Connecting multiple speakers to one output.

 

New member
Username: Jkingma

Post Number: 1
Registered: Nov-11
I want to connect 8 speakers to my receiver but there are only connections for 4 speakers. Can I connect 2 speakers in parallel to each jack or will that damage the speakers and/or receiver?
 

Gold Member
Username: Hawkbilly

Nova Scotia Canada

Post Number: 1441
Registered: Jul-07
I think the general rule is that for parellel connections the impedence is halved, and for series it is doubled. So, assuming you have 8 ohm speakers, connecting any 2 of them in parallel would lead to a 4 ohm load. Keeping in mind that the impedence of your speakers flucuates across the frequency spectrum (above or below 8 ohms) the overall impedence could at times be closer to 2 ohms. Most big box receivers will struggle mightily with that type of load, which can overheat your receiver. Frying your receiver could also lead to unfortunate results for your speakers as well.

A series connection may be more advisable but I'm far from an expert.

Why would you want to connect 8 speakers ? Are they in different rooms ?
 

New member
Username: Jkingma

Post Number: 2
Registered: Nov-11
"Why would you want to connect 8 speakers ? Are they in different rooms ?"

Yes, thats correct.
 

Gold Member
Username: Superjazzyjames

Post Number: 1763
Registered: Oct-10
My suggestion: Connect two speakers in series to each pair of terminals. This will maintain a NOMINAL impedance of 8 ohms. Keep in mind that what Chris said with regard to impedance and receivers handling it is correct.
 

Gold Member
Username: Illuminator

USA

Post Number: 5616
Registered: Apr-05
Not only will it just overheat your receiver, but you risk frying the output IC's or components in the power supply. Once upon a time I had a flagship Onkyo TX-DS939 and I hooked up a 3 ohm load (unknowingly) to it and blew a capacitor in the PSU. Fortunately it was an easy fix (new cap for $2, though slightly difficult to find locally), but could have easily been worse.

Like James said, best to wire the speakers in series. Also, you could consider getting a speaker selector box to switch between the sets of speakers (radioshack carries these devices) if you don't need each set of speakers playing simultaneously.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16953
Registered: May-04
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"I want to connect 8 speakers to my receiver but there are only connections for 4 speakers. Can I connect 2 speakers in parallel to each jack or will that damage the speakers and/or receiver?"


"4 speakers" would normally mean two pairs of speakers and "eight speakers" would be four pairs. If "eight speakers" means eight pairs of speakers, then we need to clear up the confusion. You don't mention what receiver you have but I would hope it's a fairly safe bet to conclude any modern "stereo" receiver has two pairs of speaker outputs wired internally to be in parallel. (if you're trying to make this connection to a home theater type of receiver, we once again need to clarify what components you own and intend to use. Very little that applies to a two channel stereo receiver transfers easily to a 5.1 HT receiver when multi-room speakers installations are desired.) In other words, with a two channel system, when only speaker "A" is engaged, the amplifier sees a load which represents one pair of speakers. When both "A" and "B" speaker outputs are engaged, the amplifier sees a parallel connection which would then show the amp approximatey half the impedance of the lower impedance speaker of the two pairs. (There are also receivers being built today which do not allow both speaker ouptuts to be active simultaneously. In this case, when you engage one speaker switch, the other switch is automatically disengaged in order to provide protection to the amplifier.) Therefore, if one set of speakers presents a nominal eight Ohm load while the second speaker set represents a nominal impedance of six Ohms, the amp will see a load of approximately three Ohms. Most modern receivers would be hard pressed to withstand a three ohm load for any length of time if the volume levels are being pushed.

You also do not mention whether the speakers you intend to connect are all the same speaker model or whether they differ from each other. In other words, here you have failed to provide any information which might tell us more about the load the individual speakers will present. Further, if one set of speakers is rated as a "nominal" or average eight ohm load, the strong possibility exists that any speaker will not remain at eight ohms for its entire frequency response. With a wandering impedance from each speaker set it would be quite possible for even two pairs of "nominal eight Ohm" speakers to show the amp a load which would qualify as dangerous. Since we know nothing about the impedance of each speaker set or the capacity of youru receiver to drive low impedance loads, the safest way to recommend you go about this matter would be to suggest you insert a master speaker selection switch box between the amp and the individual speaker pairs.

Only connecting speakers in series presents a few problems. By using a series connection between the speaker pairs both speaker sets must be playing at the same time - there is no way to switch off "set one" and only have "set two" playing. The same problem would apply to volume control, both speaker sets would have to be playing at an identical master volume level. Connecting two sets into speakers "A" on the receiver and two pairs into speakers "B" on the receiver without any intervening volume controls would further mean all four pairs of speakers will be set at the same output level by the master volume control of the receiver. It would be a very unusual installation where all four pairs of speakers were intended to play all at once and all at the same volume level.

Buying a small speaker switch box to insert between the receiver's speaker outputs and the individual pairs of speakers will; first, provide control over which speakers are playing at any one time. If there will only ever be just one pair of speakers playing at any one time, the switch is all you will need. However, it is also highly unusual for a multi-room installation to only have one pair of speakers playing. More likely is the siutuation where you want more than one pair of speakers playing and that you would also want to control the volume level of each pair of speakers. Now, if your system requirements are typical, you will require volume controls to be inserted into the system either at the master control area of the receiver and speaker selector or you could use a switch box located with the receiver and individual volume controls in each room with the speakers. You'll have to decide which set up is the most convenient for your installation. If you are doing a pre-wire of a new house being built, then individual controls located with the speakers is the best overall choice. For pre-existing construction, it's often simpler to locate the vc's in the same spot as the speaker switch box.

Using autoformer type volume controls or an autoformer based speaker switch box is the best way to ensure the safety of the installation. Autoformers inserted between the amplifier and the speakers will always ensure the amplifier sees a solid eight ohm load which would never vary up or down no matter how many speaker sets are in use. This is the safest way to protect your receiver from a dangerous drop in impedance load. Use either individual autoformer volume controls or a single autoformer based switch box with volume controls. You only need the autoformers in one location. If you buy the autoformer switch box, then use conventional L-pad type volume controls. If you use the autoformer type volume controls, then a conventional switch box is your choice.



There are less expensive switch boxes and volume controls available. IMO the autoformers are well worth the investment as they will last for the life of the install and there should never be a situation where the receiver blows up due to impedance loading. Any shop that specializes in full house automation or sound systems should be able to recommend the appropriate products once you've explained how you intend to use the system. The autoformer volume controls and switch boxes are also available on line. Generally, I recommend you go through a local dealer whenever possibe for after the sale assistance should you have problems installing the devices.




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New member
Username: Mike_q

Post Number: 1
Registered: Nov-13
I also have a 140 watt mini stereo with only 2 outputs. I want to connect it to 4 8-ohms speakers. What would be the best connection in my case? Series or parallel? Your feedback is appreciated. Thank you
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 17807
Registered: May-04
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Are your intentions to simultaneously run all four speakers? Or is this an either/or situation?
 

New member
Username: Mike_q

Post Number: 2
Registered: Nov-13
Yes I like to run all four speakers simultaneously.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 17808
Registered: May-04
.

With a mini-system, there are no good options. Speakers are not just 8 Ohms and, if they swing their impedance by much, any connection scenario can cause problems. Try a parallel connection and don't push the amp. Check to make sure the amp is not running hotter than normal. If you feel it is heating up, try the series connection and again check for excessive heat.



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