rca connection question

[atldohc]

im a bit of an audio noob and have been reading some of luke's $500 audio system sticky. some of the head units mentioned appear to have only 4 rca preouts:

http://www.sonicelectronix.com/pictures_new.php?id=60593&picture_id=1183015

my question is how would this be connected to a 5 channel amp? are people using an rca splitter for the 5th subwoofer channel, or is there a function of the planet audio 1800.5 amp mentioned that can split the signal from the provided channels and provide one for the woofer? i have an old kenwood kdc mp238 head unit with 4 rca preouts, http://www.sonicelectronix.com/item_...KDC-MP238.html and am wondering if it would be advantageous or necessary to get a new head unit when the time comes to upgrade my system.

[AndrewBird]

A 5-channel amp needs 3 pairs of RCA's (6 individual connectors). 1 pair for the front speakers, one for the rear and one for the sub. Some amps only have a mono input for the sub, so you will need a Y to connect the pair of RCA's to one jack.

Your stereo only has 2 pairs of pre-outs. You will need an amp that can split the signal like you mentioned to get the subwoofer level outputs. Either that or run a 4-channel amp with one pair of RCA's to 2 channels and then bridge the other two channels for the sub. Then drive the rear speakers off of deck power or just eliminate them all together.

For a good soundstage, you want most of the sound coming from the front anyway, so most people will often turn the rears down (via the gain controls on the amp) in comparison to the fronts. Running them off of the headunit and not the amp will basically do this, plus then you can use the balance control on the HU to turn the rears down further if needed.

[StereoInstaller1]

im a bit of an audio noob and have been reading some of luke's $500 audio system sticky. some of the head units mentioned appear to have only 4 rca preouts:

http://www.sonicelectronix.com/pictures_new.php?id=60593&picture_id=1183015

my question is how would this be connected to a 5 channel amp? are people using an rca splitter for the 5th subwoofer channel, or is there a function of the planet audio 1800.5 amp mentioned that can split the signal from the provided channels and provide one for the woofer? i have an old kenwood kdc mp238 head unit with 4 rca preouts, http://www.sonicelectronix.com/item_...KDC-MP238.html and am wondering if it would be advantageous or necessary to get a new head unit when the time comes to upgrade my system.

No worries, no need to change that deck first.

Most 5 channel amps have an "input mode" switch that allows use of 4 channel inputs. They have a "summing" circuit that makes up its own "sub input".

The only thing to watch for is some have that switch, but no ability to use a sub level controller, like the Soundstream RUB5.580...no port at all (the bastards!)

Sometimes you see them labelled as "INT" or "EXT" meaning internal or external connection. Same switch though, works the same.

Some, for example the hifonics Brutus, can drive all 5 channels from only 2 inputs, but most all 5 channel amps offer some form of "input mode" switch, and do just fine with a "2 pairs" (4 channel) preout deck.

Think of that switch as a glorified version of the Y cords. However, I HIGHLY recommend you run 3 pairs of RCAs so you can easily upgrade later.

HTH

Luke

[atldohc]

thanks for the clarification guys that cleared up a lot of my questions. i will probably be going with that planet audio amp and it does look like it has that feature as described in the users manual on page 7:
http://images.planetaudiousa.com/man...Y_AB_EN_UM.PDF.

[StereoInstaller1]

Yes it does, and if you go to most good sales sites (sonicelectronix, etc) they have views of the switches so you can see for yourself.