Actually, I am using Infinity 3-ohm 6x8s for my rear deck speakers. Factory is 4-ohm on all
the 6x8s, and I am using Kicker 4-ohm 6x8s in the doors. They are much louder than the deck
speakers too. The reason I went with 3-ohm on the back was to get some volume from them,
because of: if you look? The stock front shaker 6x8s are 45 watts, indicated on the back of the magnet.
The rear ones? 25 watts, so where is the power differential coming from? I put in an aftermarket
Eonon unit, and the front speakers still over power the rear ones, with no fade bias. I cannot find any
other amplifier for the front door 6x8s, unless they're in the doors? Just wondering, since the fronts
are still much louder, at 4 ohms, then the rear infinities at 3-ohm. I really have to fade rear to even
it out. I do have a brand new kicker Amp I can put on the rear speakers if I wanted to.

 

 

Interesting about the volume biased even with the 3ohm in the back. Only thing I might suggest is swap the Kicker and Infinity speakers to see if the biase still persists? What's the sensitivity on both speakers? I can't imagine Infinity having a lower sensitivity. All things equal, a lower sensitivity would reduce the sound level at the same volume setting between speakers. Are there any audio modes on the Enon or EQ settings like the OEM HU with Driver, Passenger, and Rear settings that automatically bias the system? There are no amps in the doors. I can guarantee that. I had my panels off for replacing the pleather inlays that were peeling off and replacing the 6x8 speakers as previously mentioned.

As for 45w vs 25 watt front vs rear that's just because the factory HU probably had built in bias. Less power to the rears...after all it's a Mustang, who's gonna sit in the back seat?

 

Yeah, but even if the radio has a bias, my Eonon Android radio does not, and the
front Kicker 4-ohm are much louder than the Infinity deck 3-ohm. I would think the
Shaker has a bias, but not an aftermarket radio.

Infinity PR8602cf, Sensitivity: 93dB
Kicker CSC68, Sensitivity: 90 dB

 

Welcome new guy.

Here are some pics of the sub enclosure and what you have to work with. From everything I've read, the limiting factor hasn't been the depth of the speaker, or the cutout diameter, its been the diameter of the magnet. The RT Kicker has a 5" speaker diameter. I had a chance to open up one of the sub enclosures while I was working on other stuff this past weekend and I took some measurements. That shelf is about half way down the opening and is what gets most people hung up. Some have cut it off (stupid move since you have now compromised the enclosure) and others have used a heat gun and some 'gentle' persuasion to round it out a bit. When you look in the door where the sub enclosure fits, the opening does not need a shelf and the window doesn't go near it so, rounding it out would be my choice.

3.5 Inch top mounting depth at shallowest point (bottom of door)

Shelf in the upper right quadrant of opening in Drivers door. Passenger door would have it in upper left.

Nice 7.25-7.5 inch cutout diameter. Shelf sticks out about 2 to 2.5 inches from the edge

 

Hmm...strange indeed. Stupid question but did you confirm the +/- on the rears with a VOM or do they sound ok other than the lower output?

 

I am using IMC AUDIO 72-5600 harnesses, all four speakers, so there is no hooking them
up backwards. Yeah, they sound fine if I fade all the way back, they even have some
bass kick to them.

Even if they were hooked up backwards, both, they would sound fine, but the imaging
would be wrong, airy treble, and bass suffers because the speaker pulls in bass instead
of kicking outward. Anyhow, no they are hooked up right... Some people can't even
tell the difference when every speaker is hooked up backwards.

 

 

Thing is, if you hook up GOOD Subs backwards in a plexiglass bandpass enclosure,
some experience people may not hear the difference. I had a 4th order bandpass,
where you can see the subs through the plexiglass. I hooked them up backwards
to see, and the bass was not too different. One of the only ways you can tell is
to stick a corner of a sheet of people half way over the port. If it pulls in first, then
out, it's correct. If it's pushed out, then pulled in, it's wrong. It takes so much power
to drive these type of speakers because the speakers need it to push because
of the unforgiving plexiglass. So, hooking them up wrong, it's still harder to move
the cone with the sealed plexiglass in front of the cones. I have experimented with
all kinds of stiff. I even mounted a sub in a drum set TomTom.. Worked...

 

Llke this? I just saw this recently in my sub research...interesting.
http://drummagazine.com/yamaha-skrm-...kick-reviewed/