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#399184 - 12/10/13 10:53 AM series and parrallel ohm question
jimmydj Offline

Registered: 12/09/13
Posts: 8
Hi Jus wondering I have a 7.1 receiver I'm just using as a stereo , 4 stereo speakers 8ohm, if I run them in series I understant the ohms would effectively quadruple ,or if I hook up Jus 2 in series the ohms double, so would this make the receiver run more efficient since there's less resistance,and would it have an effect on the sound

#399185 - 12/10/13 11:51 AM Re: series and parrallel ohm question [Re: jimmydj]
ClubNeon Offline

Registered: 02/06/09
Posts: 3466
Loc: Western Maryland, USA
The lower the resistance gets the more the load starts to look like a short. Think about it, if you took a piece of wire, with a resistance of virtually 0 Ohms, and put it across the speaker terminals, the receiver would shut down. Lower resistance isn't always better. What you want is a load that's compatible with what the receiver is expecting to run into.

Running speakers in series will present higher resistance, and won't make the receiver act like it is shorting out, but speakers aren't fixed loads like a simple resistor. Speakers are reactive to the frequency they are reproducing and can run from less than 2 Ohms to over 20 across the audible range. And different speakers react differently at different frequencies. So yes, this will have an effect on the sound.
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#399187 - 12/10/13 12:23 PM Re: series and parrallel ohm question [Re: jimmydj]
Murph Offline

Registered: 10/05/06
Posts: 6955
Loc: PEI, Canada
Your receiver likely has an option to assign a second pair of outputs as fronts. You would then have two left channel outputs and two right channel outputs. It might even have an option to change all 6 outputs to fronts so you have 3 left and 3 right. I believe this is called "all channel stereo" mode on my Denon.

There will be no efficiency gain but it will allow you to connect all four speakers in a much safer manner.

With great power comes Awesome irresponsibility.

#399195 - 12/10/13 09:34 PM Re: series and parrallel ohm question [Re: jimmydj]
JohnK Offline
shareholder in the making

Registered: 05/11/02
Posts: 10644
Jimmy, welcome to Axiom. You sort of have the ohms/impedance relationship backwards. Yes, connecting speakers in series increases the ohms, but this results in more resistance(impedance), not less. Since the resistance is greater, the amount of current flowing at an instant in time is lower because, following Ohm's Law, current equals voltage divided by resistance. Since the voltage at that instant is the same(isn't changed by an ohm difference)the higher resistance lowers the current. Power is the result of voltage times current, so the power used will be lower and the effect on the sound will be that it's less loud at the same volume control setting.

The opposite result occurs when the speakers are connected in parallel and the ohms(impedance)are lowered. The sound will be louder at the same volume control setting, but this isn't necessarily all good. Since the current will be higher the heating effect on the amplifier will be greater, and depending on how loud and how long this goes on, the amplifier may start to overheat and its protective circuits will temporarily shut it down.

If you have four speakers and a seven channel receiver(which you haven't specifically identified)you shouldn't limit yourself to listening to them only in stereo. If the receiver has a surround mode such as DPLII you should connect two of your speakers as side surrounds and listen to 2-channel material in a more realistic surround fashion.

Enjoy the music, not the equipment.


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