Flanger is an effect original done with two tape machines. Both machines played the same signal and were synchronized to each other. The engineer would manual grab the edge of the tape reel to slow it down and then let it go to allow it to catch back up with the other machine and repeat the process. This varied both the timing and the pitch of the signal. Modern processors usual use an LFO to adjust both the delay time and pitch of the duplicated signal. Unlike Delay and Chorus, Flanger can’t be made into a stereo effect by simply panning the dry signal to one side and the delayed signal to the other, it only works if both sounds (wet and dry) are coming out of the same speaker. Many Flangers create a stereo effect by do the same effect to both left and right signal with some variation to make the signal bounce around the stereo field.