help me design Xover for my car

[sifis_samos]

Hi everyone, i need some help on my car speakers setup.
I have on each one of my cars front doors a pair of 6" woofers and a tweeter, driven by a 2x 450Wrms @2Ohm Audison amp..
Since now i was using Signat H16 Woofers which although they were really cheap (about 50e pair), they sounded really great, and a pair of tweeters Infinity Kappa perfect T that sound Super.
So i burned 2 of my woofers, and i bought 2 pairs of Hertz HV165L woofers to replace my signats. But the result is quite dissapointing.Although they play much louder and cleaner they arent so musical.They simply dont have the shinny mids and shinny overal sound in compare to my previous ones. So i want to play with the crossover in order to get a better result. Please suggest me what do you think might be better!

My tweeter specs are these:
Infinity Kappa perfect T

Impedance 4 ohms
Power Handling, RMS 100 Watts RMS, 400 Watts Peak
Frequency Response 3.5kHz - 21kHz (+/-3dB)
Sensitivity 89dB
Crossover Frequency(ies) 3500Hz
Tweeter CUT OUT DIAMETER - 1-3/4" (45mm)
Mounting Depth 1-3/16" (31mm)
Fs 1370.65Hz
Vas 0.0000565 cu.ft.
Qts 1.56

and my woofer is this
http://www.hertzaudiovideo.com/Doc/H...rgy_HV165L.pdf

This moment i cross them at 4K using a 2nd order crossover made by Magnat.
One great Need is that i want protection on my tweeter. The crossover i use cuts off the tweeter when i overdo it in order to avoid tweeter burning. How can i implement this in a crossover?. I am thinking of building a 4rth order cross at 3K-3.5K. Do you think that my tweeters will burn if i cross them at lower freq? maybe at 2.5 - 2.8K? Can you help me on my design?.

[sifis_samos]

oh i forgot, i only use crossover only on my tweeters , not the woofers. The current Cross i use as i said before, cuts the tweeter at 4K 2nd order (with protection).
I also use my cars cd, high pass filter to cut too low freq from my woofers, i cut everything below 50Hz.

[Glowbug]

Honestly, with how cheap active Xover-capable head units are these days, bi-amping is much easier

And you'll be able to adapt to any drivers you might get in the future, instead of having to re-build passives again. I wish someone would have given me that advice when I was just starting out.

[sifis_samos]

well i do know that and i understand it but, i dont intent to buy a 4 chanel amp since i got last year a 2x450wrms Audison at 600e and i already made the wiring in my car.

[thunk303]

Hey mate...

Without looking at your old signat response graphs its hard to compare why your hearing different outcomes but it seems like your new drivers get a bit ragged above 3k on-axis and are 3dB down off-axis at 3k also. So 'I' wouldn't cross them above this point.

You could consider a lower tweeter XO but this tweeters has a reasonably high Fs so will need a steeper slope as you go lower. ( I wouldn't go below 3k with it, if that depending on distortion)
A good rule of thumb is to keep your tweeter XO 2 to 3 octaves above the tweeter's Fs.. 3 octaves is generally safer but you can go lower using steeper slope XO's
Perhaps try an 18 dB XO using an 8.8uF cap in series, 0.16 mH coil in parallel and another 26.5 uF cap in series.

You can use car taillight globes as cheap fuses so look around and do a few tests for what wattage you might need so it pops before the tweeter does.

Although You didn't have a woofer Low Pass XO on the last woofer i suspect by looking at the response graph that your new one may need one with those approx 6/10 db peaks causing all sorts of problems. A 12 DB XO also at 3k might do the trick.

As far as parts go..

1. Buy cheap coils that use decent gauge wire (1mm or more)
2. Buy a heap of cheap but decent electrolytic caps ranging from 2uf to 50uF (buy a pack with 5 to 10 of each to save more money) and simply bypass (run parallel) them with 1uf poly caps.

Everybody raves about expensive caps and coils but at this point you will need to try different variations before you get close to what sounds good for you so do NOT buy expensive parts.

Also look at matching your driver (woofer/tweeter) SPL levels by using an L-pad on whichever is more efficient. start with guessing which one might Be playing louder(W/T?) and, using the software, attenuating it by 2 then 3 then 4 dB, see how it sounds.

Download 'Speaker Calculator' from www.mhsoft.nl to get you started, Its very easy to use

Try not to get too caught up in all the possible things you could think about at this point, start trying some different XO options (12dB or more), you'll be surprised what a difference it makes.

I hope some of this helps. Have fun Dean.

PS... You start getting hearing damage at 80 dB

[PeteMcK]

the efficiency of the tweeters doesn't match the new woofers, is there an L pad in the tweeter crossover you can tweak?
try a polyswitch for protection...

[thunk303]

Pete's onto it, a polyswitch for protection is a much better idea

[sifis_samos]

a polyswitch is something like a thermistor i guess?..what part may i look for, for example to cut my tweeters at about 100Wrms?.. i am thinking of building a 4rth order Butterworth filter for my tweeters and a 2nd order Butterworth for my woofers.,,i ll go tonight to buy them and i ll post back my results.