1/19/2008
Copyright
2005 – Tim Hoerning
39
“Analog” vs. Digital
•Many guitarists talk about the difference between “analog” versus digital delay based devices
•In truth, there are no completely analog delay circuits (except for tape-echo units). In “analog” delay pedals, the delay unit is a bucket-brigade chip
•A bucket-brigade chip is an integrated circuit with a
large number of capacitors and
transmission gate transistors.
–The signal is sampled (into discrete time), and the
sampled voltage is placed on the
first capacitor
–The sampled voltage is then passed to the next capacitor
at the rate determined by the
sampling rate control.
–If the sampling rate is too low, the voltage on the
capacitor will “bleed” down
and distortion will occur.
–This gives the signal a “warm” quality that many
appreciate.