Generally, there can be different reasons for dips in the transfer function. Some can be corrected for (mostly broader dips). Others (cause by acoustic cancellation at the listening position, usually very narrow)
must not be corrected for. Separate controls for positive and negative gain would be welcome addition.
The graphs shown in the WiiM Home app are generally fine, but only for peak (PK) filters. High shelf (HS) and low shelf (LS) filters don't reflect the Q value. Everyone's invited to vote up my feature request:
The PEQ feature in WiiM's products has developed very well over time and definitely turned into an extremely powerful tool. One great feature is the support of fully flexible filter Q values, not only for peak filters, but also for high shelf and low shelf filters.
Unfortunately, the effects of different Q values are currently displayed for peak filters, only.
For example, here are the graphs for a 200 Hz +10 dB PK filter with either Q=1.5 or Q=0.15. The difference is obvious and understood very intuitively.
In contrast, the graphs for a 200 Hz +10 dB LS...
Let's not forget that the goal of this thread is not to discuss the dos and don't of WiiM room correction, in the first place.
@Vignus had asked for help understanding the PEQ filter section. It was in this context that
@Wiimer had recommended dealing with RC first. At leas RC will create a set of PEQ filters (only PK peak filters), so you can look at the results and see how the values for frequency, gain and Q have been set.
From there on you can modify either of theses settings (best to do it one change at a time)mans just learn how the curve changes and what difference in sound it makes.
Sounds like a good idea to me if someone doesn't want to dive deep into theory.
