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EQ/X-over/Subout from OEM headunit idea


rebourne

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So I have this idea* in my head, and I want to run it by all you audio gurus. I searched around and couldn't find anything similar being done.

 

First off, this is only going to work for the CD player and iPod (centerpunch, jazzy style). For me, besides AM radio for news and traffic, thats all I listen to in the car anyways. So, it might not be for everyone.

 

Take the audio on the ribbon cable coming out of the CD, intercept it (ie: CUT ), solder the CDplayer/ipod jack side to a pair of RCAs (OUTs). Then solder the radio/amp side to another pair of RCAs (INs). Now send the outs to an EQ w/ sub out. High pass it and EQ it, but don't add gain, and send it back to the INs. I happen to have an old skool AudioControl EQX (13 band EQ with 24db/octave x-over) laying around which would be perfect for this.

 

On your EQ/X-over, set the frequency high pass in the 80-120hz range, and send the low pass to your sub. If you have replaced the stock speakers, you now can EQ to help remove the built in stock EQ that is taylored to the stock speakers.

 

And the fact that when you switch to AM radio, the sub and EQ all dissappear doesn't bother me. In fact, an AM radio sub turn off seems brilliant to me. As far as FM radio goes, I havent set any FM stations since I removed the radio to install the jazzy ipod jack... they are still all at the default (LOL!!). But still, broadcast FM will be okay, it just won't have the bass. Broadcast FM has limited LF anyways.

 

Okay, so, what do you think? Will this work? Am I missing something? Probably need a pair of GLIs...

 

radio shack quad rca mount

 

 

*A couple of nights ago as I was fading to sleep I had this above epiphany about the OEM stereo. Usually when I wake up the next day, I see the big flaw in my delerious logic and promptly forget about. But in this case, I think I might be on to something...

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So let me wrap my noodle around this. You want to take the CD signal & EQ it, rather pre-EQ it and have a second input on the EQ for an Ipod to do the same thing, right? Then send the low-pass to a sub & the hi-pass back thru the HU amp?

 

Interesting idea. Problem one is sub gain/volume will be independant of the mains, so you'll be playing with 2 volume knobs at once. Next problem is splitting the ipod signal into the EQ with the CD input - impedance issues.

 

I did something similar & toyed with the idea of using the Jazzy board for a clean CD out, but I almost never use the CD over the ipod so it seemed fruitless. I have the CD player doing speaker level in now, it's fine for me.

 

http://legacygt.com/forums/showthread.php?t=15580&highlight=updated

 

Good luck wth it, let us know how it shapes up.

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How is this going to EQ the system since once you pass through the ribbon cable on the CD input (basically) you're going to run through another OEM EQ?

 

Basically, you're just going to EQ the sound twice. One will be good, then the OEM EQ will filter bass etc. based on volume.

 

Am I not understanding everything?

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He'd just invert the stock HU's EQ curve with the outboard EQ, the two would balance out. Not ideal, but it works. I think it'd be much simpler to use a cleansweep, not to mention functionally better, but would need outboard amps etc.

 

But if you did do it, you could put an in-line volume control between the EQ output and the HU and set the HU volume at a fixed level, like 25 for instance. If the volume control you add is 4-channel (rare) then you could route the low pass thru it also and be back at a simple single-volume controller.

 

Or add a second X-over between the EQ out & HU, and put the volume control (2-channel, easier to find) in-line before you split the highs & lows (IE - don't use the X-over in the EQ). A whole lotta work in place of a cleansweep tho.

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It sounds like we're still trying to get this to work with the stock volume control though. So ultimately, this project sounds ill-fated. If there was some way to defeat the factory "dynamic" EQ. The bass roll-off is the only thing that bugs me. It seems like I am always playing with the EQ dependent on volume.
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