Epiphone Valve Jr - Part 2 Isolation Cabinet Switch

Switching between Modes

• Recording
• Practicing
• Jam Sessions
• PA sound mix management
• Live Performance

I figure I needed a way to select the following:

• The internal speaker only (in the V3 Valve Jr Combo, this is a 16 ohm load)
• Both the internal speaker and external speaker - in Parallel - 8 ohm load
• The external speaker only (has to be 16 ohm load)

Here is how I will wire it:

Some points to consider:

• The Rotary Switch will be mounted on the back of the cabinet.
• Output transformers do not like to run unloaded, so to make sure that there is always a load available, I will force the use of a dummy load in case no speaker is plugged into the external speaker jack (using 2 8 ohm Non-Inductive 10 watt resistors wired in series).
• There will be 2 cables that plug directly into the speaker Jacks on the Valve Jr. One will plug into the 8 ohm jack, the other will plug into the 16 ohm jack. The Rotary switch will select the right impedance for the mode that the switch is set to.
• This has to be simple to use, I can't have it so complex that if someone is helping me setup or tear down that there will be anyway to screw things up.
• This is not designed to use speakers of other impedances - all individual speaker loads will be 16 ohms. Don't ask me about using other impedances - I won't reply back if you do.
• While I plan on using this external speaker jack for a Isolation Cabinet, it will work fine with any 16 ohm speaker load.

Questions? Comments? Suggestions?

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