When I say classic, I meant the classic from 1800's, you know when Volta, Faraday and other were experimenting with different wet/dry electrolytes between the zinc/copper discs. Citric acid as electrolyte holds 1.2V and is easy to buy from you local supermarket.

https://en.wikipedia.org/wiki/Voltaic_pile

So there you have a third datum confirming that the voltage is dependent on the materials used.