Overdrive pedals mostly provide a tone control to adapt the frequencies of the distortion to the amp and the guitar.
Unfortunately, many delays lack this feature or you will at best get a low pass or low cut filter.
Although for delays in particular, it is important to fit into the mix quite well.
A dark sounding analog delay might emphasizes the bass too much while digital delays mostly stress the treble a bit too much.
But the decisive frequencies – the mids- are mostly set permanently so the guitarist is unable to alter them.
Even some quite expensive delays prohibit this kind of adjustment.
There are countless delay pedals but an analog of digital delay with a complete tone control might stay a dream, although this feature would definitively make sense.
The effect loop
If your delay pedal provide an effect loop you can help yourself with a combination of pedals.
Habitually this effect loop is used for modulation effects to make the delay signal sound more vivid and warped.
But by using a filter or an equalizer you will be able to vary the general sound of your delay pedal.
A Boss GE-7 for example is pretty suitable to cut off the bass and stress the mids.
Or, if the delay signal has too much midrange, you will be able to bring it down infinitely variable.
You can also use a parametric equalizer to search for certain frequencies you would like to emphasize.
Or even use a preamp pedal to edit several frequencies.
Also interesting is the use of a filter or a wah. These pedals will cause a peak in the midrange which emphasizes a narrow band of frequencies.
When you use an equalizer pedal, it is important to adjust the volume of the pedal carefully otherwise the volume of the eq pedal will influence the number of the repeats and by this might lead to an oscillation of the delay.
The effect loop of a delay pedal is not only suitable for an additional modulation, it is also appropriate to alter the sound of a delay.
Click here for some sound files relating to this topic.