Reception problems can degrade an NTSC picture by changing the phase of the color signal (actually differential phase distortion), so the color balance of the picture will be altered unless a compensation is made in the receiver. The vacuum-tube electronics used in televisions through the 1960s led to various technical problems. Among other things, the color burst phase would often drift when channels were changed, which is why NTSC televisions were equipped with a tint control. PAL and SECAM televisions had no need of one, and although it is still found on NTSC TVs, color drifting generally ceased to be a problem for more modern circuitry by the 1970s. When compared to PAL in particular, NTSC color accuracy and consistency is sometimes considered inferior, leading to video professionals and television engineers jokingly referring to NTSC as "Never The Same Color", "Never Twice the Same Color", or "No True Skin Colors", while for the more expensive PAL system it was necessary to "Pay for Additional Luxury".