I am thinking about installing a 3way front stage in my skyline. The midbass will go into custom baffles behind the stock grilles in the doors.
The mids and tweets will go in the kickpanels aimed at the opposite side headrest. I assume it would be better to position the mid and tweeter one above the other rather than side by side because it is more difficult for our ears to detect seperation on a vertical axis. I tried some listening tests with different speakers but found due to the time it took to make changes that it was hard to pick the difference between similiar results.
Is there a rule of thumb as to whether the tweeter would be better on the top or the bottom. What are the most important factors influencing this?
Are tweeters or mids most sensitive to pathlength differences?
Avoiding reflections off hard surfaces under dash, window glass etc.
Avoiding obstructions like pedals and feet.
Acoustic intermodulation?
In the end it always comes down to what will fit and clear the accelerator pedal but I don't want to compromise too much.
Thanks for any help or ideas.

sounds like a good approach you're taking.

i believe higher frequencies are more subject to 'direction' and pathlength difference. this would make the tweets most important to optimise with installation.

however, i guess that presumes our ears are most sensitive to treble than midrange? not sure about this. then consider that there may be more 'info' in the midrange bandwidth than treble.

it would also depend on the design of the drivers. if the midrange is a soft-dome type, it should have better dispersion for off-axis performance. and a larger tweeter dome will help here too (eg: 1" vs 0.75").

i'm not sure whether there'd be any significant difference between having tweet above the mid or vice versa (with all else being equal).

IMO, it makes sense to give the tweeters the clearest, most equal path. but that again presumes the treble is most directional and our ears are most sensitive to this.

i'll be interested too to hear other peoples' thoughts as i'll be tackling a similar upgrade soon!

i think the mids placement is more important if the tweeter is crossed fairly high, not to say the tweeter isn't as important, but i think getting the tweeter to image better is a bit easier.
I have found tweeter in kicks with better pathlengths and in the dash has made less difference than getting the midrange right. Tweeters in dash or a-pillars can work quite well...

most of the voices come from the mid and that will be the most noticable difference in imaging as I have found out recently.

I can now see why so many of the american competitors go to so much effort fitting in 6" drivers (for 2way systems) or their midranges (3way systems) in the kicks

I have my mids above the tweet, i did the testing so long ago, so cannot offer any real help :cry: . I did this mainly because it took up less room around the feet. I don't think that it would really matter as long as path direction and length were similar. I found that aiming just behind the rearview mirror gave me the best results. Good luck

Cheers
The Beaver

I have found that many recognised home audio speaker designers believe that accurate midrange response is more critical than highs when it comes to correct imaging.

This is part of the reason that many high end 2-way loudspeakers have the mid placed right at the top of the cabinet, above the tweeter. (The polar tilt due to misaligned acoustic centres is generally the rest of the influence for this setup.)

On the subject of Pathlengths:
You want to keep the pathlength differences to a minimum.
Especially in the midbass and midrange regions the difference between left and right path lengths is critical. Between about 100Hz and 400Hz the angle of the drivers won't even matter as imaging cues are almost 100% determined by pathlength not by intensity differences.
Above about 2000Hz imaging cues can be controled by speaker angle and other intesity controling techniques and so pathlengths above 2Khz are not critical.
Midbass frequencys can make a difference in the percieved stage depth and centre image stability. but the midrange and high frequencys are responsible for stage height,width and depth as well as image focus.

To answer the question because of the way drivers work. Its better to keep the tweeters under the midrange. The difference compared to home audio is because of the drivers been so low down.
Because of the human hearing we are most sensitive in the midrange frequencys for locating sound (human voice, animals sounds etc) so angling of the midrange drivers is the most important aspect to get right.

Thanks for the input guys.
I'm expecting my new front stage to arrive any day now. I can't wait to pull the kicks out and see how they will fit.
Does aiming the mids and tweets at the opposite side head rest usually offer the best results?
It's going to be quite a challenge getting that much angle on them. I think I'll have to relocate the ECU to the front of the footwell under the carpet and bend the pedals a fair bit.

What model skyline? If r33 then i know how to do as my friend and i doing kickpanl install on his r33 and we had to relocate the comp as well

it's probably the best place to start, but worth experimenting.

different mids/tweets have better off-axis performance, so it just depends. 'dome' mids are designed with off-axis performance in mind, and probably offer better performance with this than normally-coned mids.

if the mids aren't a sealed unit then you will want to have a reasonably well-sealed kickpanel. 'size' of such an enclosure won't be so critical where low-end response is not very important.

what splits again?

The mids are MD140/2s with Esotec tweeters.

Here you go first attempt kick panel aiming and fine tune the angle from there

The way i aim kicks for first attempt and it works well. Ive been doing it this way for 9 years.

1. get a friend of average height and build.
2. push both front seats right back and have the backrests set at your normal slope.
3. get your friend to sit in the drivers seat of the car. shut the door and stand outside your car.
4. Now from the outside drivers side of your car look for the middle of his/her ear (through the glass)
5. measure 1.5 inch down from that point
6. now from that 1.5 inch down measure 5 inch forward.
7. mark this final spot on the outside of the cars window with a bit of tape masking tape works well.
8. now get your friend to sit in the passenger seat.
9. Now from the outside passengers side of your car look for the middle of his/her ear (through the glass)
10. measure 1.5 inch down from that point
11. now from that 1.5 inch down measure 5 inch forward.
12. mark this final spot on the outside of the cars window with a bit of tape.
13. you should now have two tape crosses on your windows.
14. now get a laser pen or long dowl of wood.
15. stick the dowl or laser pen on the kick panel were the speaker is going to be.
16. point the laser pen or dowl at the cross mark point on the window opposite the kick you are working on. ie point the passenger side kick at the cross on the drivers window and drivers kick aimed at the passenger side cross on the window.
17. these are the angles you need for a first attemp good kick build for a novice.
18. more experianced system builders get your IASCA test disc out and listen and fine tune the angle's from here as no two cars the same and speakers all have different offaxis responses that can change the required angle.

woops just noticed the last two posts how did i miss them!

Thats the dynaudio domed mid if i remember right. you will probably be better mouting it off axis in the kicks and using underdash mats to help absort the huge dispersion of that diver.Domed mids take a bit of experimenting to get the correct image from them.

you may want to take a look at a friend of mines install for ideas
http://www.auscaraudio.com/forums/phpBB-2....opic.php?t=1248

yeah, the dyn dome mids have good off-axis performance, so if the angles are not perfect (due to space limitations) they are quite forgiving.

While it may come across like a sales pitch, the next issue of Auto Salon Magazine (on sale Wednesday) has the CAA 'Under $1,000 SQ Challenge story', and in it my Honda project is compared for imaging and staging to two CAA cars. T-Bro was a judge and his own Magna was used as a reference.

The two CAA cars use traditional kickpanel mounted tweeters versus my Honda's 'other' approach. It would be well worth reading this articale before deciding as it is very relevant to what you are trying to achieve.

ive had great imaging from indash tweeters (but not with tweeters reflecting off the glass)

a pillar tweeters can sound ok...but even the best a pillar tweeter positions doesnt give the results i prefer in a soundstage.

kickpanel tweeters can also sound excellent but there are other drawbacks

the kickpanels that i really loved were in the sony xes demo car a few years back. the depth of soundstage was excellent and image placement was the best ive ever heard....but the soundstage was at the dash and below.

a while ago in adelaide there was a pioneer odr system very nice with tweeters on the dash.

mounting in dash is good/bad...mounting in kicks is good/bad...mounting in a-pillars is good/bad...

very general statements.

It often depends on what crossover point is used and what is the crossover slope.

A crossover point too low for a tweeter when firing into the windscreen in the dash may have sibliance problems.

A crossover point too high for a tweeter when used in the kickpanels may not help imaging too much as it is not doing so much to the overall system except creating the sounds i would associate with 'brilliance'.

Mounting tweeters in different places cannot be generalised unless more parameters of the overall system are known.