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Rear fill: Should I or shouldn't I?

1579 Views 6 Replies 7 Participants Last post by  FoxPro5
I've never really been much of a rear fill kinda' guy, but I'm considering it for a few reasons...

1. I have the power for it
2. I can get a great deal on a set of Boston Acoustic RM6 2 ways for the rear doors. Used but in immaculate condition.

Right now:

GT-40 4 channel: 240x1 @ 2 ohm to an SQ10, 2 channels (55x2 @ 4 ohm) unused
GT-22 2 channel: 100x2 @ 4 ohm to a set of ID CXS64 comps

Thinking about:

GT-40 4 channel: 240x1 @ 2 ohm to an SQ10, 55x2 @ 4 ohm to the Boston RM6 2 ways
GT-22 2 channel: 100x2 @ 4 ohm to a set of ID CXS64 comps

Another option without rear speakers:

GT-40 4 channel: Bridged to 2 channels, 190x2 @ 4 ohm to the CXS64 comps
GT-22 2 channel: Bridged to 1 channel, 500x1 @ 2 ohm to the SQ10 with gains turned down

Some relevant info... the Boston amps are 1 ohm stereo/2 ohm mono bridged stable. The SQ10 is in a 0.3ft^3 sealed enclosure.

In almost all of my installs I've typically just disconnected the rear factory speakers and focused on having a nice set of components for the front and a sub or two.


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Rear speakers are barley even noticeable when you're in the front seat. I wouldn't put anything in the rear that was a lower quality speaker than what I had up front, that would be pointless. I tried it once and the sound from the rears bled through a little and just ended up detracting from the sound as a whole. Personally, I'd only do it if the rear speakers were matched to the front ones, even then it isn't necessary. I had Diamond hex components in the front and rear doors of my last car and when I turned the rears off with the fader, it was BARLEY even noticeable up front. Your sound stage and presence will benefit far more from adding some 5 1/4 components in the kick panels than adding rear fill. That's what I'd use the extra power for.
It is a waste if you don't have people sitting on the back seat.
It is a waste if you don't have people sitting on the back seat.
IF you have some signal processing for it, it can add a great sense of ambience and space. Simply hooking them up in stereo will hurt the front image but increase the over all level. It all depends on your objective!
I had rear fill for passengers, but yanked it for two reasons.

I wanted gain control for my separate tweets and my HU only supports 3 way active with individual gain control.

My small rear doors had resonance at about 160 hz that muddied the sound and fatigued my ears. It may have been fixable, but wasn't worth the effort since it was only rear fill.

I could get my rear fill back with features on a 4 channel amp, but TA would still be an issue that an amp can't solve.

I tried just leaving the TA and parametric EQ settings from the front and letting it apply to the rear. No go. Then I tried turning each off (PEQ and TA) separately. I could do much better using that processing on just the fronts.

... like Andy said, processing. If I had a way to EQ (cut) the rears at 160 hz, use 4 way gain control, and 4 way TA I'd be happy. Since I can't see that head unit or processor showing up my price range any time soon, I vote "shouldn't". Plus what would I really get for all that money? ... but maybe you have more resources than me.
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Yes, as long as you cannot hear the speakers and they add to the sound (what Andy said). Search "delayed ambient rear fill" [i think] on here or the web for the theory and application of such a thing.
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