Sound Skulptor forums

Build help and troubleshooting => MP566 Tube microphone preamplifier => Topic started by: Antipathie on November 25, 2021, 09:36:20 PM

Title: Shut down tube while not in use
Post by: Antipathie on November 25, 2021, 09:36:20 PM

Hi everyone,

since that's my first post I hope, no one has ever raised that question :)

I have a MP566 and like it pretty much. However on many occasion I use my 500 rack but won't touch the 566. I assume the tube is powered up the whole time, right? Is there a way to turn off the tube like it is on guitar amps?

Title: Re: Shut down tube while not in use
Post by: JPK on November 26, 2021, 08:36:11 AM

A connection that would discharge C25 (like a 1k resistor across the pins) would shut down both the heater and the high voltage.

Title: Re: Shut down tube while not in use
Post by: jtyghe on June 15, 2023, 08:39:01 PM

I’m interested in this too. Would putting the resistor work as JPK mentioned, so that when I switched it to mute the transformer and valve would be starved of power and therefore be off? 
Also wondering if it’s possible to have somehow add a bypass switch or have the channel be bypassed when in mute position?

Thanks

J

Title: Re: Shut down tube while not in use
Post by: JPK on June 16, 2023, 11:49:01 AM

You could disconnect the mute switch from the circuit (by cutting some tracks), reconnect the output transformer primary to the signal (TP4) and to ground and use the switch to cut the tube power and activate a bypass relay.
But this is a lot of modifications!