Sanity Check: Disaster Area Designs MJ-STT

[Big Monk]

Just looking for a peer check on my breakdown of this simple cable:

MJ-STT Strymon Tap Tempo Cable — Disaster Area Designs

Custom-made cable to connect standard tap tempo outputs to Strymon pedals.

www.disasterareadesigns.com

After getting my new switcher hooked up, I noticed a small 1-2s lag time for the trigger outputs to engage my favorite settings on my Flint and El-Cap. Not a huge deal as I’m a bedroom basher.

In a recent Strymon thread over at TGP, I learned that with other switchers, such as the Boss ES-8, this lag is more pronounced and is a result of the microcontroller based switching initiating the trigger switches.

The above cable incorporates a pull up resistor to mitigate this lag by not allowing the digital input/output of the trigger to “float”. At least that’s how my ape brain interpreted it.

I’m more than willing to buy one of thy else and open it up so that I can then make 4 of these cables to have and use, but my thought process on how they are constructed is as follows and I could save myself the $24 with shipping:

1.) For favorite or tap tempo operation, the Strymon pedals only use the conductor attached to the ring of the TRS jacks on either end to supply power to the external switch LED.

2.) Since Disaster Area describes these having a pull-up resistor rather than pull-down, my assumption is that they are connecting the resistor to power at the Strymon.

So, short story long: It seems that if I have a TRS plug on one side with an appropriate value resistor attached from tip to ring and attach a 2 conductor wire to the other other end terminating at a mono plug, then I have essentially recreated this cable.

Any thoughts?

 

[benny_profane]

Pull-up/down here is referring to the (logic) states for the signal. If an mcu is expecting some sort of logic input, but there is nothing connected to the pin, that is the ‘floating’ state—there is nothing determining what the mcu will interpret as its logic state. If there’s a cable connected that is only acting as a spst interrupt, it’s essentially unconnected, thus ‘floating.’

To implement this in the cable itself, find out what is connected to logic high (i.e., Vcc= 3.3V or 5V), what is the logic low (i.e., GND), and the signal. Put a resistor (start with 10k or so, but ensure the current provided is sufficient) between signal and logic high. This will allow the input pin to receive logic high when the button is not pressed and logic low when the signal is shorted to GND.

 

[Big Monk]

Pull-up/down here is referring to the (logic) states for the signal. If an mcu is expecting some sort of logic input, but there is nothing connected to the pin, that is the ‘floating’ state—there is nothing determining what the mcu will interpret as its logic state. If there’s a cable connected that is only acting as a spst interrupt, it’s essentially unconnected, thus ‘floating.’

To implement this in the cable itself, find out what is connected to logic high (i.e., Vcc= 3.3V or 5V), what is the logic low (i.e., GND), and the signal. Put a resistor (start with 10k or so, but ensure the current provided is sufficient) between signal and logic high. This will allow the input pin to receive logic high when the button is not pressed and logic low when the signal is shorted to GND.

I'm am 95% certain that Strymon uses the Ring as a power carrier, especially since you don't need external power to light the LED for their Favorite switch or aftermarket or DIY switches.

So i think it's basically a 2 conductor cable with a TRS plug on one end and resistor attached from tip to ring.

 

[benny_profane]

I think that makes sense. I'm wondering why there isn't an integrated pull-up on the host side already, though. In any case, you should be able to easily test it with a breadboard setup before you commit to a cable build.

 

[Big Monk]

I think that makes sense. I'm wondering why there isn't an integrated pull-up on the host side already, though.

I'm not sure, but I believe it's because Strymon designs the Favorite/Tap Tempo function to be performed on their dedicated external switches or a similar DIY solution and not a trigger output like on most switchers.

In any case, you should be able to easily test it with a breadboard setup before you commit to a cable build.

I have a spare TRS cable I'll mangle to test.