playing with russian ROD valves.

[Nick]

Hi Amie.
Cannot say I've had trouble in that way. I did have some issue when I made an RIAA equaliser and preamp for my Pye Black Box to enable the use of a low output ceramic cartridge. The issue was hum, I tried everything till I screened the valve with some thin steel tube of the correct diameter which effected a cure, it was caused by stray magnetic fields from the gram motor.

Picked up a few sheets of mu-metal some time ago - very useful stuff to have around although you have to be careful how you bend it else it can lose some of its effectiveness.

Foil is also available, e.g. https://www.ebay.co.uk/itm/171173026902. The stuff I have is stick-on - I got it to line the inside of very low noise pre-amps.