Is the idea that you have the capability to reconfigure the amp, or that you want to be able to toggle the setting, and have the switch mounted somewhere accessible?
Call me a Cautious Old Hector, but I would be worried about operating the switch with the amp powered up. Maybe you need X2 caps as well to quench sparks?
One option is to use an octal tube Base with silicon rectifiers inside. Then it is not possible to operate the switch when the amp is powered up.
Call me a Cautious Old Hector, but I would be worried about operating the switch with the amp powered up. Maybe you need X2 caps as well to quench sparks?
One option is to use an octal tube Base with silicon rectifiers inside. Then it is not possible to operate the switch when the amp is powered up.
Yes, that's the plan for the SS/Tube rectification and also for the UL/Triode and CFB switches. I want to plan for these switches when I'm doing the chassis layout and fabrication so, following George's advice, I will install them but not wire them into the circuit until after the basic amp checks out and is running without issues. That said, I will probably settle on one option or the other for rectification and not use the switch much or at all after that, although different output tubes may have different rectification "tastes".
I have been on this planet long enough to become a cautious old guy also
I will be using slide switches with very short actuators, or even a screwdriver slot actuator, to avoid any "accidental" switching.4A or 5A @ 125V AC are readily available and I'm thinking that those ratings would be acceptable in this amp.
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The SS/Tube switch will see up to 560 volts peak (400 VAC * 1.414) to ground. Finding a switch with that kind of rating could be difficult, expensive, or both. I used ordinary "appliance switches) that snap into a rectangular hole in the chassis that were rated for 10 amps and direct connection to a 240 VAC line voltage. These have a completely plastic body with no exposed metal except for the terminals on the rear.
Whatever you use for the switch, do not activate any of them while the amp is powered up. At a minimum you will get a loud POP in the speakers. Repeated flipping of the UL/Triode switch brought sparks inside an EL34. Granted it was a poorly made tube that I used for testing stuff that could end badly, but it could happen to an expensive tube as well.
Whatever you use for the switch, do not activate any of them while the amp is powered up. At a minimum you will get a loud POP in the speakers. Repeated flipping of the UL/Triode switch brought sparks inside an EL34. Granted it was a poorly made tube that I used for testing stuff that could end badly, but it could happen to an expensive tube as well.
Thanks George. Practical reality has resolved a design issue for me - there will be no rectifier switch in this build I will stick with the augmented tube rectification and if, for some reason, that is unsatisfactory I can install D1 and D2 at a later date.
Caution noted about flipping any switches with power on.
I will stick with the augmented tube rectification and if, for some reason, that is unsatisfactory I can install D1 and D2 at a later date.Caution noted about flipping any switches with power on.