In the diagram shown above, the path of the signal is along the blue arrows. The red connections represent the internal connections of the dpdt switch and the dotted lines in the switch signify that the poles move in unison. As you can see, the signal flows from the input into the switch, from center to bottom lugs via the internal poles and a jumper wire connects the sections together. It then goes to the output jack with no actual connection to the circuit board when in the bypass mode.

Compare the true bypass to the more simple method (shown below) used in many vintage pedals where the input of the circuit is left connected to the signal path at all times. This type of switching was used because SPDT switches are cheaper and easier to find than quality DPDT types required for true bypass.

As one can see, only the output jack is being switched. It can connect to the output of the circuit board for the sound of the effect, or to the input jack for bypassing the effect. However, when the input and output jacks are connected by the bypass switch as illustrated above, the input to the circuit board is still connected to the signal path and the input impedance of the circuit is loading the signal line. This type of switching can cause loss of high frequencies and overall volume, and is the reason that many wah-wah pedals "suck tone". Contrast this to the true bypass method where input and output jacks are effectively connected by only a piece of wire with absolutely no connection to the circuit board.

With true bypass switching, the input impedance of the effects pedal has ZERO influence on the discussion we are undertaking. Why? The true bypass is designed and used to eliminate the effect of a pedal's input load on the signal... the pedal is completely disconnected when the switch is bypassed so the input impedance of the circuit is not relevant! It does not matter if the circuit has a high impedance like a tube amp or is a low impedance transistor load - it is not a factor with true bypass.

Furthermore, while vintage pedals like a Big Muff can have a low input impedance, 40k for example, or even lower for a Fuzzface, this is not relevant either since the circuit is designed around that input, and tone or volume loss is compensated by the rest of the circuit design. In other designs, such as clean boosts the input impedance is 1M as with most tube amps. But again, it is not a factor in this true bypass discussion because the circuit board is completely disconnected when the switch is in the bypass position.

Let's not just theorize about the subject, we want to take some measurements of cables to see what kind of real world parameters will be encountered in working with a pedalboard and its connecting cables and then apply some basic electronics math to see what effect that might have on the signal.

Typical Cable Measurements
Radio Shack 1' jumper	0.1 ohms	0.17 nF	0.003 mH
Hosa 1' jumper	0.1 ohms	0.16 nF	0.002 mH
20' Planet Waves cable	0.4 ohms	0.8 nF	0.031 mH
20' Low Capacitance cable	0.9 ohms	0.47 nF	0.019 mH

20' cables into 6 pedals w/1 ft. jumpers
6 Pedal chain	13.9 ohms	0.61 nF	0.165 mH

You know, that's not too bad. The capacitance of all the cables does not add together to produce a substantial load on the pickups. The total capacitance of five jumpers and two 20' connecting cables is really about the same as one of the long cables alone. This is likely due to the fact that the bypass switches in the pedals are breaking up the connection of the cables and preventing the summation of capacitance as one would think would happen. The series resistance and inductance appear to be a sum of their respective values but do not present any real problem to the signal flow.

Notice that I used 1' jumpers and 20' connecting cables since those are the most commonly available lengths, although 6" jumpers are sold as well. I only used six pedals since there were only five jumpers on hand for connecting them together, but it demonstrates the principle well.

In summary, this quick experiment with a real world setup has shown that the series connection of true bypass pedals does not result in an excessive load nor does it reduce the quality of the audio signal because of the long cable runs since the capacitive load is much less than previous conjectured. So when you hear the term True Bypass again you will know.