Hi guys,
I recently decided to get rid of my old Digitech RP300 multi effects processor and form a set of stomp boxes (single effects units) as my effects loop. One reason for that was my processor was driving me crazy sometimes, especially with the knobs (if it gets hit, or shaken, settings change, which happens during performances) and also I wanted to have a collection of stomp boxes (recently I was in a shop to buy one, I felt like a kid in candyland!). Currently I have 4 of them, and I'm planning to add more. The ones I have are:
- Dunlop Crybaby (Wah wah): 9V, 43 mA, 2.1mm x 5.5mm connector, barrel positive.
- MXR Carbon Copy (Analog Delay): 9V, 26 mA, 2.1mm x 5.5mm connector, barrel positive.
- Boss MT-2 (Distortion): 9V, 20 mA, 2.1mm x 5.5mm connector, barrel positive.
- Boss NS-2 (Noise Suppressor): 9V, 20 mA, 2.1mm x 5.5mm connector, barrel positive.
But, I'm planning to add one or more of them to my loop, for example a phaser, flanger and/or a rotary speaker. But as I get more effects, possibility to do "tap dance" to chance them during playing also increases. So professionals use something called loop switcher, which is a unit that you program and when you press a button, it changes the effects you are using. But they tend to be expensive and buying is no fun but making one is! :) So here is the project outline:
- Make single switch units: There will be one for each effects pedal. It uses a DPDT relay for passive switching. There are schematics available buy there might be a "pop" sound while switching. Some say that I need something called snubber circuit (an RCD circuit) for protecting the relays and making them switch slowly to get rid of that "pop". Others say that a buffered effect connected before the loop can take care of this. Bought the components and will do some tests soon. 4 audio connections: Input, Send, Return and Output. These can be connected in series by connecting Input to previous effects Output.
- Make a controller: A PIC microcontroller will check for button presses and control relays and LED's for indication. A MIDI controller interface can also be added. Also it might control an LCD for displaying other values. Configurations are stored in EEPROM for easy editing and storage.
- Power supply: As you can see, all my effects use 9V and 9V batteries are expensive and run out of juice quickly. Also the controller and relays need 9V so a 9V power supply can be added (or at least a 9V adapter can be plugged in and distributed around the board.
- Cable tester: A simple mono guitar cable tester can be added to test out my short patch cables and longer cables. I ran into a problem during the final rehearsal, had to get a new cable just before the performance.
So these are the outlines. Any comments (especially about switch units and snubber circuitry) are welcome. I'll start with a crude power supply (an adapter and lots of jacks connected in parallel) for beginning. Then I'll check out switching units, controller and cable tester. I'll post my progress here as I go.
Thanks. I have looked at many links but seems lıke I cannot find it now. :S There are basically two connection options with DPDT relay:
1) Send and Return are left floating while the effect is not in the loop.
2) Send is grounded and Return is left floating when effects is not in the loop.
Some use 1 and run 1M resistors from Send and Output pins to ground to get rid of possible DC buildup. I guess I'll try 1 first, if there is no "pop" then I'm good to go.