Friday, May 29, 2020

Switches & channels

Switches, either mechanical or digital, provide opportunities to route different part of the circuits around in some interesting ways.

To start, I have always been a fan of having two channels on pedals, something attracts me to that sort of design. Probably my early exposure in pedals to the DBA soundsaw and kill kill filter.



Recently, there is a Big Muff by Wren and Cuff ("Garbage Face")  that has been released which allows for two different volume settings for a channel.


I can't say for certain how they implement this, but if I had to guess it would be like the old Beavis audio, two pots on a stomp with an LED approach. http://beavisaudio.com/techpages/switches/

Not a bad approach at all! Easy to implement, minimum parts count and greatly expands the sonic pallete of a certain pedal.  In fact the DBA KKF uses this type of control, to change the tone potentiometer. Move this over to the potentiometer for gain, and you can have two channels which allow you to vary the saturation of your dirt circuit. All of this with a 3PDT switch (Stomp or toggle pick your poison)

If you don't care for the LED indicator, you could get by with the DPDT. But wait!!! What about other options.  As far as mechanical switches go, we can move up the the 4PDT. Which depending on how we want to implement it for channel switching, we could get creative and allow changes to be made to 3 controls of a circuit, but would need to isolate components so they don't interact across channels. I.e. the we don't want the volume control for channel one to change the volume of channel two. Digital switching systems are more complicated, but offer a longer life-span and the potential for more parameters of the pedal to be channel switched.  This comes at the cost of more knobs to interact with though. Digital presets are the next evolution which allow you to have the base number of potentiomers and the ability to cycle through "saved" states.  The challenge with this approach is not being able to see what the preset was.

The NEW DBA ROOMS pedal looks to have 3 channels switchable on their "ALT" footswitch. While there are large knobs for Frequency, Depth, and Time, there is also a smaller 9mm potentiometers for F, D, and T which I am going to guess is tied to the ALT footswitch.


This of course depends on how the potentiometer is oriented in the circuit to begin with. This is most ideal for potentiometers set up as voltage dividers.


This is brief post covering aspects of mechanical switches for "multi channel" modifications to your pedal, but also serve as a backdrop to part of the process going into the Sound Saw REMAKE. The pedal toggles back and forth between the boost and the filter sides of the circuit.





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