Center channel off-axis measurements

[robbnj]

Hi, all.

'Wondering if anyone has done on/off-axis measurements of their center channel? I used the search function, but didn't find any relevant posts in this subforum.
I replaced the dome tweeter in my center with a BMR unit, and ran 7 sweeps, 2 feet apart, across my listening zone. Calibrated mic, at ear level.Doing this just for fun, experimentation, education.

I'm wondering if the graphs show decent off-axis compared to on-axis performance, or if I've even set up the graphs right to show the differences well. I chose VAR smoothing, and focused on a range just below the crossover point, to a little below my hearing capability.
Thoughts?

Feel free to tell me to change the graph smoothing, etc, if needed to get a better understanding of performance

As a sidebar, how do these decay times look? Am I correct in thinking that having that slope end just shy of 300m is a pretty good spot to be in? I went through Jerry's guide, but that focuses more on the bass.

 

[robbnj]

Well, THIS one got no tractrion, lol.

 

[John Mulcahy]

Decay times look good. To measure off-axis response you'd usually need to move the speaker as far as you can from surfaces, ideally place it on a turntable, and make the measurements at 1m distance. There's a guide here.

 

[robbnj]

Decay times look good. To measure off-axis response you'd usually need to move the speaker as far as you can from surfaces, ideally place it on a turntable, and make the measurements at 1m distance. There's a guide here.

Hahaha, thank you John. Do you think there is any value in doing an off-axis with the speaker in place, to see how things work in the actual listening environment? Or is there just not enough accuracy with a consimer-grade measuring setup.

I honestly didn't even start looking at decay times until just before I made the post. I know my room sound changed when I added curtains, did a cloth (felt) blackout ceiling, etc, but was never unhappy with the room sound (and have very few options for room treatments). I looked at some of the RT60 charts from measuring my mains, and I "think" they fall in line with what would be considered good. Maybe slightly dry?.

Again, I enjoy the heck out of the system, but I really like using your software, and learing so much because of it.

 

[John Mulcahy]

Do you think there is any value in doing an off-axis with the speaker in place, to see how things work in the actual listening environment?

I'm not sure what the benefit would be. What would you do with the results?

 

[Keith_W]

What is there to say? You chopped off the labels, we don't know what those graphs mean.

Hahaha, thank you John. Do you think there is any value in doing an off-axis with the speaker in place, to see how things work in the actual listening environment? Or is there just not enough accuracy with a consimer-grade measuring setup.

There is plenty of accuracy in a consumer-grade measurement setup. The only question is whether you can take free-field anechoic measurements - and that depends on how low your centre speaker goes, the size of your backyard, and how high you can elevate your speakers.

I suspect that you don't need to measure off-axis performance and you are asking the wrong question. The more relevant question is, "are listeners seated off-centre hearing the same frequency response?". That is fortunately quite easy to answer. Just place your microphone at that off-axis position and sweep.

The only reason to take anechoic off-axis "loudspeaker only" measurements is if you are a loudspeaker designer (since that influences your design) or a reviewer (since that influences what you say). As a consumer, you already own the speaker. Your only decision is to keep it or sell it.