Digital delays

In the 1980s, the first digital chips were used to produce delay pedals. The advantage was, that these racks and pedals were able to offer a longer delay time than the analog delays of those days and, at the same time, produced less hiss.
Although many musicians accredited a lack of character to this kind of new technology, the digital delays caught on and are still famous for certain styles of music.
Currently, analog delays also are equipped with extended delay time and digital control, though they catch up regarding the aspect of functionality.

The first digital delays

One of the first digital delays was the Boss DD-2, based on a chip from the Roland Rack delay. This chip is as large as the whole width of the circuit board.
A fact, that only few know: the first digital delays that were said to provide a digital and therefore sterile sound, were built up analog.
The DD-2 as well as the famous TC 2290 only used the digital technology to create the repeats. The remaining signal and the filter stayed analog anyway.
But the digital chip made the delay signal much clearer. For percussive repeats, this sound is essential – blurred repeats and short slapbacks sound much better with an analog delay.

Today, there are numerous simple constructed digital delays that have been designed to sound like analog delays. These pedals are mostly based on a PT2399. Basically, these pedals are built up like an analog pedal which uses a digital chip instead of a BBD.
Because the pretty similar filtering of the repeats, the Boss DD-2 gets pretty close to the sound of an analog delay.
The DD-2 and the early DD-3 delay pedals are very nice sounding though they are frequently used as the basis for modifications.

Other digital delays are built up completely digital. One of the first was the DD-5. It was my first delay pedal as well and prevails a very percussive sound.
In contrast to its successors, the signal stays digital all the time, without any analog filtering.

Current digital delays

The current digital delays are mostly modelling effects. Amongst them Strymon, Eventide, Empress and Source Audio delays. Their digital algorithms allow these delay pedals to emulate almost every delay (depending on the effort capacity of programming sometimes better or worse). Thereby, it is possible to emulate and create analog, tape and digital delays in a very confined space.
Some of these pedals prevail an analog dry through. To be honest, this only means that the dry signal will be added to the digital delay – in the end stays the delay digital anyway.

Even though pedals, that also digitalize the original signal have a (extremely short) latency, they provide various options to tune the sound. Thus, they are able to emulate the preamp of a Tube Tape Echo, for example.
There is no good or bad. There will be an adequate delay for every style of music, every personal preference and every rig. It does not always have to be an analog delay.