4 ohms or 8 ohms

amplifiers, receivers and loudspeakers
DagnyT
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4 ohms or 8 ohms

Post by DagnyT » 14 Mar 2019 00:21

I have a receiver that can output either 4 or 8. Also, the speakers I have are also rated for both. At the moment I have the receiver set to output 8. I think I read the receiver doesn't have to work as hard at 4 ohms. Is that better? Thoughts?

Spinner45
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Re: 4 ohms or 8 ohms

Post by Spinner45 » 14 Mar 2019 01:48

The difference is really neglegible, honestly.
As long as the speakers are within the capability of the amp.
4 ohm speakers, if used with solid state amps, will only make the amp produce a bit more wattage for a given sound level.
I wouldn't worry about it.

Sunwire
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Re: 4 ohms or 8 ohms

Post by Sunwire » 14 Mar 2019 02:27

What are the make and model of your speakers and your amp?

Agrippa
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Re: 4 ohms or 8 ohms

Post by Agrippa » 14 Mar 2019 08:09

Spinner45 wrote:
14 Mar 2019 01:48
The difference is really neglegible, honestly.
As long as the speakers are within the capability of the amp.
4 ohm speakers, if used with solid state amps, will only make the amp produce a bit more wattage for a given sound level.
I wouldn't worry about it.
^This^.

If in doubt, just try both settings and use the one you like best, given that you can hear any difference at all.

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Re: 4 ohms or 8 ohms

Post by raphaelmabo » 14 Mar 2019 09:41

Lower impedance means more current from the amp is needed. There are often two impedance values in tech specs for speakers: 1. Nominal impedance and 2. Lowest impedance. Nominal impedance is like an average impedance across the frequency spectrum, the speaker will go above and below this value at different frequencies. The Lowest impedance is the lowest the speaker will go. So you can, for example, have a nominal impedance at 8 ohm and then the lowest impedance can be 3.5 ohm or something else. But this is perfectly fine for most solid state amplifiers. For tube amps, they can be more sensitive to lower impedances.

DagnyT
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Re: 4 ohms or 8 ohms

Post by DagnyT » 14 Mar 2019 13:50

Sunwire wrote:
14 Mar 2019 02:27
What are the make and model of your speakers and your amp?
Just getting started. Pieced together on a very low budget.
Yamaha RX-396 Receiver
Onkyo CP-1010A TT
Bose 4001 Speakers

Now that I'm running something and able to play records I'll look to upgrade over time. I just wasn't able to find a definitive answer on 4 versus 8 ohms.

Jim Leach
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Re: 4 ohms or 8 ohms

Post by Jim Leach » 14 Mar 2019 14:07

I've never seen a speaker with "selectable" impedance... Can you post a picture of the back of the speaker (binding posts), as they typically state nominal impedance there, and that is generally the number used for compatibility? As Rafael stated, the actual impedance will vary based on the program material, going both higher and lower than the nominal as frequency changes.

The amp similarly will have a rating, and it is typically at 8 ohms. Probably something like "100 watts at 8 ohms" which may go on to say "150 watts at 4 ohms". The better amps will state additional ratings at lower impedance, but in general, if the nominal rating of the speaker is in line with the perceived need for stated wattage at the same impedance, then you are good to go.

Be sure to mind polarity of your connection wires.

DagnyT
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Re: 4 ohms or 8 ohms

Post by DagnyT » 14 Mar 2019 14:46

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jdjohn
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Re: 4 ohms or 8 ohms

Post by jdjohn » 14 Mar 2019 15:22

Actually, the impedance output choices on your Yamaha are for either 4-8 ohm speakers (switch left), or 6-12 ohm speakers (switch right). You want to use the 4-8 ohm setting.

The Bose speakers have no choice for settings...it's just telling you to use an amp that has output impedance of 4-8 ohms.

DagnyT
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Re: 4 ohms or 8 ohms

Post by DagnyT » 14 Mar 2019 15:49

So with the switch to the left I'm getting 4 ohms when only using A or B but if I run both together it's 8 ohms per speaker. So it's not like I have a choice, correct?

KentT
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Re: 4 ohms or 8 ohms

Post by KentT » 14 Mar 2019 16:09

I would stick strictly to 6 ohm (1 pair only) or higher speaker loads on that Yamaha. And avoid reactive loads, which dip lower depending on frequency.

DagnyT
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Re: 4 ohms or 8 ohms

Post by DagnyT » 14 Mar 2019 16:14

KentT wrote:
14 Mar 2019 16:09
I would stick strictly to 6 ohm (1 pair only) or higher speaker loads on that Yamaha. And avoid reactive loads, which dip lower depending on frequency.
So you'd switch it to the right.

What do you mean by reactive loads and frequency dips?

Still learning and trying to understand.

KentT
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Re: 4 ohms or 8 ohms

Post by KentT » 14 Mar 2019 16:19

Some speaker system's impedance load dips lower with frequency. Use efficient, easy to drive speakers with the Yamaha. Examples of speakers not to use with this Yamaha are B&W anything, KEF anything, Magnepan, Quad, or Martin Logan just to name some. 8 ohm loads which are easy loads, are best.

DagnyT
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Re: 4 ohms or 8 ohms

Post by DagnyT » 14 Mar 2019 16:40

KentT wrote:
14 Mar 2019 16:19
Some speaker system's impedance load dips lower with frequency. Use efficient, easy to drive speakers with the Yamaha. Examples of speakers not to use with this Yamaha are B&W anything, KEF anything, Magnepan, Quad, or Martin Logan just to name some. 8 ohm loads which are easy loads, are best.
I truly appreciate all the information. I've been wanting a place to start and I now have that.

I will switch my receiver over to 8 ohm setting and see if I notice a difference.

Now I can start researching upgrade options for all of my components. But where do I start?! :shock:

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Re: 4 ohms or 8 ohms

Post by Jim Leach » 14 Mar 2019 17:06

I would use the left (4 ohm minimum) setting with ONE pair of speakers.

And, the Bose indicates 4-8 ohms; the "6 ohms IEC" is the nominal impedance, and what we use for comparison. But since the speaker indicates a lower end of 4, I'd suggest sticking with the left setting. Lower impedance is harder to drive, so with the option you have, I'd go that route.

You could experiment and see what sounds better, but I would think at higher volumes in particular, the left setting will be a better match. At very low volume levels, there probably is not any appreciable difference.

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