Could be a busted little capacitor on a filter or pre-amp stage… charging/discharging spontaneously.

Could be a lot of things really, easiest way to track it down is to rip it open, use an oscilloscope to work out which component it starts from.

Good news – it’s unlikely to be the main amplifier (usually a single integrated component with lots of legs).

Having said that, check it’s definitely the amp and not a dodgy cable or instrument plugged into the amplifier – try swapping the input cables around and see if the fault follow the leads (if it does, then the cable is faulty, not the amp).

@DaftFader 498700 wrote:

make sure to leave the amp unplugged for a fair while before opening it (if you decide to do this)as the capacitors can hold a dangerous charge for some time after you unplug it.

A fair safety point, but a quicker way is to run an earthed insulated cable over the circuitry before you touch it with bare skin. Dumping it on a earthed metal draining board like a kitchen sink area prior to examination will do the same thing. Sparks and pops though.

Capacitors can hold charge for quite a while. I’ve played with some very dodgy gear that wouldn’t drain away after I’d left it for 3 days or more.

I had forgotten that “amp” covers a wide variety of equipment – you can get some pretty nasty injuries or even die messing around with the big gear if you don’t know what you are doing.

@BeanieT 498668 wrote:

hey peeps just after sum advice on what could b causing my amp to give out a heartbeat sound though 1 channel when no music is playing? 🙁 any help would be greatfull

another thought, as well as posting up the full info about this amp (which could be anything from part of a hi fi system to a pro audio amp) perhaps use a portable audio recorder if you have one or the video / sound recorder on your smartphone to record the offending noise, and post it up to soundcloud? that way we can all listen to it – a variety of faults can make these noises – or it could be part of the design for larger power amps with switch mode power supplies…