JJ has a good point I did not consider since I use a switcher and isolate pedals. There also is a problem with true bypass and if you use any vintage Fuzz pedals. Pete Cornish writes a lot on the subject and doesn't like true bypass and wants to keep impedance high. Les Paul was the opposite and actually designed pickups for low impedance to record, but he played live with the same guitar.
Pete writes here;
http://www.petecornish.co.uk/case_against_true_bypass.htmlHe states to design your guitar to hit a high impedance load the same as your amp, first. This maintains the pups and then distribute the signal from there. The switchers I had made do have a 1 meg input inpedance, but is adjustable if oyu have a active preamp.
To understand what buffered bypass is, we have to first understand what a buffer is.
A buffer is a circuit that changes the impedance of a signal. It is more properly called a "buffer amplifier" since there are lots of buffers in the electronics world, but we can call it a buffer for simplicity. All buffers use some sort of semiconductor - either a transistor or an operational amplifier (aka op amp) - and they require a power source (a battery or a DC power supply).
TIP: if you have a pedal that has no power source, such as a passive volume pedal, it is definitely not buffered.
The signal coming out of your guitar is a high impedance signal. This is another way of saying it is very weak. A buffer lowers the impedance without changing the fundamental character of a signal. There is no net gain; only a change in impedance.
Why do some effects have buffers? Because they work better when given a stronger, low impedance signal. This is especially true of digital effects, like delays and choruses, but most overdrive and distortion pedals also rely on a buffer for good tone. It's like building a bridge out of pine versus building a bridge out of steel girders.
This brings us to buffered bypass. In a buffered bypass effect, the buffer is
always on and lowering the impedance even if the effect is off. There are a few good reasons you'd want to build a pedal this way; the main one being to maintain the volume level between the effect being on and the effect being off. Some pedals without a buffered bypass are a lot louder when you turn the effect on.
A buffer also helps your guitar signal make it to the amp if you have a lot of cable to go through. An unbuffered signal will degrade over a long enough distance, causing loss of high frequencies in particular.
Lastly, most buffered bypass pedals use what's called a "logic switching" system to turn the effect on and off. The switching is accomplished with transistors. This eliminates any audible pops or clicks when switching.
The downside to buffered bypass is that some buffers will affect your tone. Some people talk about buffers "dragging down" their tone, or they use the obnoxious "tone suck" term. With buffered bypass, the buffer's negative effects are in play even when the effect is off.
Additionally, some pedals, especially vintage fuzz circuits, actually expect a high impedance signal coming in. If you put a buffered pedal in front of them, they may behave unexpectedly (i.e. they will sound bad).
Examples: any BOSS pedal, the Ibanez Tube Screamer (all versions), DOD, Digitech (except Hardwire).