Connecting Tweeters/Crossovers

[Solarian]

My car came with non-premium sound originally, and the PO had put some random Kenwood speakers in the back that overpowered the fronts. I slowly started collecting pieces, so now I have E30 premium rears and E34 mid-bass fronts, but no tweeters installed yet.
Now, the simple solution would've been to get GAS crossover networks, but as nice as they are, they are also very expensive, and I'm in Canada, so when you factor in international shipping, and our low dollar, it gets really really bad.

So this is what I picked up:
-Parts Express tweeters (the recommended 1" silk dome ones)
-A 5kHz high pass filter

Now, what I'm thinking I need to do, is just wire it like this (parallel) (high pass and tweeter in series) (4ohm resistor and midbass in series), and this should give me a working component system up front with a 4 ohm impedance overall. Y/N/Maybe? I'm pretty good with mechanical stuff but not so much electrical.

I'm also looking into ways of custom-mounting the tweeters, as people are asking for a firstborn for their oem tweeter pods. I'll post up whatever I figure out if I can get it to look clean.

[Solarian]

I managed to get a good deal on OEM pods, still not sure if I'm doing the right thing wiring-wise. Has no one ever done their own components?

[reelizmpro]

It's been a long, long time. Most good head units these days have built in filters as well as amps. Since you bought one it should be simplified for you by the IN and OUT labeled on the board. Just run it inline between the mid and tweeter and you'll be fine.

[Solarian]

Just to make sure I'm not misunderstanding, is this how I should be wiring it? My amp does have filters built in, but I'd only be sending one channel per location, so I can't feed the tweeter and midbass separately.

Is the 4Ω resistor actually necessary? I'm really just trying to achieve a 4Ω overall impedance. Is there a point to me doing that, or? I'm operating under the assumption that the high pass filter is a 4Ω load, so in series with the tweeter that's 8Ω. Then parallel to it I have the 4Ω midbass, so I should throw in a 4Ω resistor before I reach it so that it's all "happy". I'm not getting this from a place of knowledge and experience though, so if I should be doing something else instead, please feel free to correct me.

[reelizmpro]

Are you sure the HPF has a 4 ohm impedance? I'm reading it as it yields a 5khz frequency cutoff @ 4 ohms. The frequency would be different if you were using an 8 ohm tweeter. Anyway, I would avoid using the 4 ohm resistor as it's just wasting power. I understand why you want to use it but it's not necessary.

[Solarian]

Ohh, you're probably right. But then wouldn't I be running it as a 2 ohm load? I'll double check the amp, that might be fine actually.

[StereoInstaller1]

When properly filtered, 2 4 ohm speakers in paralell only show the amp a 4 ohm load.

The reason for that is the filter only allows the "load" to show over the frequencies it plays.

Let me explain very quickly that the difference between "resistance" (which we don't care about) and "impedance" (which we care about a lot!) is that impedance is "frequency dependent", meaning it can vary dramatically across the spectrum, so part of a crossovers job is to control impedance response.

For example, the 4 ohm tweeter will only play over 5Khz, while the mid probably does cover that region, its impedance would be dropping off at that high a frequency, so when in paralell, the "nominal" impedance should be right around 4 ohms...or close enough.

Best of luck!
Luke