Wiring home speakers in series/parallel - AVS Forum
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post #1 of 7 Old 01-16-2008, 10:03 AM - Thread Starter
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I have a Sony STR-DE685 receiver, my two mains are Infinity Primus 360 towers. I am replacing the towers with Infinity Beta 20 bookshelfs due to size issues (TV upgrade caused me to run out of room.)

Can I add two more front speakers along with the Beta 20s and wire them either in series or parallel? I have some nice, very small 3-way Yamaha bookshelf speakers, dual 4" and a tweeter, and between them and the Beta's I think I could get some good sound.

Thanks
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post #2 of 7 Old 01-16-2008, 10:35 AM
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You can, but before you do you have to gather some information first. Making the wrong decision will damage your amp.

You have to find out the ratting of your amp. (ie 100w @ 8 ohms) and
what ohms the speakers are.

when adding two speakers in series it will increase the ohms.
when adding two speakers in parallel it decreases the ohms.

in series, when increasing the ohms, your amp will not put out the power it is rated at. 100w at 8 ohms may only be 60w at 16 ohms.

parallel. If you go below the ohms your amp is rated to run safe at, it will burn out your amp.



Edit:
Now that I think about it. Neither option is a "great idea". Running your amp below the ohms it is rated to run is the worst case, but under-powering your speakers at high volumes may do damage to the tweeters.

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post #3 of 7 Old 01-16-2008, 11:29 AM
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In parallel is the only way to go, but you won't have a great soundstage with duplicated drivers and different timbres... is this part of a 5.1 system? If you run them in series the impedances of the two speakers will interact... For example, if the impedance of the Infinities is really high at a certain frequency range, the Yamahas will not receive enough current at those frequencies and the balance will not be good.
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post #4 of 7 Old 01-16-2008, 11:36 AM - Thread Starter
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Thanks for the advice. I think I'm going to wait until the Beta 20's come in to see how they sound. Hopefully between them and the 10" sub with the crossover set high then the sound will be okay.

FYI the Yamaha's are 6 ohm, which seems odd. They were part of a 5.1 set that included 5 identical speakers and a powered sub.
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post #5 of 7 Old 01-16-2008, 03:54 PM
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Don't bother. You will only muck up the sound of your new speakers by adding the old cheapies.

Kal Rubinson

"Music in the Round"
Senior Contributing Editor, Stereophile
http://www.stereophile.com/category/music-round

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post #6 of 7 Old 10-28-2013, 04:47 AM
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no worth it

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post #7 of 7 Old 10-28-2013, 05:32 AM
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Quote:
Originally Posted by SCutchins View Post

I have a Sony STR-DE685 receiver, my two mains are Infinity Primus 360 towers. I am replacing the towers with Infinity Beta 20 bookshelfs due to size issues (TV upgrade caused me to run out of room.)

Do you have a subwoofer? If you used the available resources including bass management properly, there isn't that much difference between Primus 360s and Beta 20s in actual use.
Quote:
Can I add two more front speakers along with the Beta 20s and wire them either in series or parallel?

If you put them in series then you will waste the power capabilities of your AVR. Series operation = 16 ohm load which decreases the current flow to the speakers and causes a net loss of dynamic range for your system.

If you put them in parallel, then parallel operation will probably drop the load on the AVR well to below 4 ohms, and that has the effect of also decreasing maximum output.

If you run two speaker systems like this there is also a issue related to acoustical interference. The phase of their acoustical output will vary over the audible range and may cancel at some frequencies, causing rougher frequency response and bands of missing music.

The Beta 20s have a higher power rating than your AVR and are unlikely to be overloaded by carrying the load all by themselves.

If you lack the room for the Primus 360s, how is it that you have space for both the Beta 20s and Yamahas?

I'm wondering why you didn't choose the brandmate Infinity Primus 163 speakers - they have an excellent reputation.
Quote:
I have some nice, very small 3-way Yamaha bookshelf speakers, dual 4" and a tweeter, and between them and the Beta's I think I could get some good sound.

Looks like you have a solution looking for a problem. If its not broke, don't fix it. use the smaller speakers to set up an office or kitchen system, or something like that.
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