Simple questions for an Audio Ninja

[TTBlues]

I'm a total noob to car audio, though I know how to wire things (and work in a music studio)

I have a 2003 Toyota Tacoma. Stock speakers. Head unit is Kenwood KDC 355U.

I want to install an Alpine MRV f300 and use it for the door speakers and an 8" sub (eliminating the rear speakers).

I get the basics of how it will be wired, but my question is regarding the front speakers:

1. Am I going to have to run new leads from the amp to the speakers? Where will I connect them? Splice them in behind the stereo (to keep all the stock wiring) or run them straight from the amp to the doors (disconnecting stock wiring in the doors)?

2. The Kenwood has 3 rca outs, two for the car speakers and one for a sub. If i run RCA's from these to the amp, do I also have to disconnect the speaker outputs going out of the HU through the stock harness? How do I do that? Or does the HU understand that I've attached RCAs and stop sending signal out the speaker outputs through the harness.

3. Can I have the amp drive the fronts and sub and let the HU drive the rears if I want to try keeping them live? I understand this may not sound good, just wondering.

Thanks Ninja.

Click to read more...

 

[TTBlues]

After more research it seems that splicing in behind the stereo will work, but is not preferred because of wire gauge and length. Running leads to the doors is optimal.

My door speakers are the stock component speakers. I think for now, I may splice in behind the stereo until I have some new components to install. At that point I'll run new leads as I'll have to wire the new crossovers and tweeters anyhow.

I still don't know about my question #2 . If I just splice at the adapter I know the speakers will only be receiving signal from the amp. But I'd still like to know if the speakers outs from the HU will be hot or not, or if they are turned off by the insertion of RCA's.

 

[What was that? 10+ year member]

Not to sure if most hu "shut off" speakers but I know some some don't. Take a electrical tester to the speaker leads. Probably take less time than researching the answer for your hu. To partly answer a lot of people use the head unit to power their rear fill speakers. Still sounds fine as long as your not trying to be loud with the rear. Even factory speakers sound better amplified. I always just take the speaker leads out of the harness and power the stock speakers.

 

[Dub7sonoma Premium Member]

After more research it seems that splicing in behind the stereo will work, but is not preferred because of wire gauge and length. Running leads to the doors is optimal.
My door speakers are the stock component speakers. I think for now, I may splice in behind the stereo until I have some new components to install. At that point I'll run new leads as I'll have to wire the new crossovers and tweeters anyhow.

I still don't know about my question #2 . If I just splice at the adapter I know the speakers will only be receiving signal from the amp. But I'd still like to know if the speakers outs from the HU will be hot or not, or if they are turned off by the insertion of RCA's.

1) A lot of people say you need to run new, heavier gauge speaker wire to the door speakers when you amp them. If you are planning for a small 50-75watt per channel, then just leave the stock wiring for now. If you are just looking for a decent upgrade over stock then I would recommend the Alpine KTP-445u. It does 45rmsx4 and can be installed in the dash behind most radios and its easy to wire.

2) Once you run the RCAs to the amp and you are running the speaker wire from the amp to the door speakers, you must disconnect the door speakers from the head unit. The head unit doesn't know how you are choosing to use its output so will still be sending signal through its pigtail harness wiring. If you wire the amp into the speaker wires without disconnecting the head unit, it will burn.

3)Yes a lot of people do that to still keep some kind of rear fill. Me personally, I amp both front and rear speakers and then control the outputs with the amps

 

[TTBlues]

Thanks you guys for the replies. I already ordered the MRV-f300, so I cant consider the power pack. But the MRV-f300 is a 4/3/2 amp so I can bridge two channels and run a small sub, when I find one.

One last question. The manual for the MRV says it can take up to 8gauge power wire. The prior owner of my truck left the wiring for his old setup, but it's 4 gauge. Since, it's a bigger wire, would it be okay to use (assuming it can even fit the terminals on the amp)?

The manual also calls for a 40amp inline fuse. But the best 8gauge wiring kit I've found so far has a 50 amp fuse. Will that be okay? Most kits I've seen have 60 or 70 amp fuses.

Amazon.com : New Kicker 09DPK8 8 Gauge D-Series Power/Ground Car Amplifier Wiring Installation Kit - 100% Oxygen Free Copper : Car Electronics

 

[What was that? 10+ year member]

You can reduce the wire at the end to fit into the amp. They sell reducers specifically for this or you can trim a small amount of wire from the end until it fits. The inline fuse protects the wire. The amp has it's own fuses. With power cable bigger is always better, just not always necessary. Use the 4 awg, buy a fuse that fits the wires capabilities. CCA and oxegen free cable have different ratings. Do a little research, learn about what you equipments capabilities are, and don't abuse it.

 

[TTBlues]

You can reduce the wire at the end to fit into the amp. They sell reducers specifically for this or you can trim a small amount of wire from the end until it fits. The inline fuse protects the wire. The amp has it's own fuses. With power cable bigger is always better, just not always necessary. Use the 4 awg, buy a fuse that fits the wires capabilities. CCA and oxegen free cable have different ratings. Do a little research, learn about what you equipments capabilities are, and don't abuse it.

That makes sense, thanks.