What does "off axis"mean?

[Good4it]

I hear it used but am not sure what it means.

 

[j_garcia]

 

[MR.MAGOO]

pictures help, but it would be great to really hear it. Maybe a high-end stereo shop would demonstrate, or are there any products out there to do this?

 

[Steve81]

are there any products out there to do this?

Sit 5 feet away from a speaker, directly in front of it with the speaker at ear level. You're on the speaker's axis. Move five feet to the right. You're 45 degrees off axis, in the horizontal plane. Stand up, and you'll also be off axis in the vertical plane. That's all on-axis vs off-axis is referring to.

 

[shadyJ]

'Off-axis' is just the sound coming from the speaker that isn't directly in front of the speaker. It is important that a speaker have a uniform off-axis response because much of what we hear from a speaker system isn't sound coming directly from the speaker but reflected sound from the walls, floor, ceiling, and intervening objects. You can have a speaker with a perfect on-axis response still sound terrible if its off-axis response is very rocky and uneven.

 

[Dennis Murphy]

'Off-axis' is just the sound coming from the speaker that isn't directly in front of the speaker. It is important that a speaker have a uniform off-axis response because much of what we hear from a speaker system isn't sound coming directly from the speaker but reflected sound from the walls, floor, ceiling, and intervening objects. You can have a speaker with a perfect on-axis response still sound terrible if its off-axis response is very rocky and uneven.

True to a degree, but it's easy to overstate the importance of smooth off-axis response. What you hear from a speaker is dominated by it's on-axis and early reflected sound. If a speaker is pretty well-behaved +/- 30 degrees off axis horizontally, it should sound respectable. That's not just an opinion, you can see it in the total response of a speaker that is measured with a wide sampling window that shows you all of the reflected sound as well as the more direct sound (and that can be done using the Parts Express Omnimic system). All of those reflections tend to follow the trend established by the on-axis response. Vertical off-axis response is something of a mess on just about any speaker that doesn't have the drivers concentrically mounted. That's because the distance relationship of (in a 2-way) the tweeter and the woofer changes as you move up or down, which changes the relative arrival times of the drivers, which in turn changes the phase relationships and causes a large dip around the crossover region. You can hear that if you listen appreciably above the seated position, but in most listening situations it's still not a problem.

 

[herbu]

If a speaker is pretty well-behaved +/- 30 degrees off axis horizontally, it should sound respectable.

On/Off Axis and Soundstage are two things I hear about also. My pedestrian method of testing is this: I sit in the middle and get a stereo music source with a voice that clearly sounds like it's coming from dead center. Then I'll stand up, move left, sit, move right, sit. The degree to which I can move around and the voice still sounds like it's coming from dead center defines on/off axis and soundstage for me.

Is that a fair pedestrian evaluation?

 

[avliner]

^^

I think it is Herbu!

I might be completely wrong on my assumption, but that's one of the reasons why I do prefer having 03x centers horizontally laid on my front array, though

 

[Swerd]

My pedestrian method of testing is this: I sit in the middle and get a stereo music source with a voice that clearly sounds like it's coming from dead center. Then I'll stand up, move left, sit, move right, sit. The degree to which I can move around and the voice still sounds like it's coming from dead center defines on/off axis and soundstage for me.

That's a good working definition for off-axis sound, and an easily done method to hear it .

Here's one I used to do, but isn't so easy anymore. Listen to a single speaker with FM radio as the source. Switch off the FM hiss filter and tune to an empty area on the FM dial, where all you can hear is the interstation hiss. Walk around, left and right, and note how far off-center you have to be when the hiss noise fades. It used to be a quick & easy way to compare the off-axis high frequency performance of different speakers. Now with digital tuners, or no FM available in stores, it isn't so easy.

 

[ManBarra]

I might be completely wrong on my assumption, but that's one of the reasons why I do prefer having 03x centers horizontally laid on my front array, though

That's interesting for your front stage.. I've tried a tower as a center and it feels very narrow. I'll have to see if I can try out 3 centers haha