EQing delays: two different approaches

Delay plugins frequently have low and high EQ built into them. But, also, you could put EQ after the delay with a separate plugin. So, what are the differences between the two approaches?

• EQ in the delay: the biggest thing to know about the EQs in delay plugins is that, most of the time, they are inside the feedback path. What does this mean? It means that the EQ is applied to the delay tap, which is then sent back into the delay circuitry as per the feedback control — meaning that each successive delay tap has more of that EQ imprint on it.
  
  For example, imagine that you have set your delay plugin’s low EQ control to like -5 (for a shelving-type EQ) or like 400Hz (for a HPF-type EQ). The first delay tap will have less low end than the original signal. And then it will get sent back into the delay circuitry, and it will get EQed again — meaning that the second tap will have less low end than the first tap. And the third will have less than the second … and so on, until the taps have faded out as per the feedback control.
  
  So, in this example, the delays will sound like they thin out and evaporate upwards! Pretty cool. And you can also do the same thing with the high end! And with delay EQs that go positive as well as negative, you can have the low end or high end increase with each successive tap. Or you can have the low end decrease while the high end increases. Lots of different effects and emotional nuances to be accessed here.
  

• EQ after the delay: because the EQ in this scenario isn’t part of the delay plugin, it doesn’t interact with the delay’s feedback circuitry. So, this doesn’t create evolving delay taps like the other way does — but it’s great for fitting delays into a mix!
  
  Something I like to do sometimes is to set up a longer delay with a fairly high feedback, and not to use the EQ in the delay at all, so that the delay taps are essentially static in terms of their sound. And then I’ll put an EQ plugin after the delay plugin, and use not just highpass and lowpass filters but also sometimes targeted EQ pokes, to help the delay texture sit in a really specific, small place frequency-wise, so it’s just hovering back in the mix, creating emotion in a subtle way while not interfering with the other stuff that’s happening.
  
  (I love using super steep HPFs for this sometimes — a 48dB/oct HPF will basically just totally cut out the frequencies below where I want to hear the delay. A filter that steep can sometimes sound a bit weird on the LPF side of things, so I’ll often do something gentler up there, but there aren’t any rules; do what sounds good.)

Tap tap tap — jamie