Flipping record causing series of loud pops

 Static electricity with the vinyl record and the cartridge as you flip it? I have owned tube phono stages for decades an have never had any pops. Does it seem controllable with flipping... or does it just happen if it sits there? I assume the table is grounded. 

You left the volume UP flipping records?

You say you swap, you have a switch or have to swap leads?

Make sure the ground and the leads are tight and plugged in all the way.

It's new? After it's warmed up tap the valves with a pencil. Make sure the volume is down. Up to two weeks to find out if transportation caused valve damage. It's just the cost of transporting valves via shipping..
Pull and reseat the valves..

If the timing of the "Pops" is random something is loose. Is something being shaken when the pops occur? Are you moving the tonearm?

Little more feedback about what you are doing..

Regards

The solution is what you are supposed to always be doing regardless- mute or change the input before doing anything with the turntable.

Interesting. Never heard this one before. It sounds like the record is discharging to the plater when you lift it up. So first off you have a static problem. Get a conductive brush for cleaning the record and short it to ground with a wire. Discharge the record before you pick it up and see if the popping stops. If it does disconnect the ground wire from the phono stage, play another record and without using the brush pick up the record. If the popping is gone and the system does not have a hum you are all set. If the popping is gone but you have a hum I would say the design of that phono stage is bad or it is defective in some way. The choice of what to do is yours. Either way you have to create a system to defeat static. Using the brush before and after play is fine. I use a conductive sweep arm that cleans and discharges the record during play.