Imaging, phase, and soundstage

[Tirefryr 1,742]

Maybe that's what I was thinking of.

[jemorgan85 0]

I haven't read the other posts, but..

If you are having phasing issues in your vehicle, remember these things...

1.) Most of the time, the higher end of the audio spectrum can be heard best when notes generally above 2000 hz are positioned (tweeters) lower in the front door panels. From studies I have read about, you want to keep the tweeter pretty low, without having your legs and other obtrustions in the way of the sound waves. It can be difficult to place your components for the simple fact that a car is so irregularly shaped, and waves have lots of different surfaces to bounce off of. If you can fire the tweeter and midrange directly at your head, while keeping them fairly close to the ground, you will have a better chance of proper imaging. Keep in mind though, that the passenger side door panels will have an awkward angle doing this, as they are farther away from your head than the driver's side.

2.) Also note that speakers in the back of the car will grossly take away from proper phasing. With them still in the back, you will be dealing with major cancellation on select frequencies because the waves from the back and the waves from the front will hit your ear at different points on the sine wave. Thus, cancellation. You can however incorporate lower end notes by placing midbass in the back panel, providing they are filtered to the 100-200 hz range, where the phase problems tend to not be so bad.

3.) Besides the normal problems that people expericence with subwoofer drivers, this will probably be the least of your worries with phasing. Sure, drivers sound the best in one particular spot in the car, but the low end notes don't have as bad of a phasing issue as the higher ones.

Hope this helps. Most of this info comes from Geolemon, if anyone remembers him.

[Supa_c 1]

Wow, just show up out of no where why dont you !

I prefer a high soundstage, im tall, so it makes it nice.

[jntar 15]

I haven't read the other posts, but..

If you are having phasing issues in your vehicle, remember these things...

1.) Most of the time, the higher end of the audio spectrum can be heard best when notes generally above 2000 hz are positioned (tweeters) lower in the front door panels.  From studies I have read about, you want to keep the tweeter pretty low, without having your legs and other obtrustions in the way of the sound waves.  It can be difficult to place your components for the simple fact that a car is so irregularly shaped, and waves have lots of different surfaces to bounce off of.  If you can fire the tweeter and midrange directly at your head, while keeping them fairly close to the ground, you will have a better chance of proper imaging.  Keep in mind though, that the passenger side door panels will have an awkward angle doing this, as they are farther away from your head than the driver's side.

2.) Also note that speakers in the back of the car will grossly take away from proper phasing.  With them still in the back, you will be dealing with major cancellation on select frequencies because the waves from the back and the waves from the front will hit your ear at different points on the sine wave.  Thus, cancellation.  You can however incorporate lower end notes by placing midbass in the back panel, providing they are filtered to the 100-200 hz range, where the phase problems tend to not be so bad.

3.) Besides the normal problems that people expericence with subwoofer drivers, this will probably be the least of your worries with phasing.  Sure, drivers sound the best in one particular spot in the car, but the low end notes don't have as bad of a phasing issue as the higher ones.

Hope this helps.  Most of this info comes from Geolemon, if anyone remembers him.

<{POST_SNAPBACK}>

Good tips, I have read everything you have suggested at one site or another.

My current mounting locations look like this...

I was thinking of simply angling them more tword the opposite headrest.

[psycho72 1]

**after reading jemorgans post**

Okay now I am confused (again). I thought that phasing only had to do with the arrival time of the sound from the speakers. The goal being both right & left low, mid & high arriving at the same time. Which you manipulate by wiring the speakers or by way of time alignment in a signal processor.

So I am obviously getting something confused. Can someone please explain. Also can you explain imaging and soundstage because these all seem to go hand and hand and I think I am getting those confused as well. Although I am faily certain that soundstage has to do with the perceived size of the virtual stage and the location of the instruments that are in the music piece.

p.s. after seeing those pics, seems like your idea is the best but not necessaily aiming at the headrest, I would say try different spots in the general area as maybe there might be a better spot.

[Tirefryr 1,742]

Phasing will affect just that as well as any cancellation issues.

As for the difference between imaging and staging, imaging is going to be your left/right bias and the soundstage will be height and depth.

[jntar 15]

I just had to post a reply cause the section was at 666

[Aaron Clinton 2,372]

I just had to post a reply cause the section was at 666

[Steven Kephart 0]

Wow, this section doesn't get much traffic. Hopefully my information will still be helpful to you and others.

I have been learning a lot about front speaker installation recently from my boss, Dan Wiggins. I've been trying to figure out what is really important, and what isn't. I've found out that there are a lot of myths out there on this subject.

For one thing, I've found that people put too much emphasis on speaker aiming. It is only important if the speakers are going to have beaming issues at the axis they will be mounted at. However if you aren't taking the speakers up that high in frequency, then it isn't an issue. For example, let's say you are running your 6.5" mids to only 2.5 kHz or so and letting the tweeter take it up from there. Then you shouldn't need to aim the mid.

The second one is mounting location. People spend a great deal of time and money on placing their speakers in the kick pannels. However I've found out that it might not be a wise thing to do. For one thing, the timing differences doesn't audibly effect imaging cues. The idea is that kick pannel locations will equalize the pathlength differences between the two sides. But when you actually understand how our hearing works, you will find that it isn't necessarily true.

So let's look at two things you must understand about our hearing. First of all, you must understand where we get imaging cues from. For frequencies 1000 Hz and up we get our imaging cues strictly from amplitude differences. In other words, if a tone within this frequency band is played louder on the left side than the right, then the sound will sound like it is coming from the left side. For frequencies 500 Hz and down, we get our imaging cues strictly from timing cues. Now you will notice that midrange drivers do play a majority of those frequencies effected by timing. However there is another limitation of our hearing that you must understand. That is called the Latent time of Fusion. What that is is a limit of how quickly our ears can preceive a sound. This limit is around 3 miliseconds. If a tone is played twice within 3 miliseconds, then it will sound like one sound. So how far would you have to move your speaker to effect a 3 milisecond change? That would be around 3 feet. So unless you are moving the speakers that far, then the imaging won't be effected by timing cues.

Now that's not to say that your speakers won't sound different in the kick pannels. It's just saying that any differences you hear won't be caused by the above as usually claimed. The differences are frequency response related and come from changes in tonality from comb filtering and differences in reflections due to the new mounting location. This change in frequency response could be good or bad. It is usually the latter as the speakers are now located deeper in a hole with even more surfaces to effect them. The question you have to ask yourself is if it is worth the extra time and money to take the chance.

Steven Kephart

Adire Audio

[Impious 1,476]

Wow, this section doesn't get much traffic.

No...unfortunately....it doesn't

For one thing, I've found that people put too much emphasis on speaker aiming.  It is only important if the speakers are going to have beaming issues at the axis they will be mounted at.  However if you aren't taking the speakers up that high in frequency, then it isn't an issue.  For example, let's say you are running your 6.5" mids to only 2.5 kHz or so and letting the tweeter take it up from there.  Then you shouldn't need to aim the mid. 

The speakers off-axis (or on-axis) frequency response wouldn't play a roll in this decision? Is it safe to make the blanket claim that with no speaker does aiming matter?

What that is is a limit of how quickly our ears can preceive a sound.  This limit is around 3 miliseconds. If a tone is played twice within 3 miliseconds, then it will sound like one sound.  So how far would you have to move your speaker to effect a 3 milisecond change?  That would be around 3 feet.  So unless you are moving the speakers that far, then the imaging won't be effected by timing cues. 

Hmm....I dunno. After reading this I decided to go out and play around in my car some (since I have digital time alignment available in .1ms steps). Mids and tweets mounted in doors. I must say....the difference between 0 delay and 2.0ms delay, imaging and tonality wise, was huge. With 0 time delay the sound was diffused, no real center image to speak of at all, and you could clearly tell that you were sitting directly next to the speakers on the driver's side. With 2ms time delay the sound was much more coherent, tonality improved greatly as it didn't sound like a mumbled up mess, and the image was fairly well centered now.

Tried this with both music and the 7 drum beat track. Experienced the same affects on both. And as you turned the knob to increase or decrease delay, you could clearly hear the image and diffusion (or coherentness) increase and decrease....almost like it was sliding along a scale.

Psychoacoustics? I guess I can't write it off completely, since I have no way of doing an ABX test. Or maybe the deck's "2ms delay" isn't a true 2ms? I dunno.......

[Steven Kephart 0]

The speakers off-axis (or on-axis) frequency response wouldn't play a roll in this decision?  Is it safe to make the blanket claim that with no speaker does aiming matter?

<{POST_SNAPBACK}>

That's what beaming effects is the off-axis response. If you are crossing the driver over before the off axis is rolling off then aiming probably won't help any.

Hmm....I dunno.  After reading this I decided to go out and play around in my car some (since I have digital time alignment available in .1ms steps).  Mids and tweets mounted in doors.  I must say....the difference between 0 delay and 2.0ms delay, imaging and tonality wise, was huge.  With 0 time delay the sound was diffused, no real center image to speak of at all, and you could clearly tell that you were sitting directly next to the speakers on the driver's side.  With 2ms time delay the sound was much more coherent, tonality improved greatly as it didn't sound like a mumbled up mess, and the image was fairly well centered now.

Tried this with both music and the 7 drum beat track.  Experienced the same affects on both.  And as you turned the knob to increase or decrease delay, you could clearly hear the image and diffusion (or coherentness) increase and decrease....almost like it was sliding along a scale.

Psychoacoustics?  I guess I can't write it off completely, since I have no way of doing an ABX test.  Or maybe the deck's "2ms delay" isn't a true 2ms?  I dunno.......

<{POST_SNAPBACK}>

I kept my comments mainly to actual speaker positioning and really didn't mention time alignment. Changing time alignment in intervals smaller than 3 miliseconds will make a difference in the frequency domain, which is most likely what you were hearing. If you noticed, I mentioned that the new speaker locations would also have a change in the frequency domain. There are several ways this is effected. The main one I remember Dan telling me was that you change the spectrum of comb filtering.

I guess what I learned from all this, and I hope others do as well, is that kick pannel positioning isn't always THE BEST solution. Generally speaking, the easiest and best way to set things up is to use the stock, lower door locations and utilize proper processing.

Steven Kephart

Adire Audio

[Aaron Clinton 2,372]

Hi ya Steven,

any info you add is awesome, and yes I would love it if this section got a little more traffic,

I wanted to see if members would start posting up tech papers or helpful directions for different parts of the audio world,

[Supa_c 1]

Thanks for the great info Stephen.

Good to see you posting on this forum, we need more people like you around.

Would it be safe to say that time alignment in a H/U would be better than making custom pods for your mids ?

[Steven Kephart 0]

Would it be safe to say that time alignment in a H/U would be better than making custom pods for your mids ?

<{POST_SNAPBACK}>

Each vehicle/system is so different it is very difficult to say. It also depends on the persons abilities to set the time alignment properly. Keep in mind that custom pods are generally aimed, so they are more on axis. This could be a benifit if falling into what I described earlier. I guess the point of my comments isn't to completely rule out kick pannels. It's just to help people get a realistic idea of what the benifits/weaknesses are.

My plans for my car is to put the mids in the lower doors, and put the tweeters up in the A-pillars. But then I've got some pretty crazy processing available with 72 dB per octave digital slopes on the crossover which will greatly reduce comb filtering and allow me to run the tweeter much lower. I'm also going all active so I can adjust the time alignment on the tweeters and mids seperately. And finally to tune everything from there I have a pretty crazy parametric equalizer. The results should be pretty amazing, I hope.

Steven Kephart

Adire Audio

[Supa_c 1]

The thing is.....you dont sit in the center of the car while listening to music.

Time alignment is really a necessity if you want your imaging to be spot on.

measuring the distance from your head to the speaker takes much less time than making custom brackets/pods to get your sound on axis.

Your car should sound very " sick".