Valvecaster with 12AT7 tube

[peterg]

Is there any reason that a 12AT7 tube would not work in a valvecaster that works with a 12AU7 tube? It runs with 9V well.

[peterg]

Bump

I topped up an order of 6111 tubes to get to thhe minimum order value by adding the 12AT7/ecc81 tube with the though of getting some different sounds from my valvvecaster.

My valvecaster works great with the 12AU7/ecc82 tube but I get no sound with the AT tube. The tube lights and warms up and I don't see any loose parts inside or cracks in the glass.

I understood that the 12AT7/ecc81, 122AU7/ecc82 and the 12AX7/ecc83 tube were interchangable. Do they need different circuit components? The pins are the same.

[psychedelicfish]

12AT7s won't work at 9V, they work well at 24V though

[PRR]

These tubes are designed to run with 100V-300V power.

They are far from "interchangable", though it is true that at nominal voltages you can often sub one for another and it "works".

That the 12AU7 "works" on 9V is due to its very low leverage (low plate voltage pulls poorly, but low-leverage grid doesn't much slow the few electrons that pass.)

Voltage readings might be useful. Particularly plate voltage as a fraction of the supply voltage. If supply is 9.0V and plate sits at 8.8V, that's the problem: high-leverage 12AT7 just isn't allowing any useful current to pass. You can try reducing any cathode resistor toward zero. You can try increasing grid resistor to 22Meg. You can try 12AU7.

[peterg]

Looks like I've got another project on my hands to make use of the 12AT7 tube?