after a quick tune of my system I found my ID10V3 sounds boomy with a LP set over 60hz @ 24db slope (20L sealed box) and the focal 165kp's sound punchier when high-passed at around 100hz @ 12db slope. both points are guestimates from the amps pots.

is it ok to have such a wide spacing between crossover points?

You should really underlap them for best results. Maybe try dropping the focals down to around 60-70hz and go from there. Just play with a few different things and see what sounds best for you, but you really shouldn't leave massive gaps like that!!

Boomy? The box is too small.

yeah that was my first guess....if ur box isnt built to spec (using the subs theille/small parameters) then i would think it is the box that is holding the sub back from playing higher, and causing it to sound boomy.
also, have u tried moving the sub so that it fires from a different position in the boot/in a different direction? this can also affect how the sub sounds.

for reference, my splits are HP at 50Hz, and the sub is LP at 43Hz - works fine

oh, both 24dB butterworth

Just because you have a gap on the electrical side doesn't mean that acoustical result in the car will have a gap.

The sub is most likley peaking around 60-80hz in the car, when you set the x-over at 60hz the x-over slope in combination with the rising response of the sub creates a plateau that continues untill the sub stops peaking and the rolloff resumes, so even though the x-over is set at 60hz, the sub acoustically doesn't start to roll off untill 80hz (eg). A similar suitation can also happen with the mids.

Volenti is right on the money. There must be clarity around the fact that electrical slopes and acoustic slopes are different beasts by nature and one must take into account the mechanical and electrical characteristics of the driver/s in question. Understanding that a paper cone driver will roll off differently than a poly or kevlar cone will bring the analogy into play. Also the windings, gap, magnet field strengths etc. (regardless that two drivers may share the same Re & L factors) will also adversely affect this issue. Thus why passives are built to exacting driver tolerances (good ones anyway). And this is the reason that active CO's must be tuned to perfection before they sound like they should...

Cheers

lol you'll also need to take into account the accoustics of the car. You will lose bass if it is a sedan with no ski port that vents into the cabin. So theoretically flat response may not be flat in the car. I have a huge overlap with the crossover points but they dont peak.

thanks for the sugestions.

the cars a Holden Ute and I'm experiencing some strange acoustical effects compared to my last cars which were a hatchback and sedan. both the hatch back and sedan made lots of bass and had a good cabin gain (they had a 12" and a 15" respectively). the Ute on the other hand has little sub bass and the focals over power it on a much lower gain setting. I'm somewhat limited on the subs location (behind drivers seat). I have played with phase and it has a huge effect. opening the passenger door creates a big sub bass increase as well.

as for the sub box being the wrong size; it is on the larger side of recommended (.7cf compared to .4 to .8 recommended) winisd also thinks the box is about right for a flat response and lowest roll off point (neglecting the cabin effects).

I'll play with the gains and crossover points again this weekend and see what happens.

where do u have the sub mounted, as I dare say u realise thats pretty bad cancellation occuring there, is there any other way for the sub to be mounted that can possibly help with this.

Have you blocked off the holes in the doors? I had a similar experience with my K2Ps and bought the K3P add-on woofer kit to boost the mid bass and fill the gap between midrange and sub. But I blocked off the holes in the doors and has made quite a difference. I haven't installed the woofers yet due to not enough time but even so I'm pretty happy the way it sounds

Utes are very difficult beasts, especially like yours where you are limited for space.

I'm not sure what size sub your using, but it's likely you will run into poor results if your using 12" or larger.

I found in my Falcon ute cab, which is bigger and has more room behind the seats, that 10" subs didn't need such a large area for the bass to propigate, and the result was the 10" subs would play both deeper and higher Tones much larger and more developed.

Firing into the seats, unfortunatly is probably the worst possible setup you could have, as this leaves little or no room for the Bass to propigate (grow) And can cause all kinds of cancellation effects. Most car audio shops will tell you differently, simply because it's too hard for them to do anything else, and they don't want to spend the time or the money (or convince you to spend the money) to do it any other way.

subwoofers, and bass in general has to have a certain amount of room in front of it, and distance from the listening ears for it to sound right.

Like you say you are having funny accoustical effects, I'm not surprised.

A Few things i can suggest,
try a smaller sub, possibly a number of smaller subs.
look for positions for the subs, that are further away from your listening ear, and also have the longest possible distance in front of them clear. Any good installer will tell you, match the size of your subs to the size of the cabin space. 12-15" in single cabs (not space cabs) rarely sound any good at all.

Use some Good Acoustical Damping inside the sub box, this will make a dramatic difference in the sound of the subwoofer, and make it much more linear and clearer with less distortion, I'm not talking Dacron either, thats only mildly effective, a combination of Regular open cell foam about 1cm and 3mm Closed Cell Foam works wonders, a off the shelf similar product is Focal Plain chant, but a little on the pricy side, a trip to Clark rubber and a can of contact adhesive makes pretty awesome highly effective damping. At least 10 times more effective than Dacron.

the next is to make sure your cabin is well deadend where possible, Especially the Roof and Rear wall.
also make sure your doors are massively deadend, Sealed if possible and use accoustical damping behind the midrange, to further enhance the clarity of the midrange and again further smooth out your frequency response. Products like Focal plain chant, Dynamat Dynaxorbs or a visit to clark rubber and make your own is your options. The accoustical damping would be fairly ineffective if you havn't deadned the doors first however.

I would play around a little bit with Crossovers from 60-80hz area in a ute,
I know that lower crossovers seem like they are sounding better for the sub, in terms of less distortion and deeper output, This is somewat because of the way it is installed. However you may find you will lack in the 60-100hz area if you crossout at 60hz or lower.

it's possible your location and setup is a bit wrong, so your at a massive disadvantage to try and tune your problems out to start with.

Juls

A picture paints a thousand words

10 times more effective than Dacron? Have you got the test results on hand? Effective in what manner?

LOL I should read properly.. you already have a 10" sub

see if you can mount it firing across or up, or anywhere other than into the seat.

Also, time delays can play a big part, when all the speakers are close,
if you deck has time alignment, Please use it, it will help make the bass sound more "together"
rather than BANG BOOM or BOOM BANG.. (boom being sub, bang being midbass)

Juls

If your sub box is solidly built, internal damping is going to make 3/5ths of sweet stuff all difference to its sq.

I was waiting.. I was waiting..
(personal joke between me and liquidity, I'm staying out of the arguments this time)

What's so funny? :S

Where's the test results that say it will make it 10 times more effective?

I guess this is why sub phase is having a large impact on the sound.

I'll try lowering the mid crossover and rasing the subs and see what happens.

Yeh I'd give that a shot,
do you have time alignment? that would help make the bass sound equal,
you said it's behind the seat? is it just 1 sub?

is it behind your drivers seat or the passengers?

if it's behind your seat, try placing it behind the passengers seat.

or, this might sound stupid, but toss the box on the floor on the passengers side, firing at the back corner of the roof. you'll see what I'm talking about.

Juls

I've no doubt it could be more effective then dacron, at some higher frequency well outside the range we are interested in...

Let's apply some acoustic theory;

Now, while anything you put in the enclosure will provide some degree of damping, if we look at the test case of Juls 13mm thick layer on the walls, it will be most effective on frequencies whos wavelength is 1/4 it's thickness or shorter (velocity absorber), it's effect will drop dramatically the longer the wavelength becomes (the peak velocity region of longer waves lie outside the material, hence it has little effect).

13mm is a quarter wavelength of ~550hz, and a full wavelength of 2200hz where it will have the most effect, since the entire wavelength will have to pass through the damping layer (twice).

Dacron is also a velocity absorber, but since it is filling almost the entire enclosure volume it has damping effects at all frequencys, especially so at resonance since that's when the wave velocity is highest.

You can measure the effects of stuffing with an AC volt meter, test tones and a large value resistor (~1kohm).

Hook up the resistor inline with the driver and measure the voltage across the terminals of the driver while you play the test tones through it, the tone that gives the largest voltage reading is the resonant frequency (you can also do this with the driver suspended in open air, to find it's natural resonant frequency)

Now, typically the difference between a completly bare enclosure and an "idealy" stuffed one is the stuffed one will have a slightly lower resonant frequency (by a couple of hertz) and will have ~half the impedance (at resonance) of the bare enclosure.

Stuffing does 3 things;

1. slight apparent enclosure volume increase caused by the adiabatic effect of the stuffing material (as evidenced by the resonant frequency drop)

2. signifigant damping action as seen by the halfing of the drivers impedance at resonance (this can lower the output of the system by up to 3db around the resonant frequency, also diminishes the ability of standing waves to form)

3. direct absorption of higher frequency sound (usefull for reducing motor and other aberrant distortion causing noise in the enclosure).

Ummm well first find me a sub that plays at 2200hz.... Ahhh yes they are called tweeters.... Pitty they are in sealed enclosures them selfs tho... Too much theory not enough practise. As liquidity said, a proper built SQ box will sound as good as a SQ box with dacron.

if u read his post u will realise that when ppl use dacron they apply it so its more than 13mm thick, therefore it works at lower frequency's

Wavelengths

At 100hz its 3 metres long

At 50hz its 6 metres long

At 25hz its 12 metres long



So according to this for the thickness of the dacron needs to be 1/4 of the length of the sound wave.

So
at 100hz the thickness of the dacron will need to be 75cm
at 50hz the thickness of the dacron will need to be 150cm
at 25hz the thickness of the dacron will need to be 300cm

That is a lot of dacron! A normal box may have about 20cm worth of dacron and it'll be crammed in there. Dont think you'll fit that much dacron in a normal box

Perhaps I wasn't clear enough, damping material in an enclosure effects the resonant behavour of the driver/box system, this effect is independent of the wavelengths involved, I explained how to measure it, go see it for your self.

I'll put it another way, the volume of air in an enclosure is often refered to as an "air spring", you tap a driver in a box and it resonates at a given frequency determined by the drivers parameters and the enclosure volume.

Now look at the suspension on a car, we have springs supporting a given weight, push down on the car and the springs will resonate at a given frequency, however in a car we have dampers that resist the movement of the springs, reducing the spring resonance to negligable levels.

When you put damping material in an enclosure you put a damper on that air spring, reducing it's resonance.

If you think that can't make any difference in an enclosure you're kidding your self. It's all objectively measurable effects, no audiophile jiggery-pokery needed.

look at the velocity damping of the material as PDmax increases - the box effectively become slightly 'elastic' as the pressure changes, so the woofer sees a Cms which varies with deltaP driver velocity... interesting to see if this affects linearity in a good or bad way.

Too much theory, not enough practise as PhatDevil said! I'm still waiting for Juls reply?

Measurable by a machine and measurable by a person is 2 different things.

Ask yourself this, can you spot a difference between 2 pieces of strings, where 1 is 20 mm long and the other is 21mm long with your eyes from a metre away?

Secondly has the car that the sub box is in taken into account? Loss due to sound needing the travel through the seats? Sounds rebounding everywhere inside the boot, reflecting off the windscreen. Everything you said in theory is most probably correct but does it mean anything inside a car?

Congratulations, you've just discovered aperiodic membrane theory!
However, it only applys when theres a vent on the other side of the damping material. The air inside a sealed box compresses/decompresses. There isnt that much actual air-flow movement around the box.

i stand by my theory. Dacron etc may have an effect, but its the same as using thicker speakerwire..that is...not sufficient to be audible. Like capacitors, its a band-aid that isnt neccesary with proper installation (read, thick, braced, solid box).

I can if they are different colours!!