Subwoofer amp wiring

[valleyman]

After becoming inspired by HwyCruiser's post on subwoofer amp installation I went out and got a Kenwood KAC-5201 stereo bridgeable amp. I soon realized that not only do "I don't know nothin' about birthin' no babies," but that I don't know nothin' about no car audio wiring, either. Will someone please tell me how to wire this thing into the MM's system?

On one side of the Kenwood unit are the speaker outputs and I have no problem there: I know how to bridge them and connect the speaker wires to my subwoofer. However, adjacent to these speaker output connections are:
1) the main ground (no probem there -- per ultravorx's tip in his thread I'll connect to a ground point under the rear seat),
2) the power connection (again, no problem -- I'll fuse it and run 20' of 10 guage to the battery), and
3) a terminal that Kenwood calls the "Power control (remote) terminal." What goes here? My guess is that I'm supposed to connect it to an accessory circuit or some other lead that is connected to the car's ignition switch. Otherwise that hot lead from the battery would always be powering the amp even while the car is parked in my garage. So, how do I do it? Is there a suitable lead in the OEM wire harness in the trunk that goes to the 6 pin connector to the OEM subwoofer amp?

On the other side of the Kenwood unit are four speaker level inputs that I'm pretty sure that I won't be using in this application, right? And adjacent to them are the left and right "line in" RCA connections. RCA connections? What goes there? I pulled the whole radio/cd unit out of the dashboard and there's nary a RCA connector on it anywhere (not counting the antenna connection). So, where do I splice into the MM's system for the left and right "line in" signals? Do I use any of the wires in the OEM bundle in the trunk with that 6 pin connector that I disconnected from the OEM subwoofer amp?

And where in all of this does that little widget go that changes some 7.4 VDC signal into a 12 VDC signal so the subwoofer amp recognizes when to turn on?

And how do you people know these things?

[HwyCruiser]

Jeez, I didn't think anyone read my posts :D

I spliced in the rear speaker wires to the amp's speaker inputs. Worked fine.

The remote wire (white/violet) was the only wire I used from the factory amp plug. The OEM head unit puts out +7.4 VDC when on to turn on the OEM sub amp. The Kenwood may need +12 VDC to turn on. Try it. If it doesn't turn on, try jumpering the power wire to the remote input. If this works, you're going to either have to wire a switch or get a "low voltage trigger" like rookie1 pointed out in the install thread (I made my own).

http://www.cardomain.com/item/PERLVT2

Edit: BTW, you are using the same size gage ground wire as the power wire right?

I hope you like your new tunes!

- JD

[valleyman]

OK, now it makes a little more sense. It sounds like I don't use the line level RCA inputs on the Kenwood at all. Those must be for a set-up where the original radio unit has got line level outputs, and ours obvioulsy doesn't. Instead I DO use the speaker level inputs on the Kenwood amp and I just tap in to the left and right channel rear speakers. As long as I don't fade out the rear speakers with the OEM controls the new amp will work just fine, right? And if my Kenwood needs to "see" 12 VDC from the white/violet wire, that's where I hook in the "low voltage trigger" widget.

I found the connector in the trunk in the wiring diagram, it's connector #C466. I'm able to identify the hot lead, the ground, the lead that's hooked to the ignition switch (although the book diagram labels it as a dark green/violet instead of white/violet), and two remaining wires described as "TX signal" and "RX signal." Do you have any idea if "TX signal" and "RX signal" is electrical engineer-speak for left and right line level?

And thanks, HwyCruiser.

[HwyCruiser]

i tried hooking up the TX and RX (always meant transmit and receive to me :confused: ) to a speaker and no go, so I assumed it was a mono pre-amp signal. Maybe a stereo pro can chime in as far as terminology and function.

You could try kludging on an RCA plug and Y-adapter, but I wasn't all that impressed with the bass output of the OEM head unit so why take garbage in? The input impedance of the amp should be high enough not to effect the speakers, it worked fine for me. You'll get full freqency range and let the amp do its job as far as filtering.

- JD

[valleyman]

JD, bueno bueno. Thanks again.

[rookie1]

I've had some puter probs the last cpl days, sorry I didn't read this earlier.

I don't understand exactly what you are trying to do, If you are trying to wire a new amp to power strictly the subwoofer, you will soon melt the voice coil in the factory subwoofer(this is often called "blowing" the speaker).
Using the rear left and right inputs as the input to the amp is fine but the factory subwoofer wiring has a mono rca signal already there. You just have to go to Radio Shack and buy and wire up an RCA plug(takes 2 minutes), then you can connect the pre-amp level plug you just wired to the input of the amp. If your amp doesn't have a mono rca input, just buy a splitter cable(looks like a "Y") and use the left and right inputs.
If you need the wire color codes just holler an I'll repost them.

[2003 MIB]

I don't understand exactly what you are trying to do
Rookie1 are you gonna be at Indy??? I've recently discovered all the fancy switches, buttons and dials on the back of my amp and have no idea what any of them do- of course, that didn't stop me from messing with them....I bet there are quite a few of us that would appreciate your opinions on our audio choices....:rock:

[valkyrie]

Rookie1 are you gonna be at Indy??? I've recently discovered all the fancy switches, buttons and dials on the back of my amp and have no idea what any of them do- of course, that didn't stop me from messing with them....I bet there are quite a few of us that would appreciate your opinions on our audio choices....:rock:


I've just put in a new amp, head unit and all speakers except for the Subwoofer and I am very disappointed.

I have a hiss sound at all times.

I was originally told that it was because I was using the factory head with the amp and new speakers.

I changed the head unit also and it is still there.

[rookie1]

I've just put in a new amp, head unit and all speakers except for the Subwoofer and I am very disappointed.

I have a hiss sound at all times.

I was originally told that it was because I was using the factory head with the amp and new speakers.

I changed the head unit also and it is still there.


Did you do the installation? Did you or the installer use the speaker level inputs to the amp or line level inputs(rca cables)?
Things that can cause hiss:
low quality amplifier
using the speaker level inputs
using poor quality line level converters
using line level converters that are not turned up enough
using line level converters that are turned up too much
home burned cds from downloaded mp3s
faulty ground at amp(in rare cases).
out of phase speaker wiring
over active treble settings
hyper active tweeters

It CANbe corrected with patience and a good installer.

[rookie1]

Rookie1 are you gonna be at Indy??? I've recently discovered all the fancy switches, buttons and dials on the back of my amp and have no idea what any of them do- of course, that didn't stop me from messing with them....I bet there are quite a few of us that would appreciate your opinions on our audio choices....:rock:

I'm not sure, I only live 90 minutes away but I have a big member/guest tourney at my golf course that weekend.
Careful with your amp adjustments, tweaking can be addicting.

[valkyrie]

Did you do the installation? Did you or the installer use the speaker level inputs to the amp or line level inputs(rca cables)?
Things that can cause hiss:
low quality amplifier
using the speaker level inputs
using poor quality line level converters
using line level converters that are not turned up enough
using line level converters that are turned up too much
home burned cds from downloaded mp3s
faulty ground at amp(in rare cases).
out of phase speaker wiring
over active treble settings
hyper active tweeters

It CANbe corrected with patience and a good installer.

I was thinking of a good sqeezing of the neck of the original installer, should help him want to fix it.

When I get a new Subwoofer and amp I was going to have someone look over the entire system. :uzi:

[valleyman]

I've had some puter probs the last cpl days, sorry I didn't read this earlier.

IUsing the rear left and right inputs as the input to the amp is fine but the factory subwoofer wiring has a mono rca signal already there. You just have to go to Radio Shack and buy and wire up an RCA plug(takes 2 minutes), then you can connect the pre-amp level plug you just wired to the input of the amp. If your amp doesn't have a mono rca input, just buy a splitter cable(looks like a "Y") and use the left and right inputs.
If you need the wire color codes just holler an I'll repost them.

Rookie1-- thanks for trying to help but please understand that I am not familiar with audio jargon. When you say the "factory subwoofer wiring has a mono rca signal already there" are you talking about the 6 pin wire harness that connects to the subwoofer amp when you refer to "there?"? If so, which wires and where do I connect them? What do you mean when you say, "Wire up an RCA plug?" And what is a "pre-amp level plug" and what input on the Kenwood amp are you talking about? My new amp only has "line level" RCA inputs and the "speaker level" inputs. You obviously know what you're talking about but you're assuming way too high a level of knowldge on my part. Alas, I am one of the ignorant car audio unwashed masses. Please try again to educate my ignorant a$$. Thanks

[rookie1]

Rookie1-- When you say the "factory subwoofer wiring has a mono rca signal already there" are you talking about the 6 pin wire harness that connects to the subwoofer amp when you refer to "there?"? If so, which wires and where do I connect them? What do you mean when you say, "Wire up an RCA plug?" And what is a "pre-amp level plug" and what input on the Kenwood amp are you talking about? My new amp only has "line level" RCA inputs and the "speaker level" inputs. Alas, I am one of the ignorant car audio unwashed masses. Please try again to educate my ignorant a$$. Thanks

1: yes, I am referring to the 6 pin harness that connects to the OEM sub amp, the breakdown is here:
Brown / Orange to Green = TX (pre-amp positive or signal)
Red / Black to Black = RX (pre-amp negative or reference)
Green / Violet or White / Violet to White = remote 7.4VDC "on"
Black / Green to 2 Reds = Ground to lug attached in the car behind the back seat
Red / Yellow to 2 Yellows = Battery 12.8VDC always hot unless fuse gone

2: Go to Radio Shack and ask for a male RCA plug. Connect the Brown/Orange to Green and the Red/Black to Black wires to it(self explanatory once you see the plug)(it's no more difficult than replacing a plug on an extension cord). You now have a "line level" input you can use for your amplifier(line level and pre amp level are the same thing, my bad for being confusing).

3: If your amp has dual line level inputs(left and right), buy a "Y" adaptor with 1 female rca input and 2 male outputs(Radio Shack or Best Buy/Circuit City or any stereo shop). Then insert the Line Level plug you just made using the wires from the OEM harness into the female end of the Y adaptor and insert the 2 male ends of the Y adaptor into the line level inputs of your amplifier.

4: The factory sub amp harness has a remote turn on lead(Green/violet or White/Violet to White that produces a 7.4 volt turn on signal. Try using this for your amps turn on lead. It may or may not work, some amps need a 12 volt signal for this function. If your amp won't work with this signal you can use a remote trigger as mentioned earlier or you can run a wire from the fuse box from any ignition on radio fuse(old school method).

5: Make sure you take a drop light into the trunk with you and remember to use a towel d***** over the fender where the cord is resting or you'll have to spend time buffing out where the cord rubbed against your paint.

6:Don't be intimidated and don't feel like an idiot, this isn't rocket science it just sounds a little complicated but it really isn't and it can be a fun project.

7: If you want better bass, junk the factory sub enclosure and mount an 8" or 10" "Free-Air" subwoofer to rear deck. Pioneer and Kicker still make "Free-Air" subs and The Infinity Perfect series is a "Free-Air" model also.
"Free-Air" means a sub that requires no enclosure.They can be found on Ebay much cheaper than in the the stores.

8: I'm still not clear what you are trying to do based on your first post. If you are trying to connect a different amp to the the OEM subwoofer you will more than likely blow the OEM subwoofer in a matter of minutes as it is not designed to handle high power.

9: Good luck and enjoy!

[valleyman]

Rookie1 -- thanks a bunch. Now I understand, or more accurately, can follow your directions. It seemed to me that it would probably be preferable to use a "line in" input than to take the input signal from speaker leads and now I can do that. As far as the subwoofer I have already replaced my OEM with a 6.5" Rockford Fosgate in the original enclosure. I did look on e-bay as you suggested at the 8" free air enclosures already mounted in a box. If I get one of those do I just position it below the cutout in the package tray where the OEM is now attached? Thanks for all the help.

[rookie1]

Rookie1 -- thanks a bunch. Now I understand, or more accurately, can follow your directions. It seemed to me that it would probably be preferable to use a "line in" input than to take the input signal from speaker leads and now I can do that. As far as the subwoofer I have already replaced my OEM with a 6.5" Rockford Fosgate in the original enclosure. I did look on e-bay as you suggested at the 8" free air enclosures already mounted in a box. If I get one of those do I just position it below the cutout in the package tray where the OEM is now attached? Thanks for all the help.

1: you are very welcome! I've gotten alot of help on this board also.

2: Try your new Rockford sub and see how you like it. Quite a few members have done this and are happy with it. If you are still wanting more bass buy an 8 inch free-air woofer like I mentioned and it needs no enclosure. You can mount an 8" woofer directly under the factory cutout with no clearance problems. Try that first and if you still want more bass buy a 10" FA woofer but you will have to make a spacer to mount it in the same spot or the cone excursion will cause rattles from bumping the rear deck. Or you can take a jig saw and cut the hole a little bigger,

3: Again, Enjoy and happy to help.

[valleyman]

:banana2: It works! It works! Hooray! It works! I finally got my new subwoofer amp hooked up thanks to the tutelage of HwyCruiser and rookie1 and I couldn't be happier with the result. The amp is a Kenwood KAC-5201 that is bridged (supposedly) for 250W, but the guy at the car stereo store who sold it to me said it was actually closer to 175W. He assured me it would be plenty for my application of driving the 6.5" Rockford Fosgate subwoofer that I have in place of the OEM. He was right, at least for my musical tastes. I have the gain, which I think is a fancy engineering word for "volume control," on the amp turned up to just past halfway and it sounds great.

I am a neophyte at car audio and a ham-handed goober to boot so believe me when I say anybody can do this. I didn't do any soldering, instead using crimp connectors everywhere. I mounted the amp to a piece of particle board and just laid it on the same surface that the spare tire mounts to in the trunk. I removed the original subwoofer amp and placed the new one directly below where the old one used to be. To keep the new one in place I fashioned some "L" shaped brackets out of sheet metal and screwed one end into the the mounts the OEM amp used (using the same threaded fittings on the sub enclosure and Torx fasteners) and the other end into the particle board. This way I avoided any drilling around the gas tank and have the amp mounted in an orientation with the heat sink on the top.

I noticed that everyone routed their hot wire from the battery through the driver's side firewall so I asked the guy at the car stereo store if there was some reason for that. He said not particulalry, it was just that there is usually less stuff in the way on the driver's side. Since the battery is on the passenger's side and I didn't like the idea of routing that hot wire all the way across the inhospitable environment of the engine compartment, I routed mine through the passenger side firewall instead. I don't know if you're supposed to do this but I did it anyhow. I drilled a 7/16" hole through from the interior side of the car down around where the passenger's feet would be. Once I took off the two pieces of interior trim plastic (oh, and about a foot or so of the weatherstripping on the door but it comes off and goes back on real easy) the carpet can be pulled back and it's easy to see where to drill. And you don't need a right angle drill. There are two big wire harnesses that pass through the firewall there and they're a couple of inches apart. I looked at them from the engine side and there is nothing but sky around them so I didn't have to worry about the drill bit punching through and destroying anything expensive or mysterious. So I just drilled my hole more or less in between those wire harnesses and it worked out just fine. You do have to pull off about an inch or so of what looks like insulation or sound deadening material from the metal before you drill, or it will wrap all around your drill bit. For a grommet I used some 7/16" vacuum hose, about two feet of it. I just snaked the hot wire through it from inside the car. This way the 10 gauge hot wire is safely ensconsed in rubber almost all the way to the battery. The vacuum hose/hot wire lays on top of the plastic fender wheel well in the engine compartment, well away from any sharp surfaces or heat sources. And I did stick in an in-line fuse.

An added benefit to punching through on the passenger side is that you don't have to take off the door sills or anything except the rear seat to get the hot wire into the trunk. I don't know about the driver's side but on the passenger side the area that runs under the door sills contains three channels for wire harnesses but only two of the channels are used. One of them was completely empty. I thought this was too good to be true but it's true. The 10 guage wire snakes right through the empty channel, no hang-ups, no problems, and pops out back by the rear seat. Sweet.

To wire up the new amp in the trunk I followed rookie 1's suggestion and got that low voltage trigger widget that he has a link to in his post. My local car stereo shop had it ($12.99). It's called a model LVT2 by Peripheral and has four wires on it. I mounted it right on the same piece of particle board that the amp is sitting on and connected it to the wires that are in the OEM harness in the car. Other than the direct hot wire from the amp to the battery and the main ground from the amp, which I connected to the rear seatback/seatbelt stud in the interior compartment, all of the other needed wiring is in the OEM harness. The harness comes out of the middle of the back seat to a male 6 pin connector. The female end that connects to that connector contains wires that lead to a connector that attaches to the OEM amp. I cut off the connector that plugs into the OEM amp and connected the exposed wire ends as follows:
red (there's two of them on the same pin. I snipped one off)---black on the
LVT2
yellow (there's two of them on the same pin. I connected both since they're
hot all the time)---yellow on the LTV2
white---green on the LTV2
black--- ground connection on an RCA male plug
green---hot (i.e., the tip) connection on an RCA male plug

By far the easiest way to convert the black and green OEM wires into a single male RCA plug is to buy Radio Shack part #42-2445. It is a 12 foot patch cord that has two wires going into a male RCA plug. Cut those wires leaving a couple inches sticking out of the male plug and and then splice that cutoff plug onto the black and green wires on the MM. One of the wires on the Radio Shack RCA plug will be marked somehow -- probably with a dark stripe. That is the hot wire and conncts to the green wire from the MM. The remaining wire then goes on the black wire on the MM.

The RCA plug then connects to a "Y" splitter like rookie1 describes in his post. The two RCA connections coming out of the "Y" then plug into the "line level in" RCA inputs on the amp.

I hope this helps someone.

Oh yeah. I forgot. The fourth wire coming out of the LVT2 is a blue one and it connects to the amp at the treminal labeled "Power control (Remote) terminal."