wanted to do so.

    Sometimes I did, most most times I did not.

    There are a zillion ways to set up audio systems. Using only two speakers cover's many but not all of those ways.

    If some "audiophiles" feel that their system sounds best with two speaker's, fine, let them run their own system that way.

    I am fine with that.

    It's not like most of the world, doesn't do it that way?

    According to the research conducted by Dr. Floyd Toole, before his retirement with Harmon International, pointed out, that about have the listener's preferred listening with two speaker's and the other half, preferred a more immersive listening experience.

    There is no correct way to do audio, there are many ways to set up an audio system.

    It all depends upon someone's gear, their room and their personal listening preferences.

    There are people out there who prefer to listen in mono, using only one speaker.

    There are people out there who prefer two speakers, but still prefer to listen in mono.

    How cares? let people listen to music and their system's any way that they want to.

    Don't people realize that those who have elected to use four speaker's in the same room, started out by using only two speaker's in the same room?

    The people who are using more than two speaker's completely understand the two speaker's is best audiophile thing.

    They know what two speaker's in one room sound like.

    They are just opting for a different way.

    It is simply their choice, not to follow the crowd.
  21. classicrocker

    classicrocker Life is good!

    Worcester, MA, USA
    Ran 4 speakers, opposite rnds of the room, for years when I had an old 1980's JVC 120W/ch receiver and it sounded fantastic. As long as you use check impedances and have an amp with sufficient power there is no reason not to see if you like how it sounds.
  22. SandAndGlass

    SandAndGlass Twilight Forum Resident

    I bet you have great tunes in your garage. Perhaps not as great as your main system but great for a garage system.

    Just don't alert the "audiophile" police! :cop:
  23. quicksrt

    quicksrt Senior Member

    City of Angels
    Yeah, because (first) one needs to hear how the speaker performs by itself - and how wide the dispersion is without any additional help from another set.

    Also most folks will not spend the cash on two sets. most wives might not be real up for 4 speakers either.

    You think if someone spent say 8 grand on a set of very high end speakers, another 8 Gs for a second set comes easy? No it's not that easy.

    It is not because serious audiophiles or over-priced sales rooms guys know so much more than I do.
    Last edited: Dec 25, 2018
    sberger and classicrocker like this.
  24. F1nut

    F1nut Forum Resident

    The Mars Hotel
    It's called STEREO for a reason. I think some of you have never heard a properly set up and driven 2 channel system.
    marcb, bever70 and Frost like this.
  25. quicksrt

    quicksrt Senior Member

    City of Angels
    Four speakers does not change stereo into anything other than stereo. It only puts more of the listening space on-axis. Do you know what on-axis is? If you do, please explain your case. You seem to be sinking here unable to think outside your 2 speaker box.

    4 Speakers does in a room what headphones do in a small enclosure near your ears. Many many listeners like that result.

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