This replaced the stock C12K Jensen in a ‘65 Deluxe Reverb. I have a second identical amp that still has the stock Jensen, and the difference was like night and day. The Ruby made the Jensen sound, to me, muddy, incoherent and unfocused. There might be variations between the two amps but these should be minor. The Ruby delivered poise, control, definition and clarity, from the tight lower frequencies to a wonderful, detailed, ringing top end.
The woeful performance of the stock Jensen worked out rather well for Lean, as I had little option but to order another Ruby to replace the humbled Jensen.
The Ruby is a very recent addition to the Celestion alnico range. It has much to live up to, but on this showing Celestion should be congratulated. The Ruby is a winner, and highly recommended.