Subwoofer Wiring Problem (One works well, the other barely moves)

[superbike81]

I'm going to try to give as many details as possible, so I think it will be easier in a list.

Ok, here's the problem, I've got two subs, one or the other will hit pretty good, the one not hitting good makes a small vibration, so it's getting a signal and power, but putting out VERY little bass. When I switch wiring around, the sub that wasn't working so well before works fine, and the one that was working barely vibrates.

I know enough about car audio to do an install like this myself, but I'm not exactly an expert either.

1) Running 2 SVC 4-ohm 8" subwoofers

2) Running a 4 channel amplifier bridged into two channels. Amp is PPI S580.4

3) Single sub-out on deck, Y-splitter to run two RCA's, and then two more Y-splitters to make a total of 4 RCA plugs for input on the amp.

4) Have tested two brand new amps, both work fine running my components, both have trouble with the subwoofers

5) Wiring to the subs is exact same length. Not bridged or in series, just straight from the amp to the each sub.

6) Have tried switching wires, switching channels, switching amps even, still same problem.

7) Using brand new wiring, have tried different wire as well, same problem.

8) The same symptoms occur regardless if the sub is installed in an enclosure or not.

I know this has to be something simple I'm not seeing, if you have any more questions or suggestions please share. I appreciate the help.

Thanks!

Jason

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[superbike81]

Oh, and I can "solve" this problem by turning the gain higher to one sub than the other, but then I've got one sub at about 1/4 gain, and the other at 3/4. It shouldn't be that way I don't think. Not running two of the same subs from the same amp.

 

[keep_hope_alive Premium Member]

when you switch speaker wires - does the same sub remain quieter or does it change to the other sub.

if it changes, then it's the amp - possibly bad Y-adapters

if it stays the same then it's the sub. use a DMM an measure the leads.

 

[dumple 5,000+ posts]

out of phase?

 

[keep_hope_alive Premium Member]

out of phase?

unlikely - they are SVC subs so there are no coils to wire incorrectly. also, if they were out of phase with each other they would still move equally.

if anything, one of the Y-adapters could be made incorrectly and have the pin and shield swapped - resulting in an out of phase RCA signal. that can be checked by unplugging one of the RCA's. if it gets louder with only one RCA - you should replace your cables.

 

[dumple 5,000+ posts]

i dont get why you have it split into 4 wires if the amplifier is bridged then wouldnt only channels 1 and 3 need an rca input?

 

[keep_hope_alive Premium Member]

i dont get why you have it split into 4 wires if the amplifier is bridged then wouldnt only channels 1 and 3 need an rca input?

bridging channels 1 & 2 takes the signal on channel 1 and gives that to the (+) sub terminal, then takes the signal on channel 2 and gives it to the (-) terminal. these two signals are out of phase by design so that they combine at the sub for a doubling of voltage. i can expand on this if you need.

with some amps, if you don't have an input on both channels, it's not bridging since there isn't signal on the other channel.

you can test this with a bridged amp by unplugging one of the RCA's. it should get much quieter. now, i don't recommend messing with RCA's when the amp is on. you need to turn the system off to change RCA's or you can damage the amp, head unit, or subs/speakers.