Delays enrich the guitar-signal and create a vivid sound. There are numerous songs that get their very own character through the sound of a delay (f. e. many songs of U2).
There are different types of delays; each of them has got its advantages and disadvantages.
The analog delay was one of the first possibilities to emulate a natural delay. Internal so-called bucket brigades cause a delay of the signal by transmitting it in the way like water is passed from one bucket to the next. As the name indicates, the signal stays analog at all time. While the maximum delay-time of the first analog delays varied between 300 and 450ms, there are actual pedals with delay-times of 1200ms.
But the analog delay frequently creates some kind of hiss. Most of the analog pedals use a filter to reduce it but by this the sound becomes a little bit dusky. The wet signal becomes less striking but therefor it fits perfect into the sound of the guitar without overlaying it. Accordingly you can thicken your guitar-sound without an effect being heard.
The Deluxe Memory Man and its successors are very special analog delays, created by Electro Harmonix. It has been developed in the 1970s and its sound is brighter than the sound of many other analog delays. In combination with the in-built preamp the sound of the Deluxe Memory Man gets pretty close to the sound of a tape-delay while it needs less care.
What first has been developed for rack-systems soon was available as pedals: the digital delay.
Mostly it has got several delay-functions (reverse, modulation, ducking). But its real strength is not the emulation of analog delay-sounds but the creation of transparent and brilliant delay-signals. This facilitates a rhythmic guitar-play with the delay that might sound as if you play two or more guitars.
Frequently the digital delay is said to sound some kind of sterile. But exact this could be the advantage of a digital delay. It just reproduces the recorded signal without tampering it. Besides, digital delays mostly provide several features. The stereo-function of a delay can be a very interesting option. Although it is not always possible to use two amplifiers – it is worth it to try it out. A ping-pong- delay with modulation and a ducking-effect is able to create totally new soundscapes and to me it is absolutely inspiring. Click here for a ping-pong-effect- soundfile with the Chase Bliss Audio Tonal Recall RKM.
Although some tape-echo-modulations sometimes muffle the signal in a certain way, the tape-delay-sound is more close to the sound of a digital delay. The Echoplex for example creates an almost transparent and percussive delay which of course is modulated by the flutter.
Click here for various soundfiles of the Fulltone Tube Tape Echo.
The disadvantages of a tape-delay are obvious: It is big, heavy and needs a lot of care (change of the tapes, cleaning of the record- and playback-head). But the sound is unique. In the end I think it is more appropriate for soundfreaks and studio-recording.
Fortunately the Tap Tempo is (no more) a unique selling point of the digital delay. You can even find analog delays as well as tape-delays with this feature.
Every delay has got its reasons for being and in my opinion it is not always possible to replace them by emulation or another device. I think it makes sense to use several delays on your pedalboard so you can alternate between different sounds.
Because two delays are better than one.