Audio system cutting in/out

So I have had this issue with the truck since day one. When i bought the truck previous owner had installed some sort of aftermarket system controlling the sound as far as I can tell its got the stock ford sync system with zapco equalizer some amp under rear seat two tens and jbl speakers in doors and kick panels. Every time I turn the volume to a moderate volume and lower it will act like the signal is lost (only dash speaker works) turn volume up a tad amp kicks back on system works again. If I turn the system up to a rock your socks level it's fine. Never shuts off. I'm not familiar with the sync system and how it sends a signal to the amp but is it possible that there's some sort of device that intercepts/notices output to speakers and kicks the amp on rather then just a switched 12v amp on controlling the aftermarket??

usually its the opposite. loud volume cuts the sound out. without knowing what equipment you have and how it is wired into the system, its going to be difficult to troubleshoot

It's almost like when u have the volume turned down to what I would call a moderate to quiet level it will not recognize the input and no sound will come from the jbls however the center dash speaker still has sound then as soon as you turn the volume up any at all it kicks back on. I've looked a little bit and I can see there are crossovers running the jbls and a zapco equalizer I still have to pull the box from under the seat to see what all is down there. How r the sync systems normally interfaced with aftermarket amplifiers?

Its probably using the sense on from the head unit to the amplifier instead of on/off...

Icecobra said:

Its probably using the sense on from the head unit to the amplifier instead of on/off...

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I'm not familiar with the sync system but yes that what it sounds like it is doing "sensing" audio input to kick the amp on rather then a simple "on/off" source. Guess I need to start tracing from my amp back to HU

the center speaker will work because they did not disconnect it when upgrading the system. unplug that pos and get rid of it. you can connect the amp trigger wire to an accessory wire and see if that changes anything. if they used a signal sensing trigger, it may cause this problem you are having

Take and wire the amplifier to on constant to test and if you can adjust the volume the problem is the sensor on the amplifier..