# Amp powers on, no sound from sub



## therover1991 (Dec 4, 2011)

I recently hooked up an alpine pdx m6 amp to my cda 117 headunit. The m6 is running a swr1043 however when i turn the car on there is absolutely no sound coming from the sub. but the odd thing is when i turn the car off the sub makes a loud thump. I also have a pdx f4 hooked up driving my door speakers and both amps turn on no problem and the f4 plays the door speakers flawlessly. 

I have the subwoofer set to on on my headunit and on the amp i have the low pass filter set at 80hz with the gain about half way up and no sound at all. Ive tried switching wires, checking all connections, wired up sub to alpines diagram specs. If anyone has any input id greatly appreciate it.


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## bigfdaddy (Dec 29, 2009)

Sounds like not receiving signal through rca.the thump is the amp turning on and off.so its getting a signal from head unit to come on.if its not the rca could be bad speaker outputs on the amp...

Sent from my SPH-D710 using Tapatalk


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## therover1991 (Dec 4, 2011)

thanks for the advice. however I plugged my mp3 player to the amp via rcas and sound played from the sub, and when i reconnected my radio to the amp the sub began to play but very low even with volume and gains turned up. im really at a loss.


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## azngotskills (Feb 24, 2006)

you may have bad sub preouts or a damaged RCA cable going to the subwoofer amp


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## shortydoowop138 (Oct 15, 2011)

Try switching the RCA's.. Depending on how they're ran you might not be getting a good signal cuz 1 is damaged.. Try adding a 1 female to 2 male splitter to then end of the RCA to see which end is bad..


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## 07azhhr (Dec 28, 2011)

You can also try temporarily using one of the other sets of RCA's that are being used for the 4 ch amp. Just be sure to turn off the HPF going to that set of RCA's.


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## joemk69 (Dec 3, 2010)

Check your headunit settings and make sure 
1- The sub is turned on and
2- Check the sub level control


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## therover1991 (Dec 4, 2011)

ok so i tried all my rcas in the sub amp and none put out a signal. i then tried the sub rca in my 4 channel and they work. So i am assuming there is something wrong between the amp and the sub but I do not know what.


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## therover1991 (Dec 4, 2011)

thanks to everyone for their help I got it up and running however the sub still makes a pop when I turn it off.


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## 07azhhr (Dec 28, 2011)

Glad to hear that you found the problem. So what was it?


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## OldSchoolAudioandVideo (Nov 14, 2011)

You shouldnt get that pop. Amps these days dont do that. 
Sounds like there may be a problem with the amp or the RCA wire to the amp is grounded. 

Try turning off the car but leaving the radio on. 
Still a pop? 
Does the pop only happen when the radio is turned off?
Also usually when there is a pop like this , the amp also pops just before it cuts on, but not as bad.
If so, you should make sure the amp chassis is not grounding ( screwed ) to metal and make sure the amp rca wiring is good. 
Its possible that you may have a bad amp.


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## therover1991 (Dec 4, 2011)

07azhhr said:


> Glad to hear that you found the problem. So what was it?


i just kept playing around with the wires and settings. The speaker wire inside the sub box kept coming loose so I think that it wasnt making a good connection or even a connection at times so I replaced it with a longer run of wire and it worked lol.

The static in my door speaker was because my rca cable at the headunit was loose so I just made sure it was on tight and it worked fine.


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## therover1991 (Dec 4, 2011)

OldSchoolAudioandVideo said:


> You shouldnt get that pop. Amps these days dont do that.
> Sounds like there may be a problem with the amp or the RCA wire to the amp is grounded.
> 
> Try turning off the car but leaving the radio on.
> ...


I do not believe its the amp being screwed to metal because I have 4 rubber feet underneath it to keep it raised. 

When I turn the car off and the radio is on their is no pop. But once I open my door and the radio cuts off the pop happens.


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## OldSchoolAudioandVideo (Nov 14, 2011)

Does it happen when you just turn the radio off and the car is still on?


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## therover1991 (Dec 4, 2011)

OldSchoolAudioandVideo said:


> Does it happen when you just turn the radio off and the car is still on?


That I have not tested out yet. I know for a fact it happens when the car is off and the radio turns off when I open the door.


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## OldSchoolAudioandVideo (Nov 14, 2011)

Also try this
Unplug the rcas from the amp but leave the everything else plugged in so the amp turns on.
Then try to make it pop.
If it does NOT, Then you found the problem, Its the RCA connection. Your amp is either broken or being grounded to through the RCAs,
If the amps pop with our without the RCA's plugged in, the amp is damaged. 
Amps these days have a turn on delay that dont allow that pop to get to the amplification section of the amp so you shouldnt get that noise

Back in the day, it was very common. I had 4 Orion 15's in a bandpass box in a quarter shell of an S10 on about 1000 watts. WHen I turned the truck off it was like a SPL burp. LOL Aggrivating


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## therover1991 (Dec 4, 2011)

OldSchoolAudioandVideo said:


> Also try this
> Unplug the rcas from the amp but leave the everything else plugged in so the amp turns on.
> Then try to make it pop.
> If it does NOT, Then you found the problem, Its the RCA connection. Your amp is either broken or being grounded to through the RCAs,
> ...


So unplug the rcas and do everything normal and if theres a pop then its the amp? and if no pop im gonna need new rcas correct?


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## OldSchoolAudioandVideo (Nov 14, 2011)

therover1991 said:


> So unplug the rcas and do everything normal and if theres a pop then its the amp? and if no pop im gonna need new rcas correct?


Thats right.

OR the amps RCA inputs are bad

OR the RADIOS RCA outputs or bad


If the amp DOES NOT POP and the RCA's are removed.
Tempoararily use a diffferent set of RCA cables and redo the pop test.

Id even go so far as to use that 4 channel amp ( one channel ) on the sub ( connected to the sub outs of the headunit ) and see if it still pops.
If that sub still pops and you have now used an entirely different amp, then you KNOW its either the RCA cables or the head unit.

As you can already hear from the 4 channel ( on your door speakers ) there is no pop. This is how it is suppose to be. So , you already know that amp is working fine. Use one channel on that amp to test the pop. Just maek sure that amp channel can handle the ohm load on that sub. You dont have to turn up the amp. Just connect it to the sub and the headunits sub output.


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## therover1991 (Dec 4, 2011)

OldSchoolAudioandVideo said:


> Thats right.
> 
> OR the amps RCA inputs are bad
> 
> ...


I would like to think the amps rcas and such are fine considering it is brand new but you never know. 

Thanks for all the info, Im gonna test it out tomorrow because I have work for most of the day. Will post back when I figure out anything further.


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