ryguypv

I wanted to post something and see if anyone has either done this or would know how to do this. It would be useful to anyone trying to install an aftermarket head unit while powering their system with the factory amp.

I am planning on installing a head unit into my 95 LS 400, and I want to see if I can just use the pre-outs on said unit, and wire them to the appropriate inputs on the factory amp (nakamichi). In theory, this would be great, but you need to figure out which wire sends which signal. I am guessing a multi meter is necessary. I'm pretty much resolved to the idea of panning and fading, then testing the line to see if there's signal.

Anyone have ideas or more in depth technical expertise that could shed some light onto this concept?

5sp_jzz30

iTrader: (2)

you could find a buddy that works for a retail electronics store and have them look up a tech sheet for you with all the wire colors for inputs and outputs. i would do this for you but im away at school. ill be home tomorrow. if i dont forget ill look it up.

ryguypv

That would be extremely helpful, as I am sure others would want this info too!

basketthis

it would be good to hook up to the output wires of the amp (the wires going directly to the speakers) rather than to the line level inputs. This will give you a direct connection to each speaker and theoretically remove the amplifier from the system (which is what you want when replacing the unit).

you may be able to simply buy what's called an amplifier integration harness and plug it in behind where your factory radio already exists.

i will post wire colors later if someone else doesn't beat me to it. GL

skotter

All of the install guys in my area said you need to bypass the amp all together or your burn it out and could damage your head unit. Has anyone else heard this?

ryguypv

The only way I can see this happening is if the amp has a differing input level from the output level of the head unit. If the head unit sends it's signal at +4dbu (which is roughly 1.2v) but the amp accepts only -10dbv, (which is only .3v) you're sending a significant difference in power. My thoughts are that since just about every piece of regular consumer audio gear is -10dbv, you won't have an issue. AND, unless the amp happens to be ungrounded, how can it send voltage back through it's input? If that could happen, you'd be at risk of blowing everything regardless of the connections you make.

In a round about way, I'm trying to say that you'll be fine, and be wary of retailers trying to make you buy gear. Heard and experienced many horror stories of big retailers selling their installation and then doing a crap job (not all the time though, let's be fair)

Either way, I think I'm going for a separate sub configuration. The stock sub was weak in the nakamichi system anyway.

5sp_jzz30

iTrader: (2)

there is no problem integrating an aftermarket deck into a factory amplified system. when you integrate using facotry amp use the low level, RCA outputs. this way your new stereo is not using the internal amp. it is only sending the signal to factory amp.

when you bypass the amp you use the high level, speaker line, outputs and use the amp built into the aftermarket deck.

i have done both methods in just about every car there is and it will not cause issues.

basketthis

+1 very true...

And throughout the years I've noticed some engine noise when using the factory amp with an aftermarket headunit when the volume is turned down all of the way. Gets a little annoying so I usually bypass the amp anyway. Some don't have the problem, so if you don't, you shouldn't worry.

Just using the integration harness will be fine and you won't have to worry about "burning" anything up or hurting anything despite what those installers tell you. I am a Master Installer for 7 years now and can tell you from experience.

pwrdbyrice

would the quality of sound be better without the factory nak amp? because i recently bought a kenwood deck with the metra 70-8112 amp integration wire harness...it really doesnt sound different...

basketthis

you probably won't be able to notice a sound difference with the volume up. turn the volume all the way down to maybe 1 or so and roll up your windows. if you can hear a whining noise coming from the speakers as you accelerate, then you need to bypass the amp. otherwise,

captainsc

iTrader: (1)

When I had my new HU installed they also told me that bypassing the amp had to be done too.

pwrdbyrice

alright ill try that and get back to you...i also noticed that it doesnt really get that loud =\ lol...ive turn my deck all the way up (35) i was hoping it could be louder.

pwrdbyrice

hey so i found out that the metra harness that i bought...i could actually split up the rca wires into + and -...so what i did was take them apart and wired them up correctly to the aftermarket HU...sounds so much better! louder etc.

basketthis

Good job on figuring it out! details please! did you take the rca's coming from the aftermarket hu and wire into the factory wiring? or you cut the rca ends off and wired them directly to the speaker outputs from the aftermarket unit? if you did the latter of the two, i would be careful. it's going to be very easy to blow your speakers and amp... it's louder, but at the expense of pushing everything up to and past it's limits sometimes....

pwrdbyrice

yeah so what i did was cut out the rca's from the metra wiring harness and separated them and connected them to the corresponding speaker wires...even if its easier to blow...it definitely sounds better LOL...but yeah im not gonna be slapping them hella hard so hopefully they'll last