hi guys,





iv always wondered how the winning IASCA cars win with the mids mounted on axis facing straight forward in the dash???



wouldnt this cause massive side bias??



i see it alot with DLS nobelium mids in the dash...



if its so great, why dont we do it here??



any ideas???



charlie




p.s. like so

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to hard. to do it properly u have to have the mids recessed back into the dash as they have. i had mine bluetac'ed up there and i couldnt get them to sound nice. to do it i would've had the cut the dash up like that and i wasn't interested in doing that sort of crap. plus, the only place i could put it was where my fuel gauge is.



u *could* have them mounted in a box on the dash, which worked a lot better, but it also obstructed my view waaaaaaaaaaaaay to much.

so your saying this car wouldnt have massive side biased due to the location and angle of the woofers and escecially the tweeters???

i know u know wat time alignment is for.



with those angles, i doubt he would have any issues with compressing the sound stage. should work well, but for that effort, i would've *considered* horns. im not that much of a fan of horns, but if ur going with all that effort, they could turn out quite well aswell.

is it judged for one side or both???

it couldnt possibly image for both sides, if you time align one side, itll throw the other one out further??

and with the tweeters directly on axis to the isde there on, it looks diastorous...

??

i know the tweets look killer. and they mounted them to the door, i would've thought mounting them on the dash behind that mid would've been better off?



yer, i dont know how it is supposed to image for both sides. is it supposed to?

I remember reading somewhere that those kind of angles and locations can work out quite well, and if tuned right can actually result in very good imaging etc... from both seats.

Here is some some pics of something similar again...

This is what the owner has to say about the positions. quote "This car has one of the widest soundstages with the most accurate horizontal and vertical placements that you are likely to find anywhere. We are not fully happy with the stage depth and there is a fair bit of final tweaking left. But that´s what it´s all about right? "


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Yes the steering column has been moved towards the centre and lengthened to move the seating position back aswell..

and incase you where wondering what type of car it is

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Old skool Capri I like...

link to more pics spread throughout thread http://www.diymobileaudio.com/forum/showthread.php?t=5157
Luke

Oh, and a link to the install handbook they made up for the judges...

http://n-core.se/images//judgeing.pdf

The only advantage in a "angling" a driver is because the off axis response changes.



If you have a small cone diameter in relation to the frequency, then, the off axis response should be the same as on axis (IE the wave radiates as a sphere)The main audible change must therefore come from baffle step response.



Your biggest problem would be path length differences which cannot be corrected for two seat listening.Dash installs work when the dash is extremely deep. Most of these installs would be for one seat judging. I have to say a pet hate of mine is having the tweeters closer than the mid range. There is a reason all high end systems the tweeter is offset back in relation to the mid range.

Lets see some more pics of dash installs like the one above...

Im having ideas...

Wood

my thoughts exactly. see i have been reading up on wave guides and the like







but, yer i thouhgt the tweeter should be behind the mid, and preferably either above or below it vertically as well.

Iasca is judged from the drivers seat, hence one sided staging.

it looks very expensive woody,

and im certain you need cone mids,

dome mids dont have the off axis responce to do this...

HUH? I think you have that confused, I was under the impression that Dome mids perform much better off axis, then any cone mid could ever dream of.

dome mids ala morel dyn dls,

are all like laser beams, very good on axis, but poor off axis,

cone mids like focal, Oz etc, are excellent off axis due to their dispersion....

that is why noone uses dome mids for these sorts of application...

No you have it completely the wrong way around, Domes have good off axis response but won't play overly low, whereas Cone mids are terrible off axis but will play lower.

This is why you always try to get your cone mid on axis in a 2 way setup otherwise you can lose alot of midrange detail.

Besides if domes where good on axis every decent home audio setup would use them which they don't, they use cone midranges because they will be placed (hopefully) on axis to the listeners position. But, on axis is hard to achieve in a car setup which explains the popularity of dome mids due to there good off axis response and are actually best suited to being placed slightly off axis for best results.

The reason OZ and Focal probably both use cone mids is because of there ability to play lower (most likely) and therefore allowing most of your musical information to be coming from one location.

Luke

dome mids are a pain in the butt off-axis. when you get domes right, it's nice, but cone mids are a lot easier due to better off-axis.

What-the I'm really starting to get confused I've nearly always been under the impression that domes are better off axis compared to cones.... but maybe i've always been wrong lol....

You could use an L3 by H.A.T., Wide bandwidth IB 3" midrange that has exceptional off axis response. It's a mount anywhere driver because of it's characteristics.

http://www.hybrid-audio.com/

impressions and facts are two different things my friend...

the hybrid legatia is a sweet driver,

im tempted to get a pair, and do a comparo between them and my cdm88

wats the 88 like? i have a pair of 54's but, i never really liked them

Off axis response is almost solely determined by the ratio of the frequency to the cone/dome diameter. In theory, a cone and a dome will have the same off axis response if they are the same diameter. Yes there other variables that contribute to off axis response, but they are VERY minor compared to diameter ratio.



What is the difference between cones and domes?



The way they deal with modal problems. A cone has them radiating from the centre (apex) to the edge where they are decoupled by the surround. A dome has them radiating from the edge to the centre, In each case the termination is the key to reducing major audible distortion. We could do a combination of dome and cone driver, with the centre of the cone being driven by a driver motor, and like the dome another (or the same) driver motor we drive the edge as well. (The motor is a VC and magnet) So both the centre and edge are driven by the motor.

The best of both worlds?



Unfortunately not. With both the edge and apex being driven on a cone, the modes would radiate to the edge, where they would be terminated with a closed termination.

This would reflect the modes back towards the centre, where they would sum and cancel, causing extreme distortion. This is the reason why your car door outer, is very important to sound deaden. The modes travel from the centre to the outside , where they are reflected back to towards the centre.
Where they sum and become highly audible
The solution is to use a decoupler (sound deadening) and possibly add mass to change the frequencies at which this will occur (Lower and therefore require more energy to generate them)
With a dome the material must act as an internal sound deadener (Vulcanised rubber), this helps, but the modes are too strong. The modes radiate to the centre, where they cause considerable disruption and distortion. Solution? Don't listen to a dome ON axis. With cones, we can use a rigid material, and allow the surround to decouple the modes. Eventually the surround causes its own resonance (Surround step frequency), this is particularly audible. If we were to operate cone without a surround, the modes would travel to the edge, where they sum until the rigidity of the cone is overcome, creating a very unpleasant listening experience.



Point

Domes suck on axis.

Cones don't suck on axis.

Cones have much less distortion the domes.

Domes are ideal where enclosure space is limited, and you can have them off axis.

so the reason domes most domes are not as good off axis is due to the size???

i know the dyn morel and dls are all 3" or so, with most cone mids being at least 4 inch, bar the L3...


very interesting...

how much are the legatia AUD$+ postage bro?..............cors

Domes are not as good as cones.

Because of there limited ability to decouple modes, their usable frequency bandwidth is heavily compromised. The only way to increase the usable bandwidth is to increase the diameter, however this creates it on sets of major problems. Ever wondered why you never see dome sub woofers? Domes will always have more distortion than cones of similar value.

Cost me $330aud landed (July 06.) but I think that included the L1 I'll have to check.
this may be more up to date:

http://www.hybrid-audio.com/Spring%20Fever...le%20-%20UK.pdf

Why are these flaws not as inherent with dome tweeters, or are they just outside of our audible range (being smaller domes)...?

We should all turn our a-pillars into electrostatics!

What about the Stoker and Stroker Pro???

They're both domes.

while we are on the subject, what sealed back 4" mids(cone or dome) are worthy of attention?............cors

WooHoo!! So I was only half wrong, I was sure of one thing Domes should not be used on axis, and are better off in a off axis position.


But I learnt some more interesting stuff which is always good, problem is with all this information it gets hard to retain it all.

Luke

I dont know of any 4" domes. Dyn/Morel/DLS are all 3". Excluding mounting flanges of course.

And I dont think any cones are sealed backs...

there are a few sealed-back cone mids, but mostly the cone mids require about 0.5 to 1.0 litres for optimal performance.

On higher frequencies (tweeters) the internal dampening is often sufficient to deal with modal problems. It is still there, but as you suggest most of it is inaudible.



The strokers are cones, IE driven from the apex rather than the edge.



Anybody that considers modal problems to be insignificant (none in this thread) should wonder why a driver has an FS. This is where the cones/domes resonance is so great the motor cannot overcome it. This is the reason for the domes limited bandwidth, IE the domes resonance is too great to be overcome. Could imagine how difficult a dome sub woofer would be.

abmolech, What about ceramic domes??

how do they overcome modal problems?

My understanding is they are woven material (rather than a solid) and therefore have inbuilt dampening.

Another nice dash mounted setup...

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Is that a Toyota Echo? Obviously an overseas version, but that dash/cluster setup looks familar. I could be wrong though.

Its an awesome idea, cluster in the middle, means theres empty space on the drivers side for that same setup. Remove the passenger airbag, and its perfect.

Nice find!

Any more?

It sure is an Echo, if its the car I think it is, there is a sub enclosure at the base of the dash, right in the centre console. Very cool.

pretty sure it is that car sir teg.

the bubble has heaps of room to do a whizz bang install in the dash. Shame the whole thing is made of plastic = harder to control reflection off of and the fact that on the dash = one seat wonder..

Looks like a nice application of Alcantara to keep reflection down tho Dave, surely that's not standard

Alacantra looks sweet too.
The good old dash mat makes a good improvement over the standard vinyl.
Made a diff in the Soob, made a diff in the Nimbus and the MR2 will get the treatment as well.

MT-23 tweeters and CDM-88 mids will be up top.