This article is a work in progress......

What is the difference between the Silent Step and the Parasite true bypass modules?

We'll start with the Parasite.

The Parasite is a cost effective solution for relay true bypass. It's a simple circuit that relies on the pedals electronic switching to actuate the relay. This works with any Boss, Ibanez, Maxon or any pedal that utilizes the flip-flop (see pic below) type bypass. We've even installed it in DOD and other pedals that use CMOS switching.

The Parasite grounds the effect input when the pedal is bypassed. This is to help eliminate any popping noises. It's small size at only 19.05 x 16.21 mm makes it easier to fit in tight installations. Installation is rather easy. It's pretty much the same as a typical or normal true bypass other than you have to run V+ to the Parasite and run a "P" wire from the Parasite to the flip-flop so the flip-flop can control the relay.

The LED is still controlled by the flip-flop. The Parasite is only switching the input and output of the pedal. The Parasite also uses the stock pedals momentary bypass switch so there isn't any drilling to keep the stock look of the pedal.

This is the typical flip-flop circuit and it's pretty easy to spot in most schematics:

The Silent Step:

The Silent Step uses a microcontroller to actuate a relay. Using a microcontroller adds a few benefits. It turns on/off the LED which is isolated from the rest of the circuit to help eliminate any popping noises, there is a few millisecond delay (it's so fast it totally inaudible) in switching the pedal from bypass to on to also help eliminate any popping. It also allows us to control the power on state of the pedal so you can have the pedal on or off when it's powered up. Because the Silent Step doesn't rely on the flip-flop switching, it can be installed in pretty much any pedal. We've also included jumper pads on it so you can use it as a typical DPDT or have the effect input grounded when bypassed to help avoid any popping.

At a size of 21.59x 25.0698 mm it's just a little bigger than the Parasite but fits easily in most pedals without having to sacrifice the battery compartment to put it in. Installation is pretty much exactly the same as a typical true bypass other than you run V+ to the Silent Step.

What makes the Silent Step and Parasite different or better than just using a 3PDT?

The upside to using a 3PDT is you can get them rather cheap. If you are true bypassing a lot of pedals, it may be a cost effective way to do it. The major downside is they usually don't fit very well in a lot of pedals and you most likely will be drilling holes to make it fit. The major benefit to using a relay bypass like the Silent Step or Parasite is it uses a momentary switch so if the pedal already uses a momentary switch, like Boss, Ibanez, Maxon, DOD, Digitech, etc., then you can use the stock switch. Even if the pedal uses a latching switch, like Dunlop, MXR, etc., replacing the latching switch with a momentary footswitch maintains the stock look and no drilling.

The Silent Step controls the LED completely so it's isolated from the relay switching and rest of the circuit. It has it's own voltage regulator. This helps eliminate any popping. The Parasite technically isolates the LED also as it's controlled by the old switching circuit and not the Parasites relay but it shares a common power supply and doesn't have it's own voltage regulator. A 3PDT doesn't isolate the LED from the rest of the circuit.

Because the Silent Step and Parasite use momentary switches, there is less to no mechanical switch pop noise. This is great in a studio situation, in larger pedals where the sound is amplified, or just because you don't like the thunk noise. To be fair, there are some 3PDT switches that are quieter than others but not momentary switch quiet.

Summary:

Both the Parasite and Silent Step will essentially operate in the same way. They are both relay true bypasses. The Silent Step just adds a few more features and can be installed in pretty much any pedal. For stereo pedals, you can actually operate two Silent Steps or Parasites with one switch.