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High inputs or RCA inputs


Elite Explorer
December 3, 1999
Reaction score
City, State
Penobscot, Maine
Year, Model & Trim Level
'92 XLT
I just bought a 4 channel amp that has 2 separate sets of RCA level inputs and 2 sets of speaker level inputs. My headunit only has one set of RCA level outputs and I was wondering what will be the best way to connect the amp. I'm going to run the front door speakers with 2 channels of the amp and eventually run a sub with the other 2 bridged. I'm either thinking to run wires from where the speaker wires go in to the factory amp(from the head unit) into the high inputs of the amp and then run wires from the speaker outputs of the amp back to where the speaker wires leave the factory amp for the front speakers. I could than use the RCA outs of the headunit hooked to the rear channel of the amp for the sub. This option would allow me to keep the fade control. The next option would be to run the RCA cable from the headunit to one input in the amp and than run a short set of RCA cables from the preamp outputs of the amp to the other channel of RCA inputs in the amp. This would make cleaner connections and my actually allow better use of fade control since I still have the weak factory speakers in the back doors. Plus I can always turn the the bridged channel up higher than the front channel on the amp right. These are my thoughts, what do you guys think. Also, I'm thinking about mounting the amp under the rear seat, will I still be able physically to fold the seat down. I know I probably shouldn't run it hot with the seat down. Any help would be greatly appreciated.

You lost me with the wiring description. I can tell you what I have, though. I have the factory head unit running four RF 5x7's in the four corners, and a RF 150a2 amp running rear speaker level input spliced from the rear speaker lines under the passenger kickpanel powering 2 JL 10" subs. My amp is mounted in an interesting location. Don't mount it under the rear seat. If you have a 4 door and can't emulate my amp location, I'd recommend mounting it up under the dash (there's plenty of room and ventilation in my Explorer there), mounted to the wall of the cargo area, or on your speaker box. There are tons of other places you can mount the amp, but I'm assuming you want it incognito, or at least not interfering much. Go to my webpage for info on my setup.

If you have an aftermarket head unit with only one set of preouts, it'll depend on your head unit. Some RCA outs are full range, but some are there just for subs. If they are full range RCA outs, then you'll have to think about what you want to do and see how they react to your fade control. Since you only have one set of RCA's it would be weird for it to control the front and rear, because you only have one set of RCAs. You'll have to find out if they're

1: full range or sub only, and
2: if the RCAs either are not affected by the fade, or only respond to front or rear.

That will help you out immensely with deciding your setup.

My advice would just be to keep it simple for now. *If your amp is 2 ohm stable*, wire your 2 left speakers in parallel to the one channel, the 2 rights to another channel
and then bridge the sub on the last two channels. You won't really have front and rear anymore, but you'll still have left and right. However, everything will then be connected to the amp using RCAs, Y-splitters prior to the RCA inputs so that your single set of RCAs is now connected to all the amp inputs and powered by the amp. If you want to start thinking about splitting up your signals, then later on you can either think about a different head unit with 2 sets of RCAs or get a X-over, or a handy-dandy EQ like the good ol' Kenwood 5 or 8 band available almost anywhere that'll split the single into 2 sets of RCAs.

Either way, you're starting to get pretty elaborate. Even if you wanted to use the speaker inputs, I'd say do the even simpler method of running new wire from the back of your aftermarket head unit's speaker out to the amps high level inputs. It'll be much easier than cutting and splicing all that mess in the back, then just tuck the wire under the rug.

Must my 2 cents


[Edited by JTang on 11-03-2000 at 05:48 PM]

Thanks JTang, your input was really helpful. The amp is 2ohm stable but i'm not going to power the rear doors because they're just the stock ones and i don't want to blow them, i might get another set of 6x8s along the way. I think I'm definitely going to use y-splitters or try running anotehr RCA cable from the amp RCA out to the other RCA in. Either of these methods should give me what I want, if the RCA's from the headunit are full range. (fingers crossed) Thanks again.