Back in the day

 

Before the days of more advanced audio technology, music employing a delayed echo had to be recorded in a naturally reverberant space. This was often an inconvenience for musicians and audio engineers. The popularity of an easy-to-implement real-time echo effect led to the production of systems offering an all-in-one effects units. They could be adjusted to produce echoes of any interval or amplitude. The presence of multiple “taps” (playback heads) made it possible to have delays at varying rhythmic intervals. This allowed musicians an additional means of expression over natural periodic echoes. So, the change in available technology during the mid-1970 led to the birth of analog delay units. At that time, affordable delay chips became available.

 

Analog vs. Digital



An analog delay is an effective device that is similar to a digital delay in that it is an all-electronic device that temporarily stores the audio signal in order to create a time delay. The analog delay differs in a manner it stores an audio signal. Both units sample the input signal by chopping the waveform into thousands of equally timed segments per second. The main difference between these two delays is that analog delay unit converts each sample to an average voltage value.

 

BBD

 

Instead of using ADC, numerical (digital) memory registers, the analog delay uses a sample and hold circuit to convert the continuous input signal to a string of voltage values, plus a large number of capacitive storage devices known as bucket brigade devices (BBD`s). The voltage stored in one bucket is poured into the bucket in sequence. The sampled voltage eventually reaches the output.  Strobe signal transforms the voltage from one registry to another. This is much like a digital delay`s technology. Many of the same special effects are available in the typical analog delay line.

Unlike in a digital delay, a narrower bandwidth usually limits an analog delay line. It is generally somewhat noisier. The characteristic warm, smooth and organic sound of an analog delay is actually due to its limitations. Not because of any mystical mojo in a chip. Effects with BBDs at its core are a great example of how an effect can inspire a whole generation of musicians and artists. Nevertheless, it technically isn’t a “perfect design”.

 

Musical Special Effects


The analog delay units became more popular by the end of the 1970`s because they were less expensive to produce than digital delays. Back then, and even today, producers mostly use them as musical special effects. Many producers and musicians alike claim that analog delay units have somewhat warmer and fatter sound than the digital delays. On the other hand, there are differences in processing. As the time passed and as the cost of digital components came down, digital delays have pushed the analog delay to a small corner of the market.

 

Additional Resources & Source Texts

 

I Love Analog Delay But What Is A BBD?