Room Treatment Issue - Huge Dip in Mids

[spiderjazz]

I've started doing some treatment in the room I use for mixing, and I'm getting undesirable results! In this album, you can see the layout of the room at the moment, where I have treatment put up and the freq measurement that I have taken with a measurement mic at the listening position.

http://imgur.com/a/mtsxz#0

I have 4 foot rolls of rockwool in the corners as bass traps, three 24"x48"x4" panels at my first reflection spots (sides of the listening position and above me). In the picture there are panels on the rear wall, these are yet to go up. The wardrobe to the left of my listening position is built in so can't be moved. There was also a bed in the room which I have put up against the wall. I am using HS50m's, and these are currently on the same desk as my laptop in front of the window. I have them on foam and they are pointing up towards me (I plan on getting stands for the monitors so I can separate them a bit further and get them up a bit more)

From the frequency curve, my big problem areas seem to be the nulls at 100hz and the dip from 2khz onwards. The 100hz dip I imagine is a case of more bass trapping and moving the speakers around to make sure I'm not in a mode. However the mids issue is the one I'm worried about. Does anyone know what could be causing such an issue? I've spent the last two days measuring and moving, and there doesn't seem to be any huge changes in the 2khz+ region.

 

[~BURNY~]

I'm not an expert (then again few people are on this board) but you probably need mid frequencies diffusers rather than absorbers. I'd blame the three panels at the first reflection spots. Maybe start by removing the left and right ones and see if it improves things a bit.

 

[vespiz]

I'd guess the dip in the mids is due to comb-filtering from the desk. Getting them to their own stands behind the desk would be a good place to start.

I wouldn't take down the the panels on the walls. But check with a friend the reflection points using a mirror on the walls to see where to place the panels.
That is, you sit on the listening spot and your friend moves the mirror on the walls and where you see either of your monitor tweeters, you should put a panel there (be it the walls, ceilings or floors!).

Do you have any panels up on the ceiling, where it slants? Some reflections could be bouncing off there (just guessing here).

 

[vespiz]

One thing I forgot: Have you experienced the dip while listening or is it only through measuring?
If so, comb filtering will occur in the frequency plot if you use both speakers at the same time; use only one at a time when doing measurements.

 

[spiderjazz]

Thanks for the replies!

I'm not an expert (then again few people are on this board) but you probably need mid frequencies diffusers rather than absorbers. I'd blame the three panels at the first reflection spots. Maybe start by removing the left and right ones and see if it improves things a bit.

From my research that I did before putting up the treatment, the first thing that everyone recommends is bass traps for the corners, and panels up at the first reflections spots. I'll try from the start again though and I'll measure after putting up each panel and see how it affects the measurments.

I'd guess the dip in the mids is due to comb-filtering from the desk. Getting them to their own stands behind the desk would be a good place to start.

I wouldn't take down the the panels on the walls. But check with a friend the reflection points using a mirror on the walls to see where to place the panels.
That is, you sit on the listening spot and your friend moves the mirror on the walls and where you see either of your monitor tweeters, you should put a panel there (be it the walls, ceilings or floors!).

Do you have any panels up on the ceiling, where it slants? Some reflections could be bouncing off there (just guessing here).

Hopefully I'll be able to get stands in the next month or two and get the monitors off the desk.

First reflections spots are good, I got the GF to do the mirror test, and the panels are big enough that they should give a bit of lee way with regards to the placement.

I don't have any panels up on the slants, just one over my head. I'm in rented accomodation, so I want to minimise the amount of drilling that I have to do to the walls.

One thing I forgot: Have you experienced the dip while listening or is it only through measuring?
If so, comb filtering will occur in the frequency plot if you use both speakers at the same time; use only one at a time when doing measurements.

To my ears, it sounds fine when I'm listening to it, it's only when I'm measuring that I see there is a drop in the mids. I'll measure again using only one speaker and see what occurs.