Does the Stock Amp + HU Filter at the Source?
 

It looks like all speakers which need a high pass filter (tweeters only?) have an LC in line with them as a 6db high pass crossover.

Does this mean the HU and the door amp are putting out a full range? I only ask because I'm interested in just changing the speakers.

I also understand that the stock speakers are at 2 ohm. What kind of class D amp trickery are they using, if it is a stock 25w or so per ch amp @2ohms, will it mean only 12.5w @ 4ohms?

Anyway, thank you for reading and any input.

The stock headunit puts out full range, the stock amp has some lpf built in, although idk that I have even seen anyone measure it. The stock amp is replaceable with the ktp-445u or other 15A similar amps, but this can introduce other issues of passing full range amplified signal into the doors if you don't use a passive crossover anywhere. @daskaman thread is basically about how doing this can lead to the sound being peaky and bright if you also put speakers with a tweeter in the door.


edit: corrected hpf to lpf


While you can replace the speakers 1 at a time, it is easier to replace them all together with a passive crossover set. but more expensive, to it depends a bit on what your goals are on whether this is a practical route to go.

I'm hoping to replace the doors with 5.25" Soundstream units from days past; I'm 3D printing my own replacement part to fit them. It's unfortunate that there's a LPF on the doors, do you happen to know what kind of voltage the line is to the mini amp? Is it something like 5V or so?

I'd love to replace them all at the same time, just going to be rough to get all the parts together, shouldn't have given them away with my RX-7 that I sold.

it's 12V, with full speaker level lines from the HU as inputs and lines that go to the doors speakers, check out this thread, lots of good info on the stock amps wiring
http://www.ft86club.com/forums/showthread.php?t=42239


this is not the definitive thread on the topic, but it's a good start.

I can confirm.

Did head unit, and all speakers but didn't do enough research. Doors are bright AF and the speaker is doing too many things. Trying to figure out a LPF somehow or might have to approach the doors with new speakers.

The rest of the speaker however, dam it cleaned up the sound nice!

Basic low pass filters are easy. They may not do exactly what you expect without actual data modeling, but many people don't know the difference...

https://www.parts-express.com/cat/as...crossovers/308

I want to ask a question on this subject. Does it matter what Head unit you have with the stock speaker and amp? I replaced my 2013 one with an aftermarket Boss unit and a pre-made harness from Crutchfield. I don't remember vocals coming from the door speakers in stock form. Does this mean the hpf/lps(not sure which is correct hear) is not working?

With the stock speakers and stock amp it is aftermarket stereo ready just by running full signal into the stock harness behind the headunit. The stock amp has the lpf for the doors built into it. The issues only come if you look into replacing the stock amp with an aftermarket one with more power.


If you want passing full signal or even 80hz HPF (from the headunit into front channel), you should be fine. If you are running an aftermarket unit, running the front channels with an 80hz or even a 63Hz HPF will take out a lot of the lowest bass out of the doors which can make them rattle less, but if you do not have a subwoofer, you might not want to do this. depends a lot on your personal preferences.