Speaker pop and phono amp

[da2222]

Hi

I'm currently having rather annoying problem with my phono set up that I hope someone might be able to help me with... A single 'pop' is emitted through the speakers every 20 minutes or so. Loudness is dependent on the amp volume setting. It sounds like the release of static build up but I’m not sure if it is, or indeed, the cause. A dodgy cap maybe? I'm pretty sure I’ve isolated it to the phono amp as it only happens when both amps are actively playing music or indeed, on idle with the TT off. It doesn't occur when I switch the power amp (valve based 300b) to my digital source so it can't be a tube issue. (I've also checked the various cables) The phono amp is a Valab LCR. Any tips that might help me locate the problem would be appreciated.

[Light Dependant Resistor]

Hi

I'm currently having rather annoying problem with my phono set up that I hope someone might be able to help me with... A single 'pop' is emitted through the speakers every 20 minutes or so. Loudness is dependent on the amp volume setting. It sounds like the release of static build up but I’m not sure if it is, or indeed, the cause. A dodgy cap maybe? I'm pretty sure I’ve isolated it to the phono amp as it only happens when both amps are actively playing music or indeed, on idle with the TT off. It doesn't occur when I switch the power amp (valve based 300b) to my digital source so it can't be a tube issue. (I've also checked the various cables) The phono amp is a Valab LCR. Any tips that might help me locate the problem would be appreciated.

Hi Drew
At first look this appears as the classic kitchen fridge turn on -turn off problem.
See if you can monitor the fridge to see if it is turning on or turning off at the same moment

I would check that your turntable is grounded.
Turntable grounding is discussed here: https://www.vinylengine.com/turntable_forum/viewtopic.php?t=36516

Your Valab LCR appears to have a grounding post on its rear panel, are you using that already ?

[Barry]

Fridge thermostat switching spikes would appear to be the most likely cause.

If you use a ring main and the fridge is plugged into a socket close to the socket into which your system is plugged, the problem will be exacerbated. First of all determine that the fridge is to blame. If it is, then a RIFA click suppressor can be fitted across the thermostat contacts.

[da2222]

Thanks for the replies. I’ll check out the fridge possibility though I seem to remember the sparky said my hifi sockets were linked to the light supply and not the kitchen appliance sockets. I’ll get back later, thanks again!

[hifi_dave]

Sockets to light supply - never, can't be.

[da2222]

Sockets to light supply - never, can't be.
Hi

I may may be wrong of course but I seem to remember the electrician mentioning that... I should say I live in Italy where bathrooms are regularly filled with plug sockets above and below sinks!!!!

[hifi_dave]

No idea of the regulations in Italy but I doubt that sockets would be on a lighting circuit.

[da2222]

Just checked... the sockets aren’t connected to the lights circuit. There are 5 different circuits in the block and the one I use for hifi is for the 10 amp rated plugs in the house while the fridge (and others) are connected to the circuit for 16 amp sockets...

[Barry]

Are the fridge and your system separated by a wall? Even though they are on separate circuits, switching spikes from the fridge generate EM fields which could interfere with the more sensitive parts of your system, such as the record playing cartridge and phonostage,