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View Full Version : Sound Imaging, the evasive pleasure, how do I catch it?



MediumTech
01-08-2012, 01:12 PM
I've had only a few chances to hear a nice sound system that was able to produce what I understand is "imaging", which is the ability of a system to have sound qualities beyond treble, bass, and left/right channels. Kinda like 3D sound.

I'm talking about the sound in which the vocals sound like they are coming from the middle of the windshield, the bongos are somewhere in the other lane, and the drummer is somewhere around the hood ornament.

I understand that speaker placement, speaker quality, especially tweeter quality are all big factors.
I just read that the fine-qualities of the amplifier may have something to do with it.

On amps, I thought all there was to it was; real power RMS, and Total Harmonic Distortion being less than 1%.
Is there more to it?

My signature shows what I have, and what I'm shopping for. Only the front 4) speakers are installed at this moment.

I've been impressed with the front door mounted Hertz ESK-165L's running on the stock head unit, and I understand they will really come to life with the "soon to arrive" Scosche EFX Hyperdrive HD4300, 4ch amp.
I've not been very impressed with the rear door mounted 6.5inch Infinity Kappa 3-way's, but I'm holding on to a little hope that they will become much better with the 4ch amp.

I'm starting to shop around for a head unit. I'm thinking that a head unit with "timing" adjustments may be the ticket?

Advice?

duanebro
01-08-2012, 01:29 PM
I don't have the money to get into ta. But I might be able to clarify the term "imaging"

your definition includes something called "sound stage" This is where sounds seem to come from beyond the speakers.

Imaging is all about placement, where every sound has its place, and doesn't move. Like the singer in the windshield.

Both are sq issues, and hard to get right. It is even harder to get both at the same time. ta is pretty much required to get it right. (At least in a car, at home it is much easier)

MediumTech
01-08-2012, 01:43 PM
I don't have the money to get into ta. But I might be able to clarify the term "imaging"
your definition includes something called "sound stage" This is where sounds seem to come from beyond the speakers.
Imaging is all about placement, where every sound has its place, and doesn't move. Like the singer in the windshield.
Both are sq issues, and hard to get right. It is even harder to get both at the same time. ta is pretty much required to get it right. (At least in a car, at home it is much easier)

Thanks duanebro.
Thanks for the clarification on "sound stage"
What is ta?

duanebro
01-08-2012, 01:47 PM
time alinement <-- I can't spell, so I shortened it.

06goat
01-08-2012, 01:53 PM
time alinement <-- I can't spell, so I shortened it.

Time alignment*

Also duanebro I see your local, nice to see some MI guys on the forums tired of all the Cali people. If youd like to get into time alignment you can get a HU with ta for under $200

duanebro
01-08-2012, 02:25 PM
used?

BTW: Thanks for the spelling lesson! ;)

pickup1
01-08-2012, 02:30 PM
Are you going to expect great soundquality out of that efx amp?

MediumTech
01-08-2012, 09:45 PM
Are you going to expect great soundquality out of that efx amp?

I read one report that said it was decent. I'm getting this one for $120 shipped. I'll see how it works, and I can pursue a fancier amp after I research more. I figure it will be kinda cool to check the difference between amps with identical speakers. I figure the amp will be easy to change. I don't want to spend alot on an amp right now because I'm spending money on other parts of the system at the same time. At $120, I figure I'll be able to get much of my money back if I decide to change.
If I'm lucky, I'll be happy with it and I'll be done. ... we'll see.
It will probably take me a week or more to get everything put together.
This is still destined to be the best system I've ever had. It will be like the holy grail for a while.

Why So Cereal?
01-08-2012, 10:17 PM
I agree up above, you'll need some T/A to get a good centered sound stage. Sometimes you can play around with flipping phases on the drivers to get a little closer but T/A is really good for tweaking. Since you're in the market for a HU, do it right the first time and get as many features as you can (T/A, active xovers, slope changes, etc) My dad bought my current HU as a gift for me and I love the unit and the "Sonic Center Control" is decent for helping me center my stage, but I cant go active, nor can I run rears with proper processing.

On the note of amps, you dont necessarily have to spend tons to buy top notch but make your dollar stretch by going used on some nice equipment. DIYMA is a great place to look for nice SQ amps. As long as your amp is setup correctly with your speakers, you will be able to do fine with any amp of decent quality. I've seen some SQ cars that run the "Almighty" McIntosh Amps; I've also seen some that run the Polk PA series amps. Big price jump, but both cars were able to place in SQ competition. With SQ, install is everything. So get decent equipment from the jump (especially your HU, this is where I'd spend the most if i had to start over) and get ready to tweak and tweak and tweak until your head hurts. lol

keep_hope_alive
01-09-2012, 12:03 AM
You can get a used Alpine CDA-9835 for your budget. Or a CDA-9887. Gives you 6-channel time alignment and front active features. Invest your speaker money on front speakers only, you don't have the budget for rear speakers. Just run factory rears.

T/A is the cheapest way to get a better sound stage. Heavily modifying the vehicle is another.

MediumTech
01-09-2012, 06:12 AM
Thanks again guys.

trumpet
01-09-2012, 01:35 PM
Imaging is a psychoacoustic effect of picturing something specific in our mind as a result of hearing a sound, like visualizing a snare drum if you hear a recording of a snare hit. Sound staging is directing and focusing certain instruments, vocalists, and so on so we're tricked into believing they're not coming from the speakers. The usual goal for staging is the vocalist centered, guitars on the sides, drums at the rear(this is from depth, which we can get into later).

The quality of the music or source material plays a big role in all of this. Sound quality reference CDs such as the Focal/JM Labs 6-disc set or any of the Alpine Reference discs are great tools.

I wouldn't worry about or expect a big change in imaging based on your choice of amplifier. I have personally heard a change in imaging from switching amplifier brand and class, and others will swear on their career they have heard massive changes from upgrading to high dollar amps. Get what you can afford and buy from an authorized dealer. It's more important to have a good quality head unit and don't cut corners on the installation basics. Set the gain knobs correctly.

I agree with the suggestion of buying an older Alpine head unit with time alignment. The 9835 would be a fine choice. I see you are considering the Eclipse CD7200 MKII. Right now I think that's too much of a head unit for you.

5.3bowtie
01-09-2012, 02:27 PM
The alpine 9833 is also another good choice from everything I have read about it. I was able to pick one up off ebay for under $100 and will be installing it shortly.

keep_hope_alive
01-09-2012, 05:03 PM
Agreed about the 9833. same as the 9835 but without the biolite display. i have a 9833 in the wifes car. i can easily shift the center image to the middle of the car though she likes it just off center (between gauge cluster and rear view mirror).

Yes, the 7200mkII is a nice piece, but also cumbersome. Alpine is generally easier to use.

hispls
01-09-2012, 05:10 PM
You should lurk DIYMA forum. To be done properly in a car will always involve some sort of processor and almost always require some creative mounting of components. Selection of amps and components is way way down on the list of priorities to get it "right".

Throw your rear speakers out entirely unless you plan to play music that is RECORDED in 5.1 surround. What concert have you ever been to where the singer/drummer is behind you, or behind you and in front of you? It will invariably be an accoustic nightmare without carefuly selected source material and really good processing power.

keep_hope_alive
01-09-2012, 06:47 PM
You should lurk DIYMA forum. To be done properly in a car will always involve some sort of processor and almost always require some creative mounting of components. Selection of amps and components is way way down on the list of priorities to get it "right".

Throw your rear speakers out entirely unless you plan to play music that is RECORDED in 5.1 surround. What concert have you ever been to where the singer/drummer is behind you, or behind you and in front of you? It will invariably be an accoustic nightmare without carefuly selected source material and really good processing power.

except... rear fill should really be used to recreate a "room". we are used to listening to music in a room - where we get delayed reflections from behind us. the amount of delay gives us an idea of the size of the room we are in. that is how i use rear fill - to simulate diffuse room reflections to add depth to the sound stage and give the illusion i am in a space bigger than a car. full range drivers ran with a bandpass crossover can achieve this with careful level balancing. adding delay will allow you to simulate a larger space and take some control over the front soundstage.

getting diffuse rear information is the tricky part - and one that processing may play a role in. i may work on this a bit more - as an acoustical engineer i spend a lot of time designing/testing acoustical treatments for rooms and performance spaces. we also write our own simulation programs, and we can apply filters to program material to simulate a room. i'd like to design a rear fill processor some day that has all of the necessary controls/filters/effects needed to properly simulate rear reflections. just and issue of spare time.

MediumTech
01-11-2012, 05:51 AM
except... rear fill should really be used to recreate a "room". we are used to listening to music in a room - where we get delayed reflections from behind us. the amount of delay gives us an idea of the size of the room we are in. that is how i use rear fill - to simulate diffuse room reflections to add depth to the sound stage and give the illusion i am in a space bigger than a car. full range drivers ran with a bandpass crossover can achieve this with careful level balancing. adding delay will allow you to simulate a larger space and take some control over the front soundstage.
getting diffuse rear information is the tricky part - and one that processing may play a role in. i may work on this a bit more - as an acoustical engineer i spend a lot of time designing/testing acoustical treatments for rooms and performance spaces. we also write our own simulation programs, and we can apply filters to program material to simulate a room. i'd like to design a rear fill processor some day that has all of the necessary controls/filters/effects needed to properly simulate rear reflections. just and issue of spare time.

Wow, Thanks guys. This is certainly more stuff to consider. Thanks for the info.

GammaRadiation
01-11-2012, 06:09 AM
Sound imaging is about stereo separation. Does the bassist sound right stage, lead left, vocals and drums center, etc... This is as much about the mastering of the track as it is the stereo it is played on, so make sure you've got a good track when determining imaging. It's going to be all about speaker placement and time delay. Yes, you want to minimize distortion, but simply for the sake of minimizing distortion. Getting near equal separation between the speakers and putting them as wide as possible will most often give you optimal results. High end head units also have time delays to correct for distances. Then there is also the issue of sound stage height. Ideally it should sound as if the music is coming from eye level. Unless your mids are on the dash and the tweeters are on the A pillars, this is very hard to replicate in a car. You can also improve your overall sound quality by lowering the noise floor. This means deaden everything, particularly large, flimsy panels such as door skins and the roof. A subwoofer that doesn't play too high is essential. If you're getting much response in the 80-120Hz range you're muddying up the sound stage for bass guitar. Steep roll off (18-24dB/oct) starting around 60Hz is my personal choice. The rest of your crossovers will have to depend upon the speakers you choose. I will promise you this, you're better off investing in a good active crossover compared to anything else. If you head unit has a solid crossover, even better.

TaylorFade
01-11-2012, 07:25 AM
If you're more of a DIY kind of guy, the best money you can spend on processing is a miniDSP. You can get the 2 way active one (2x4) with the software plug in for ~ $110 shipped brand new. Time alignment, crossovers, reverse polaritys, a TON of EQ and more. The software has free lifetime upgrades too.

As has been mentioned, speaker placement and install is HUGE when trying to get an accurate and convincing soundstage. It can be done with the factory locations if you have the time and ear to get it right. I sat in the world championship "beginner" SQ vehicle at finals this year and it was amazing. In beginner class, you can only utilize the factory locations with an additional 1" tweet in the pillar. I honestly don't know how they did it. The stage was amazing and they even managed to accomplish "ambiance" with the factory locations and no rear speakers. Insane.

I have yet to experience a car with true "depth" that everyone talks about. Where certain material truly sounds like it's coming ffrom beyond the loaction of the drivers. Seems as if this is one of the most difficult aspects because physical location is so important there and there is only so much that procesing can do.

SQ is a fickle and mysterious mistress. Good luck tracking her down! My advice is to head over to DIYMA and start reading.

keep_hope_alive
01-11-2012, 04:40 PM
If you want to read more, don't start with DIYMA. There is some good info there, but also bad info, and if you don't know the difference then the source isn't useful. Pick up a book on acoustics. PM me for some reference material recommendations.

This is from the 09 edition of NFPA seventy-two. We care about room acoustics, location cues, intelligibility, etc. for fire alarm and mass notification speaker systems. Building a stereo is one thing, designing a life saving speaker system is another!
http://i38.photobucket.com/albums/e128/phat_funky_beats/Sound%20Domain/HRTFexplained.jpg

MediumTech
01-11-2012, 08:03 PM
Cool info, Thanks again.

MediumTech
01-13-2012, 07:12 PM
Well, I just bought an eclipse 7200 mkII
Should be installed tomorrow.:)

keep_hope_alive
01-14-2012, 11:16 AM
it is a nice piece. the faceplate mechanism is cumbersome and may interfere with some dash kits - but that is a small price to pay for a good SQ unit.

MediumTech
01-16-2012, 12:51 AM
delay on installation: the eclipse should be in this week sometime

duanebro
01-16-2012, 01:04 AM
delay on installation: the eclipse should be in this week sometime

Sorry to hear that, I hate waiting to get a new toy installed!

MediumTech
01-16-2012, 06:42 AM
Sorry to hear that, I hate waiting to get a new toy installed!
Yeah, the installers (or at least one of the lazy ones) told me they ended up booked-up on Saturday, and advised trying again another day.
Installers and waitresses should not be pissed before you receive service right?

MediumTech
01-20-2012, 12:44 AM
the new sound system is in.
I am very impressed.
I am especially impressed with this eclipse 7200 head unit.
this is the best sound system I've ever owned.
thank you all for your help in developing this

dumple
01-20-2012, 12:47 AM
now get it all tuned up and youll be having eargasms

MediumTech
01-20-2012, 12:33 PM
now get it all tuned up and youll be having eargasms
I bought the eclipse cd 7200 mk2 at a $200 discount from a shop that had it as their demo unit.
I got the remote with it, and now I need to print a manual to learn the k-nobs and buttons.

Eargasm's- is that where ear wax comes from????

I've got FL & FR time delay set at 4.0 m/sec, and vocals seem to be coming out of the windshield and door glass....

mylows10
01-20-2012, 01:07 PM
nice glad to hear it all came together for you.

keep_hope_alive
01-20-2012, 03:11 PM
I bought the eclipse cd 7200 mk2 at a $200 discount from a shop that had it as their demo unit.
I got the remote with it, and now I need to print a manual to learn the k-nobs and buttons.

Eargasm's- is that where ear wax comes from????

I've got FL & FR time delay set at 4.0 m/sec, and vocals seem to be coming out of the windshield and door glass....

m/sec or meters per second is a unit of velocity or speed
msec or milliseconds is a unit of time

:)

Glad you are enjoying the new system

trumpet
01-20-2012, 07:00 PM
I've got FL & FR time delay set at 4.0 m/sec, and vocals seem to be coming out of the windshield and door glass....

Decrease the delay on the FR channel with the same music playing and report back.

duanebro
01-20-2012, 08:20 PM
Decrease the delay on the FR channel with the same music playing and report back.

I was thinking the same thing, but I don't have a an hu with that type of control. And I didn't want to give bad advice.

MediumTech
01-21-2012, 09:36 AM
Decrease the delay on the FR channel with the same music playing and report back.
OK, now I'm getting to understand this better. My first setting was my first experience with time delay, just one hour after the new unit was installed, and I knew very little about it.
I'm in a 4-door SUV with front and rear door speakers, and a sub behind the rear seat.
I started with the Sub (farthest) at zero time delay, but then I added "-1.0msec" to everything so I could have the flexibily to move the Sub both up and down because my unit does not adjust beyond zero.

(each of these numbers have "-1.0msec" added to them for flexibility with the sub while I'm experimenting & learning)

-5.0msec, Front Left (Front seperate components near front edge of door)
-2.1msec, Front Right
-5.4msec, Rear Left (Rear 6.5" triaxial, at lower front of door)
-1.1msec, Rear Right
-2.2msec, Sub (behind second row seats)
(I started with the Sub at 1.0, but then I "played" with moving it around a bit, and ended up here. I'll probably keep checking on this)

Now I think I need an audio test CD, or test-tracks to download.

whitedragon551
01-21-2012, 10:03 AM
First and foremost you dont need to delay all speakers. You dont delay the speaker furthest from you. You delay the rest of them so they arrive at the same time as the furthest speaker.

http://i128.photobucket.com/albums/p187/whitedragon5515/Car%20Audio/AlpineTimeAlignment.jpg

http://i128.photobucket.com/albums/p187/whitedragon5515/Car%20Audio/TimeAlignmentEquation.jpg

trumpet
01-21-2012, 08:29 PM
If your subwoofer is the farthest driver use that as your reference point, meaning leave it at 0.0 delay always. Your delay is increased incrementally with the nearest speaker delayed the most, with the farthest speaker delayed 0 ms. It helps to write down the formula whitedragon's post shows in the image and get out a tape measure so you can calculate the delay for each speaker location. For me I understood it a lot better when I went through this process. From there you enter your delay numbers into the head unit and listen to music. The delay from the math is most likely not going to be the best.

Time delay can do some great things for making your bass sound like it's all up front, plus it can really improve midbass.

MediumTech
01-21-2012, 08:31 PM
Thanks

whitedragon551
01-21-2012, 08:32 PM
If your subwoofer is the farthest driver use that as your reference point, meaning leave it at 0.0 delay always. Your delay is increased incrementally with the nearest speaker delayed the most, with the farthest speaker delayed 0 ms. It helps to write down the formula whitedragon's post shows in the image and get out a tape measure so you can calculate the delay for each speaker location. For me I understood it a lot better when I went through this process. From there you enter your delay numbers into the head unit and listen to music. The delay from the math is most likely not going to be the best.

Time delay can do some great things for making your bass sound like it's all up front, plus it can really improve midbass.

I find it best to use the math to get a starting point and then tweak from there based on your ears.

MediumTech
01-21-2012, 08:37 PM
Thanks

keep_hope_alive
01-21-2012, 11:26 PM
Note that above 3kHz ITD is not as important as IID. Delaying tweeters isn't as useful as controlling level with aiming. You still want some channel separation from the HRTF, so tweeter placement is very important.

Some people lean when they drive, so measure from you normal head location, measure the left speaker distance using the left ear location, Same for right. It helps to have a friend do this with you. Measure to the woofer voice coil, meaning add an inch or two if you have to stop at a grill.

The reason we tweak with our ears from here is because speakers are usually poorly aimed, they beam, roll off from being off axis in factory locations, and suffer phase interference from reflections.

I made a spreadsheet in excel and I keep a laminated version in my car with all 10 front speaker locations listed, as well as rear and sub. Yes, I have 10 front speaker locations, but I only use 6 at a time. Door, floor kick, side kick, apillar, & dash. I test often. I miss the H701 for that reason, but I don't miss the added noise.

I don't like that the 9887 uses distance as its metric (in or mm), I prefer msec units. I may try a 7200mkII.

MediumTech
01-22-2012, 03:47 AM
Wow, cool, thanks again

duro78
02-01-2012, 07:54 AM
I would get an external processor. Preferably an ms8 it puts your imaging together in Minutes. I fiddled around with my 9887 for weeks and never got right. A lil tip make sure all speakers are in phase or you'll never get the image right