Which ohm is best, 4,6, or 8?

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rlyddane
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Joined: 25 Oct 2011, 07:23

Which ohm is best, 4,6, or 8?

Postby rlyddane » 25 Oct 2011, 07:51

I have all 3 sets of speakers. Which ohm gives the best quality sound? Can I mix sets? I have a Yamaha HTR-5950 reveiver. It lets me choose between 2 options. 1. Less than or equal 6 ohm is one choice. 2. Equal or greater than 8 ohm. If I want to (or am allowed to) use all 3 ohms, which setting do I choose, 1 or 2? This is very important, because it will determine which speakers I need to buy, if I need to (or should have) all speakers the same. I have 2-8 ohm mini speakers, 5-4 ohm mini speakes, and 5-6 ohm Yamaha mini speakers. Also a Yamaha YST-SW012 sub woofer. None of these speakers are great quality, but they are adequate for now.

Any advise you can give me would be appreciated. I am planning on buying a Samsung UN55D6000 or 7000 series HDTV within the next 6 months, and I would like to have everything in place by then.

Thanks in advance for your help.......................Rich

JazzGuyy
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Re: Which ohm is best, 4,6, or 8?

Postby JazzGuyy » 26 Oct 2011, 09:45

The connection to use is dictated by your loudspeakers. If you have speakers rated at a nominal 8 ohms or higher, use the 8 ohm setting. If less than 8 ohms, use the 6 ohm. If you are using mixed ohm rating speakers, use the setting for the lower number unless your receiver lets you make specific selections for specific speaker connections.

Rodolfo
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Joined: 01 Sep 2004, 20:46
Location: Lansdowne VA

Ohms rules

Postby Rodolfo » 26 Oct 2011, 10:37

Rlyddane,

Since you are planning to use different impedances of speakers connected in parallel directly to the amp, rather than using a speaker switcher/selector with impedance compensation (such as Niles), you would have to make sure your total impedance (the one the amp sees when connected to all the speakers) is not drop below a safe level for the amp, otherwise it would overheat and shutdown, especially at high volume levels driving all the speakers at once; heat reduces the life of your equipment and you run the chance to even kill it.

Here is formula that you could use to calculate total impedance in ohms for paraller speakers (+ connected to +, and - connected to -):

(Sp1 x Sp2) / (Sp1 + Sp2) = Total impedance the amp faces

For example: 2 pairs of 8ohm and 8ohm connected in parallel would be:

(8x8) / (8+8) = 64/16 = 4 ohms which is low enough for many amps/receivers
---------------------------------
If using 4ohm speakers:

(4x4) / (4+4) = 16/8 = 2 ohms, you may fry eggs on your amp before it shuts down.
---------------------------------

Add more speakers in parallel, and/or lower the individual sp ohms, and the total ohms drops further, a number closer to zero is short circuit between the + and - speaker connectors in back of your amp.

Some people cheat the formula and puts some speakers "in series" combined with "in parallel" because when they are in series (the + of one speaker going to the - of the next one) they add impedance (resistance) to the final number while the parallel reduces it, but the sonic balance of such approach is not as good as the impedance problem it solves on the amp, plus you have no control of individual volume levels.

If you have an all-over-the-house parallel speaker installation that is already done I recommend a good speaker switcher/selector with individual volume control and impedance matching per speaker (such as Niles), and connect the amp to it so it will see a balanced impedance regardless which speaker is on and at what volume.

Good Luck.

Best Regards,

Rodolfo La Maestra

gartrste
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Re: Which ohm is best, 4,6, or 8?

Postby gartrste » 27 Oct 2011, 03:31

According to Dharmic religions, eight oms would be better. https://secure.wikimedia.org/wikipedia/en/wiki/Aum

Rodolfo
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Location: Lansdowne VA

Why using ohms as the only selection criteria?

Postby Rodolfo » 27 Oct 2011, 10:54

rlyddane,

I am not sure I understand how you plan to use the existing speakers with your comment of buying a new pair. Would the new set replace the several multi-ohm speakers? Would it be added to the group? If the new speakers would be added to the group then use the other post as a guide.

Regarding choosing a speaker by its impedance I would only drive the selection that way if the system (amp/existing speaker setup) does not have the flexibility, otherwise I would select primarily by sound quality and room dimension/speaker sensitivity, tonality matching with existing center speaker, trusted manufacturer, etc.

If your room is large and your amp is low in power buying a speaker with more sensitivity in dB and lower impedance in ohms could make the speaker generate more sound-pressure-level (sound louder) than otherwise. Another possibility for large rooms is to install active subwoofers to avoid the demand of power from the main amp when having to reproduce the more hungry low frequencies.

Best Regards,

Rodolfo La Maestra


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