Adding Tweeter - Xover Question

[Mobile 10+ year member]

I am adding a tweeter to by boss stereo to give it some top-end sound. The factory "tweeter" has a 22ufd cap on it giving it a highpass xover of 1800hz. I am looking for a xover of around 3800hz for the Aura Tweeter I'm installing. I calculated a cap of 10ufd to do the job

Question: I will be tapping into the tweeter before the stock 22ufd cap, but will that affect my calculations at all for the cap size? What about impedance change because of the extra tweeter - something to consider? The factory tweeter runs at 4ohm.

Basically I am looking for someone to check my work here. Will a 10ufd cap wired to the new tweeter (before the stock 22ufd cap) give me a xover of about 3800hz?

The tweeters are good to 3000hz so there is a good amount of wiggle room, even considering the 6db xover slope.

Cheers!

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[bustaplz 10+ year member]

You'll be wiring the tweeters into parallel, this will drop the overall resistance to 2ohm if the new tweeter is also 4ohm. Your calculation for the cap sounds fine, as long as you are tapping into the speaker wire before the 22uf cap you shouldn't have to adjust your calculations. But look into what ohm-load the amp will see and make sure that won't cause any issues.

 

[Mobile 10+ year member]

You'll be wiring the tweeters into parallel, this will drop the overall resistance to 2ohm if the new tweeter is also 4ohm. Your calculation for the cap sounds fine, as long as you are tapping into the speaker wire before the 22uf cap you shouldn't have to adjust your calculations. But look into what ohm-load the amp will see and make sure that won't cause any issues.

Ok so If the speakers impedance drops to 2ohm - then doesn't that mean that I have to calculate the cap for a 2ohm load? Which would make my 4ohm load calculation wrong?

 

[qkassidyw 10+ year member]

It drops the overall resistance the deck/amp sees but the cap still acts as a crossover on the 4 ohm speaker. If you calculated it correctly then running it in parallel will be fine. But there are programs out there to design crossover networks so you can still maintain the same impedance even with two tweeters.

You will be going into a higher order crossover (inductor, cap, resistor, wired in varying combinations of series and parallel), think external crossovers in component setups.