The 12AY7 and 6072 are the tube designations for a dual triode with medium gain that shares the same pin-out configuration as the 12AX7 and its variants. Pretty boring as a description goes. To put it differently, the 12AY7 can often replace a 12AX7 in your amplifier and give you a rich, warm tone with lower gain than a 12AX7. (View our gain comparison chart for similar compatible dual triode tubes).
The 12AY7 tubes are not 12AX7’s and have many different properties. They draw more current than a 12AX7 as well as having different internal capacitance between elements and a different plate dissipation. Because of these differences, they sound different in a circuit designed for a 12AX7 tube. The 12AY7 tube could cause problems in related gain stages by changing the operation of those other stages, but this is rarely an issue.
All things considered, the 12AY7 has what I would call a blues sound. Warm, rich, and smooth while still delivering a good strong signal.
Electro-Harmonix 12AY7EH / 6072 and Electro-Harmonix 12AY7-EH / 6072 Gold - The Electro-Harmonix brand is well established and produced in Russia. Compared to products from the USA, it has a smaller plate structure and a fatter glass envelope. The sound quality is very good and the price is excellent. Sonically the tone is all American, making it an affordable alternative to something from Westinghouse or Sylvania. Not as sensitive or bright as a Russian 12AX7, while providing smooth mids and ample bottom end. If you are experimenting with gain, this is the one you want. The only difference between the standard model and the gold, are the gold plated pins. If you have problems with corrosion, it would be worth a few extra dollars to go with the gold.