I have been intensely researching topics in car audio the last 2 days and have finally decided on what equipment I want to go with for my install (at last). I want to run a 2 channel amp w/ components. At first I was going to run the components off of the external amp and the rears off of the HU internal amp, but according to http://www.bcae1.com/asystems.htm, this would not be an ideal set up, and instead recommends running all 4 speakers off of the 2-channel amp.

Now, I think I may be suffering from information overload so this may be a blatantly obvious, but I can't seem to picture how this setup would be feasible:



How would this setup sound compared to running the rears off of the HU? I want to leave the rears stock, would this be harmful to the amp? Finally, would I notice that much of a difference if I wired it this way versus going fronts on external amp, rears on HU amp?

Has anyone wired their systems this way? I would intuitively think that each speaker gets its own channel instead of sharing it with another speaker. I guess this makes me rethink my install and whether or not I go with a 2 Channel vs. a 4 channel amp.

 

if you want to run 1 pair of components off a 2 channel amp that is fine

most comps are 4 ohm


i use a 2 channel amp to run , 1 pair 6.5" comps with 1 " tweets, and 1 pair of 5.25" comps with 1 " tweets , my crossovers have not only an output for the midrange , and the tweeter , but also an output for an image tweeter , so i use 4 each 3/4" image tweeters in my a -pillars

so i am using 1 , 2 channel amp to run 4 midranges and 8 tweeters , with no issues

 

If you read exactly what bcae1.com said about running a pair of speakers off the headunit, it says:
"...the front speakers are being driven from the HU's internal amplifier and a pair of rear speakers are being powered by an external amplifier. This type of system has very little chance of sounding good..."

You would want the fronts off the external amp and the rears off the headunit. The rears don't need as much power to provide adequate rear fill.

 

haha sorry, I forgot to say that the speakers were reversed, as I obviously would be running the fronts off an amp and the rears off the HU I'm more concerned about the quality: would it be a noticeable difference if I wired it either way? (ie. both sets off the ext. amp, or fronts off amp, rears off HU)
I guess its safe to assume that since we are only using the rears as fill, it shouldn't make too much difference then?

All of this audio stuff is mind numbing at times! I need a break haha

 

The difference would be negligible. I am not a fan of running components at a 2ohm load, when most amps see a 2ohm load it increases distortion and this is noticeable in your mids and highs (it is not noticeable in your subs which is why it's fine to run subs at less than 4 ohms). I would run your components off an amp and the rear fill off the headunit. you are going to be fading the rears down anyway.

 

Thanks for all of your help! I guess my last question is: amplifier... class AB or class D, much of a noticable difference to warrant the price?

 

The headunit should have a remote on to connect to the amp and turn it on. Your going to need to attach that power antenna lead to the power antenna on the wiring harness to power on the booster our z's use.

Street's right on the money for connections, run the front components off the amp and the rears of the power of the headunit. If you use the above diagram you will have no way to control front and rear independently.

Class D amplifiers offer more power and cooling and are used for subs typically. A or AB class amps usually offer less Total Harmonic Distortion and as such are more suited to running component or coax speakers where THD makes more of a difference.

 

Class AB or a full-range class D (Eclipse XA or Alpine PDX amps) is always recommended for mids and highs. You could also use a class T or K, but these are rare in the car audio industry. Traditional class D introduces unwanted harmonics into the sound, but are super efficient and thereby are fine for subwoofer usage.

 

I am using the harness provided by Crutchfield to make my connections. In my last install (back in 04) everything worked fine. With the Alpine HUs, doesn't the antenna just plug into the unit and the provided harness takes care of the power?

Damn, thats a good point about the independent control. Told ya: information overload has handicapped my common sense (along with being at work at 7AM )

I definitely have made my decision on what to buy now: I will go with the Alpine MRP F550 4 Channel Amp in case I decide in the future to run another set of speakers or sub off of it. I was going to get the PDX 2 Channel, but I don't think the overall quality difference will be that noticeable for the price difference, and running 4 channels in the future wouldn't be an option.

Thanks a lot for the help fellas, definitely made my day!

 

Yes, you will be fine.

 

You might want to look into a 4x3x2 amp like the MRV-F345. A unit like that will allow you a lot of flexability in setting up your system in case you decide that it isnt worth two channels of amplifier to run those rear speakers.

I opted to disconnect the rear speakers altogether in my setup as they were so close to you, I felt they interfered with my front stage.. even turned down.

 

Dude, nice recommendation, as this is something that would make a lot of sense. Plus it would cut down on me using another amp to run a subwoofer in the future. I also like the Amp Link feature that lets you control it from the HU.

So many choices!

 

Well, I have made the decision on the amp, thanks Ichigo Now I just need to decide what sub to get, but that won't happen for a while because I am not sure where I am going to mount it. I really want to put it in the stock location, but because that sucks, I am not for certain. Either way, I am going to wire my car this weekend for the amp and sub even though I don't have them yet.

My big ? for this is: I ordered a 1000W amp install kit, which comes in 8 awg. I know this will be fine for running the Alpine MRV-345 and the Infinity Comps on CH. 1 & 2, but will it support the amp when I eventually bridge Ch. 3 & 4 to power the sub as well?

Edit: I don't want to run 2 pairs of RCA's... I have some Y-adapters, can I just use these for the fronts and sub inputs?

 

The max recommended fuse size for 8awg wire is 50 amps. The Alpine MRV-F345 has an onboard 60 amp fuse (30x2) even though I doubt it will pull 60 amps even at full volume with gains turned all the way up. As long as you keep the in-line fuse near the battery at 50 amps you should be just fine.

 

You could, but you will lose any subwoofer control through the headunit, and you will be effectively cutting your line voltage in half.

 

Cool. 2 sets it is Thanks again for your help. I vote for you as Audio Forum Moderator.

 

Thanks for the props, but I'm not sure I want that responsibility....it gets hostile in here once in a while

 

+1

 

I believe if one were to split RCA cables with Y-adapters then the voltage would remain constant but the current draw would increase, right? It's just parallel wiring.

Edit: It turns out there is a slight voltage decrease due to the increased current draw being affected by the head unit's output impedance. Slight as in a split 4V preout will provide, for example, 3.56V to both amps as opposed to 3.76V if the signal was not split. Here's the link with the math:

http://stason.org/TULARC/entertainme...head-unit.html

 

Interesting stuff! Thanks for the link. I just learned something. This just proves you can never be too old to learn something new