II Kings 16:14

And the Copper Altar … he brought, etc. It is impossible to say that this was the Copper Altar that Moshe made, because it was hidden. It is also impossible to say that his was the stone altar that Shlomo made, and he called it the “Copper Altar,” because it was impossible to move it from one corner to another without taking it apart, but we learned that the fire that descended in Shlomo's time, did not leave the altar until Menashe came and removed it, for he demolished the altar, as we find in the Aggadah of [the chapter entitled] “Cheilek.” I have no way to explain this “[copper] altar” except as [referring to] the basin and the bases of copper, which were accessories of the altar and were near the holy altar. Now, when Achaz made the altar for the idols, he removed the basin and moved it to another side, [farther] away from the Temple, so as not to intervene between the altar he made and the Temple of Adonoy, and he placed it next to the holy altar on the north. We find that our Rabbis explained a passage in a similar manner, ”And they came and stood next to the Copper Altar.” Did the Copper Altar exist? He said to them, ”Begin from the place where they recite songs before Me.” Thus we see here that copper musical instruments are referred to as a “[copper] altar.”