4 ohms or 8 ohms

amplifiers, receivers and loudspeakers
zlartibartfast
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Re: 4 ohms or 8 ohms

Post by zlartibartfast » 14 Mar 2019 17:32

I have used that Yamaha receiver before - you'll want to use the 4-8 ohm setting, to get the best dynamic range.

I don't know the rated efficiency of those speakers, but I'm guessing it's not especially high, so you're likely to be setting the volume on the amp up a bit.

https://assets.bose.com/content/dam/Bos ... n_4001.pdf

Spinner45
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Re: 4 ohms or 8 ohms

Post by Spinner45 » 14 Mar 2019 17:33

Before this thread turns into a nightmare, just put that switch to the left and be done with it.

Sunwire
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Re: 4 ohms or 8 ohms

Post by Sunwire » 14 Mar 2019 18:31

I'm going to be the contrarian here.
Your speakers are 6 ohms impedance.
Put the receiver switch on the higher setting: 6/12 ohms.
DON'T TOUCH THE SWITCH WHILE THE RECEIVER IS ON. TURN IT OFF FIRST.
This article defines the terms involved and may help understanding of speaker impedance, etc..
https://www.audioholics.com/audio-ampli ... r-switch-1
The video explains why you should leave the switch at the higher setting. That's the only way to get the full rated power from the receiver. It's perfectly safe to use this setting for 6 ohm speakers.
On the lower impedance setting, the receiver will start to clip (cause high distortion) at a lower volume. This causes risk of speaker damage (and worse sound!).
The switch is there to protect the receiver from damage when using lower impedance speakers. If you don't have those speakers, don't worry about it. Honestly, if you have low impedance speakers, get a different amp or receiver that can supply more current. This one has limited current capability.

Sunwire
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Re: 4 ohms or 8 ohms

Post by Sunwire » 14 Mar 2019 18:42

Cizek speakers are one example of speakers that had switchable impedance. There might be others.
They had a "Q" switch that changed the low frequency response and roughly doubled or halved the impedance of the speakers, depending on the position chosen.
I worked in a store where we sold the line. They were excellent speakers and very good value for the money.
I owned a pair of the Cizek 3s for several years, but later sold them to my brother.
http://cizekspeaker.weebly.com/cizek-i.html

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Re: 4 ohms or 8 ohms

Post by jdjohn » 14 Mar 2019 19:49

DagnyT wrote:
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?
It's not what you're 'getting' from the amp, but rather it's choosing a setting to best match your speakers. Yamaha is saying (with the switch moved to the left) if you run one pair of speakers (A or B), that pair should not be rated below 4 ohms (e.g., 2 ohms is too low). If you run two pair (A + B), neither pair should be rated below 8 ohms.

Bose is so weird with their specs. It is one of the reasons they have such disdain among many audiophiles. Instead of just plainly stating the impedance of their speakers, instead they say 'compatible with amps that run 4-8 ohms'. You could use a multi-meter to test the impedance yourself just to get an idea. An impedance curve is what's really needed. You'll also notice that Bose doesn't even provide the frequency range for their speakers. Their speakers are shrouded in mystery.

If we assume that those speakers are truly 6 ohm, I agree with Sunwire that the 6/12 setting is a better choice for the amp...within reason. That 4/8 setting is likely choking the output of the amp in order to protect itself. Since the amp is not uber powerful, it wants to prevent going into clipping if lower impedance speakers are used. The 6/12 runs more open, so you must be responsible with the volume knob. If the amp goes into protect mode and shuts down, then of course better move the switch to 4/8. But again as already mentioned, ONLY MOVE THE SWITCH WITH POWER OFF.

Sunwire
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Re: 4 ohms or 8 ohms

Post by Sunwire » 15 Mar 2019 00:22

The Bose speakers say 6 ohm impedance below the part that says 4 or 8 ohm amps are OK.
Please watch the video in the link I provided.
The lower impedance position on the receiver will clip SOONER than the 6/12 position.
The lower impedance position is not to prevent clipping. It's to prevent overheating due to excessive current flow.

nniemiec
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Re: 4 ohms or 8 ohms

Post by nniemiec » 15 Mar 2019 11:26

jdjohn wrote:
14 Mar 2019 19:49
DagnyT wrote:
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?
It's not what you're 'getting' from the amp, but rather it's choosing a setting to best match your speakers. Yamaha is saying (with the switch moved to the left) if you run one pair of speakers (A or B), that pair should not be rated below 4 ohms (e.g., 2 ohms is too low). If you run two pair (A + B), neither pair should be rated below 8 ohms.

Bose is so weird with their specs. It is one of the reasons they have such disdain among many audiophiles. Instead of just plainly stating the impedance of their speakers, instead they say 'compatible with amps that run 4-8 ohms'. You could use a multi-meter to test the impedance yourself just to get an idea. An impedance curve is what's really needed. You'll also notice that Bose doesn't even provide the frequency range for their speakers. Their speakers are shrouded in mystery.

If we assume that those speakers are truly 6 ohm, I agree with Sunwire that the 6/12 setting is a better choice for the amp...within reason. That 4/8 setting is likely choking the output of the amp in order to protect itself. Since the amp is not uber powerful, it wants to prevent going into clipping if lower impedance speakers are used. The 6/12 runs more open, so you must be responsible with the volume knob. If the amp goes into protect mode and shuts down, then of course better move the switch to 4/8. But again as already mentioned, ONLY MOVE THE SWITCH WITH POWER OFF.
I'm glad you weighed in - i have a similar issue (I'm about to pick up a pair of EPI's w. a switch for 4 ohm vs. 16 ohm) My question to you is:

If I have 1 pair of 4 ohm speakers (EPI switched to the 4 ohm load) & 1 pair of 8 ohm speakers (wired to same amp in another room) & I'm using a Yamaha amp w. the same switch, where position should the switch be- left or right? The amp has a power rating of 100 watts into 8 ohms. I think my concern would be frying the 8 ohm speakers if run (A+B) at the same time as the other pair if EPI speakers are in the 4 ohm mode & the amp switch is also in the 4 ohm position?

DagnyT
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Re: 4 ohms or 8 ohms

Post by DagnyT » 15 Mar 2019 13:02

Sunwire wrote:
14 Mar 2019 18:31
I'm going to be the contrarian here.
Your speakers are 6 ohms impedance.
Put the receiver switch on the higher setting: 6/12 ohms.
DON'T TOUCH THE SWITCH WHILE THE RECEIVER IS ON. TURN IT OFF FIRST.
This article defines the terms involved and may help understanding of speaker impedance, etc..
https://www.audioholics.com/audio-ampli ... r-switch-1
The video explains why you should leave the switch at the higher setting. That's the only way to get the full rated power from the receiver. It's perfectly safe to use this setting for 6 ohm speakers.
On the lower impedance setting, the receiver will start to clip (cause high distortion) at a lower volume. This causes risk of speaker damage (and worse sound!).
The switch is there to protect the receiver from damage when using lower impedance speakers. If you don't have those speakers, don't worry about it. Honestly, if you have low impedance speakers, get a different amp or receiver that can supply more current. This one has limited current capability.
Thank you for this link to YouTube video. I did switch to the 4 ohm mode and didn't notice anything different to my very untrained ear. I will move it back based on yours and that videos advice as it really seemed to make a lot of sense.

Now on to seeing what I should look to upgrade first. 😊

DagnyT
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Re: 4 ohms or 8 ohms

Post by DagnyT » 15 Mar 2019 13:28

zlartibartfast wrote:
14 Mar 2019 17:32
I have used that Yamaha receiver before - you'll want to use the 4-8 ohm setting, to get the best dynamic range.

I don't know the rated efficiency of those speakers, but I'm guessing it's not especially high, so you're likely to be setting the volume on the amp up a bit.

https://assets.bose.com/content/dam/Bos ... n_4001.pdf
Just noticed your handle. Funny because last night I played an old record of The Restaurant at the End of the Universe.

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Re: 4 ohms or 8 ohms

Post by jdjohn » 15 Mar 2019 15:39

nniemiec wrote:
15 Mar 2019 11:26
I'm glad you weighed in - i have a similar issue (I'm about to pick up a pair of EPI's w. a switch for 4 ohm vs. 16 ohm) My question to you is:

If I have 1 pair of 4 ohm speakers (EPI switched to the 4 ohm load) & 1 pair of 8 ohm speakers (wired to same amp in another room) & I'm using a Yamaha amp w. the same switch, where position should the switch be- left or right? The amp has a power rating of 100 watts into 8 ohms. I think my concern would be frying the 8 ohm speakers if run (A+B) at the same time as the other pair if EPI speakers are in the 4 ohm mode & the amp switch is also in the 4 ohm position?
I don't think you'd be in danger of 'frying' your speakers either way. That occurs when there is too much clipping/distortion going into the tweeters; hopefully you would hear that and back-off before damage was done.

Those switches are meant to protect the receiver/amp...not really the speakers. I'd bet your Yamaha receiver has a protection mode (besides the switch) that would shut it down if it got too hot. You can keep the switch on the right at 6/12. If the amp starts to shut down on a regular basis, I would first switch your EPI speakers to 16 ohm. If that doesn't stop the problems, then as a last resort move the receiver switch to 4/8...or buy a better amp :D

Remember, it's not the amp pushing the speakers too hard...it's the speakers requiring more current from the amp and potentially damaging it. It is often said that lower impedance speakers are 'hard to drive', as if it is a train struggling to get up a hill. It's actually more like a runaway train going downhill that can't be controlled; the train's engine can't keep up, so it crashes and burns.

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Re: 4 ohms or 8 ohms

Post by Spinner45 » 15 Mar 2019 16:47

DagnyT wrote:
15 Mar 2019 13:02
I did switch to the 4 ohm mode and didn't notice anything different to my very untrained ear.
As I mentioned before the thread became complicated, the difference is negligable.
All that switch does is select a slightly lower or higher power supply voltage that is fed to the output transistors.
There are also clipping limiter circuits involved to help protect the outputs.
You really won't hear any difference.
Now everyone can add Page 3,4,5, of this thread babbling about nothings, and adding more confusion.

DagnyT
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Re: 4 ohms or 8 ohms

Post by DagnyT » 15 Mar 2019 17:23

Spinner45 wrote:
15 Mar 2019 16:47
DagnyT wrote:
15 Mar 2019 13:02
I did switch to the 4 ohm mode and didn't notice anything different to my very untrained ear.
As I mentioned before the thread became complicated, the difference is negligable.
All that switch does is select a slightly lower or higher power supply voltage that is fed to the output transistors.
There are also clipping limiter circuits involved to help protect the outputs.
You really won't hear any difference.
Now everyone can add Page 3,4,5, of this thread babbling about nothings, and adding more confusion.
I didn't think I was ever going to harm either the speakers or the amp. Mostly looking for the most appropriate settings. The video linked to earlier did a great job explaining.

I'm sure the debate may continue but my question was answered to my satisfaction. Lol

Sunwire
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Re: 4 ohms or 8 ohms

Post by Sunwire » 15 Mar 2019 18:45

nniemiec - what is the model of the EPI speakers you're going to pick up? I'm curious about the impedance switch on the speakers.
FWIW: the 16 ohm setting will be safer for your amp, but the 4 ohm setting might sound better.

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Re: 4 ohms or 8 ohms

Post by nniemiec » 15 Mar 2019 18:56

Epicure 202 - the bidirectional speakers.

zlartibartfast
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Re: 4 ohms or 8 ohms

Post by zlartibartfast » 15 Mar 2019 20:02

this part I find odd:
"Impedance: 4 or 16 ohms"

there is a switch to put the drivers in either series or parallel mode?

http://www.humanspeakers.com/e/epi202.htm