No Sound Rear Speakers Help

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I've recently bought a 4 channel amp (Hifonics HFI 55) and tried hooking my Polk Audio db651s speakers to it. Front left/right speakers emit sound okay, but the rear left/right speakers only have a low sounding base coming from them.

My head unit is a Pioneer Avic U310BT. The amp kit I'm using is Monster cable. I have speaker wires running from each speaker to the amp directly. Two RCA cables (one set of two for the front and back, total of four) running from amp to the back of the head unit.

What am I doing wrong? Should I disconnect the speaker wires from the head unit's wiring harness, since they're not connected to the speakers anymore?

I'm also planning on adding a amplified Bazooka tube. I was going to wire this to the rear speaker wires from the head unit, since all four RCA inputs are taken by the amp. I have yet to do this, 'cause I'm trying to get all four speakers to work first.

Please help.

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Originally Posted by TOLMACH

Sounds like LPF (low pass filter) is engaged somewhere: either at the head unit or at the aplifier that "cancells" everything above the cross-over point (usually 40-120 Hz)

Check the crossover panel at your amp .. if no cause is found, check HU settings | correct RCA pair at the HU back

Re hi-level speaker cables from the HU to the speaker - why would you connect them if you have amp? No need to disconnect , but make sure the internal amps of te HU are switched off (if your HU allows it, check seetings) to save power and prevent HU "heating"

Hi thanks for the info/reply. Unfortunately none of it worked. I did however manage to get sound on the rear speakers, but not the way I wanted to.

I basically hooked up only one set of RCA cables to the front L/R inputs of the head unit to the amp, and switched my amplifier from 4 channel mode to 2 channel mode. Now there's full range sound in all four speakers. I'm leaving the other RCA inputs for my amplified Bazooka sub (BTA6100). Can I leave it at this setup, or will it break something?

Thanks for all the help.

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But I really wanted to use the 4 channel mode to drive all four speakers. My current setting is set at 2 channel mode for all four speakers. I guess if it works, it works right?

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Originally Posted by TOLMACH

But each speaker is connected to its own channel at the amplifier, right?

Yes. But I really wanted to run the amp in 4 channel mode to run all 4 speakers. Instead I have to run the amp in 2 channel mode to have all 4 speakers having full range sound.

This is my setup:

-4 speakers connected directly to 4 channel amp
-One pair of RCA cables connected from amp to back of head unit
-Amp in 2 channel mode.

[RawrDaddy]

You would need those two RCA plugs if you got the Bazooka tube btw.

so I may suggest to keep it in the 2-Channel mode if it seems to be working.
..just to keep the installing of the bazooka a little less messy when you get it.

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Problem solved - my Pioneer headunit's preout setting was set as "sub" for subwoofer, changed it to "rear" and now all four speakers get full range sound on 4 channel mode in the amp.

Thanks for all the help.