I was looking at new head units in Best Buy and the sales guy told me that the X has a propriatary amp built in that they have to bypass because it only works with the factory head unit.

Wanted to charge more money for the bypass wiring.

has anyone run it to this, or his he full of crap?

If you have the RF system, yes it has an amp. If you do not, there is no amp.

Plenty of people do not bypass it when installing a aftermarket HU. They just hook the wiring harness up and go. I haven't heard of any problems that have occurred because of this, but have been told that there may be some.

He's correct when referring to the upgraded Rockford Fosgate audio system. The RF system utilizes a passive head unit and an external amplifier that powers the speakers. This amp has proprietary connectors on it and it is underpowered compared to aftermarket amps that can be purchased in the $100 - $200 price range.

I believe that the 300 watt power rating of the RF audio system is rated at 2 ohms and the 300 watt value is it's peak power not RMS. So in reality, this amp is outputing around 150 watts (PEAK) at 4 ohms but more than likely you are only getting about 75% of that power RMS. So the real life numbers of that amp are 112.5 watts (RMS) at 4 ohms which is 28.125 watts (RMS) per channel. NOTE - These numbers are an approximation and may change slightly depending on actual values.

If you were to purchase an NEW aftermarket amp you would expect to pay for the installation of it. This normally includes the connection of the amp to your HU, the wiring to power it, the wiring to whichever speaker(s) it will be powering and the mounting of the amp. All of these charges are standard and will vary from shop to shop based upon the quality of cables/wires used and labor costs. Of course, there may be additional hardware required to make your system work properly which will add to the price of the install. Overall, I would estimate that an average amp would cost you around $150 to install, maybe more, maybe less.

If you are interested in upgrading your audio system I would start with the HU. A quality, aftermarket HU can be purchased for around $300 and provide you with plenty of options when you start adding additional amplifiers and better speakers. Once you start adding external amps into your system you will appreciate the options that a quality HU offers. Options like high voltage pre-outs, electronic crossovers, RCA outputs for front/rear/subwoofer connections, auxiliary inputs, electronic EQ's, MP3 playback and satellite radio compatibility.

Sorry.

I just reread your original post and figured out that I misunderstood it.

The guy at Best Buy is correct. They will need to bypass the external amp in order to hook up your new HU to the factory speakers. You can hook up your new HU to the existing factory speaker wires in one of two ways:

1) Tap into the factory speaker wiring and connect the HU to the taps.

2) Purchase an adapter harness that will plug into the factory harness on one side and the new HU on the other.

If they try to sell you on a complete rewiring job then go elsewhere because it's simply not needed. It may be necessary to run new power and ground wires but new speakers wires is overkill.

Just for giggles, how much does BestBuy charge per hour to do install work? New head unit, amp, two subs, new component door speakers. Hope it's not too much, got my vehicle slated for an install this weekend and not sure if I want them to do it after reading the post about the cost to install an amp.

FWIW, I did not attempt to bypass the existing amp when installing a new HU. I simply plugged my wiring harness adapter into the wiring that plugged into the OEM RF HU. Worked like a charm. Now if that somehow bypassed the RF amp, that's fine, but I simply hooked everything up in the simplest manner imaginable and it worked fine.

Hey I just put in a JVC KD-LH300 HU in my 2002 XE and I'm getting some distortion in my factory speakers when it gets a little loud. I'm thinking I need to bypass the factory amp. Anyone know where it's located? Would I be able to to just disconnect it? Thanks

You should have bypassed your factory amp when installing the new aftermarket headunit. If you hooked up the factory amp inline with the new HU and speakers then your system is not installed correctly.

The factory amp utilizes the same logic as aftermarket amps when installing. There are a set of inputs and a set of outputs on it. The RF HU is connected to the inputs on the amp and the speakers are connected to the outputs of the amp. Essentially, you should tap into the speaker wires that are connected to the factory amp's outputs. Your factory amp should not even be hooked up to anything, it should just be taking up space.

To locate the factory amp remove the plastic molding that surrounds the stereo. Down on the floor is a plain, silver box about the size of the original RF HU. That is the factory amp. If there are any wire harnesses connected to it then disconnect them, locate the speaker wires and tap into those directly from the new HU.

If the distortion problem is happening only at loud volumes you may be hearing a clipped signal. If this is the case then playing music at those volumes will damage the speakers and eventually blow them.

Here's some info on that deck from Sound Domain.

Clicky Click!

No you can't just disconnect it. It has to be rewired. there are a couple of ways to rewire it. One to keep the factory amp, and the other is to bypass it. I would have to hear it, but I suggest just turning the loudness off and adjusting the bass to a lower level. I have heard that radio (and many others) distort on systems that don't have a factory amp. The other thing to do is, make sure all of the connections are good and taped up properly. If you have any speaker wires making contact with themselves or anything else, at higher volumes, you will get distortion.
Just remember, when you change out the headunit and keep the factory speakers, you are giving them more power than they are probably rated for, so you have to keep the bass down, and don't turn it up all the way... It's bad for your ears anyway Good Luck

I disconnected mine by removing the wiring harnesses that snapped into it. It took all of 5 minutes to locate the connectors and remove them.

and did you have sound after you disconnected it? In an earlier post, you described rewiring around the amp. This cannot be done by just unplugging it. at least not in my experience.

The post was asking about bypassing the factory amp due to the installation of a new aftermarket HU. Since he has a new aftermarket HU then he doesn't need the power from the factory amp. Make sense?

The factory RF amp is designed to specifically work with the RF headunit. Any other application of that amp is really more trouble then it's worth.

Yes it can. If I remember correctly, there are three wiring harnesses hooked up to the amp. One is an input and comes from the factory RF head unit, the second is an output which attaches to the speakers and the third is power/ground.

In order to hook up a new after market HU you would disconnect the speaker harness from the factory amp and tap into those wires from the new after market HU. You would also want to disconnect the other two harnesses because you are not using the amp so there is no reason to have it hooked up.

The person asked if you could disconnect the amp in order to defeat the factory amp and get rid of the distortion(or at least that was my understanding). You cannot just unplug the amp and still have sound. you must as You say:
This is far from just disconnecting the plug. It might have taken you 5 mins to disconnect the plug, but I highly doubt it took you 5 mins to locate the correct wires and properly connect them.
I have bypassed my own rf amp and understand exactly what you mean.

Are you even reading my posts?

Nowhere did I ever say it took me 5 minutes to find and tap into the speaker wires. Where did you get that? Just for clarification, I said it took me 5 minutes to locate where the wire harensses hooked into the factory amp and to disconnect them. Add on another 30 minutes or so to read the wiring diagram, locate correct speaker wires and tap into them.

As for the amp issue it really is common sense. Using the factory HU? Then use the factory amp. Not using the factory head unit? Then don't use factory amp. Quite simple.

ok lets go back and look at what was previously written...
first... then I said: Basically saying the same thing you said in the post above this. And THEN you said:
This would lead me to believe that you just disconnected your amp and the problem of distortion was solved.
so I asked: and then you said again making it sound like it would fix the problem: So I am READING your posts, but I guess I'm not understanding what you are trying to say...

The Fact is, if he wants to get better sound quality, he has to either turn down the bass, not turn it up so high or rewire around the amp. Whether he unplugs it or not doesn't really matter. The amp won't be coming on if the remote amp turn on wire (that connects to the factory radio harness) isn't connected, unless he used a harness adapter, it probably isn't. AND if he used a harness, that means the company that made the harness meant for you to use the factory amp... I can disconnect my headlights too, but that won't make my radio sound any better.

First of all, DO NOT let WorstBuy install your stuff.

Secondly, most good aftermarket HU's come with pre-amp outputs. So regardless of whether the factory HU is internally amped or not, the factory amp should still work with it ($50 for hard-wiring).

There might be an adapter available to connect to your amp. you can ask on the forums here:

http://www.rockfordfosgate.com/forum/

Unless you want to lose sound (If you have the Sub, you WILL with no amp), you will havta spend about $1000 bucks to bypass your amp and replace amp and HU.

I don't have the time, but I bet there is an adapter available somewhere.

cdoliver,

I don't want to be rude but you are obviously not reading my posts or at least not reading them in their entirety. Please go back and reread everything I posted. If you are just reposting the same things I already wrote then why do that since I already covered the subject.

Anyway, I think this thread is getting to the point of overkill. The answers to all questions have been posted and the resulting posts are only arguing symantecs.

Good day.

This is just an opinion. It all depends on the experience level of the installer doing the job. I've had experience with Best Buy in years past and I never had a problem with the install.

If you peruse automotive audio forums you will find horror stories about well known and trusted installers. It all depends on who is doing the install and how experienced the tech is.

Even though this is technically accurate why would one want to spend money and time trying to find a work around for a cheap, under powered, 2 ohm rated amplifier. For $130 one could get a decent 2 channel, 200 watt amp that's rated at 4 ohms.

You do understand that the sub in the Xterra is not operating the same as an aftermarket sub would be? In an after market setting one would purchase an additional amp that would be dedicated to pushing the subwoofer. In the Xterra RF stereo setting the 8" sub is hooked up inline with a tweeter, much like the front 6.5" components. The sub is only drawing 1/4 the power that the stock amp is outputting which is the same as each speaker in the system. Other than a slightly lower frequency response the power and volume levels are the same as every other speaker.

Not true. If one picked up a quality HU for around $300 (say 50watts x 4) and tapped into the factory wiring (w/o swapping any speakers) they would get cleaner sound in the existing factory speaker setup. If one were to add an after market amp with an aftermarket sub then the bass output would also increase.

I'm sure there is but, again, why would one want to spend the time and money trying to make that under powered amp function with an after market setup?

Some tidbits of info on the stock RF amp:
The stock amp is rated at 300 watts PEAK power at 2 ohms. To make an honest comparison with after market amps we would have to find the values based off of 4 ohms not 2 ohms. So, in reality, this amp would output approx. 150 watts at 4 ohms. Now, RMS power is normally 75% the peak power, so we're really looking at 112.5 watts RMS at 4 ohms. Break that down into 4 channels and we're looking at 28.125 watts RMS at 4 ohms.

Now compare the factory amp to the JL Audio 300/4 amp I just purchased. The JL amp is also rated at 300 watts with the difference being it is rated at 300 watts RMS at 4 ohms. Break that down into 4 channels and we're looking at 75 watts RMS at 4 ohms. Quite a difference wouldn't you say?

Some tidbits of info on ohm ratings:
The higher the ohm rating the cleaner and purer the power being outputted from the amp. So, 100 watts at 8 ohms is significantly better then 100 watts at 4 ohms and tremendously better then 100 watts at 2 ohms.

When one reduces the ohms by half they can effectively double the power output of the amp at the expense of sound quality and power efficiency. This method of reducing ohms to double power is frequently used when hooking up sub woofers because the bass frequencies are much more forgiving to the less pure signal the amp will now output. If sound quality is of the utmost concern then reducing ohms to gain wattage is not recommended.

I'm not 100% sure, but aren't the speakers in a RF unit all paralleled 8 ohm speakers? Meaning each front component(the door speaker and tweeter)are each 8 ohms thus creating a 4 ohm load on the amp. same thing with the sub and it's tweeter, and the 6X9 and it's co-axial tweeter. And an amp doesn't give off 2 ohms it recieves a load, which can be stable to 2 ohms, 3 ohms, 4ohms, or whatever.

It was my understanding that this wasn't the case, although it is feasible. From my understanding the final output was rated at 2 ohms.

When amps are rated as being 2 ohms stable this means that they can withstand the stress put on it by bridging channels and/or hooking up speakers to it in parallel. Each time you reduce ohms to generate more power you exponentially increase the load on the amp. When this happens you increase the chances of blowing fuses or burning out your amp and a worse case scenario would be frying your car's electrical system.

When an amp is rated at being 2 ohms stable the manufacturer is saying: "Hey, we tested this baby at 2 ohms and it performed flawlessly without any adverse side effects to the amp or the vehicles electrical system." I've seen amps that were rated as being 2 ohm stable being run at 1 ohm which resulted in a blown amp.