DiyMobileAudio.com Car Stereo Forum banner

1 - 20 of 49 Posts

·
Registered
Joined
·
1,261 Posts
Discussion Starter #1 (Edited)
In the RTA thread from Bikinkunk I asked:
Can you do an impulse response in the car? just curious. (http://www.diymobileaudio.com/forum/build-logs-project-install-gallery/144399-rta-walkthrough-usage-thread-video-2.html#post1828301)
yes. but your question has multiple meanings. So, can you be more precise as to what you're asking?
While I asked about impulse response, what I wanted to know is impulse and step response. Just trying to figure out if John Dunlavy had a point with his opinion on impulse and step response. See: Loudspeaker designer John Dunlavy: By the Numbers... Page 2 | Stereophile.com

Dunlavy said:
I think a lot of people, especially those who don't listen to live music a great deal of the time, are not really concerned with whether the music they're reproducing matches the live performance. They're after more of an effect. And so the accuracy of their systems doesn't need to meet the same criteria that would have to be met if one wanted to make a loudspeaker where you couldn't hear the difference between it and the original performance. And that's what we're into. Certainly there's plenty of room in the marketplace for what might be called "good-sounding" speakers, "sweet-sounding" speakers, "nice-sounding" speakers, "pretty-sounding" speakers—everybody hears differently. On the other hand, there are a lot of people who regularly attend live concerts who want accurate reproduction.

Designing with higher-order crossover networks greatly simplifies the blending task between drivers. But what most people don't realize is that one of the really great difficulties in designing with higher-order crossovers is that they store energy. That's very visible when you look at the impulse response of a speaker that has a second-, third-, or fourth-order network. And the step response also looks terrible.

Of all of the measurements that we take that come more close to predicting, or most close to predicting how a speaker is going to emulate a properly recorded live performance, it's step response. Everything is implicit if you know how to interpret a step response...if my life depended upon my describing what I thought a speaker was going to sound like, all other factors being equal, I would choose step response. And feel very confident that I would be spot-on.
There's also a paper from Dunlavy going further into what he thought is important in speaker design. I'm just trying to connect the dots between your power response case, backed up by views from Linkwitz, Geddes and Tool etc. and the views from Dunlavy, Vandersteen, Thiel... what if you get both power response and timing right? Would that work even better? Is it possible?

Here's Dunlavy's digest take on power response:
Atkinson and Dunlavy said:
Atkinson: You talk about accuracy, but so far you've just defined that in terms of the impulse or step response on the speaker's intended listening axis. What about the speaker's power output into the room? That surely has as much effect on the perceived balance as the on-axis performance?

Dunlavy: That's certainly true. We pay an awful lot of attention to the power response of the speaker into the room. Because that's one of the things that permits us to determine whether we're listening to a live instrument, let's say with our eyes closed, in a typical room. We hear two things. We hear the direct sound of the instrument, but we also hear all of the reflected sound, the reflections off of all of the boundaries of the room. And the ratio between that direct sound as a function of frequency and the reflected sound determines to our ears whether we perceive it as being realistic or not.

We spent a lot of time and money, over 20 years ago, doing measurements in an anechoic chamber of the three-dimensional response patterns of 17 different musical instruments, including drums, string bass, cello—we measured a bassoon, a clarinet, a violin. If a loudspeaker's directivity pattern is incapable of emulating the aggregate, the average of the patterns of all of these musical instruments, it will never sound "accurate."

Most musical instruments are almost omnidirectional at low frequencies, as are most loudspeakers, so it doesn't pose a problem. But as you go higher in frequency, to between 100Hz and 300Hz, if you don't get the beam-width of the speaker correct in this range—and by "correct" I mean that it simulates most live instruments—it will add warmth, unnatural warmth, to the sound of voices and musical instruments. It'll make the average male voice sound too chesty, very unnatural. As you go up higher in frequency, if you have a tweeter that radiates too broad a pattern...it's going to produce shrieky sounds, it's going to sound too zippy. I think everyone's experienced that, especially from inexpensive speakers that have a rising high end.

So a good designer certainly knows that he has to pay a lot of attention to the polar response of a loudspeaker.
What does the step response look like now with 12 dB slopes and what does it look like if you used 6 dB slopes. (obviously louder volumes would be dangerous for the tweeter).

Just trying to learn, no hidden agenda here. I can relate to both theories, just trying to figure out what works. Speakers like Magico get rave reviews and they use eliptical slopes, kinda like brick walls. So who is right, or is there even such a thing as beeing right? What theory comes closer to the real thing, that beeing the music that was recorded? I know it all sounds different compared to each other. Or am I not able to hear that? I was intregued by your test with 4th order and second order networks. If this is not the place for this question I understand. But if we can test the impulse response and step response we might get closer to our goals. I wouldn't know where and how to start, what software to use etc. but I'm sure that can be found somewhere. It's much to cold over here to do it myself in my Garage at this time but I thought it might fit in and make us learn something.

I looked at a lot of speaker reviews on stereophile to see their power response and the subjective opinion on them, just to learn. There were quite a few with good power response that showed a step response that was way different from the ideal step response Dunlavy descibes. I also focussed on resonances from the box itself, trying to figure out what combination would give us the best compromise. That last point is something Magico has high on their list of priorities. And that is something we deal with in the car as well. The things Highly did with his sub construction to decouple it from the car comes to mind.
I decoupled my sealed sub from the car the best I could and noticed improved low bass that seems to float giving more depth. It caused less resonances that way.
 

·
Registered
Joined
·
1,261 Posts
Discussion Starter #2 (Edited)
But the above isn't all that I want to discus. Every major speaker builder seems to have it's own key element they focus upon. What I would like to know or find out is what elements are most important?

Bowers and Wilkins (and from the same people involved Vivid Audio) have a big focus on backwave damping and diffraction, Dunlavy, Thiel and Vandersteen on time coherence. Magico on cabinet construction and pistonic drivers. Geddes and Linkwitz share views on power response. What are the best ingredients to good sound? And what parts of that can we apply to Car audio?
 

·
Registered
Joined
·
5,098 Posts
Whats important in a car? Placement and install 40%, Tuning 40% and equipment 20%.....:)

Curious as to how much of what applies to home audio is relevant to mobile audio, given the radically different environments. All ears on this thread.
 

·
Moderator
Joined
·
18,547 Posts
The issue I see is the ability to accurately measure the initial impulse. I stated in the thread and my build log that its all but impossible for a number of reasons which I've posted in a other thread. Mainly, it's broken down in to one issue: reflections. Of course you can measure *a* impulse but its immediately colored by reflections which drive the settling time and behavior.

This is why, in my build log, I discussed measuring my mid/tweet outside if the car to determine crossover points. I found at that time the coincident driver I use is EXACTLY time aligned between mid and tweeter.


IOW, if you measure the speaker in a reflection free environment you'll get a clean impulse response. But once it goes in the pillars, the impulse is altered. This is especially true for something like a tweeter where it's mounted near a window or dash. All of this means that determining step response inside a car is not at all trivial. But, I'll try to address it with real world examples soon.
 

·
Registered
Joined
·
1,622 Posts
But the above isn't all that I want to discus. Every major speaker builder seems to have it's own key element they focus upon. What I would like to know or find out is what elements are most important?

Bowers and Wilkins (and from the same people involved Vivid Audio) have a big focus on backwave damping and diffraction, Dunlavy, Thiel and Vandersteen on time coherence. Magico on cabinet construction and pistonic drivers. Geddes and Linkwitz share views on power response. What are the best ingredients to good sound? And what parts of that can we apply to Car audio?
I have been thinking about this too lately. I am fairly new to this scene, but it bothered me somewhat from the start when people referred to reproduction of live performances as the goal in all of this. But that didnt make sense to me exactly. The reason being that there is usually an electronic interface between the instruments and/or voices and the use of electromechanical drivers. Rarely are live performance instrument and/or voice only. So what exactly are we trying to reproduce?

Got into this thought process after I bought some Celestion midrange neodynium drivers from PE. I only bought them because they were on sale for $8 (still available but more than twice the price now) and needed some test drivers. For that price, I couldn't turn them down.

But the Celestions were designed for use in acoustic guitar amps. No doubt they were designed with a signature sound in mind. I wasn't sure how they would sound with all music, but the should sound perfect for acoustic guitar:p. I actually think they sound good in general. But do you see my point?

Hope I am not threadjacking. Maybe I misinterpreted part of your question, but it seems it applies to the original topic.
 

·
Registered
Joined
·
4,982 Posts
But the above isn't all that I want to discus. Every major speaker builder seems to have it's own key element they focus upon. What I would like to know or find out is what elements are most important?

Bowers and Wilkins (and from the same people involved Vivid Audio) have a big focus on backwave damping and diffraction, Dunlavy, Thiel and Vandersteen on time coherence. Magico on cabinet construction and pistonic drivers. Geddes and Linkwitz share views on power response. What are the best ingredients to good sound? And what parts of that can we apply to Car audio?
Interesting thread ;)

True that speaker manufactures seem to focus on different things. I tend to look at it this way;

Do I want accurate* reproduction, do I want realistic* sounding reproduction or am I after an effect* (i.e coloration based on preferences)?

Keeping the discussion within car audio, my opinion is that accurate reproduction in car is impossible. A "flat" system don't sound good in small rooms like a car, it will sound really really bright. If we add a theoretical "perfect" curve to the accurate "flat" system to compensate for the room/environment we get a realistic sounding system* instead. This might not sound good to sound people anyway, we might want less highs and more lows so we continue to alter the response until it sounds good to us. This is how most people tune their systems and they are basically colored, "close to realistic sounding" systems.

Most people choose to have an effect added to the sound. In a car we don't have much choice either, since accuracy ain't a viable goal. So I think Dunlavy is correct when assuming that people are not really after 'accurate' reproduction in general (in car audio that's even more true).

Let's break it down, loudspeakers reproduce the signal they're fed with. If we ignore the signal path before the speakers, what differs from the original sound? Basically speaker distortion and room artifacts (which also can be referred to as distortion). If there wouldn't be any speaker distortion or room interaction we would have accurate reproduction (not even sure how that would sound, guess it would sound like sitting inside the recording studio...). Anyway we know that no speaker is distortion free neither are the "room" even close to anechoic. Break it down even more; What type of distortion is most audible? Can we address it somehow? In a car, most of us probably agree that it's the "room" that affect the audible distortion the most. No system will sound better than its weakest link, in car audio that's most likely the environment (if not the install/equipment suck, that is).

So the environment huh... How can we deal with it? In a car we are limited to do this. The most effective helper we can get is a DSP. EQ won't fix modal issues or lessen decay times though. This have to be done as a physical sense, frequency absorbers etc etc. 'Patrick Bateman' recently posted a thread discussing this. Many solutions are unfortunately impractical in a car since we have limited space.

What about the speakers then? These are prone to add several types of distortions that blends with the original sound, it's these distortions that cause the "sonic signature/character" of the drivers. The distortion can be divided into a linear and non-linear compartment. Linear distortion is basically related to the frequency response, the non-linear part are divided into harmonic and inter-modulated distortion and these are furthermore divided into different "orders".

So why am I rambling about all these things? Because there's so many aspects to consider. Things like step response (which basically is how the system responds after being fed with a square wave), time/phase coherency and diffraction/reflection control needs to be placed in relation of much they affect the sound compared to other things that degrade the sound.

I won't go in too much detail here, simply because I'm not that knowledgeable when it comes to the more advanced aspects of audio/electronics. My experience tells me that working with the environment and compensating the perceived frequency response yields the biggest difference by far. The key element would therefore be the environment, i.e the listening space - what we can do with it. Diffraction control is a doable option and works for higher frequencies. Frequency absorbers should work as well, haven't tried this out much yet. DSP's works awesome but they don't "fix" physical issues in the room. Check a "Decay" or "waterfall" plot in REW for example to see how the frequency response change as time decays.

I'm not sure how much the square wave (step response) thing correlates with transient response and such. Most people complain about sloppy bass but a big part of their issues are often related to integration between drivers and frequency response.
 

·
Wave Shepherd
Joined
·
2,409 Posts
I like the article you shared. More and more frequently I see the terms impulse and step response being mentioned in the more advanced discussions of sound reproduction. I would like to find more reading about impulse response, but would really like to learn more about step response. Any ideas on resources for these?
 

·
Registered
Joined
·
1,261 Posts
Discussion Starter #9
Ok, lots of different views rolling around here but not yet a pattern we can use.

I'd like to break down these points I made in the first posts by what we do or can do to get to better sound in the end.

Erin allready showed his way to improve power response. That is not to say it is the only way but I think it is a good way using these KEF coaxials as the measurements he showed speak for themselves. But it won't be the solution for everybody, the speakers are kind of big and not everyone can house those in their pillars.

There is always a big focus on Install beeing important. I agree here but let's examin that a bit further. Aside from choosing a wise place to mount the speakers we also need to make sure the baffle is sturdy enough not to cause vibrations in the surrounding area's. That would be like focussing on dead enclosures (like Magico). I have seem examples on this forum where they made sealed enclosures in doors and mounted them with vibration dampeners. That seems like a good way to prevent rattles and resonances.

I have to go now, will be back later...
 

·
Registered
Joined
·
1,310 Posts
I don't have much time to contribute right now, but I'll say this...decoupling should always be a last resort. If you decouple because something rattles/resonates, you aren't fixing the problem (the rattle) by decoupling, you're masking it.

If you've ever worked on root cause analysis or lean initiatives, you'd know that you don't stop till you've found and fixed the problem (the rattle). If you find the source but can't fix it, then you move "downstream" to contain it (in this case, decouple). In short, don't mask a problem unless you MUST.

My .02
 

·
Registered
Joined
·
1,261 Posts
Discussion Starter #11 (Edited)
I don't have much time to contribute right now, but I'll say this...decoupling should always be a last resort. If you decouple because something rattles/resonates, you aren't fixing the problem (the rattle) by decoupling, you're masking it.

If you've ever worked on root cause analysis or lean initiatives, you'd know that you don't stop till you've found and fixed the problem (the rattle). If you find the source but can't fix it, then you move "downstream" to contain it (in this case, decouple). In short, don't mask a problem unless you MUST.

My .02
I think it depends on what you have to go on and why that rattle exists. I have no problem with decoupling a sealed box from it's environment to prevent rattles and resonances. You can't always fix the rattle in another way. Why not prevent it from beeing exited in the first place?
I had resonances in my dash and floor when my sub box was tightly bolted down. The box transmitted the waves and exited the FS from the surrounding sheet metal. Once I decoupled that box with some foam, longer bolts and three small pieces of rubber and bigger holes so the bolts didn't touch the box that resonance problem was gone. It wasn't exited trough the music but due to the mounting area of the sub box itself exiting a nasty drone in the car body.
Works much in the same way as using spykes to decouple standing speakers from a floor. Are there other ways? sure! But those ways are not always practicle. You could increse the mass of the standing speaker to get a similar result. To talk about my car I wouldn't want to do that! I wouldn't want more weight if there are other ways to achieve similar or close to the same results.

I think the way Mercedes mounts woofers in the structural area up front is a cool way to deal with it though: http://www.theabsolutesound.com/articles/mercedes-benz-introduces-innovative-frontbass-car-audio-system-and-exclusive-signature-sound-demo-disc/
 

·
Registered
Joined
·
1,261 Posts
Discussion Starter #12
I like the article you shared. More and more frequently I see the terms impulse and step response being mentioned in the more advanced discussions of sound reproduction. I would like to find more reading about impulse response, but would really like to learn more about step response. Any ideas on resources for these?
Here's the white paper from Dunlavy, also a good read: Legacy Whisper Dunlavy SC V opinions
 

·
Registered
Joined
·
1,261 Posts
Discussion Starter #13
The issue I see is the ability to accurately measure the initial impulse. I stated in the thread and my build log that its all but impossible for a number of reasons which I've posted in a other thread. Mainly, it's broken down in to one issue: reflections. Of course you can measure *a* impulse but its immediately colored by reflections which drive the settling time and behavior.

This is why, in my build log, I discussed measuring my mid/tweet outside if the car to determine crossover points. I found at that time the coincident driver I use is EXACTLY time aligned between mid and tweeter.


IOW, if you measure the speaker in a reflection free environment you'll get a clean impulse response. But once it goes in the pillars, the impulse is altered. This is especially true for something like a tweeter where it's mounted near a window or dash. All of this means that determining step response inside a car is not at all trivial. But, I'll try to address it with real world examples soon.
I can see this happen. But what I wondered about is what dunlavy had to say about the electrical slopes. We won't be able to measure the impulse and step responce in the car. But what I am wondering about is how do they differ out of the car with 12 dB/oct and 6 dB/oct slopes.
 

·
Registered
Joined
·
1,261 Posts
Discussion Starter #14
Interesting thread ;)

True that speaker manufactures seem to focus on different things. I tend to look at it this way;

Do I want accurate* reproduction, do I want realistic* sounding reproduction or am I after an effect* (i.e coloration based on preferences)?

Keeping the discussion within car audio, my opinion is that accurate reproduction in car is impossible. A "flat" system don't sound good in small rooms like a car, it will sound really really bright. If we add a theoretical "perfect" curve to the accurate "flat" system to compensate for the room/environment we get a realistic sounding system* instead. This might not sound good to sound people anyway, we might want less highs and more lows so we continue to alter the response until it sounds good to us. This is how most people tune their systems and they are basically colored, "close to realistic sounding" systems.

Most people choose to have an effect added to the sound. In a car we don't have much choice either, since accuracy ain't a viable goal. So I think Dunlavy is correct when assuming that people are not really after 'accurate' reproduction in general (in car audio that's even more true).

Let's break it down, loudspeakers reproduce the signal they're fed with. If we ignore the signal path before the speakers, what differs from the original sound? Basically speaker distortion and room artifacts (which also can be referred to as distortion). If there wouldn't be any speaker distortion or room interaction we would have accurate reproduction (not even sure how that would sound, guess it would sound like sitting inside the recording studio...). Anyway we know that no speaker is distortion free neither are the "room" even close to anechoic. Break it down even more; What type of distortion is most audible? Can we address it somehow? In a car, most of us probably agree that it's the "room" that affect the audible distortion the most. No system will sound better than its weakest link, in car audio that's most likely the environment (if not the install/equipment suck, that is).

So the environment huh... How can we deal with it? In a car we are limited to do this. The most effective helper we can get is a DSP. EQ won't fix modal issues or lessen decay times though. This have to be done as a physical sense, frequency absorbers etc etc. 'Patrick Bateman' recently posted a thread discussing this. Many solutions are unfortunately impractical in a car since we have limited space.

What about the speakers then? These are prone to add several types of distortions that blends with the original sound, it's these distortions that cause the "sonic signature/character" of the drivers. The distortion can be divided into a linear and non-linear compartment. Linear distortion is basically related to the frequency response, the non-linear part are divided into harmonic and inter-modulated distortion and these are furthermore divided into different "orders".

So why am I rambling about all these things? Because there's so many aspects to consider. Things like step response (which basically is how the system responds after being fed with a square wave), time/phase coherency and diffraction/reflection control needs to be placed in relation of much they affect the sound compared to other things that degrade the sound.

I won't go in too much detail here, simply because I'm not that knowledgeable when it comes to the more advanced aspects of audio/electronics. My experience tells me that working with the environment and compensating the perceived frequency response yields the biggest difference by far. The key element would therefore be the environment, i.e the listening space - what we can do with it. Diffraction control is a doable option and works for higher frequencies. Frequency absorbers should work as well, haven't tried this out much yet. DSP's works awesome but they don't "fix" physical issues in the room. Check a "Decay" or "waterfall" plot in REW for example to see how the frequency response change as time decays.

I'm not sure how much the square wave (step response) thing correlates with transient response and such. Most people complain about sloppy bass but a big part of their issues are often related to integration between drivers and frequency response.
I agree on the environment, but what can we do to get the best out of it, before we need the DSP to try and fix what we can't solve otherwise. Can we learn something from home audio speaker builders to help us there? What applies to the car much in the same way it does in the home environment.

For instance, would it help to absorb back waves in a door mounted speaker and how do you do it with the moisture etc we can have there. I am convinced part of the sound we hear inside the car comes from the cavities behind the speaker. My sub sounded way different when lightly stuffed with glass fibre. Tried some other materials as well to find the sound I liked best.

I think Highly has an advantage there with his infinite baffle aproach. The backwave can escape without beeing reflected back as coloration trough the cone: http://www.diymobileaudio.com/forum/1459529-post14.html
But if we don't dare cut up our car like that, what to do (besides deadening) to the back wave? I use CLD tiles, aluminum covers for the holes, MLV and open cell foam in/on my doors to make it a better enclosure. but the backwave is not treated (yet). I've had egg carton shaped foam in there behind the speaker on the outside door skin but it got wet a lot. Probably not a good idea to use. What else can we do?
 

·
Moderator
Joined
·
18,547 Posts
I went digging for some more information on this topic. I wanted to make sure my understanding was correct. I found this, from the same source you used, and it looks like it answers the question regarding importance of the different aspects:

Measuring Loudspeakers, Part Two | Stereophile.com
(pg4 of this article)


Does a loudspeaker's time coherence matter? A "perfect" speaker, of course, would have both a perfect impulse response and a perfect frequency response (at one point in space). Another way of looking at a loudspeaker's time-domain performance is to examine its acoustic phase response, the phase angle between the pressure and velocity components of the sound plotted against frequency.

Again, this is an aspect of loudspeaker behavior that has proved controversial. One school of thought holds that it is very important to perceived quality; another, which includes almost all loudspeaker engineers, finds it unimportant. Floyd Toole, now with Harman International but then with Canada's National Research Council, in his summary of research at the NRC into loudspeaker performance that is described in two classic 1986 papers [32, 33], concluded thusly: "The advocates of accurate waveform reproduction, implying both accurate amplitude and phase responses, are in a particularly awkward situation. In spite of the considerable engineering appeal of this concept, practical tests have yielded little evidence of listener sensitivity to this factor...the limited results lend support for the popular view that the effects of phase are clearly subordinate to amplitude response."

This is also my view. Of the 350 or so loudspeakers I have measured, there is no correlation between whether or not they are time-coherent and whether or not they are recommended by a Stereophile reviewer. However, I feel that if other factors have been optimized—on-axis response, off-axis dispersion, absence of resonance-related problems, and good linearity—like a little bit of chicken soup, time coherence (hence minimal acoustic phase error) cannot hurt. In my admittedly anecdotal experience, a speaker that is time-coherent (on the listening axis) does have a small edge when it comes to presenting a stereo soundstage, in terms of image focus and image depth. But time coherence does not compensate for coloration, poor presentation of instrumental timbres, a perverse frequency balance, or high levels of nonlinear distortion.

The above essentially states time alignment to the nth degree is a less important factor than proper sound power, and response deviation. I can't say I feel the same way because, frankly, I don't have enough experience comparing a poor response/power response setup with excellent coherence vs a smooth FR/power response setup with poor time alignment to back the claim up. But, from everything I've read - namely Toole, who is quoted in the article above - good linear distortion (ie: smooth response) with good sound power is the most important factor. Based on my own install and experiences, I can at least say that these two factors have been the most helpful means to gaining the best audio system I've heard/had in my car to date. I've seen people here discuss phase/time response. Phase in regards to polarity is important BUT this shows up in sound power. Once that's understood, it makes sense.


Cliffs:
Smooth speaker frequency response and sound power are the most important speaker design factors. I've yet to see anything that debunks this. Once these are accounted for, time coherence can help take the design further.
 

·
Registered
Joined
·
1,261 Posts
Discussion Starter #17
Measure it. You'll have your answer. :)
I'm not aware yet how to do that but will look into it ;), maybe not for my car but for my home speakers (crossoverless line array) I'd like to know how that comes out.
 

·
Moderator
Joined
·
18,547 Posts
I'm not aware yet how to do that but will look into it ;), maybe not for my car but for my home speakers (crossoverless line array) I'd like to know how that comes out.
gotcha. I kind of figured you did based on some of your other posts, but no biggie.

Once I get a bit further in my rta tutorial thread, we'll have you ready to do so. :)
 

·
Registered
Joined
·
632 Posts
I don't have much time to contribute right now, but I'll say this...decoupling should always be a last resort. If you decouple because something rattles/resonates, you aren't fixing the problem (the rattle) by decoupling, you're masking it.

If you've ever worked on root cause analysis or lean initiatives, you'd know that you don't stop till you've found and fixed the problem (the rattle). If you find the source but can't fix it, then you move "downstream" to contain it (in this case, decouple). In short, don't mask a problem unless you MUST.

My .02
Isn't decoupling only solving a issue?

As soon as you decouple you are not allowing the resonance to reach the part that used to "rattle"

That's problem solving....

With damping ( adding mass ) you are actually masking the problem by rising the fs of the rattling part...

Not really masking, but shifting the problem to another frequency range...


BTW Subbed!:D:D
 

·
Registered
Joined
·
1,261 Posts
Discussion Starter #20
I went digging for some more information on this topic. I wanted to make sure my understanding was correct. I found this, from the same source you used, and it looks like it answers the question regarding importance of the different aspects:

Measuring Loudspeakers, Part Two | Stereophile.com
(pg4 of this article)





The above essentially states time alignment to the nth degree is a less important factor than proper sound power, and response deviation. I can't say I feel the same way because, frankly, I don't have enough experience comparing a poor response/power response setup with excellent coherence vs a smooth FR/power response setup with poor time alignment to back the claim up. But, from everything I've read - namely Toole, who is quoted in the article above - good linear distortion (ie: smooth response) with good sound power is the most important factor. Based on my own install and experiences, I can at least say that these two factors have been the most helpful means to gaining the best audio system I've heard/had in my car to date. I've seen people here discuss phase/time response. Phase is important BUT this shows up in sound power. Once that's understood, it makes sense.


Cliffs:
Smooth speaker frequency response and sound power are the most important speaker design factors. I've yet to see anything that debunks this. Once these are accounted for, time coherence can help take the design further.
I was just about to post this very same article :D. It shows how the step response is calculated from the impulse responses of the seperate components of the speaker.

I'll gladly accept this as a good answer on that part of my questions. It remains uncertain if time coherence plays a big role, but it does have other potential draw backs to try and implement it with those shallow slopes.

I''ll look into the measuring techniques needed for this when I finish my home speakers.
 
1 - 20 of 49 Posts
Top