I want to power 4 speakers with an amp and my 2 subs with an amp. How can I do this with 1 set of preouts?

 

its simple. you cant!

since your running 2 amps, you need at minimum 2 sets of preouts.

 

splitters?

 

no.. becuz you need a different signal to you subs than you do for your fronts

 

I'm not saying it can be done or anything, I'm just curious for myself- If you took all the signal from one cable, ran it through splitters, and then used the various crossovers in the amps, could it be done then?

 

there is absolutely no way to run 2 seperate amps useing 3 sets of RCA's off of one set of preouts from a head unit. it can not be done. period.

 

That's not true. You can start with the same signal (assuming those preouts send everything - 20hz to 20khz – which they most likely do since there’s only one set), split it, and then put a low pass filter on one of the splits for the sub amp and a high pass filter on the other set for the other amp. That or you can just run the 20-20 signal to both amps and use their built in filters (sub amps almost always have a variable low pass filter and your typical 2 or 4 channel amp usually has a variable high pass filter).

If you think voltage is going to be a problem because of the split (it wont be since you're running in parellel), you can always install a line driver. The difference in load shouldn’t matter since all we really care about is voltage.

The only problem I can possibly see is that the preouts are already cut off at some frequency (ie they’re only 20-125hz for a sub amp). Consult your user manual or run cables off the head to one of your friend’s amps and see what happens.

 

At first I had the RCA's getting split at the amp for my front speakers and back speakers. I had my 2 JL's running off the WIRES from the back speakers. Basically the HU was powering the subs and it sounded good. Two bad I couldnt split it again and run it to another amp. Dont mind me if I sound stupid. I had NO clue on car audio

 

i did the same thing to my pioneer IMPP12" in the tube b4 i got my system.. ran it offa my rear speaker lines.. i thought it sounded good too, untill i heard the new system i put in..

you could try splitting the signal but the sound quality will be for crap.

id take this opportunity to upgrade head units to one that has front rear and sub pre outs.... they can be had for a good price online

 

yeah definitly go with upgrading your head unit. as bob said, head units with 3 sets of preouts can be found online for $200 (thats the lowest ive seen one but then again i dont look around because i already have one) but that would be your best bet and that way you would get more out of your system. better sq and sp (sound quality and sound pressure aka db rating)

 

If you were to take the 3 preouts from my Alpine CDA-9833 ($500) and combine them into one set, all you would lose is the ability to control everything from the head unit, but you could still control it all at the amps (subwoofer level, front rear fade, etc). My speakers would sound the exact same due to crossovers on the amps. Having a 20hz-20 kHz signal coming from a single set of rca pre-outs is not the end of the world because your sub amp could cut off everything above xxx Hz and your 2/4 channel could cut off everything below xxx Hz.

The only argument that can be made against your head unit is that better units typically have more preouts while lower end units only have one set.

Having more preouts will not make you louder. Having more preouts will not make you sound better. The only thing that might ever go wrong is that you could split the signal too many times and pull too much load from the HU and eventually fry something. Keep in mind; by splitting the signal all the amps would receive the same voltage since you would be running them in parallel.

Also, keep in mind that he is talking about running all his amps off the preouts and then running the speakers from the amps, not wiring the subs to the wires the rear spires should get. That would be completely different.

Why? Again, the only reason I can see is that lower end units are typically the only units that have a single set of preouts.

 

This is what I have. What should I wire in and not wire up. In the past the fronts sounded 10x's crisper with the amp.

Front 4x6's Boston Acoustics. 80W max
Rear. 6x9 Kenwoods 3 ways's
Subs JL 10w-3's 2 of them
Amp Alpine 4C MRP-F240

 

It sounded like you were going to be running two amps from your original post.

You really shouldn't run your subs from any of the speaker wires off your head unit. Even though it might sound ok to you, it will sound nowhere close to what it could sound like. Also, by wiring your subs straight off your unit, they will be playing the full frequency range since there will be no filter on their signal. They will also not get fed nearly enough power (your average head unit is putting out between 20 and 26 watts RMS and your subs want 300).

You also should not wire your subs to a 4/3/2 channel amp for the same reasons - they will try to play all the frequencies due to lack of filtration and they will not be getting very much power.

Running your four main speakers off your amp (front l/rear l bridged and front right/rear right bridged) will give you considerably better sound quality than what your head unit can deliver. It will even produce a bassier sound.

A short term alternative is to run the front speakers off two of the amp’s outputs and then run the subs off the other two. Again, this won't sound that amazing due to lack of power and because the subs will be playing everything and not just the bass.

Long term, you should at least buy another amp for your subs.

 

use a pair of hi/lo coverters attatched to the speaker wires behind the deck, most 4ch. amps will have a passthrough to go out to the sub, or you could use the rear out on the back of the deck, some decks allow you to change the rear output to a sub out.

but the better thing to do would be get a new deck, however the above info is another option.

 

get a new head unit...Head units with 1 preout are always garbage.

You could get an EQ which would only cost about 30.00+shipping but a good head unit is well worth it.

 

Forgive me if I repeat something somebody said, because I couldn't keep track of what correct information was given among all of the bullsh*t.

I'm just going to spew random (but related) information in hopes that it sheds some light on whatever may not have been addressed yet.

If your head unit has 1 set of pre-outs, you've got all you need. You can use an RCA Y-adapter to split the signal, and it's not going to degrade your sound quality. Almost every amp on the planet has built in filtering abilities, so you can feed a full range signal to both sets of inputs on the amp, then use the filter on the amp to high-pass the speakers and low-pass the subs.

One feature that a lot of newer amps are coming with is the ability to accept 1 set of RCAs and send it to all 4 channels if necessary. It simplifies installation in cases like this where only 1 set of RCAs is being used.

Another feature that a lot of amps have is an RCA pass-thru. This is where the amp has a set of RCA outputs. This pre-out can be re-routed to the input of the 2nd pair of channels on the amp if it doesn't have the feature mentioned in the previous paragraph.

If your head unit doesn't have RCA pre-outs, you can use a LOC (Line Output Converter), but generally the results are less than stellar. You can buy a good quality LOC from davidnavone.com, but you're really better off having a deck with at least 1 set of RCA pre outs.

Now that head units are coming with more control ability than ever, it can be nice to fool around with a lot of the filtering abilities, but if you don't want to pay for all of the bells and whistles, you can buy a more affordable head unit and take advantage of the filtering abilities of the amp.

In my installs, I almost always run just 1 set of RCAs and let the amp(s) deal with filtering.

 

Jim already hit it, but this is not true. RCA splitters, amps with pass-through, line drivers, all kinds of options. What HU and what amps are we talking?

 

Ok guys, a few questions here.
I would defer to Jim on this subject, but, Couldn't he use LOC's on his mains, (y'know the frt/rear/right/left), convert those to RCA's, and still use his pre-outs for the subs??

 

i stand corrected... but i did read somewhere( slips my mind right now but i think it was on here) that if you split the RCA you stand a greater chance of introducing noise to the system

 

I get no credit. I posted more or less what he said first with loads more words minus the LOC part

If you read Jim's post you will find:

And finally...

Forgiven People on these boards tend to look for a name they reconize and only read the first post or two in a thread before they reply. KEVIN G's question (quoted above) is a perfect example of this...

 

I'm sorry but YOU missed MY point. Please do yourself a service and re-read MY post.
My question was in reference to using the LOC's IN ADDITION TO his pre-outs that already exist.
NOT WHAT IF he did not have pre- outs. But thanks for attempting to put words in my mouth anyway
I think i would know, if I read every post or just skimmed Thank You very much.

 

Roar to you too. To answer your question, my alpine powers all 3 sets of RCA's all the time. You can turn it's 4 channel amp on/off. I would assume that this is the case for most all units, the only problem would be sound quality and the only question would be why?

I promise you that I read everything, I just may not have comprehended it all

 

what happened to the guy who started this thread?

 

I'm trying to understand all of this. lol. i get no it cant be done and yes it can. I'm not really smart with audio so...

 

jimiroc is really knowlegable and so is needaz... id go by what they say first, thats why i corrected myself b4

 

yes it can be done but you should add another amp for the subs.

 

I understand that, but where do I get the RCA's for that amp?

 

Two choices, split the rca's (head to radio shack for $4 splitters) or use the line out on your current amp if it has one.

 

http://cgi.ebay.com/ws/eBayISAPI.dll...ME:B:EOAB:US:6


this is my amp

 

By glancing at the image google turned up, it looks like you have inputs for front l/r, rear l/r, and a l/r out. If you have a set of rca's labled out on the amp, you can just connect those to another amp.

 

so thats a good thing? Means I can run the rca's out of the amp to another amp........ Correct?

 

ya

 

Exactly.

Look at the side of your amp that has all of the RCA connections. The set of RCAs on the left says "PRE OUT". That's an RCA output just like the head unit has. You can connect that to another amp that's driving your subs.

 

Gummie, I here by give you a large helping of credit. It’s the ‘loads more words’ that through me. And Bob, on cheap equipment you can jet into some problems if you’re splitting the signal up to multiple times to several amps. Jensen comes to mind. They use and odd-ball matching network on the pre-amp outputs. But that’s only a problem using cheap amps to, like Jensen’s. Their amps low-level, high-impedance RCA inputs aren’t all that high-impedance. Run three or four of their amps off of one of their HUs with this little gem of a matching network, and high frequency roll off could become a problem. Jensen’s official fix for this was to jump out one of the coils in the network. Then they stopped using it. Thing is there stuff sounds so bad you’d probably never notice the problem. With any half way decent amp, the 10K input impedance is a lot closer to 10K. Those problematic amps where closer to 800 ohms, sad.

 

thats why i love this website soo much... i really havent found a better site online for any info pertaining to cars.

i wish there was a TGO for Monte Carlos because i could use it for my bros car....

 

well do what you want but I still highly suggest a tri output head unit. It made worlds of difference when I had a trans am. You can also adjust your subs right from your seat if you have this too. Alpine I heard has came down in price dramatically.

 

Jim, what is the point of this?
You seriously only run one set of RCA's and then piggy-back them from one amp to the next? Doesn't that put a lot of stress on a single set of pre-amp outputs on the headunit, since it would be sending a signal to power your entire system? You would also lose the option to fade front to rear, or independently adjust subwoofer volume via the subwoofer output (if one is available). This also defeats the purpose of built-in crossovers within the headunit (if one is available).

 

good point. Having a independent subwoofer level **** on a stereo is a good feature.

 

I could care less about head unit crossovers. In fact, when I built the system in my IROC, I bought a Kenwood PS907 excelon deck. This was back when high end stuff purposly came WITHOUT any of that extra crap because they knew that 99% of the people buying that deck was running an external filter anyway. The filter in the amplifier(s) was more flexible and higher quality than what you could get in a head unit at the time. Having a subwoofer level control is also useless to me because once I get it set properly, I don't screw with it.

Anyway, daisy chaining the preamp level to a couple amps has absolutely NO impact on the RCA signal coming from the head unit. It goes to 1 amp, then that amp takes the signal, pre-amps it, and sends it off to the other amp.

Now that head units have more sophisticated filter control, there's no disadvantage to taking advantage of them, but you shouldn't feel like that's your only option.

 

Good to know. I wouldn't use the headunit crossovers as my only option, but I would think its more efficient for the headunit to only send the frequencies you want, or at least frequencies in the same ballpark. You can also get a steeper crossover slope, for instance, if you cross your headunit and your amp at 80 Hz.
I would still like a subwoofer volume control, for the times I don't want the bass.

 

JUST BUY A 3 WAY CROSSOVER ITS A LOT CLEANER