Ok, thought I'd post this here cuz I'm baffled:

Yesterday, I installed a 10" Infinity Kappa Perfect in the trunk of my TSX. There is plenty of power going to it, but it just doesn't seem to be "puching" as hard as it should. Here are the details:

-Infinity Perfect 10" (10.1): 4 ohm, SVC, 300W RMS.

-Sealed enclosure : 0.66 ft^3, recommended sub volume is 0.6 ft^3 (could this tiny difference be the problem??)

-Infinity Reference 7521A amplifier, bridged: 287W RMS

The RCA cables are taken from the RCA ouput of my other amp (Pioneer 6100F) and fed to the input of the Infinity amp.


The following might be good clues, or might not be related to the problem at all:

There is a 'clipping' LED on the front of the Infinity amp, and it starts blinking as soon as the gain knob is turned even 1/4 of the way up.

With just the Pioneer amp powering my regular speakers, I did not have ANY noise. Now with the Infinity amp powering the sub, I get alternator whine (this is the weird part) through the regular speakers (they aren't even hooked up to the new amp, except through the RCAs that go from amp to amp).


now, the sub plays just fine. It just doesn't have much "umph" to it. With the volume as loud as it'll go, you can stand outside the car and barely tell that there is a subwoofer attached. I've checked the polarity of the speaker wire, and it doesn't seem to make much difference either way (i'm pretty sure it's hooked up the right way anyhow)

Any help would be greatly appreciated.

 

Are you getting you input signal to the Pioneer amp from the factory deck(before the factory amp) or after the factory amp? If you are using the signal from after the factory amp to the doors, this signal has a high pass filter on it and explains the loss of bass in your sub.

 

^yes, I am pulling the signal directly from the HU. Totally bypassing the factory amp.


One thing occured to me: I am using balanced RCA connectors, and inputs on the Pioneer are designed for balanced signals.

Now, assuming that the Pioneer just passes that balanced signal along to its RCA outs, the Infinity amp does not accept balanced inputs. Could this be causing the problem? Somehow the balanced signal is getting misinterpreted by the Infinity amp, and causing attenuation??


this is driving me nuts.

 

A balanced signal wouldn't be causing this. Does you Pioneer amp send a full signal out or does it mirror the settings on the amp. Some amps will send the same frequencys or the opposite signal out. Basically that means if you have the amp set up for high pass it could be sending the same signal out and some amps have it were it sends a low pass signal out depending what the amps crossover is set at. Could be that the Pioneer's RCA output are very weak and not driving the sub amp with enough voltage.
Try and plug the RCA's from the deck directly to the sub amp and see if the bass seems alot louder.

 

thanks for your input.


The Pioneer supposedly passes an unaltered signal to its RCA out. Either way, I have the Pioneer amp setup to full range on all channels, so it shouldn't be an issue.

Connecting the rear RCAs directly to the Infinity amp will be the first thing I try when I get off work, hopefully that will fix it.

I agree with you, and it was my first thought too that the problem is with the RCA signal coming into the Infinity amp. It seems like the signal coming into the Infinity amp is much lower than the amp thinks it is. Which is why it's driving it into clipping, even when the sound is not very loud.

 

this may be dumb, put check the polarity of the wires going to your sub... i had a similar problem once and realized the installer connected the speaker backwards...

 

also, just check to make sure you aren't sending a crossed signal out of pioneer amp, sometimes theres a little swtich on there to change it (i.e.. high pass/low pass/full range)

 

thanks for the suggestions everyone.


The signal coming out of the Pioneer is not crossed over in any way.

I reversed the polarity of the sub wires just for giggles, and honestly I couldn't tell much of a difference either way.

Still kinda baffled by this...

 

I'd hook the sub up to the Pioneer amp and see if that gives any clues. Like, disconnect the rear speakers, and bridge the amp, assuming that the amp supports that. (Or just hook the sub up to one channel.) In this way, you can try to isolate the problem and find out if it even has anything to do with your other amp.

As far as wiring backwards, sometimes you want to reverse the polarity on purpose, because with the distance between the sub and your ears, it's possible for there to be a noticeable phase change that could interact with the other speakers.

 

thanks for the ideas everyone. I've made a list of things I'm going to try, in order from simplest to most complex.

I'm determined to nail this thing this weekend, and I will report back in hopes of maybe helping someone out who's in similar predicament.