Stereo upgrade plan

**Fireballs** · 05-22-2006, 01:56 AM

I'm about to begin a stereo upgrade from Sound Group II (322 watt 6 disc 7 speakers) in my Charger with steering wheel controls. I'd like your input on whether or not there is a better approach. I want full range clarity above all else, power to play heavy metal properly, and sensitivity to handle classical.

I really like the head unit and steering wheel controls, so changing the head unit is out. My first preference would be grabbing the signal between the head and amp with a Peripheral CHYAA or Pac Audio C2A-CHY, but neither is in production now (May 2006). So, I have to use speaker level inputs to a line output converter with channel summing. I'm planning on using an Audio Control LC-6i.

Having researched the factory speaker outputs by reading this forum and 300C Forums, I put together this chart that I think is correct:

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Location  Watts   Frequency  Speaker
Dash       24     100-16k    3.5
Doors      60     <120       6x9
Deck       60     100-18k    6x9
Sub        46     <50        8

Here's the part I'd like input on: which channels go where on the LC-6i. Here's my plan:

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Speaker wires  LC-6i in          Notes
Dash              N/A               To Infinity Kappa 3.5" in dash
Doors             Channel 2       Summed to Main Channel
Deck              Main Channel   To main amp F&R
Sub               N/A                Disconnected

It looks like there will be excess signal strength from 100 - 120 Hz due to the crossover overlap. How much of a problem will that be?

Here's where the signals will go next:

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LC-6i out  Amp Input
Main       Y preamp cables to F&R main amp channels
Channel 2  subwoofer amp

That means I'll lose fade adjustment at the head unit, but I can adjust it by altering the relative amp input levels. No biggie. The main amp is an Infinity 7541A 111 watts x 4 channels. The sub amp is an old Jensen 4 channel I have sitting around. It can be bridged to 150 watts x 2 channels, thus the DVC sub. The LC-6i and both amps will mount to the rear seat backs.

Now to the speakers:

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Amp output  Speaker  Location
Front       6x9      Doors
Rear        6x9      Deck
Sub         10" DVC  Deck

Having owned Infinity Kappas with CMMD drivers, there simply is no other choice for me. Since the current generation Kappas have fiberglass cones, I bought two 6x9 CMMD pairs used via eBay. One pair is 3 way for the doors and the other pair is 2 way for the deck. The sub will probably be a 10" Infinity DVC that I plan to mount free air by cutting the deck. For me, thump is just not worth sacrificing much trunk space for and I expect the four 6x9s to do most of the sub's job anyway.

The factory amp will still power the dash speakers, mostly to raise the sound stage. Since the door speakers will be full range, I won't need much output from the dash speakers to do that. I swapped the dash speakers for Infinity Kappa 3.5s a few months ago.

Is that a sensible plan? Where did I go wrong?

**robbyho** · 05-22-2006, 10:32 AM

Not a bad system design you have going on there.

My first thought is that you lose all fade control, as you mentioned.

Why would you sum the front two door channels for your subwoofer, when you already have a subwoofer channel from the factory? If you do use the door signal, I'm sure your Jensen amp has a crossover that could be used to filter out anything above 80hz or so.

I've never used an LC6, but I think it would be possible to sum the door speaker and the dash speaker to get a full range signal for an amp. You could still use the factory amp to power the dash speakers (just tap into them, don't cut), but have a full range signal to power your door speakers and keep fader controls. Then use the other two channels of the LC6 on the rear deck speakers. You would still need a subwoofer channel, which could be attained by an LOC on the subwoofer output, or a Y connector on the right or left rear channel and use the amp's crossover (assuming it has one).

As for the sub in the rear deck, power to ya! That is called "infinite baffle" or IB and produces the lowest and flattest frequency response of any enclosure type. It will be important to seal off the trunk from the rest of the car as much as possible for best results. Another good thing abot it is that you will only need half as much power to reach the subs potential compared to a sealed enclosure.

Hope I made sense,

Rob

**Magnum-RT-AWD** · 05-22-2006, 11:29 AM

I believe in doing tweets on the dash---crossed over from 2.5Khz and have a good set of 6.5's or 7's in the doors that can play up to about 5KHz without breakup.

**Fireballs** · 07-07-2006, 01:17 AM

WOW! Now THAT'S a stereo! Now that the various adjustments are close, the muddy, overboosted bass typical of Sound Group II is gone, the midrange is crystal clear, and the high frequencies are audible all the way up to background hiss. Clarity and power: it's as good as I hoped for and completely hidden except for the LOC and amp in the trunk. My primary concern was equalization in the factory amp messing up the sound quality, but it's fine.

I experimented with unplugging the original subwoofer but couldn't tell the difference so I plugged it back in. Either way I've got just the right amount of thump and bass from the 4 full range 6x9s and I can actually hear the rear speakers now. It's true that subwoofer frequencies are omnidirectional, but the feel isn't. I like the fact that the thump comes from all directions equally.

I left room on the seatback for a subwoofer amp, but I won't bother now. I'd rather have the trunk space.