Looking at running a pair of 2" tweeters I have in the dash of my Ef Fairmont. They should fit, right? Specs of the tweeters are 6ohm 100 watt rms. Nice sounding pair I got out of a pair of top end Phillips home stereo boxes. The amp running them will be a Phillips DAP something, I am confident it will handle them.... But I want to run them side by side with the 6.5" speakers that are in the doors on factory wires off only 2 channels. The other 2 channels of the Phillips amp will run a pair of 4" Fusions in the rear doors.
I am thinking about putting a 2.3uF capacitor on each of the tweeters right near the + terminal. Will a home speaker box capacitor be alright to run on a car setup?

You pick your capacitor and inductor as a pair normally to can high freq from the speakers and low freq from the tweeters...

If the tweeters were matched to a woofer they would have came with a little box that you feed the one signal into and then had a high out and low out... You want to match that capacitor from the original crossover, or removed from the cross over as I did and remote mount it at the tweeter as the factory ones were...

I pulled both the inductor and capacitor from the cross over and mounted them at the driver/tweeter and hooked them up that way...

Ideally you want to do the same... and run your amp signal out back to the front of the car and tee off through the inductor into the woofer and then continue up to the tweeter and run through the capactior first...

I'd steer away from old components... Capacitors have poor tolerance and old ones are likely to have shifted a fair bit... Inductors are made on better cores and bipolar caps and inductors are available just about anywhere...

Unless, you mean like home theatre stereo? Not sure how that'll go? Home theatre woofers sound woeful in a car... I'd stick to neodymium tweeters designed for the purpose or such? Or buy a pair of matched splits? My JBL's were only a couple hundred bucks new never used but pre owned...

Also I'd never amp just a tweeter... The amp will kill it... tweeters all seem to be very sensitive and because they don't have much cone travel it takes little to burn them out... so I'd definitely run them crossover style with a woofer on the one channel...

Cheers,
Tim

Cool thanks. Yeah capacitors are cheap, and ill go to Jaycar for quality. Going to possibly run a capacitor off the door drivers too. They are Sony 30w el cheapo Ryda 2 way shallow mount 6.5" drivers, 4ohm car speakers. I am going to stick with them, got them for a door filler and was surprised they handled 60w rms and sound really nice. As they will be running off the same core wires as the tweeters ill have to maybe mount the filter on the inside of the doors. I want the Sony's to handle mids but cut real lows, the Phillips amp doesnt have a crossover so I will have to put one in. If I want to cut really low what filter am I after?

Ah ok...

So you want the tweeters doing high, the door woofers doing mids, and you have a sub for lows?

You pick the cross over points as far as Hz and roll off (commonly either 6 or 12db/octave) and I'll see if you can't work out what inductors and capactors you need...

Cheers,
Tim

So uF, the lower the number the high the sound cut off and with Hz the high the number the lower the cut off is? I did see a 200uF capacitor, would something like that be the go? I tried a 4uF on a 6" driver on the shed setup and it cut way too much bass out.

No...

Inductance cuts low frequencies and capacitance cuts high frequencies...

There is a formula, which I'll have to find...

Say you want your door woofers to run from 500Hz to 5000Hz... You use those two numbers, along with the db/octave roll off and jam them into a formula and it'll spit out an inductance and capacitance...

The capacitor chops off everything above 5000Hz and the inductor cuts off everything below 500Hz...

You need to google the models of the of the woofer and tweeter and find the spectograph of the frequencies for each... Every speaker is built to suit and ideal range... One particular brand of subwoofer may go from 10Hz to 300Hz effectively, while another may go from 30Hz to 400Hz effectively...

This in essence is why it is easier to buy a pair of splits that are matched to each other... The crossover point is defined already from where the mid stops and high takes over... Like I said... I'll humour you and work out the capacitors and inductors for you and draw a picture how to wire them up...

But I need the lower frequency cut off for the woofer, upper cut off for the woofer, lower cut off for the tweeter and the db/octave roll off?

The suck it and see approach isn't really an ideal way of doing this...

Cheers,
Tim

And thats why the blokes on AudioKarma arent replying to my questions about the shed setup, I dont have the right info. The Sony speakers, I should be able to read the info sheet if they came with one or find the info on the net. The tweeters in there native box had 2.3's, so Ill stick with that.
Just in case you may be able to answer this one, I want to cut the lows out of a pair of 8" drivers I have in custom boxes, they are each with a 10" driver and not designed for too low. I have zero info as it was a freeby off a customer, the net search brings nothing up. Would a 150uF or a 200uF capacitor be the go in this situation?

What's the impedance of the 8" woofers?

Yes as far as info goes, they info I've asked for the is the bare minimum to do the job... It goes a lot more deeply involved than I understand...

I'll work work out the components for first and second order high pass filters and you can try both and see which you sooner the sound of... The second order may sound better...

Cheers,
Tim

All the info I have on the 8" is 6ohm at supposedly 300w. They dont have a huge amount of movement in the driver, more tight sharp bass. Thats what im after. The stereo is running 100w rms at 8ohm

Ok...

So you didn't specify so I picked 200Hz... So the idea is everything from 200Hz down will not come out the woofer... Should this not sound right then feel free to throw another number at me...

So 1st order cross over will have a 132uF capacitor in series with the woofer...

OR

A 2nd order sub-bessel cross over will have a 66uF capacitor in series with the woofer and a 9.5mH inductor in parallel with the woofer...

And again but for 100Hz cut off is as follows...

A 1st order cross over will have a 265uF capacitor in series with the woofer...

OR

A 2nd order sub-bessel cross over will have a 132uF capacitor in series with the woofer and a 19mH inductor in parallel with the woofer...

If you don't like the frequency cut off then feel free to advise something different...