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Multi-Way Conventional loudspeakers with crossovers

How to improve step response
How to improve step response
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Old 16th January 2019, 05:54 PM   #11
denibeni is offline denibeni  Hungary
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The OP-s speaker looks like an LR2 3-way, the drivers polarity and the crossover parts values suggest this. So the best step response you can get with passive filter LR2 looks like the above-mentioned Tidal Akira or its "vertical mirror".
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Old 16th January 2019, 06:36 PM   #12
plasnu is offline plasnu  United States
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Beautiful step response can be possible with a linear phase crossover as mark100 said, but there are issues.

1. Sooner or later, you'll find that pre-ringing start annoying you.
2. Digital filter IS flat sounding, especially short FIR.

I was advocating FIR linear phase crossover for a few years, but I was wrong, sorry. If the phase response is not jumpy, it's OK. While it would not be perfect, but better than FIR linear phase, and I was using ultra long impulse, 260,000 steps.
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Old 16th January 2019, 07:10 PM   #13
mark100 is offline mark100  United States
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Very interesting.....

I tried long FIR filters too.....well a longest of 65,000 taps, that is. I'd describe the sound the same way you did....FLAT. I might have heard some pre-ringing, not sure.

At any rate, I can't use PC processing for my applications, so my long tap FIR was just an experiment vs normally using a maximal tap count of 6144 (minidsp openDRCs).

At that tap 6144 count or lower, I hear complete life, nothing flat at all. In fact, transients, clarity, and bass are so rich, it's why I'm a near zealot advocating FIR and linear phase. I have done extensive comparisons against IIR, because I use the gear for live sound, and have to eliminate latency then. There's no question in my mind that FIR rules.

I'm currently using 4096 taps per passband, on a fully integrated processor/amp platform, and on the whole it's easily the best sound I've achieved yet. (A 4-way system)

Did you use global FIR correction, applied to the entire speaker's output? Or driver-by-driver correction, with the correction (IIR hopefully) embedded in the multitude of FIR files, along with linear phase crossovers?

I'm not a fan of global correction at any tap count..... And also not a fan of trying to over correct at the driver-by-driver level....

Last edited by mark100; 16th January 2019 at 07:13 PM.
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Old 16th January 2019, 09:02 PM   #14
Cask05 is offline Cask05  United States
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Originally Posted by merlin el mago View Post
How to improve step response of a 3 way system?

Attached measurement
Your present step response can actually be read:

It really helps to have a picture of your loudspeaker in-room under test with all the nearby surfaces and microphone position in order to fully understand what you've got.

But as a stab in the dark, the following are guesses:

That initial spike is your tweeter's response, then the negative going one is the reflection of the tweeter's output off of something that's ~3.4 inches (8.6 cm) greater distance from the direct arrival path. I would guess it's the reflection off the back wall, but it could be other geometries. I would assume that you're using something like a dipole tweeter in order to see such a perfect negative-going spike at that...but I could be wrong.

The next pulse on the step plot is probably your midrange following at 10.9 inches (25.8 cm) of total delay, including the delay from your second order crossover network. The next driver (which we may not be able to see on the step response that you posted because it doesn't show anything farther than 2.75 ms from the initial pulse.

As far as compensating for the crossover network delays, you can move the tweeter back 10.9 inches to get approximate time alignment with the midrange(?). The next driver (woofer?), will likely be behind the midranges, but that distance can't be calculated without having more of the step response duration to look at--to the right of the initial pulse.

[As far as to why you'd want a good step response--a question that you didn't ask, but others imposed the question--I've found empirically that your ears will tell you why it's important. Once you get the transient response of your loudspeakers dialed in, your ears will tell you that something changed--and definitely for the better. It will likely be very subtle to describe, but extremely important to have--once you've heard it. YMMV.]

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Old 17th January 2019, 07:40 AM   #15
phase_accurate is offline phase_accurate
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This step response is a little enigmatic.
I would expect the negative going peak to be from the midrange. But there are two things that speak against it: 1.) it comes too late because the group delay of the chosen crossover frequency would be around 0.1 to 0.15 ms and the peak is too sharp (i.e. coming from a source with too high an upper cutoff frequency).
But it can definitely not come from a reflection of the tweeter signal because it is inverted - except there is another inverted tweerter somewhere (reflections can only be delayed but never inverted).
And the delay of the woofer response at this low/mid x-over frequency should be around .7 ms. This figure would actually fit the time of the negative pulse. But its shape (too steep) and polarity speak against it.
Question: Are you sure the x-over is wired correctly ?


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Old 17th January 2019, 07:54 AM   #16
perceval is offline perceval  Taiwan
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Maybe if the OP could share his frd and zma files, we could take a crack at it.

Also, what is the step response from the XO in XSim?
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Old 17th January 2019, 08:01 AM   #17
PMA is offline PMA  Europe
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Looking at step response of the speaker, in isolation, is only misleading and does not allow any reasonable evaluation of speaker sound quality. Which one of those is the "best" sounding? What is the difference, in fact, between step_1 and step_2?
Attached Images
File Type: png step5.png (35.7 KB, 199 views)
File Type: png step_1.png (38.5 KB, 204 views)
File Type: png step_2.png (49.8 KB, 210 views)
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Old 17th January 2019, 08:18 AM   #18
Juhazi is offline Juhazi  Finland
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OP's measured step includes lots of early reflections, but long delay between first and second peak indicates that something is seriously wrong. First peak is typically tweeter and mid should follow it very closely, now there is almost 0,5ms gap. It must sound strange. Listen close to each driver, are they giving the range that they should? You can also measure response in nearfield 1cm from each driver.

We need info about the construction of the speaker and measuring conditions. Crossover might have a mistake too. Someone experienced should see it and take more measurements, at least with midrange inverted.
Radikal aktivist AINOgradient speaker project
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Old 17th January 2019, 08:32 AM   #19
phase_accurate is offline phase_accurate
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I'd say the first one is from a single, very well-behaved driver in an open baffle or closed box (i.e. a minimum phase bandpass). And if it is from a multiway system it is definitley one with a crossover that doesn't have any phase distortion. Nr. 2 is most probably form an LR4. And Nr 3 could be the same but with lots of room reflections.



Edit: I am refering to Pavel's post

Last edited by phase_accurate; 17th January 2019 at 08:40 AM.
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Old 17th January 2019, 09:52 AM   #20
merlin el mago is offline merlin el mago  Europe
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Originally Posted by Lojzek View Post
Hi Merlin,

would you upload the XSim file (.dxo) here so we can get a closer look at it?
Here we go.
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File Type: zip GDO.zip (38.4 KB, 8 views)
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