55 replies to this topic

[Matt VIP]

Hi gang:



first of all, the setup:



Pioneer P80s running a 2 way system active. It has a 17 band graphic EQ and time alignment:

Seas Lotus tweeters, 24db 3.15kHz crossover

Boston Z6 mids running 24db, 63Hz - 2.5kHz crossover

installed like this:









2 x invisabass running under the front seats off 250w each



the amps are JL 300/4 and 500/1

________________________________________________________________



The good parts:

- nice midbass

- interesting subbass (makes the seats rumble)

- looks good

- stage height and width (reasonable, considering where the tweeters are, but nothing special)

- no centre console means direct axes for sound waves.



The less good parts:

- harshness (a little bit, not sure at what frequency though)

- soul (sounds tinny, but its not too bad, just not what I would have expected from the components)

- accuracy

- subbass (invisabass) is not really that great. its nice, upfront, no rattles, but its not where it needs to be. i'm not too worried about getting this spot on at the moment though.



The bad parts:

- image (read: none)

- accuracy (I know that features twice, but its kind of how I feel about it. sometimes its passable, but comparing it to Sierra's car its bad. )

________________________________________________________________

Now I need your help....

How do i go about (in an easy-for-a-noob-to-follow-process) creating an accurate and stable image? I know I need to start by trying the tweeters out in new positions (ie the dash), but i'm a bit loath to move them too far away from the mids, as apparently its better if they stay close. plus its not the stage height thats really bugging me...



Imaging occurs between 250Hz and aoub 2.5kHz yes? do I just keep messing with my graphic eq until suddenly I magically get an image? I realise the first step is to check the phasing of each component and write it down so i can vary it to see what makes a difference.



How do i go using TA effectivly? I've tried doing the auto TA thing, and its ok, but doesnt give me a fantastic image. Ive tried doing the distance measurement thing (and it gives me totally different answers to the auto TA thing!) and it works ok but not great. should I start with the auto-TA as a base, and tweak from there, doing mids, then tweeters, then subs?



Question: if phase changes 180 degress using a 12db/oct slope, does it change a full 360 using a 24db slope?



question: I'm considering looking into running a 3 way active system (running, for example, the Morel CDM54 off a PPI A300). Is this change going to specifically help me with imaging, or am I barking up the wrong tree? I also assume that running a 3 way system is going to help with the soul of the music, by allowing the Z6's to just run midbass and therefore not overextending them, but is it likely to cause as many issues as it solves?


You can see from the kickpanel installation that the path lengths at the moment are about as good as i'll probably get them. The left tweeter is pretty much on axis, and the right tweeter is aiming at the dome interior light, but I should be able to vary the angles pretty easily with a bit of mucking around.



Where do i go from here, to take this from a passable installation to a great sound system?



(PS, Sierra and Fury and Zion, feel free to comment about....now.)


oh yeah...

and thanks : )

Edited by VIP318, 09 September 2007 - 08:53 PM.

[luka]

nice enclosure .. good luck with the set up ill be watching closely

[Luke352]

I'd ignore the P80's auto TA I was reading some posts about it's Auto EQ function on another forum and the consensus was it's useless. Rule of thumb is about .8 to 1.2ms delay on the speaker side that is closest to you. Sub is one of those things that is always individual to the car I generally delay the entire front stage till the sub comes FWD then sort out the left/right delay till I get a nice middle gound that sounds good.

To give you an idea I have Front LH has 5 ms, Front right has 6 ms, and Sub 0 but then I also had to reverse the phase on the sub.


I don't think you could say Imageing only occurs in a certain freq range, possibly the strongest cues are in the 250hz to 2.5k range but I would say it exists outside that range aswell.

Here's a link to a Excel spreadsheet for figureing out TA, you'll have to click the link then download it from the page it sends you to, it's only 18.5kbs
http://www.mediafire.com/?amztbg9yrbh

Edited by Luke352, 09 September 2007 - 09:49 PM.

[~thematt~]

I would highly recommend you firstly start to investigate what equipment tuning tools you have at your disposal, and how they work. This will allow you a massive first step towards achieving that elusive image and soundstage, and answer most of your questions.

Auto TA on the Pioneer units have never been successful when Ive used them. I find them a waste of time, and do it myself. Always EQ last as well, because changes here can affect the whole system when done incorrectly. I would only start to EQ once an image as been found, and you need to sharpen and stabilise it. EQ can also be used to modify soundstage properties, like height, depth and width, but thats in the realm of the pros!!

Dont worry about Phase changes and cohesion due to crossovers either. Its almost undetectable in a controlled environment unless the changes are sharp and drastic, and inside a car even less so. Concentrate on other things, that make a bigger impact.

First step, for all frequencies below 2kHz (and above ~250) time is the major factor. Time difference between the waves from one source hitting your ears, and the other source. If they both reach your ears at the same time, then your brain will think there is only one source, and its directly in front of you (big hint there). Above 4kHz, the ears are volume dependent, so the louder the sound, the closer to you it seems (another hint, volume attenuation is the best for tweeters).

[mooingchicken]

ok without hearing your setup its really hard to give specific advice, so firstly i would try to meet up with someone to give you a hand if possible.

Quote

How do i go about (in an easy-for-a-noob-to-follow-process) creating an accurate and stable image? I know I need to start by trying the tweeters out in new positions (ie the dash), but i'm a bit loath to move them too far away from the mids, as apparently its better if they stay close. plus its not the stage height thats really bugging me...

your tweeters can be away from the mid, but most people be like to keep them close. and to get good image you dont need to move tweeters to the dash.

Quote

Imaging occurs between 250Hz and aoub 2.5kHz yes? do I just keep messing with my graphic eq until suddenly I magically get an image? I realise the first step is to check the phasing of each component and write it down so i can vary it to see what makes a difference.

imaging happens at all freq's, for a good image everything from your sub to the highest should sound like they come from infront of you. and across the width of the dash.

Quote

question: I'm considering looking into running a 3 way active system (running, for example, the Morel CDM54 off a PPI A300). Is this change going to specifically help me with imaging, or am I barking up the wrong tree? I also assume that running a 3 way system is going to help with the soul of the music, by allowing the Z6's to just run midbass and therefore not overextending them, but is it likely to cause as many issues as it solves?

3-way active isnt easy to get setup right. and could be more of a headache then it is worth.

to get your center image, idealy you should play around with diver position and placements, because as soon as you start using TA you take away from the other side of the car. (but most people do use TA)

i dont know how good the auto-TA is, as i havnt used it myself, but what you want to achieve is to have the 'center channel voice' (from my disc) in the centre of the dash. alternativly, most cd's are recorded with the singer in the centre of the image. (which translates to the middle of the dash). you can either do the sub first or the speakers. for the speakers pick a side and and turn the TA untill you can hear the image move across the dash, stop when you hear it comes from the centre. with decent recorded cd's you should be able to pick where the singer is, the back up singers ect.

[diesel]

I`m running Z-6`s also down low with the tweeters mounted in the factory speaker location and then using their imaging system to have extra tweeters in the A-pillar. still adjusting things but the imaging is great, but i`m sure can be improved on, system is only a few weeks old at present. I`ll post a couple of pics soon.

VIP318, on Sep 9 2007, 09:46 PM, said:

Hi gang:



first of all, the setup:



Pioneer P80s running a 2 way system active. It has a 17 band graphic EQ and time alignment:

Seas Lotus tweeters, 24db 3.15kHz crossover

Boston Z6 mids running 24db, 63Hz - 2.5kHz crossover

installed like this:









2 x invisabass running under the front seats off 250w each



the amps are JL 300/4 and 500/1

________________________________________________________________



The good parts:

- nice midbass

- interesting subbass (makes the seats rumble)

- looks good

- stage height and width (reasonable, considering where the tweeters are, but nothing special)

- no centre console means direct axes for sound waves.



The less good parts:

- harshness (a little bit, not sure at what frequency though)

- soul (sounds tinny, but its not too bad, just not what I would have expected from the components)

- accuracy

- subbass (invisabass) is not really that great. its nice, upfront, no rattles, but its not where it needs to be. i'm not too worried about getting this spot on at the moment though.



The bad parts:

- image (read: none)

- accuracy (I know that features twice, but its kind of how I feel about it. sometimes its passable, but comparing it to Sierra's car its bad. )

________________________________________________________________

Now I need your help....

How do i go about (in an easy-for-a-noob-to-follow-process) creating an accurate and stable image? I know I need to start by trying the tweeters out in new positions (ie the dash), but i'm a bit loath to move them too far away from the mids, as apparently its better if they stay close. plus its not the stage height thats really bugging me...



Imaging occurs between 250Hz and aoub 2.5kHz yes? do I just keep messing with my graphic eq until suddenly I magically get an image? I realise the first step is to check the phasing of each component and write it down so i can vary it to see what makes a difference.



How do i go using TA effectivly? I've tried doing the auto TA thing, and its ok, but doesnt give me a fantastic image. Ive tried doing the distance measurement thing (and it gives me totally different answers to the auto TA thing!) and it works ok but not great. should I start with the auto-TA as a base, and tweak from there, doing mids, then tweeters, then subs?



Question: if phase changes 180 degress using a 12db/oct slope, does it change a full 360 using a 24db slope?



question: I'm considering looking into running a 3 way active system (running, for example, the Morel CDM54 off a PPI A300). Is this change going to specifically help me with imaging, or am I barking up the wrong tree? I also assume that running a 3 way system is going to help with the soul of the music, by allowing the Z6's to just run midbass and therefore not overextending them, but is it likely to cause as many issues as it solves?


You can see from the kickpanel installation that the path lengths at the moment are about as good as i'll probably get them. The left tweeter is pretty much on axis, and the right tweeter is aiming at the dome interior light, but I should be able to vary the angles pretty easily with a bit of mucking around.



Where do i go from here, to take this from a passable installation to a great sound system?



(PS, Sierra and Fury and Zion, feel free to comment about....now.)


oh yeah...

and thanks : )

[Juls]

There is many things you can do,



I agree with not moving the Tweets too far from the Z6 midbass, I found the midbass driver wasn't that good in the high freq area, and the tweets didn't pull there weight down low either, so when separated, the separation and volume drop around the x/over points where noticeable, to remedy this I ran a Ambient setup like diesels above, which worked surprisingly well to raise image height, without severely effecting the stage width you get from having everything down low.



With your adjustments, Set your time alignment via the usual recipe first, which is Furtherest speaker in CM less the speaker to be Adjusted in CM Divide by 34.



IE: 160cm (furtherest speaker) - 105cm (speaker to be adjusted) = 55cm, 55cm (difference) divide by 34 = 1.61ms delay on that speaker.



once you have setup the whole car with that solution, get a TEST DISK, with a STEREO IMAGING TEST!! you NEED THIS.. you havn't got a hope without it. Forget regular recordings, they vary ALOT!!



With the test disk adjust your time alignment, to try to centre the stage, if you need to move more than 0.3ms from the suggested setting, then something is wrong, try Phase adjustments on individual speakers, or many at once, also try volumes if you feel one is off.



You can adjust stage height with both time alignment and volumes.



After you get this pretty close, you can work further on your X/overs to get it sounding just right, Focus more on power handling and good overlap, make sure your tweeter isn't distorting from running too lower x/over point, and that your midrange is blending cleanly with your tweeter, helping it if neccessary. Check your midbass has a high enough High pass to allow it to play at the volume you want, I felt the Z6 wasn't too happy below 70hz 18db, at 12db it would top out a little too easily, you could run 80 or 90hz 12db, or 70hz 18 or 24db, Ideally you don't want to run 24db cross on your high pass for your midbass, this can cause a drag in the subbass towards the subwoofer.

you can use a 24db low pass on the subwoofer, IF your midbass is strong enough to fill right up to the subbass, again important to consider power handling of your midbass when trying to find that point.


Once your happy with your x/overs, and time alignment, look at speaker placement.



Off axis speakers can often sound really really nice, but sometimes they can sound Dull and lifeless also.



Generally, midrange and tweeters prefer to be on axis for maximum frequency extension, midbass drivers while losing a little detail usually prefer to be off axis to allow some cabin gain for the bass regions (the difference can be dramatic) depending on how the system is designed, on axis can give a more stable image and stage, as well as making time alignment more effective, when trying to achieve a "single position image" meaning, your only looking to get a good image for the driver. Off Axis is often prefered when a good stage is required from both seating positions. (a compromise at best) .



There is no hard and fast rules, it's all trial and error.



once you get all the other stuff sorted,

start on the EQ, to get tonality and balance right, this should bring your system to life once you get it right, but you need to do this last, as all the other things you do before, will change the neccessary EQ'ing..



if you reach for EQ first, you'll only have to do it again and again and again anyway, and you may never get as good a result as doing the rest, with a clean EQ setting beforehand.



Good Car Audio setup takes time, and effort, most people don't have the patience or lose interest.



Juls

[Matt VIP]

juls you are a bloody champ!

(as is everyone else that has contributed to the thread so far, keep them coming!!!)

that gives me a really good beginners guide to properly setting up TA and crossover points, which has been giving me a headache. I have a funny feeling something somewhere might be out of phase, (ive tried using the inphase/outofphase part of the chesky disk, and it seemed ok to me though) as the image is nowhere to be found.
yet.

Also, does the pioneer P80 (or other pioneer) time alignment work on the principle outlined above, or do I just input the speaker distances from my ears in cm's?

Now! to all those in the know...

ambients or midrange? I cant do both (not enough $ or amp channels) but I can do one or the other...

obviously, the ambients will be easier, what might I achieve in my situation by putting in a midrange? and at what cost? (opportunity cost, complexity, installation etc)

Also, ~thematt~, apart from the Chesky disk and my HU, thats all the tools I have at my disposal. What tools should I be getting my hands on first in order to most help me along my path? maybe a mic and a copy of some tuning software? any suggestions?

thanks gang...

Matt

PS I have the effort (and I will have the time soon), its just tricky trying to change stuff around when I dont know what I should be doing...

Edited by VIP318, 10 September 2007 - 11:48 PM.

[Sierra]

Hey Matt,

I would also try to get a copy of Sheffield's My Disc.
As part of the right/left channel verification tests it also includes a centre stage test .... you can use this test to adjust your left to right T/A .... you should be able to hear the womans voice move across the stage as you adjust the T/A.

Did you have a specific desire to go 2 way active rather than start off with passive 2 way?

What made you decide to match up the Z6 mid bass with the Seas tweeter .... is this a known combination that works?
Driver combinations are important as they need to blend well together without large peaks/troughs or holes in the overall freq response.

Going active first up does complicate things with crossover points, slopes, driver characteristics etc.
Where as a decent set of passive splits would be easier to set up and may give you better results than the Boston/Seas combo

[Matt VIP]

it will become, in time, a combination that works...

and yes, I chose the drivers because they had great reviews and were cheap! surely thats a first class ticket to averageness isnt it?

basically I got trigger happy on the 2nd hand forums and bought some stuff that others recommended...

oops..

nevermind, I'll just have to work doubly hard to make it sound good now...

thanks for the tip, pity the sheffield disk is about $70..

[~thematt~]

Matt,

Firstly, dont worry about ambients. It will make things worse before they get better. Secondly, dont worry about a midrange until you can do something with the speakers you have. Adding more doesnt make things easier, by any stretch of the imagination.

By 'Tools', I was referring to Time Alignment, Equalisation and Gain adjustments (or level inputs). The success of these relies on the understanding of how we intepret sound, and adjusting the system using these tools to give us what we need. The entire time, we are trying to 'trick' the brain into thinking things exist where they dont (image/soundstage) and things that do exist, dont (transparent speakers).

Our hearing works differently at different frequencies. Below 250Hz, the wavelength of sound is too long, so that when one of our ears picks it up, and compares the signal to the one recieved from from the other ear, we cannot tell the difference in phase. This basically means, anything below this point is purely non-directional, as in you cannot tell where it is coming from. Take note that although a speaker plays below this point (such as a sub) if rattles or harmonics are loud enough, they can exist in the directional domain and 'pull' the image apart.

From 250 to around 2kHz, the wavelengths are short enough to allow comparison of phase between the signals picked up between each ear. Therefore they are time dependant (interaural time differences or ITD) and delaying one speaker against another will allow the phase of a signal to reach both ears at the same time. This will trick the brain into thinking there is an image in front of you. Any slight variation either side can move an image to the left or right.

Frequencies above 4+kHz move into the Interaural Intensity Difference domain (or IID), where the wavelengths are so short, we cannot tell phase anymore, so we use the attenuation (or volume) of the sound to place image. If both ears pick up a signal of equal intensity, the image is in front of us. This can be used to great affect for single seat image by lowering the intensity of the nearer tweeter, to move the image across the dash (and lowering both to give the perception of depth).

Next to note is time between acoustic waves. If a signal reaches your ears is say, time 0, and that same signal (either from the other speaker, or a reflection) arrives within ~8ms, then your brain thinks its the same signal, and you can use to adjust your image (this is normally within the TA domain). If the signal arrives ~30ms (such as a reflection) or more after the first, your brain thinks this is an entirely new signal, and you will hear two distinct 'sources'. Between ~8 and ~20ms, your brain treats these as actual reflections, and when used properly, can allow a sense of space and depth (think inside a large hall). Between 20ms and 30ms, your brain will start to be confused, and image/space will become smeared. If the reflection reaches your ears before the initial signal, then you'll have a whale of a time playing with your tuning

This is why reflections are important within the car environment. Windscreens, hard surfaces, soft surfaces, dashs, seats etc. all contribute to either sharpening or destroying this image. This is where the real champs shine (like Alan )

EQ in itself is an important tool, because its an indicator as well as a guide. If you need more then around 6dB of boost/cut, then something is inhibiting the signal before it gets to your ears. Interacting waves produce quiet points and loud points, and if you need to boost or cut, one of those points is at your ears. This means there is a problem with speaker placement, so you'll need to adjust (the speaker, not the EQ!!!)

When tuning, mute ALL frequency ranges you're not CURRENTLY testing. That is, when TA, mute tweeters and subs. When gain adjusting, mute midbass and subs. Also, I would recommend using a CD turned upside down on the dash (for the reflection), and when tuning with a sharp centre image (like some tracks on My Disc), look directly at the reflected hole in the middle of the CD. This is where you want your sound to be coming from. Muting and unmuting channels will also allow a single image from both channels to 'lay' ontop of each other, for distinction.

I think Ive rambled enough for now, and allow some of that to be discussed before I throw more up. Some tidbits to think about though...
- Midbass is extremely directional when on axis. Keep in mind most Xovers are not brick wall filters (180dB+ per octave), so when on axis you will begin hearing directional frequencies. Putting midbass on axis to you, will pull the soundstage down to them. Very bad. Fantasticly non-directional at close to 90deg offaxis (ie. in doors).
- Tweeters are the opposite, for similar reasons. Off axis is very directional, but 90deg onaxis is not. Put a tweeter pointing directly at you, and they are almost impossible to pick out (if crossed over high enough).
- There are some frequency bands on the EQ that can allow you to 'cheat' your way into an image. Out of phase somewhere between 1-4kHz on one side only can give great depth and space. Boost a specific range around 6-8 kHz, can give you phenomenal height. (ie. if your tweets are in the kicks). Boost just above 10kHz, can give you great depth.

[Matt VIP]

~thematt~

thanks for a mammoth post! lots to play with here, especially driver location. Interestingly, I have the left midbass on axis to me as much as possible, and the other off axis considerably, and the tweeters are (obviously) the same. I should be able to vary the angle of the left midbass fairly easily, although not to any major extend, just by adding an angled mdf spacer to pod, so I guess thats one thing to try.

I will certainly take the advice about EQ'ing last, and the in phase out of phase test on the chesky disk should provide a fairly good centre image test as well, shouldnt it? conversly, I suppose (short of buying the sheffield disk) I could just use a female vocal solo thats been well recorded?

thanks again, keep em coming... *s*

[abmolech]

Angling a driver will achieve little, unless their diameter is close is close to the frequency required to reproduce. IE an 8" driver starts to have off axis problems around 1700 Hz and above.

Since you have mounted your driver into the corner, the adjacent surfaces act as a baffle, and have much more to do with wave dispersion. (Hint they act as a wave guide). First step, if it was me, would be to enclose the underside of the dash in. This should reduce baffle step response, and dramatically increase mid bass output.



Do you have access to phase adjustment on the mid range?

If not, consider having an 8 -10 inch mid bass in the doors, running from 50 -200 Hz, and the Bostons from 200 and up, with one off the Bostons out of phase (polarity) to the other. This will increase the acoustic crosstalk, and this will centre the stage from both seats.



Three ways are much easier to get right than two ways. (Installation problems aside)

[Matt VIP]

alright. just went and did an hour of tuning, mainly for midbass and tweeter TA. I used the balance "bip" on the chesky disk and time aligned each speaker to locate the centre as best I could. works pretty well too! centre image is now much more focussed than it was before, and very noticable when I switch from "driver's seat" position selector to "front seats" position selector. No doubt there are still holes though - one of the big ones is being able to "separate" each instrument and musician on the sound stage. This was one of my big revelations listening to Seirra's car on Sat night.

secondly, whilst I've been able to make the tweeters "disappear" nicely, the LHS midbass (surprise surprise) is still able to be easily located at certain frequencies. any hints about making this better, apart from changing the angle and/or location?

Lastly - EQ'ing. What is the best way to go about doing this without using an RTA or similar SPL measurement device? I do have both ears working, but they're effectively jaycar spec ears, sure they work, but they're not particularly complex and dont have many fancy features. Cheap though!

thanks again...

[Matt VIP]

abmolech, on Sep 11 2007, 01:10 PM, said:

Angling a driver will achieve little, unless their diameter is close is close to the frequency required to reproduce. IE an 8" driver starts to have off axis problems around 1700 Hz and above.

Since you have mounted your driver into the corner, the adjacent surfaces act as a baffle, and have much more to do with wave dispersion. (Hint they act as a wave guide). First step, if it was me, would be to enclose the underside of the dash in. This should reduce baffle step response, and dramatically increase mid bass output.



Do you have access to phase adjustment on the mid range?

If not, consider having an 8 -10 inch mid bass in the doors, running from 50 -200 Hz, and the Bostons from 200 and up, with one off the Bostons out of phase (polarity) to the other. This will increase the acoustic crosstalk, and this will centre the stage from both seats.



Three ways are much easier to get right than two ways. (Installation problems aside)

abmolech thats got to be one of your easiest to understand least technical posts I've ever read. well done!

whilst I cant put speakers in the doors (new door cards are WAY too expensive, plus too much hassle) I do have speakers under the seats that can probably play nicely to about 100hz, and ok above that.....I'll give that a try. I do have phase adjustment on the HU, but not for individual speakers. just unscrew one of the z6's and change the polarity I spose...

the idea of covering the underside of the dash up is awesome. Will implement that as soon as I get a spare day or so. that will probably help to hide my godawful wiring too. Who can suggest a good way to do this? 6mm MDF with dynamat on the back?

I think I'll save buying a dedicated midrange until next year when I can re-install the G5 sub properly and have a well designed 3-way system at the front. til then Ill just keep plugging away....

cheers

Matt