opened the parts box and started brainstorming

[k0tkmnd]

i have the bespoke system in my FR-S, and am finding it good enough for now. I don't love it, but i'm not hating it. I'm also not happy with the aftermarket radio selection available on the market today, so I figure I'll stick w/ the OEM bespoke unit for the near future. The speakers though, they could use some work. So, i started reading, remembered some stuff in my parts box/closet/room, and began brainstorming.

I currently have:
Infinity reference 6020cs 6.5" component set (2 1/16" depth on woofer / 90wRMS / marked 4ohm)
alpine MRP-T130 amp (90wx2/240wx1max / 50wx2/130wx1 rms)
2 eclipse 10" dvc subs (they are at least 12 yrs old though.....)
cousic amp (?400w? its buried in a box atm, drove both subs once...)

this is what i was thinking...

premium HU has 3 preamp outs so lets use em. run 3 sets of RCA's from the HU to the trunk down transmission tunnel. Might now use all but they are there for later when i'm ready to install subs.

replace the factory amp in the trunk with either the old alpine i have, or with the alpine KTP-445U factory upgrade amp discussed alot here. Connect front channel preamp out to the new amp.

install the components in door/dash. leave the factory 3.5" dash.

front speakers line level out from HU is split. line runs to dash speakers and to amp.

This is where i had an odd thought.

if i'm driving the amp w/ the preouts, i'm not using the signal line from the radio to the amp. I can use it to drive the tweeters from the amp instead. The amp output goes into the components' crossovers (colocated w/ the amp). Low pass / woofer signal goes into original output path to the door speakers. High pass is connected to the original signal feed line. Disconnect the original speaker out from the HU, disconnect the 3.5" dash speaker, install the component tweeter in place of stock tweeter. Now i've got a line straight from the amp to the tweeter, using factory wiring. Then i can run a short line from the HU speaker out to the stock 3.5".

some questions i have...

where does the signal split happen? is it right at the back of the radio, or buried somewhere in the dash?

there are filters for the dash speakers. are they located on the speakers? is there a high & low pass for the 3.5"? assuming that leaving the stock filter in place would be good if connecting the 3.5 back to the HU.

any impedence issues w/ the HU driving only the 3.5?

how difficult would running new wire from HU to 3.5 be? trying to avoid tearing the dash apart to run wires.

would it be better to just run speaker lines from trunk, up trans tunnel, behind HU to tweeters when running the rca's? (might be better, now that i think about it)

I saw a 3.5 coaxial on sale locally for cheap. found a 800-5k bandpass filter, thought if i put that in line the 3.5 and the tweeter wouldnt' step on each other too bad. good idea or just find a plain midrange/leave stock?

the alpine mini amp runs 4 ch 2/4 ohm / 2ch 4ohm bridged. could the 3.5 be wired parallel or series w/ the crossover and be driven off the same amp output? not sure since the xover is 4ohm, if 3.5 is also 4ohm it would get either 2 or 8, not good if amp wants 4 when bridged. could run comps on 2 chan and 3.5 on other 2 chan, but over 45w isntead of 90. might be useful if noticable delay between preout signal and hu amped signal.

sorry for the ramble. i'm probably making this more difficult than it has to be. just thinking reuse of existing wires is a good thing. I know things like time correction, DSP's, etc are needed to make this sound great, but thats for the future. I'm trying for "it sounds good/better" right now.

thanks,
John