Multi Tap Tempo Hack

Someone asked me recently if the Mission Expressionator could be used as a multi-tap tempo controller, so I created this little hack to do it. It will work with any Expressionator, so read on to see how you can try this for yourself.

Many modern digital effects pedals and multi-effects units include a tap tempo capability. By tapping on a button you can adjust the timing of parameters such as delay repeats to match the tempo of the music. If you are using multiple separate effects pedals, the ability to tap a single button to adjust the tempo of all the devices simultaneously is a useful feature. There’s a more complex way to do this if the pedals are MIDI capable. If not, or you just need something simple, you can make a tap tempo switch to work with an Expressionator.

The Mission Expressionator is a device that lets you connect a single expression pedal to multiple expression controlled devices. In this hack we are going to replace the expression pedal with a switch. You’ll need the correct type of tap tempo switch. It works with a normally open momentary switch, but it needs to be wired TRS. The Strymon Tap Favorite would probably work. You can get one from the Strymon Store for $49. A mono TS only tap tempo won’t work for this, it needs to be TRS, so if you don’t have one of these, you’ll need to get one, or you can make your own. You’ll need:

1 x TRS (stereo) 1/4″ Jack such as a Switchcraft 112BX
1 x Momentary SPST switch such as Smallbear 0602A
1 x 1K Ohm 1/4W through hole resistor
An enclosure such as a Hammond 1590LB
Some hook up wire

You can get all the parts from many electronics parts suppliers.  Smallbear Electronics keeps them in stock.

Basically you are going to connect the two terminals of the switch to the tip and sleeve of the jack, and then bridge the tip and ring of the jack with the 1K Ohm resistor.

Connect the switch using a 1/4″ TRS (stereo) cable to the pedal input on Expressionator. Connect one or more outputs from Expressionator to the external tap tempo input on your pedals. For my test I used a Timeline and a Mobius from Strymon. Check your pedal user manual to for the connections and see if it needs to be configured for tap tempo. In the case of the Strymon pedals, I connected outputs A and B from Expressionator to the EXP inputs on the Timeline and Mobius using TRS cables . I set them both for external tap tempo as follows: GLOBAL – EXP MD – TAP.

Set the Expressionator outputs to raw taper and enable all the channels that you want to send tap tempo to. Tap the switch at least two times. The bar graph LEDs on Expressionator will all toggle on and off with the taps, and your pedals should sync to the tempo. In the case of the Mobius and Timeline, their own tempo LED’s also flash appropriately, and the tempo and can be shown on their LCD displays in BPM or mS.

In my testing, the Mobius and Timeline normally showed within 3 or 4 BPM of each other on their displays, which should be perfectly good enough for most applications. If you really do need more precise synchronization, then you’ll need to use a more complex MIDI based solution if your pedals support it.

Note:

The Expressionator tap tempo hack uses an analog tap tempo signal. Each receiving device will have it’s own internal clock reference and likely do some filtering and switch debouncing in software. This may result in the tempos being very slightly out of sync between multiple units and the clocks may drift over time. It probably won’t be noticeable for most applications, but If you really need a greater level of synchronization, then some pedals with MIDI inputs can be set to derive their timing from a single master MIDI clock. If your pedal has MIDI capability check the User Guide to see if this option is available, then choose a single device to generate the master MIDI clock.