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Discussion Starter · #1 ·
I installed a pair of Infinity 6820cf speakers in my front doors. The specifications say that the speakers are 2.65 ohms, but the front of the box is stamped 4 ohms and other literature indicates that it is a suitable replacement for 4 ohm speakers.

So I'm listening to my new speakers and they sound good, but not great. I fiddle with the little button on the tweeter that changes the crossover from 0 dB to +3 dB. It makes a noticeable difference, but still the sound isn't as clean as it I think it should be.

Now I'm adjusting the sound controls on the stereo and I adjust the fader to just the front speakers, and PRESTO, the new speakers volume level comes up a bit, but more importantly they sound great. Very clear, crisp and clean with better range. Just like I was hoping for.

So what is up? I'm guessing it is an impedance issue, but it's not something I was expecting. I have another set of these speakers that I can install in the rear, but I'd like to figure this out before I break open the box and peel off the door trim.
 

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Making a factory head unit or even an aftermarket head unit play low impedances is often hazardous to its health. IMO most mosfet chip amps aren't built robust enough in these types of equipment to handle it.

Try a quality amp for a change, and see how it sounds then.
 

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Do what Fourthmeal said, especially if you are not satisfied with the sound quality. You can really wake up the music in the speakers if you have a quality Head Unit and amplifier. :thumb:

I used to always replace the factory sound systems in cars that I bought, but currently and in the more recent past, I have placed my disposable income into better housing. I do spend more time in the house than the car/truck/SUV. :) If I don't like the sounds, I tend to shut the box off and drive. Most of my drives to work, church, downtown, etc. are less than 15 minutes away. ;)
 

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Discussion Starter · #4 ·
I installed the other two speakers in the rear last night and I've been playing with it this morning. It definitely sounds better than the stock speakers. The volume level is a bit greater than the previous speakers, so I have the volume turned down a bit less for normal listening. Also I can turn the volume up with very little distortion until I get to about 75% of full volume (before I could go to about 50%).

There are still differences to the tonal quality when the fader control is adjusted front and back, but I'm able to compensate with the other controls.
 

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These things you mention (and I assume we are talking about a stock HU here) are NOT normal in a quality sound system. The stock HU is distorting from the beginning, especially when trying to drive low impedance loads it wasn't meant to do.

In my research and development of my own system, I noticed measurable audible distortion from the head unit at a tick over 50% on the volume notches. Given that the volume ticks actually react more slowly in the first 1/4 of turning the dial, I'd assume that it is actually distorting at 1/3rd the actual maximum volume it can put out. In order to actually hear clearly discernible distortion (clipping solely from the amp, and not the speaker is what I'm talking about here), it has to be at least 5% and probably closer to 20% THD. I took a distortion test not too long ago and with high quality Sennheiser earphones I was able to detect 8% THD in a song, but just BARELY and that was with top-notch earphones. With car speakers in a car environment, I'd imagine I'd have to have 10%-15% THD to be even audible. If you are hearing clearly audible distortion, you are likely clipping those speakers 30-50%!!! This is not good, at all. It is what makes listening to music a miserable experience, and pretty much removes all hope of improved sound quality from ever happening.

It is the distortion that you don't hear that contributes to listening fatigue, and to the internal sub-conscious feelings of wanting to turn it down or off for some reason. Your sub-conscious mind reacts very aggressively to how things really sound, if you weren't aware. A clean, powerful and well-designed system can actually improve your mood and make you enjoy music in ways previously not experienced, especially in a car.

That is why I said to grab an amp.
 
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