Wow, so many responses. Here it goes...
I've viewed your video 3x and still cannot figure out how to do this. my metra loom has RCA's, do I use those? or wire them up separately? I just wired in a 2nd set of DB series Polk tweeters and the PS side sounds like it's blown. I cannot have 2 pairs brand new that are blown. any ideas? the DS sounds fine.
You need to use the hi-level outputs from the head unit if you are bypassing the amp. These are typically not RCAs. The RCAs in the Metra harness are for using the factory amp... which you should avoid because it will sound awful.
Thank you for this! Probably a lame question, but could one connect the non-chassis ground of the factory amp to the chassis of the after market head unit?
No, not without some serious modification. The aftermarket head units use the entire case of the unit as ground, which then touches the center dash framework when it's installed. The mounting holes for the head units thread directly into the case. To isolate the head unit from chassis ground would be an unnecessary pain in the ass involving plastic screws, sheets of plastic between the head unit and car frame, etc...
Simply touching the amps unique ground to the aftermarket ground line does nothing helpful.
Only slightly lame...on the LX anyway...maybe entirely valid for the LC. The LX amp uses chassis ground for the amp and headunit - but the ground for the speaker wire floats. Virtually all aftermarket headunits uses chassis ground throughout - hence the ground loop problem - different grounds that fluctuate with the charging system flow.
Exactly. I was frustrated with the number of threads I came across (not just on mud, but elsewhere) where folks just assumed the ground whine was due to a faulty install. In the LC that whine is inherent in the factory set-up and not many posts seem to acknowledge that.
So, I could run a separate line from the ground feed on the metra loom directly to the ground at the amp under the PS seat? That may help?
That will not help at all. The ground at the amp used for the speaker lines is 100% worthless once the stock head unit comes out.
Cause, right now I have $300 in a new HU, $500 in speakers and a ton of wasted time. The factory system sounds 1000 times better than what I have now. Heck, my audiovox boombox from the 80's sounds better!
I've been there. Trust me, it will sound wonderful running off the aftermarket head unit directly with the factory amp bypassed.
Okay, you have my interest, since my vehicle is a '99 LX w/ Nakamichi. My factory amp and an aftermarket head unit would both utilize chassis ground, yes? When you say speakers use a "floating" ground, does that mean a dedicated ground needs to come from the amp wired to the speakers?
I was wondering the same - perhaps with a noise filter in-line? Thanks for asking.
The Nakamichi system may be slightly different, but the LC amp is fatally flawed in an aftermarket head unit scenerio. The floating ground is completely unusable.
Please forget any filters. They will not solve this problem. A filter that will not degrade sound quality is very, very expensive. The cheap (under $100) car audio filters are not what you need to solve the floating ground problem.
Here is another odd observation, I turned off the loudness setting adjusted the eq and the tweeter issues went away. Although the mid rage and bass were reduced. The hiss still exists, so I'll guess I'll just have to figure out the bypass. Do I scrap the metra harness and wire it independently? For the ground, what gauge would you use? The HU wire is very skinny. Would using a larger gauge be an issue? If I got the 5 channel amp, would the wiring be any easier than the amp bypass? Or, the same?does the new amp still send a trigger to turn on when the HU is operating?
The sound is going to be all kinds of wrong until you bypass the amp. I had horrible, ear piercing screeches and pops and fading and other problems.
The Metra harness is still needed. Don't scrap that! It still provides easy access to the car's non speaker wires (accessory, battery, antenna?, ground, etc...).
Ground is not a huge issue for the head unit. match the wire size (or go larger) than what you see coming out of the back of the stereo and you'll be fine. 18 gauge or larger will be fine. 14-16 gauge is probably ideal.
A 5 channel amp will require extra labor. The bypass is easier. You can do it like mine, or you can just cut wires and use cheap quick disconnects or twist and tape or whatever. You could even use wire nuts. I wouldn't recommend that, but I've been known to be a bit "particular" about that stuff, haha.
The new amp would still need a trigger to turn on. As somebody else said, it's included in all aftermarket amps and is normally blue or blue/white.
So, like these? I have a set that I can turn speaker wire with male end RCAs that might work. That way on the other end I can do +\- via bare wires or female RCAs.
Not sure where you're going with this, but you only need RCAs if you run an aftermarket 4 or 5 channel amp. Bypassing the factory amp requires 8 wires, about 6 feet in length. That will get your hi-level signals from the head unit to the passenger seat area where you can tie into the factory wiring that goes out to the speakers.
I should also note that I added a subwoofer (8"alpine Type R) and amp when I did my bypass. I no longer use the factory sub - it's completely disconnected. Bypassing the amp and adding the sub made the system sound fantastic. The 13 band EQ on my head unit allows a lot of tweaking to the sound and even the factory speakers sound ok.
I need to polish up my video on general audio upgrades in the 100, but suffice to say I'd do it all over again in a heartbeat. The amp bypass takes a bit of careful work and the sub install adds a few steps (interior trim removal), but it pays dividends in the end. Additionally, all of my work is 100% reversible. I could revert it to stock in a single evening, save the single small hole for the power wire in the firewall. Not a single wire was cut in my entire process.
