After reading up as much as I can in the SQ section and following a few install/rides threads for a while, I am finally inspired enough to do a complete custom SQ install and compete in the 2008 CAASQ season.

I have been playing around with a few idea's to build custom pods and was going to model some drivers of choice in AutoCAD, in 3D, and design some Pods around them to suit.

Where I get stuck is I want to have the ability to change the axis of each driver, on the fly, after the pod has been fabricated and sealed to my doors Ie, I want to be able to hear exactly what the finished result is without being committed to a particular fixed axis with my pods.

From what I can gather from around here, when making custom pods, most people play around with the axis of the driver in a mock up setup, until they are happy with it, and go ahead and fibreglass their pods to finish them off.

I believe that without a full sealed pod, the driver is going to sound different than when it is in a completed, sealed, braced & deadened setup. This seems to be a time consuming and innaccurate way to test driver axis. Am I off track here?

My idea was to design a pod with a driver/drivers mount that can have an "analog stick" range of movement to play with the axis, which can then be locked once set, and remains fully sealed and strong regardless of which angle it is set at.

I am hoping to gain some feedback from CAA members, as to the pro's and con's of such an idea, before I start designing in CAD.

Once I have all of my parameters and have designed some preliminaries I will post up my renderings for review.

Ultimately, I am hoping to end up with a setup that can be easily changed while tuning, to obtain the best frequency response for MY vehicle, with almost any type of front stage.

I would like to design this to suit 2 and 3 way front ends, and almost any size driver, up to around 8 in.

Any suggestions, positive or negative, would be appreciated as many of you here have played around with the axis and placement of your drivers and have some practical experience. Better SQ is the only goal here, so please respond accordingly.

PS. Not sure if this belongs in Fabrication/ Installation or SQ Discussion, so I'm posting it here to get some SQ feedback first, if I start the project I will put an official thread in fabrication/ installation on my progress.

Please move if putting it in SQ first is an incorrect assumption- Cheers!

Scott Bulwulda was the first person to introduce such a concept in IASCA World Finals back in 97 I think....

He used hydraulics coupled with servos to rotate each speaker individually on three seperate axis, at 0.5degrees at a time.

Ill see if I can dig up some more information regarding the actual enclosures. I think its a great idea, and something that everyone talks about (rotation, positioning etc.) but no-one actually does...

mm, i been thinking about teh same thing....i dont really wanna make a full fibreglass pod, only to find out i coulda done better.....

Me three. Current (incomplete) pods are about 30° off axis and was wondering whether it was worth making new pods with the new speakers arriving soon.

Leigh

Well a lot of the problems arising from off axis response tend to be higher in frequency, 800-1000hz+, (a 5 1/2'' driver starts to beam at 2.5khz, ect), this means you don't need a "perfect" enclosure to see them (hell a simple baffle is often enough) if you don't have access to an RTA you can use pink noise and move your head around in the car/move the baffle, this often makes problems easier to hear and identify.

The one thing you may have to look out for is the tendency for most kick panel locations to get a "free" boost around the 200hz area, and ironically a very well made and sealed pod makes this worse.

Excellent!
This was exactly the kind of feedback I needed.

I have a design in mind, but I don't plan on making it motorised or to run it off servo's, that just introduces more components that can fail, or over-complicates a fairly simple idea.

I'm planning on using the K.I.S.S. principle here.. Keep it Simple Stupid!
I would even like to get it to a stage that standardised pods could be made and produced fairly cheaply, and integrated into almost any custom pod setup.

Almost like the MDF ring that most people use, setup on dowel rods and glassed.
But my ring incorporates the axial rotation needed to fine tune angles in an SQ setup.

If it's only the ring that needs the attention, the pod/a-pillar/dash/etc.. configurations could still be fabbed as per usual, allowing for endless combinations/variable driver sizes/configurations and so on.

It FEELS like a great idea, and the actual mechanics of it (in my mind) are fairly simple, so all I really need are things like technical limitations, excluded angles, and some serious downtime on the drawing board.

Oh.. and some more experience listening to cars with serious SQ setups.
That should help with achieving the sort of sound needed to actually compete sucessfully.
Will definately check out the next NSW CAASQ round.. as an observer.






I kinda thought that with woofers it may not be all that much gain, but any gain is a gain, and being able to get fast tuning results is the real goal here.
I plan on using the same design to run mids and tweets, in various locations, including dash and A-pillar.
So I suppose the base theory is still viable.

I'm aware that some tweet mounts are already designed to have a movable axis, but its only tweets that are usually are set up this way, not mids and woofers?

If there is any gain at all from the abilty to run infinite axis settings, on 3 different drivers (ie 3 way front stage), all of which are able to be set independantly, with only a few minutes to set them up, I'm all for it!!

At the very least it's a unique idea worth investigating.

To do it for midbass in a sealed inclosure would be difficult and not super beneficial because of the frequency range its playing. However doing it for mid and tweet can be beneficial.

I had my dyn MD130 in a movable pod which was able to tilt it up and down and in and out so essentially giving it full adjustability. This was done using a baffel for the speaker that is hung form a 90 degree bracket with one bolt/screw so the speaker can move in and out, and then the 90 degree braket mounted to the kick panel of the car (metal bit not plastic trim) with one bolt so it can tilt up and down. It was basic but worked quite well.

If you got some time and want to do it properly, id make 3 concentric (is that the right word) rings (laser cut from aluminium) have the biggest ring mounted to the kick/pod then a pin top and bottom holding the second ring, so it can move in and out then a pin on either side of the 2nd ring holding the inside ring and speaker so it can tilt up and down. Having them laser cut out of steel/alum would ensure thay are perfectly round and the right size and could be polished up nicely

Hope that makes sence?? Be interested to see how u go about it.

It is easy enough to do.

Make a concentric ring slightly larger than the driver flange (6 mm normally depends on the flange thickness)
Then bevel the outer edge into a "part" sphere shape.

Now make another concentric ring with an internal bevel matching the first ring. Ideally it will be too tight to snap together.Slowly increase the clearance on the outer ring until you can just snap them together.


Tips
Make the outer ring as thin as practical, it needs to expand to snap the inner into place.
Make sure the inner ring is big enough diameter to "swing" with the driver flange attached.


I normally make them out of MDF, and when I am happy I clue them together. This method is hardly infinite, however your main limiter is the driver magnet hitting your internal walls of you enclosure, so you still need to build the enclosure close to the correct angle. Neodymium -magnets make much better use of this.

There is only so much you can gain by angling drivers (amplitude/phase adjustment)
An equaliser is a phase amplitude adjuster. (OK some correct phase so they are all linear), I believe you might get the hint here.


Point to ponder.

The more you angle a driver towards the centre:
the stronger the phantom centre image.
More acoustic crosstalk helps at lower frequencies and hinders and higher frequencies.
the narrower the stage

Sound has no locational cues, only the learnt response from the brain determines this. Your brain is not easily fooled.

Spend your time studying wave guides and nearfield listening, for a greater benefit over "tuning" with driver angles.

Everything is a compromise, knowing where to save fabric is a tailors skill.

Rings made by Abmolech for my legatia 3" mids.

Those rings are very close to what I had in mind, only they allow a much reduced field of axis rotation. They would have to be car type/positionally close to optimal angle before starting to fine tune.

they look very good though I'm trying to achieve a more universal setup, with much larger range of axial motion.

Nice points to consider Abmolech, will start doing some research into near field listening and wave guides.

When describing placing the driver axis closer to the centre, you are referring to the centre of what? Is it just the image? the stage? the car? driver head placement? the dash?, just not sure what you are referring to.

Exactly

The limiter is not the rings but the magnet interference in the enclosure. All fibreglass structures shrink as they solidify. These are mainly to counteract your hard work being undone by this phenomenon.

Centre of the car was my reference.

I prefer the use of wave guides, horns and arrays to control the dispersion pattern. Considerably superior to angling a driver. Sure there is some gain to finding the best compromise for the angle of the driver, using it for dispersion is not one of them. A driver cone/dome is principally an array on vibration points, the reason for beaming (narrowing of the dispersion pattern) is the distance between the outer vibration point and the inner, that is the cone diameter. These interact as they spread into listening space, the distance apart of the vibration points determine if they will start to comb (constructive and destructive summing). Because a 8" cone diameter has these points further apart than a 4'' driver, they will cause combing at a lower frequency (longer wave length) than the 4'' driver, larger drivers "beam" at lower frequencies.

The cone angle/profile effects the phase difference of these vibration points (time) and can therefore change the combing frequency, however this is comparatively minor influence compared to the relative distance they start at.

Point

Smaller diameter drivers are more forgiving off axis, 3 way fronts may benefit from a compromise in axis.

Two way fronts, your asking for trouble.

Pretty sure the exterior mirrors off WB statemans (and a few others) are cable operated with a joystick type arrangement at the other end (3 cables per mirror) - might be a remote way to control the speaker axis. I see them at most car swapmeets I go to...

at lot of cars have that...its called power mirrors... But good idea, if you could pull the motor mechnanism out and attach to an adjustable axis pod would be sweet as. but thats provided the motor structure can support/move the weight of a speaker and pod. tweeter i imagine wouldnt be a problem, maybe a small midrange but a midbass driver might prove difficult.

anyway, this is how i'd make axis adjustable pods, with quite a decent range of adjustability, (sorry for crude pic..im no artist )
basically its a ball and cup, with the speaker inside the ball, which can swivel in the cup (note pic shows a half ball setup, if you use a full size ball it will give greater adjustability, but i imagine that range of adjustability will not be needed.

Can you please explain the term "beaming" and also elaborate a little on exactly why a 2 way front end is so much more trouble than a 3 way. Other than the fact that the disparity between driver diameters is so extreme?



I was thinking of keeping it simple, but this idea is a great one! Imagine the level of control!
Calling all custom PCB designers!!!

When the wavelength of a sound is shorter than the diameter of the driver that sound will "beam" like a torch, if your ears aren't in the beam then the higher frequencies will be reduced in volume.

I'll explain why I prefer a 3 way front;

A full range speaker in a car door will suffer from frequency response issues typically around ~500hz (dip) and ~1khz (peak), this is due to standing waves forming in the door cavity, this is very difficult to fix with sound damping materials (even with a perfectly damped door the shape it's self is the problem).

A full range speaker in the the kick panel area suffers from the 200hz boost, this is from the driver essentially sitting in the throat of a big waveguide, this boost can be 15-20db or more.

If we put a mid bass driver in the door, bandwidth say 50hz to ~180-200hz, we avoid the acoustic problem the door has, and the door cavity is large enough to house a mid bass driver nicely.

Ok so we have 50-200hz taken care of, now we put a mid and tweet in the kick, the mid runs from 200hz* up to 3khz-5kz (whatever works well with the chosen tweeter) The mid, now running above the 200hz problem area has no issues response wise, also since the mid is crossed off fairly high it opens up your driver options allowing you to use low x-max, high quality drivers.

With carefull driver choice and x-over setup you can almost get away with no eq at all, you "eq" with the x-over.

* because of the peak at 200hz the actual x-over point of the mid may need to be a lot higher then 200hz, leaving an electrical "gap" that's filled in by the acoustics of the car.

Vary well described there Volenti.

I was actually just about to write a simplified version of the same thing, but you just did the hard work for me

These reasons are exactly why I personally much prefer a three way setup over two way. The negative is that you have more drivers to mount, and more crossover points to set hence leaving more ways to make a mistake - but if done right I estimate that the three way system will outperform the similar spec two way system indefinately.

You don't want the speaker to be obscured by the ring - that will have a detrimental effect on midrange reflections/etc. causing all sorts of nasty things.

I did a calculation which is approximately correct:




I have my Dyn MW162's about 60degrees off-axis, crossed to mids at 500Hz or so. That works just fine

You can use power mirror motors and their switches to do what you want...some IASCA competitiors in the US used to use this method for getting the best out of their kick panel mounted mids and tweeters...

The ones in WB's aren't power mirrors - no power going to them! The WB ones I mentioned aren't electric mirrors and different to the ones in things like VC commo's because the cables to the joystick are about a meter long. I imagine they would support a reasonable size midrange. I'm going to a few swapmeets soon so I might pick up a set if they are cheap enough and have a play

sorry, my bad:P..but the power ones would be easier/better?

quote name='Pulse-R' date='Jan 29 2007, 09:15 PM' post='774916']
You don't want the speaker to be obscured by the ring - that will have a detrimental effect on midrange reflections/etc. causing all sorts of nasty things.
[/quote]

This is where im running into problems...

Because a centre axis has to be established, no matter how it is rotated you will get a small portion of the drivers cone firing directly into the side of the ring mount.

Here is a basic concept picture of the actual ring and mount.

So far I havent added mounting holes, locking details or basic dimensions.

The axis when set at 0 degree's will be firing directly at my head with mids and woofers, and have the tweets at a reflective angle or firing directly at my head again.

This gives me a full 20 degrees range of axial twist, in any direction. The cone *shouldn't* fire directly into the side of the ring mount if I thicken the edge of the driver mounting ring a little and do a few tests with a mock up of this.

Thought I'd post this up for review first before doing a mock up and modify to suit the idea's, opinions put forward.

Click to view attachment

Edit: If you save this as a JPG and open it image editing software or windows picture viewer, you will get a much higher resolution pic with clearer details.

I looked at doing exactly that - and abandoned it for the same reason (at that time) howver, I think it can be made to work... in a sneaky way.

if you have some sort of 'cam' arrangement, so that as you rotate an 'intermediate' ring, the inner ring angles and projects outward, then allowing you to rotate the whole assembly by the outer ring.

like a 1/4 sphere on one side of the driver, and hinged on the opposite side, so as it comes out of the assembly, the sphere section is still sealing the driver into the intemediate ring.

Click to view attachment

Exactly!

I have kinda the same sort of idea, but need to consider machining costs as well as design.

And above all trying to keep it as simple as possible.

Will post the revised drawings, including all mounting and locking set-ups I have in mind soon. Should look bling in polished alloy with countersunk allen bolt fittings.

revised drawing added to my post.

scrub the cam arrangement - this is simpler.


and you get up to 70 or so degrees of angle

I had a similar design going first, problem is it doesn't seal 100% in that configuration, for it to seal properly it has to rotate from the dead centre of both the driver mount and the baffle, Every time I model something with an off centre axis, it unseals itself at one point of another as it spins on it's axis.

Very frustrating!!

Would anymore than 20 degrees, off axis from a perfect centre image be adequate?

If so I was even thinking a 3rd ring for even more.. but I dont know..

anyway, heres the simplest(mechanical) way I can think of assembling and locking this set-up.
Would be a pain to adjust, as there are so many bolts, but if I machine it very close in tolerance I can make it seal very well just by locking the top and bottom mounting rings together, with the baffle inbetween them.
If this is too difficult it can be locked from inside the baffle with grub screws.

here it is

Click to view attachment

nah, you need to get at least 60 degrees out of it - to test off-axis up to 3kHz (for 2-way systems).

If the rear curved part of mine was machined/shaped as the arc described by the edge of the driver as it moves out from the baffle, then it would always maintain a seal.



This probably illustrates it better

Click to view attachment

Tilting up and down keeps it perfectly sealed, but what happens if it is tilted down or up and rotated left or right at the same time? \

That layout looks like would require a double axis, one for vertical movement and another for horizontal, might have a good think about that one.

the red part (mounting ring) rotates in it's own clamps, so adjusting fully.

not sure about clamping the tilt assembly though

Here was my attempt at an off centre axis, ran into trouble with the baffle sphere rotating on a different centre then the mounting sphere, it gives a better range of angle adjustment (about 45 degrees) but unseals as soon as it swings two ways, up or down + left or right.



Edit-Try this link

feel free to use the idea - I'm not selfish (go the GPL)

you're pdf is broken


front view, showing baffle rotation and clamps

Click to view attachment

The reson yours leaks is because you have not taken a 'higher cut' of the rear shell spheric to allow for the 'seal tabs' projection.

otherwise, it should work

I'll have a play with that idea Pulse-R, hmmm... really want that 60 degrees now!

the only other thing I can see is the 'choking' of the rear of the driver by overly surrounding it at the back - one reason why the off-centre works better, as you have a torus-section rather than a spheric.


so the driver rear diameter is maintained through the pivoted part. It would still need to be a little larger than the cutout to allow the driver to 'breathe'

Yeah, using a torus will maintain surface contact with the spheroid while rotatating on it's axis in 3D, it also shortens the rear surrounding area and will "unchoke" the rear of the driver. Just have to keep the axis' inline in X,Y & Z co-ordinates and it should work fine..

Off to the drawing board...

Still sketching out the mid and woofer design, heres a tweeter set-up, it's only the first one , so its pretty basic.

Click to view attachment

designing multi angle setups for mids and tweets are alot easier, the midbass one has to be really solid.
I designed one for the midbass that has a speaker offset of 13cm and has multi points of rotation that can see the drivers facing the the rear view mirror and then rotates them to fire at the chest area.Its not a unlimited type that your trying to build , but they only took me about 5hrs to make and i used kitchen products. Im gonna post them in the angled spacer tute some time soon cause they are more of a spacer than a pod............cors

for a large tweeter, that could be huge!

Yeah, but I'm using 10 mm offsets and it's more of a concept design than an actual fab plan.

Finished product would be reduced in thickness and all uneccessary angle adjustments factored out. The mounting ring will eventually be modelled to fit either my a-pillar or the stock location on a VT dash so it will come down in size quite a bit before its machined.

Im thinking of using 16 mm HDF blocks, glued into cubes before machining for some mock-ups to test the theory.

Will see what it's going to cost in aluminum aswell.

Zion- If I machine the design I have in mind for the woofers, you could run em over in a mac truck and they'd still be usable, heavily scratched! but strong enough to cop it.

Pulse-R,
Do tweets need anything more than a baffle? Is there a benefit in sealing them up? I don't think there is, but wasn't sure..

tweets are good as they are.
the 'baffle' as such acts as a dispersion plate, but not really necessary.

Mids (say 3" or 4") would need a small enclosure, depends on the model. i.e. Morel CDM54 need 250ml, focal mids need 5 litre or so. Dyn mids (MD140, etc.) are sealed back, so no enclosure.

i like your commitment ............cors

i did end up finnishing my spacers , but they are not worthy of a tute, if u wann looky they are post #122 http://www.caraudioaustralia.com/forums/in...showtopic=68028 ...........cors

Are u still working on a midrange axis model?......cors

I'm extremely interested in how these turn out. Keep us updated of the progress

I have decided to test this theory on my current system, rather than design for a proposed system that is yet to exist.
This will save me some serious work if my idea's dont work as I hope they should.

I am currently modelling up a mock up of the interior of my car (only rough, as a guide for head placement and distance) and models of all my drivers and gear.

Shouldnt be much longer and you will have some actual 3D piccies to look at.

cool

My Arvus tweeters have a gimble style built in to the housing. It won't give 60 degrees but does give some movement and it very compact...

waiting for some ideas on midrange pods?Anyone?
tweets seem to to good with bluetac, midbass has to be fairly solid , but midrange is one that could utilise some genius ............cors

for my mids, I just made a set of brackets with screws and slides to adjust angle, etc.
In the end I still had to make proper brackets, and just mod them to try different things.