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Amp shuts off at high volumes

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Amp shuts off at high volumes

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When I turn the volume up to a certain point (12 of 30 volume), the amp will begin to turn my sub & speakers on and off.  I checked all of my connections and they seem fine.  I double checked my ground point and its good as well.

pioneer AVIC z120bt

Pioneer Amp gm-d9500f

  • 75 watts RMS x 4 at 4 ohms (100 watts RMS x 4 at 2 ohms)
  • 200 watts RMS x 2 in bridged mode (4-ohm stable in bridged mode)

Pioneer TSSWX251 10" sub (200w RMS)

Polk Audio DB651S (55w RMS )

 

What should I do?

Verified Answer
  • Chowee21
    I have my amp mounted on the underside of the rear deck, is it possible that this is causing it to shut off? It will shut off even the the unit is cold so I don't think its over heating.

    Mounting amps upside down is a BAD idea.  Heat rises, right?  Instead of the heat going up to the heatsink, its lingering in the circuit board.  The amp may feel cold only because heat is not being transferred out of it.  If you've had it that way for a while, you might have damaged the amp.

    Chowee21
    I had my volume at 3/4 & I was adjusting the gain on the sub (with the front channels unplugged) and it still was shutting off even if I turn the gain up a little.

    Okay you said you got 3.8 ohms on your speakers, and that's great.  Did you measure the sub?  If the sub isn't 4 ohms (or close enough to it) it will shut your amp down over and over. 

    Since you know the other side of the amp isn't causing the shut-down, you may want to try bridging your sub to the front channels and see if it's the rear channels that are messing up.

    Chowee21
    I also took some jumper cables and ran them from the battery to the piece of metal that I had the amp grounded to and it still did it.

    Seems like you're still having some doubts about your cables.  If you want to be REALLY thorough, this is the absolute end-all most accurate way of measuring voltage drop: 

    1. Hook the jumper cable back up to the negative battery terminal and run it back to where the amp is.  Make sure it's got a really good bite on the battery.  In the interest of safety, you want to connect only one (POS or NEG) at a time to prevent a dead short. 
    2. Set your DMM to DC volts.
    3. Connect one probe to the NEG amp input, and the other to the booster cable. 
    4. Play some jammin tunes, or preferably a 50hz test tone and the DMM will display your voltage drop on the ground wire while the amp is playing.  See what the reading is with the test tone right before the amp cuts off.
    5. Repeat steps 1-4 with the POS battery terminal and the POS amp input. 
    6. A reading of 0.5 volts or higher indicates you have too much resistance in the respective cable.

     

  • kratebiker
    Install the amp properly, not upside down.

    While not totally recommended - there are ways to make this work also - get some long bolts and spacers and hang the amp right-side up from the rear deck with an inch or so of air space above it.

    This way the cooling fins on the amp still work and you still have the floor of the trunk available with the amp semi-hidden.

    Hope This Helps!!!

    Anyone else have suggestions?

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

All Replies
  • First and foremost, make sure you are using a large enough positive wire connected directly to the battery.  If the ground point is as good as you said, then do the following:

    1.  Fire up the amplifier to a level that makes it shut off.  Then, very carefully touch the top of the amplifier (don't burn your hand!).  If the top of the amplifier housing is very hot to the touch, you may want to try a different location for the amplifier with better ventillation, which should solve the problem.

    2.  I would also try other ground locations and make sure that is not the problem.  The way you are describing the problem....it is either due to overheating or the ground location may not be suitable.  Both can cause an amplifer to act up as you describe.

    I was on a recent road trip over the Easter holiday, and after two hours of continual listening at mid to very high volumes, my four-channel amp shut down.  I checked the top and it was extremely hot.  I have excellent ventilation around the amplifier (three feet of air space), so I simply let it cool down for a few minutes and was enjoying solid music for over four more hours of driving.

    If none of these solutions work, there may be a problem with the amplifiers overheat protection circuitry.  Good luck!

     

    "Just a world that we all must share.  It's not enough just to stand and stare..."        Pink Floyd   On the Turning Away

     

  • Chowee21
    When I turn the volume up to a certain point (12 of 30 volume), the amp will begin to turn my sub & speakers on and off. 

    This indicates the voltage is dropping.  Grab a digital multi-meter and set it to 20volt DC.  Touch the probe ends to the Pos and Neg inputs on your amp.  Play it at a volume just before the point it starts turning off and measure the reading.  If it's going below 12 volts (particularly pay attention to when the bass notes hit) than you may have too much resistance in your positive or negative cables.  If you get a low reading i'll explain how to isolate the problem.  

    Less likely, but it can also be due to your remote turn-on lead.  If your power and ground check out, keep it playing and touch the probes to the ground and REM inputs on the amp.  Again, it should stay above 12 volts.

    If no voltage drop is found, you need to check the impedance of each individual speaker connected.  Power off the system.  Disconnect the speaker wires from the amp and set the DMM to the lowest impedance setting (usually 200 ohms).  Probe each speaker's Pos and Neg lines and you should get a reading of approximately 4 ohms for all 5 speakers in your system.  If you find one that is suspiciously low or high, disconnect it and try playing the amp with the other 4 speakers playing.  If it doesn't shut down, the disconnected speaker or the wire going to it has a problem. 

     

  • Not extremely petinent, but are there four Polk speakers and one Pioneer sub, or only two Polk speakers (on the amp front channels) and a Pioneer sub on the bridged amp rear channels?)

    Thanks!

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • only two Polk speakers (on the amp front channels) and a Pioneer sub on the bridged amp rear channels

     

    I checked the voltage in and they both are reading between 11.5-12.2 volts.

  • Chowee21
    I checked the voltage in and they both are reading between 11.5-12.2 volts.

    You checked while the bass was hitting, right?  They are both changing that much?  A healthy battery should read over 12 volts at all times.  Take it to an auto parts shop and get them to test your battery for you.  May as well get the alternator checked while you're there (most major chains will do this for no charge). 

    If your saying the battery is over 12 and the amp is dipping down to 11.5, you've got a serious kink in your power chain.

     

  • The Power to the Amp was reading at over 12 and the remote was reading below 12. Sorry I didn't clarify that

  • No problem.  The MECP guideline for acceptable voltage drop is no more than 0.5 volts, so i almost shouted BiNGO when i saw 11.5-12.2.  Not totally sure you did the procedure right, cuz 11.5 is pretty low.  What about with the engine running?  Can you get the amp to turn off then as well?

    The next step in fault isolation would be checking speaker impedance.

  • Okay, sorry to get your hopes up, but here is what I just got for readings:

    Car on ACC:

    Remote Voltage: 11.2-11.3

    Power Voltage:12.0+

     

    Car Running:

    Remote Voltage:13.8+

    Power Voltage:13.8+

     

    Speaker Ohm: ~3.8 ohms for both

     

    I did adjust my gains & freq and that has helped to.

     

  • If those are your voltage readings at a volume just before the amp shuts down, than voltage drop is not the issue.  Your power and ground are very strong to get 13.8 at the amp! 

    Chowee21
    Speaker Ohm: ~3.8 ohms for both

    The sub should also be about 4 ohms. 

    Chowee21
    I did adjust my gains & freq and that has helped to.

    If adjusting the gain is the only thing that's getting you somewhere, let's get it dialed in just right.  Try the DMM method for setting the gain.  I've typed up this method several times so here's a link to one of them or you can do a search for "DMM gain setting".  The target for 200 watts at 4 ohms is 28.3 volts AC.

     

     

  • I have my amp mounted on the underside of the rear deck, is it possible that this is causing it to shut off? It will shut off even the the unit is cold so I don't think its over heating.

     

    I had my volume at 3/4 & I was adjusting the gain on the sub (with the front channels unplugged) and it still was shutting off even if I turn the gain up a little.

     

    I also took some jumper cables and ran them from the battery to the piece of metal that I had the amp grounded to and it still did it.

     

    All of my voltages are hitting over 13.

     

    any ideas?



    [edited by: Chowee21 at 11:02 PM (GMT -5) on Sat, May 7 2011]
  • Chowee21
    I have my amp mounted on the underside of the rear deck, is it possible that this is causing it to shut off? It will shut off even the the unit is cold so I don't think its over heating.

    Mounting amps upside down is a BAD idea.  Heat rises, right?  Instead of the heat going up to the heatsink, its lingering in the circuit board.  The amp may feel cold only because heat is not being transferred out of it.  If you've had it that way for a while, you might have damaged the amp.

    Chowee21
    I had my volume at 3/4 & I was adjusting the gain on the sub (with the front channels unplugged) and it still was shutting off even if I turn the gain up a little.

    Okay you said you got 3.8 ohms on your speakers, and that's great.  Did you measure the sub?  If the sub isn't 4 ohms (or close enough to it) it will shut your amp down over and over. 

    Since you know the other side of the amp isn't causing the shut-down, you may want to try bridging your sub to the front channels and see if it's the rear channels that are messing up.

    Chowee21
    I also took some jumper cables and ran them from the battery to the piece of metal that I had the amp grounded to and it still did it.

    Seems like you're still having some doubts about your cables.  If you want to be REALLY thorough, this is the absolute end-all most accurate way of measuring voltage drop: 

    1. Hook the jumper cable back up to the negative battery terminal and run it back to where the amp is.  Make sure it's got a really good bite on the battery.  In the interest of safety, you want to connect only one (POS or NEG) at a time to prevent a dead short. 
    2. Set your DMM to DC volts.
    3. Connect one probe to the NEG amp input, and the other to the booster cable. 
    4. Play some jammin tunes, or preferably a 50hz test tone and the DMM will display your voltage drop on the ground wire while the amp is playing.  See what the reading is with the test tone right before the amp cuts off.
    5. Repeat steps 1-4 with the POS battery terminal and the POS amp input. 
    6. A reading of 0.5 volts or higher indicates you have too much resistance in the respective cable.

     

  • J Ro
    Did you measure the sub?  If the sub isn't 4 ohms (or close enough to it) it will shut your amp down over and over. 

    Aw ha! The sub SAYS it is at 4 ohms on the specs, BUT the sub itself is producing about 2.5-2.8 ohms.  What should I do about this?

    I actually TODAY am getting rid of the TS-SWX251 and installing a Polk Audio DB1040 sub.

     

    J Ro
    Mounting amps upside down is a BAD idea.  Heat rises, right?  Instead of the heat going up to the heatsink, its lingering in the circuit board.  The amp may feel cold only because heat is not being transferred out of it.  If you've had it that way for a while, you might have damaged the amp.

    I haven't had it this way long at all, maybe a week or two.  What if I install cooling fans on either side of it?

     

    By the way, Thanks J RO, I know a lot of my questions are fairly fundamental, so thanks for bearing with me and not criticizing for my stupidity!

     

     



    [edited by: Chowee21 at 1:34 AM (GMT -5) on Sun, May 8 2011]
  • Chowee21
    the sub itself is producing about 2.5-2.8 ohms.  What should I do about this?

    There's really nothing you can do.  I can't find a Revc (tells what the ohms should read) spec for that sub.  I checked Pioneer's website and the link is broken.  It may be normal, but it does seem low.  A sturdier 2 channel amp might not have a problem with it, and any mono amp would be able to handle that load. No 4 ohm sub i've used has given a reading below 3.4 ohms. 

    Chowee21
    I actually TODAY am getting rid of the TS-SWX251 and installing a Polk Audio DB1040 sub.

    I read your other post (the plastic bucket remark still makes me chuckle) and i think you'll be a lot happier with a traditional sub and a larger enclosure. The Polk's are BOGO 1/2 off, are you getting 2 of them?  A 500 watt mono amp and 2 of those would slam.

    Chowee21
    What if I install cooling fans on either side of it?

    That seems like a lot more work than just mounting it right side up.  If its not hot to the touch, cooling fans won't do anything.

  • Install the amp properly, not upside down.  I suggested earlier that the amplifier may be overheating, causing the shutdown.  Mounting an amp upside down will cause this.  Do an experiment.  Remove the amp from its current position, make sure its oriented right-side-up and fire it up again.  Hopefully that will solve the problem.  Then just make sure it has adequate ventillation wherever you install it.  Good luck!

    "Just a world that we all must share.  It's not enough just to stand and stare..."        Pink Floyd   On the Turning Away

     

  • kratebiker
    Install the amp properly, not upside down.

    While not totally recommended - there are ways to make this work also - get some long bolts and spacers and hang the amp right-side up from the rear deck with an inch or so of air space above it.

    This way the cooling fins on the amp still work and you still have the floor of the trunk available with the amp semi-hidden.

    Hope This Helps!!!

    Anyone else have suggestions?

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs