Besides spectacular delays every analog delay produces white noise.
Generally, one can say that the proportion of white noise increases in dependency of the delay time.
To some this unintended noise represent an important part of an analog character, others prefer digital delays to produce a signal that is more clear.
The reasons for white noise
A special part of analog delays, the compander produces white noise.
First the compander compresses the guitar signal so the delay chip is able to handle the signal more easily. Afterwards it brings up the volume of the signal again.
Although this influences the sound in a certain way, the compander is important to avoid distortion and (although the compander itself produces little white noise) to reduce white noise in general.
Some analog delays use an integrated lowpass filter instead of a compander to minimize the respective frequencies.
These delays sound grittier and darker.
A prominent example for this kind of sound is the old MXR analog delay of the 1970s.
This pedal uses a variable filter that muffles the signal of long delay times and emphasizes the treble of short delay times.
The compander of analog delays has much influence on the sound and the style of the repeats.
Depending on the setting of the compander the repeats will sound percussive or washy.
The intensity of this influence varies according to the respective pedal because the trimpot is adjusted manually.
If you will get the chance, it is worth it to compare different pedals of the same manufacturer and choose the one with the sound you like best.
Its all about the chip
Regarding analog delays, there is a certain reason why many prefer the MN3005 chip (in contradistinction to the MN3008).
The MN3005 is able to create delays up to 300ms, while the MN3008 only provides 150ms.
The more bucket brigade devices (bbd) are used, the more complicated and expensive it gets to calibrate them.
This can also create white noise.
Clock noise/ high pitched whine
In addition comes the so-callled “clock noise”.
The IC acts as a metronome to the bbd. That means, the speed of the delay is controlled by this ticking pulse which can be adjusted with the delay time pot.
Especially when you use long delay times or your delay is badly calibrated this ticking pulse can reach the audible range and has to be removed by a filter.
But this ticking pulse also can be perceived as a part of the delay signal and thereby constitute the very special character of the pedal.
The Way Huge Aqua Puss is a pretty good example for that.
Analog delays without white noise ?
I guess, there will be no analog delay without white noise.
There will always be more white noise in the sound of a trebly delay like the Deluxe Memory Man than in the sound of a Moog delay.
Those who don’t want white noise at all, should use a digital delay for long delay times. But for short delay times the white noise of an analog delay has its limits and the sound is invincible.
And there are also some digital emulations of analog delays that allow to adjust the proportion of white noise.
It seems, in the end white noise is pretty musical and is an important part of the analog delay sound.