WAY OT: DIY car audio

eric · Since 13 Jan 2006 1866 Posts XTreme Poster

Interested in a DIY audio on a 2004 impreza. I'm a newb, so things like how can a 4 channel amp control 4 speakers and a sub--4+1=5--are confusing to me. Anyone on nwkite wanna answer some ignorant questions about what is needed and install suggestions?

Thanks
Eric

Kataku2k3 · Since 14 Aug 2005 3753 Posts Los Angeles, CA Videographer

Not an expert by any means, especially when it comes to the audio side of 12 volt, but it's all pretty basic. What exactly are you tying to accomplish? Using your stock head unit to drive aftermarket speakers/sub via an amp or amps? Let me know and I'll try to help ya out.

pdxmonkeyboy · Mon Sep 10, 12 3:24 pm

a 4 channel amp can not run 4 speakers and a sub. It can run one set of speakers and a sub or two sets of speakers. At least that was the case when I installed my system, maybe they have new amps now.

I would suggest amping the fronts and a sub.. no real need to amp your rear speakers. One thing you need to be aware of is the ohm rating on your speakers, sub and amp. ideally they should work in concert.

There are infinity references available on the web.

eric · Since 13 Jan 2006 1866 Posts XTreme Poster

I have a basket full of gear at Crutchfield that they recommended. Looking at four 3-way door speakers, 4 ch amp and a powered sub. I assume I run power from battery to amp and sub, so that would be two power lines into car. I guess there is also a line out of the after market hu to the amp then hook the 4 car speakers to each of the 4 amp channels. How then does the sub get it's musical information. Is there usually another line out of the hu that connects directly to the sub? Also, I am supposed to keep power away from speaker wires to avoid interference. Seems the only way to do this is run the power down center of car and speaker wire under door sills. Yeah?

Bettyboarder · Mon Sep 10, 12 3:42 pm

While your doing that buy some dynamat (off brand stuff is alot cheaper) and do the doors at the same time. It will make the music sound better. We did it in both of our old subaru's and it make a huge difference

Weaz · Since 23 May 2012 360 Posts Beaverton Obsessed

Some decks have RCA, optical, or speaker wire outs for the sub. Usually RCA.

Hein · Since 08 Mar 2005 1314 Posts Possessed

Remember to fuse all power wires by the battery. Consider a "big 3" upgrade. Grommets on any holes in the firewall. Solder and shrink wrap all connections. NO crimps or pinch connectors. Mount the amp where it can get good air circulation. 3-ways are overkill, imo. Component speakers would be nice but then there's crossovers and more wiring. Noise is often due to ground loops so a common ground is better.

Kataku2k3 · Since 14 Aug 2005 3753 Posts Los Angeles, CA Videographer

If you ARE going with an aftermarket head unit, an amp driving the speakers isn't super-critical, unless you're going all out... With a "lower" power OEM deck, you'll likely get better performance out of high-end aftermarket speakers WITH an amp. Regardless, it's your choice to spend the money if you feel you'll be able to tell the difference. The amp wiring is all going to be similar whether you're setting it up for the speakers or for a sub.

Also, by powered sub, you mean it has an internal amp, correct? You'll also need to switch on your amps with a switched 12V+. Aftermarket decks usually have a blue line for this, but you can tap any ignition power for 1st click if you're utilizing an OEM head unit.

ldhr · Since 21 Jul 2009 1490 Posts Hood River XTreme Poster

yo einstein,
2 channels go to your front speakers.
the other 2 channels go to your woofer.
the woofer filters the low bass sound.
the woofer also has 2 output channels. they get wired to your rear speakers.
i can draw you a picture if you want.
2 -> 2
2 -> 1 -> 2

eric · Since 13 Jan 2006 1866 Posts XTreme Poster

^^
That would be very convenient. At this point I've been told:
1. 4 out of hu to amp then amp out to speakers, but one hu out gets a splitter pre amp to sub
2. 4 out of hu to amp then amp to 4 speakers and look for a 5th RCA output to sub from hu
3. 2 out of hu to amp 2 to sub then 2 sub out to rear speakers

Internet resources seem to be in two varieties:

A. I can't tell if the install advice pertains to my potential setup

Or

B. the first two years of an EE degree

Laird, if you are correct that would be sweet as I want to put the sub under passenger seat and the speaker hook up would be a breeze

ldhr · Since 21 Jul 2009 1490 Posts Hood River XTreme Poster

Call Crutchfield customer support.
That's how my sub-woofer worked..... but it was 10 years ago.

Weaz · Since 23 May 2012 360 Posts Beaverton Obsessed

The main questions are

Which head unit?
Which Amp?
Which powered sub?

Most subs I've had in no way would fit under a seat. Most, even 10" subs, are too deep physically to fit under them... but if you do wimminz tend to like it...

pdxmonkeyboy · Wed Sep 12, 12 5:52 pm

tpcramer · Since 26 Jul 2010 71 Posts

ld
you crack me up.

rexsfour · Since 19 Aug 2011 14 Posts Tacoma

I say save some money and run your 4 speakers off the new receiver. Most new receivers can push you’re your small speakers to hearing loss level. Then you can better utilize your amp (or buy a cheaper one) with your sub. One of the best things you could do to help your sub is the box. If you don’t have the correct size of box you will limit your sub. I made the mistake of putting my high frq speakers on their own sub. Yeah they can go louder but I pretty much wasted money and time on a second amp.

pdxmonkeyboy · Thu Sep 13, 12 7:54 pm

Just buy a Walkman and take the bus

pdxmonkeyboy · Fri Oct 05, 12 4:12 am

What did you decide to do? I manage to blow one of my component woofers so I have been doing a little market research on a new front component set. 90% or more of your music quality is determined by the front components.

Also OT. Nak, I still have my SPL meter, and home theater equalization software. I know it's been forever but the offer is still open to run some frequency sweeps and tweak out speaker delays and frequencies. Plus I would love to hear that infinite baffle sub array. I managed to crack my basement window listening to the chemical brothers bass test through my 15" folded horn sub. Smile