Room mode reduction with each corrections

[skywind7]

My speakers would always sound like trash until recently i discovered that certain frequencies would cause this issue, when I reduced them around 130hz ish. It sounded more normal and was amazed. I understand them to be room modes, when using room correction eq. How can I reduce these frequencies being added back from the correction too loud, how can I balance room modes reduction and proper room correction. should I reduce the room modes before or after the room correction.

 

[John Mulcahy]

Dealing with modes is part of room correction. Ahead of correction you can look at speaker and listening positions and room treatments.

 

[skywind7]

oh ok, and what are sone of the downsides of correcting full range/higher frequencies
do many just correct the low end or up to 500hz.

 

[John Mulcahy]

The main problems with attempting EQ above a couple of hundred Hz are:

• The response changes a lot with position (even very small head movements), more so at high frequencies, so making a correction based on a measurement at one position can make things worse at a nearby position
• Our ears and brain are good at picking out the direct sound from the speakers at higher frequencies and ignoring the various reflections which come along after it. Those get lumped into the overall result the measurement shows unless additional effort is spent on trying to exclude them through changes in the windowing used for the impulse response, but that imposes frequency resolution limitations. Making corrections based on the measurement results can consequently make things look better on the measurement but sound worse. If the speakers don't have some acknowledged measured flaw in their anechoic response it is better to stick to low end corrections.

 

[skywind7]

many room correction software software creates multiples samples from various positions in the listening position, do these types of arrangements help with higher frequencies well. I've heard with REW its good to do multiple measurements in the listening position to get a average response.

when you say balance changes with head movements in the higher frequencies, wouldn't that be the same for the speaker in general, as studio monitors have a sweet spot. some more narrow and some have more wider output of frequencies for a more comfortable sweet spot, does the type of speaker play a role in this as well ?

 

[skywind7]

how does REW correct room modes, does it just turn them down, or is more processing involved.

 

[John Mulcahy]

REW can calculate settings for parametric EQ filters to move a response towards a target shape. Part of that can involve countering the effects of modal resonances. There are some specific tools in REW for analysing modal behaviour and a "Modal" filter setting which is a parametric filter whose Q is adjusted as its gain is changed to target a specific modal decay time. In practice the biggest subjective impact from modal resonances comes from the peaks they create in the frequency response rather than their extended decay times, so tackling the frequency response is sufficient to get a good result.

The point about head movement is that the response changes when you move, but the corrections that are being applied don't, so they need to be suitable for wherever your head may be. Averaging multiple measurements is one way to try and get a more broadly representative view of the response to use for correction.