If one hooks an amplifier up to the head unit using the RCA preamp out is signal still sent via the head unit amp and speaker wires?

The Mustang came with dash and rear seat speakers. I want to add speakers to the doors.

Can I hook the dash speakers (3.5" speakers so 22 RMS is plenty)to the head unit powered speaker wires

AND

Run a 4 channel amp to the front and rear preamps on the head unit then run the door speakers and rear seat speakers to the amp.

Or should I just get a set of component speakers for the door and put the tweeters in the dash and run them off the amp with the rears?

The answer is yes. On nearly all aftermarket radios, the outputs will function even if you are using the preamps. On some higher end models, with a dedicated set of rca outputs for each pair of speakers it used to be one or the other, but that was selectable in the programming and your user manual should tell you this. What type of radio is it? Model number?

I haven’t seen a head unit where both outputs didn’t work, by default, ever. In higher end units (my current Alpine and older Eclipse and Denons) you can often select to disable the onboard amp and only use the preamps, but that’s a function that the user turns on (in theory to improve sound quality by reducing heat generation).

You’ll be able to use both, for sure.

If the unit has an internal crossover for the speaker outputs you should activate it and highpass drivers at least at 80hz, probably more like 120hz. They won’t be able to handle the lower frequencies without sounding terrible

Older Alpine Digital Media Player with no internal crossover.
Was planning to utilize bass blockers on the 3.5s
Then use the cross over on the amp for door and rear speakers.

Never wired a radio that way before, but assuming you use both pre-amp and line level outs, will the balance and fader work with both outputs at the same time?

Is this on the LX? How are you coming along?

quote:

Originally posted by bigdeal:
Never wired a radio that way before, but assuming you use both pre-amp and line level outs, will the balance and fader work with both outputs at the same time?

I have no idea

quote:

Originally posted by Tommydogg:
Is this on the LX? How are you coming along?

It is. Sadly CREEPING, would be an accurate description.

So far I pulled the tank and rear end. Cleaned up the underside and applied Eastwoods rust protection.

Upgraded the rear end to an 8.8 with 3.73s, Koni oranges, UPR Springs, control arms, added a sway bar.

Thanks to Black Friday I picked up a new tank and sending unit for $60 already had a high flow pump to drop in.

Have an aluminum driveshaft to put in, new adjustable crossmember to put in.
Upgrading to V8 brakes, UPR CC plates, big front sway bar.

Once that is back together I will drive it a bit with the stock NA motor since it has been sitting awhile just to make sure everything is good.

I need to reassemble the interior which is why I am asking about the HU wiring so I can preemptively run wires since the interior is completely removed no desire to pull anything back out after I put it back in.

Once I drive it a bit and make sure I am running without issues.

I have turbo motor freshly rebuilt to drop in. Just need to get new clutch, flywheel, ECU, intercooler piping.
Then I'll drop the motor in.

Still debating if I want to do paint and body before or after the motor swap.

So I am guessing spring of 2019 before I am fully finished.
Hope to be up and driving come spring.