Fader set to the front and I still hear rear

[docutech 10+ year member]

I have a Alpine CDA-9855 HU and Alpine mrv-f545 pushing my comps and 6x9s. My gains are set at 1.3v on channel 1&2(front) and 2.0v on channel 3&4(rear). When I fade 100% to the front I can still hear my rear 6x9s. Is this normal or should there be no sound at all from the rear speakers?

Thanks in advance for any help.

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[spudracer326 10+ year member]

should be no sound, did you wire it incorrectly, are you running 2 rcas to your four channel and are they hooked to the proper plugs??

 

[docutech 10+ year member]

As far as I know it is right. Checked it by fading and balancing each speaker after everything was hooked up.

There isnt a LOT of sound coming from the rears, but I can still hear them. weird.

 

[yacob.naif 10+ year member]

I've owned amps where the sound would bleed a few db between channels.... Never anything as nice as an alpine, tho.

Is it actually a noticeable amount of sound? Or just enough to notice? Is it a 4-3 channel amp? Might have something to do with the bridging circuitry in the rear channels?

Just throwing it out there... I don't know for sure.

 

[docutech 10+ year member]

It is definately noticable sound. I even climbed in the back seat to investigate. Yes there is sound coming out.

Any one else have an Idea?

 

[VereChronicus 10+ year member]

Well there is a statistic with head units and amplifiers that is called: stereo separation and it is rated in dB also, most are like 60dB-ish. Since you have your gain set lower on the rear channels, if you did a swap on the test by fading to the rear, the front should be louder than the rear....by sitting in the rear of the vehicle. I don't know the specifics of that head unit, but it may not cut the signal all the way off from the rear speakers just because it's faded all the way to the front, it may just be 30-40dB attenuated. Also, are your 6x9s the same DCR as your components or are they lower impedance?

 

[VereChronicus 10+ year member]

Meant to point out that since there is a stereo separation rating, there may just as well be a front to rear separation statistic as well. I've just never seen it printed or mentioned before. The factory head unit in my Nissan does the same thing when faded all the way to the front. It's just heavily attenuated, not completely shutting the rear speakers off from the internal amplifier.

 

[docutech 10+ year member]

it may not cut the signal all the way off from the rear speakers just because it's faded all the way to the front,

It doesnt, the sound is not a "sharp and clear"sound but it is audible.

are your 6x9s the same DCR as your components or are they lower impedance?

Yes they are both 4ohm

Kicker KS65.2's and Kicker KS9

 

[docutech 10+ year member]

UPDATE

Being out of town with work and the weather being crappy I havent had much time to mess with my setup but today I figured it out!

It was the settings on my Amp all along. There are 3 modes that the MRV-f545 has as far as output options: 1/2 channel, 3/4 channel and 1+3/2+4. My amp was set for the 1+3/2+4 mode which sums the channel 1 and 3 inputs and sends it to channel 3 while it sums the channel 2 and 4 inputs and sends it to channel 4.

I just installed a set of RS 65.2's that i got from Polecat and noticed that something didnt sound right. After careful read of the manual //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif I figured it out! Now there is NO sound from the rear when faded to the front and vice versa.

Lesson learned.//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif