Small Room – How can I take it to the next level?

[Glenn Kuras]

Panels at the front of the room are 4’x2’x3.25” RealTraps Mini-traps on stands. The 2’x2’ x3.25” centre trap is a HF trap as is the right reflection point trap.

Since you bought from them I would send Ethan a email and talk with him about your room. The nice part of commercial products is some (they do and so do me) work with the customer not only upfront but also down the road to help improve the room.
Basically though it is either going to come down to more broad band bass traps in the corners and or tuned traps in the areas that the problems are coming from.

BTW there is no "rule" on where to have the best spot. If sitting at the 45% of the room is giving you the best result then that is where you should be.

[DoctorG]

Thanks Glenn, I’m sure Ethan can provide some guidance.



One thing I was considering was additional bass traps at the bottom of the front wall or maybe to treat the entire front wall with the possibility of using some kind of tuned traps. However, I don’t have much opportunity to add them in any other corners due to mounting, so hopefully this will help with the 38Hz and 125Hz anomalies.



I understand that 45% is the place to sit if its best there, but I was surprised that it wasn’t that close to the 38% rule of thumb given the room is a regular shape.

[Ethan Winer]

Originally Posted by DoctorG

• Panels at the front of the room are 4’x2’x3.25” RealTraps Mini-traps on stands. The 2’x2’ x3.25” centre trap is a HF trap as is the right reflection point trap. Panels are 8” from front wall.
• Front corner traps are RealTraps corner 4’x4’9”x4.25” Mondo traps on stands.
• Left wall panels are 4’x2’x2” Primacoustic broadband panels. Panels are 1” from wall.
• Adjustable modular ceiling cloud uses three 4’x2’x2” Primacoustic broadband panels with two 4’x2’x3” ones fitted above the monitors giving 5” in total. The cloud is angled to reduce high frequency reflection to listening position.
• 2” Primacoustic corner traps fitted to front corners.
• Rear wall corner panels are 4’x2’x3” Primacoustic broadband panels. These are the ones sitting in front of the curtains.
• Lower rear wall (and corners) also treated with Ikea book cases that are filled with 18” deep Rockwool which extends 3” out the back. I have read in another post that the lower frequency response (<100Hz) can be improved by removing the shelves or drilling (rather large) holes in them and the side walls of the bookcases. I plan on doing this – at least to the shelves which won’t be visible.
• Left over Rockwool fitted behind the rear sofa.

That's a lot of panels, but it's not clear what you have in the front corners since you list both MondoTraps (very good) and 2-inch Primacoustic (too thin for corners).

I’m not sure which figure is how I would rate my room – is it a +/-5dB result (Level 3) as in the post by Hannes_F? (See Acoustics/Treatment Reference Guide sticky). If I’m still at +/-10dB then there’s a long way to go!

If you can get the total span from the highest peak to the deepest null within a 10 dB window, you're doing pretty well. This is for no averaging, or 1/24 octave, not 1/3 octave.

[*]Apply Helmholtz or additional bass trapping between the floor and front wall to lower room mode around 38Hz. There have been some very informative GS posts on the Helmholtz designs lately, but I’m not sure if there is enough space for this type of treatment to make a difference.

I wouldn't use tuned absorption in a room that size. Adding yet more thick broadband absorption is the way to go for those corners. A trap in the wall-floor corner behind the couch might help, but only if you pull the couch forward a bit so sound can get to the traps.

[*]Beef up the left and right first reflection points by using thicker traps so they treat lower frequencies over a larger area?

Yes, that would probably help too.

--Ethan

The Acoustic Treatment Experts

[DoctorG]

Thanks Ethan.

The front corners are corner Mondo traps (i.e. the corners in front of the desk). At the rear of the room are 3” panels near the window. I’m now considering swapping the Minitraps and the 3” panels so that the Minitraps are used for the corners rather than near reflection behind the monitors.

My logic behind putting the Minitraps near the monitors was that this would give better treatment for near reflections. I’m not sure if this is where they are best used as I have some prominent modal peaks at 37Hz and 119Hz, but there are also three nasty nulls between 480Hz and 780Hz – maybe it’s a trade off. Am I correct in assuming that the nulls would be best addressed at the near reflection points and given the frequency the 3” panels would be fine for this?

The difference between the 119Hz peak and 173Hz null (tested with both monitors) is +/-7.6dB with 1/24 smoothing. If I can reduce the 119Hz peak to the same peak as the 37Hz mode (-3dB) then this will give +/- 6dB. One positive is that the waterfall at 119Hz looks OK. As you have suggested, I’ll look at adding some broadband treatment at the floor-wall points behind the rear lounge and in front of the desk in an endeavour to lower this worst peak.

Given that the 37Hz mode is going to be very difficult to address in this room, I’m happy to just apply a couple dB of EQ to at least lower the amplitude.

[Ethan Winer]

Yes, 3-inch panels are able to target those frequencies, but I still think more bass traps in the floor corners will only help further. It's impossible for me to tell remotely what will happen with different trap placements. At least you have the right tool (REW) to measure as you experiment.

I'm not opposed to using EQ to reduce a peak (only, not a null) at very low frequencies like 37 Hz.

--Ethan

[DoctorG]

OK thanks for providing some direction, I'm going to try swapping some of the panels and traps around while running pink noise and the REW RTA. I may be able to get a dB or so improvement.

I'll add some further treatment behind the sofas and in front of the desk as my next stage.

I'll also try using some sine waves to investigate the issues I have in the 500Hz area as this area may be the easiest problem to fix.

BTW - maybe someone can comment on the waterfall and/or spectrogram. I believe around 300ms (except 38Hz mode) is good - is this correct?