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TL;DR
For years, I've wondered how off-axis response affects the listening experience. Also, what power response or in room response are. And why certain speakers seem to have a great on axis response but tend to be "shouty" in the midrange in a real room. This post is all about finding answers to these questions.
The idea
A couple of months ago, I asked a question here:
"What is better, a 10" woofer with a waveguide, or an 8" with a very robust tweeter?"
There weren't any real answers, so hey. I decided to build both and see how they performe (from an objective and subjective point of view). I also added my own commercial speakers to the mix.
If I knew about on-axis, off axis, power response and in room response, and compared every speaker side by side, I thought, I'd understand what it was all about. And indeed, I learned about it.
My findings.
Results first, in case you don't want to read through all the test.
1) You cannot design a speaker with one or two off-axis measurements and an on-axis one. Likewise, if you design for on-axis response, you'd better pray your off axis is correct. And it usually won't be.
2) Power response and in room response are basically at least as important as on-axis response.
3) Designing for power and in room response (downward sloping lines) gets you a "neutral" balance, with no colorations or "shortness". Designing for flat on axis response has the most impact on how you perceive the sound of the speakers.
a) Confused? Allow me to explain. My two speakers have a downward sloping power response and they sound balanced and uncolored, without any major issues. But the flat on axis one is clearly superior, with more perceived detail.
4) Driver selection, baffle width, waveguides and driver design are extremely important. Although, as you'll see, my favorite speaker was the one that I actually thought "would never work".
A couple of notes.
1) Measurements are as real as they get. I don't have an anechoic chamber, but I do have a room 20 feet above the ground, and with no walls around it. I place the microphone at 1m away and I have resolution up to about 25 Hz.
2) I did take every off axis measurements and checked phase at each step.
The contenders.
1) The JBL Clone.
A clear (at least to me) homage to JBLs of the past, this is the 8" (SB Acoustics) woofer, mated to a Peerless Corundum 32TX tweeter. I thought this one could borderline work. With a 6th order L-R symmetrical crossover at 1.2 KHz. it wasn't cheap. Or easy to build.
It also has lots of compromises regarding FR.
Yes. That is the on axis response with a mega BBC dip on it. Because the tweeter is extremely directional at around 2 KHz. As you can see on the on axis graphs, I basically had to compensate for its response off axis by massaging the on-axis response, and this helped get a somewhat decent power response.Phase tracking is basically perfect.
2) The old school clone
This one shouldn't work at all. An old Morel 10" woofer I had around, an old Dayton RS-28 aluminum tweeter, and a Visaton WG-148 waveguide. The previous speaker was built with all new components. This one was built with things I had around the house. Plus, IMHO it looks weird. Almost ugly. Although many people have said it looks better than the previous one.
The crossover point is around 1.25 KHz. It's asymmetrical. 6th order on the woofer, 4th order on the tweeter. As you can see on the transfer function, it has a couple of corrections to the FR of the tweeter. The waveguide is bviously not part of the tweeter, so response is not exactly perfect. But with a couple of notches, everything is fine. Directionality is great, off axis is very good, and up to 75ª, response is pretty decent.
I was surprised it worked as good as I did. I wasn't expecting a 10" woofer to mate with a 1. 1/8" tweeter, and yet, it did.
3) The commercial speaker.
Focal Aria 926s. I didn't do any measurements on them. But here's some data.
https://www.stereophile.com/content/...r-measurements
Other than a slight flare starting at 4 KHz off-axis, I couldn't see anything out of the ordinary.
Coming up... in room measurements.
For years, I've wondered how off-axis response affects the listening experience. Also, what power response or in room response are. And why certain speakers seem to have a great on axis response but tend to be "shouty" in the midrange in a real room. This post is all about finding answers to these questions.
The idea
A couple of months ago, I asked a question here:
"What is better, a 10" woofer with a waveguide, or an 8" with a very robust tweeter?"
There weren't any real answers, so hey. I decided to build both and see how they performe (from an objective and subjective point of view). I also added my own commercial speakers to the mix.
If I knew about on-axis, off axis, power response and in room response, and compared every speaker side by side, I thought, I'd understand what it was all about. And indeed, I learned about it.
My findings.
Results first, in case you don't want to read through all the test.
1) You cannot design a speaker with one or two off-axis measurements and an on-axis one. Likewise, if you design for on-axis response, you'd better pray your off axis is correct. And it usually won't be.
2) Power response and in room response are basically at least as important as on-axis response.
3) Designing for power and in room response (downward sloping lines) gets you a "neutral" balance, with no colorations or "shortness". Designing for flat on axis response has the most impact on how you perceive the sound of the speakers.
a) Confused? Allow me to explain. My two speakers have a downward sloping power response and they sound balanced and uncolored, without any major issues. But the flat on axis one is clearly superior, with more perceived detail.
4) Driver selection, baffle width, waveguides and driver design are extremely important. Although, as you'll see, my favorite speaker was the one that I actually thought "would never work".
A couple of notes.
1) Measurements are as real as they get. I don't have an anechoic chamber, but I do have a room 20 feet above the ground, and with no walls around it. I place the microphone at 1m away and I have resolution up to about 25 Hz.
2) I did take every off axis measurements and checked phase at each step.
The contenders.
1) The JBL Clone.
A clear (at least to me) homage to JBLs of the past, this is the 8" (SB Acoustics) woofer, mated to a Peerless Corundum 32TX tweeter. I thought this one could borderline work. With a 6th order L-R symmetrical crossover at 1.2 KHz. it wasn't cheap. Or easy to build.
It also has lots of compromises regarding FR.
Yes. That is the on axis response with a mega BBC dip on it. Because the tweeter is extremely directional at around 2 KHz. As you can see on the on axis graphs, I basically had to compensate for its response off axis by massaging the on-axis response, and this helped get a somewhat decent power response.Phase tracking is basically perfect.
2) The old school clone
This one shouldn't work at all. An old Morel 10" woofer I had around, an old Dayton RS-28 aluminum tweeter, and a Visaton WG-148 waveguide. The previous speaker was built with all new components. This one was built with things I had around the house. Plus, IMHO it looks weird. Almost ugly. Although many people have said it looks better than the previous one.
The crossover point is around 1.25 KHz. It's asymmetrical. 6th order on the woofer, 4th order on the tweeter. As you can see on the transfer function, it has a couple of corrections to the FR of the tweeter. The waveguide is bviously not part of the tweeter, so response is not exactly perfect. But with a couple of notches, everything is fine. Directionality is great, off axis is very good, and up to 75ª, response is pretty decent.
I was surprised it worked as good as I did. I wasn't expecting a 10" woofer to mate with a 1. 1/8" tweeter, and yet, it did.
3) The commercial speaker.
Focal Aria 926s. I didn't do any measurements on them. But here's some data.
https://www.stereophile.com/content/...r-measurements
Other than a slight flare starting at 4 KHz off-axis, I couldn't see anything out of the ordinary.
Coming up... in room measurements.
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