Home Studio Treatment - Measurments and Questions

[ddude003]

At this point I would suggest looking at that http://arqen.com/bass-traps-101/placement-guide/ link and ask yourself if there are more options for absorbers in your room... Ceiling, ceiling to walls and walls... Small rooms are difficult to tame...

 

[fiskmaas]

At this point I would suggest looking at that http://arqen.com/bass-traps-101/placement-guide/ link and ask yourself if there are more options for absorbers in your room... Ceiling, ceiling to walls and walls... Small rooms are difficult to tame...

Cool, thanks @ddude003! There's definitely room for more, I'll have to go shopping for more rockwool.

 

[ddude003]

A direct quote from Tim Perry... "Here’s a cheat code you can use for treating your typical domestic room (whether it’s a hi-fi room, home theater or home recording studio): Cover 22 to 25% of the interior surface area with acoustic treatment.
That would be the total coverage provided by bass traps, absorptive acoustic panels and diffusers." and I agree and would go a bit further with 1/4 to 1/3 of the interior 6 surface areas with a balance of bass traps, wide band absorbers and diffusers...

 

[fiskmaas]

Decided to test my Dali Spektors in the studio just to sanity check the 130hz bump and it looks like the bump is present there too, so definitely seems to be the room causing issues.

 

[ddude003]

Nice sanity check... Yep, dip at ~100Hz and peak at ~130ish... I'm sure you can crush the peak(s) with a nice EQ and there is no way to boost your way out of the dips (nulls) with EQ... Big, thick, bass absorbers, floor to ceiling, in corners...

You might have a look thru some of Mitch's information at: https://accuratesound.ca/resources-audio-digital-signal-processing/

 

[fiskmaas]

So I've tried back and forth with EQ, tried different amounts of attenuation etc but I don't feel I'm getting good results. It just takes out too much energy.

So I'm thinking to make some more traps. Since the celing is slanted do I still put traps in the ceiling (top of side walls), or should I focus on the back wall? I'm thinking I can move or remove the bookshelf entirely in place of traps.

 

[ddude003]

All of the above... A cloud of traps on the ceiling above your workspace... More on the back wall, and top of side walls...

 

[fiskmaas]

Made a couple new absorbers today. Big one covering the entire back right corner (floor to ceiling) 2m tall piece, in place of the bookshelf, 20cm thick. Also made one broadband absorber 90x90cm, ~15-20 cm thick of which 10 cm is rockwool.

No change yet in terms of SPL in the 130 hz area. I tried the 2m bass trap in one of the ceiling corners of the side walls too, and there was some change in spl of around 1 db, but could also be margin of error so ¯\_(ツ)_/¯

Might try to make one or two tomorrow to fill the ceiling corners to see what it does.

Another thought I've had is regarding the material covering the absorbers. I've just used old sheets and curtain fabric but I've read that it should be pretty porus to work well. How much does that actually matter?

Edit: Updated measurements, added separate L and R

 

[ddude003]

For bass frequencies the covering material could even be 1/8 inch plywood or pegboard... Mid and high frequencies may reflect while bass is absorbed... Usually called a strike plate... You might look at GIKs designs for an example...

 

[fiskmaas]

For bass frequencies the covering material could even be 1/8 inch plywood or pegboard... Mid and high frequencies may reflect while bass is absorbed... Usually called a strike plate... You might look at GIKs designs for an example...

I've seen those, yeah. I'm more concerned about the fabric though, if it can cause issues if it's too thick, or not porous enough. Maybe I'm overthinking things.

 

[ddude003]

For mid to high frequencies you might be looking for something acoustically transparent... And your building bass absorbers don't worry about it...
Google yourself up a copy of Master Handbook of Acoustics F. Alton Everest Ken C. Pohlmann... There is a chapter or two on building acoustic absorbers...

 

[fiskmaas]

Built another trap for the left ceiling and then tried moved the right back corner trap to the right ceiling and it seems to have a better effect than in the back corner so I think I'm going to mount it in the right ceiling instead. Still some way to go but it seems to have shaved a couple db off it at least it.

 

[fiskmaas]

After mounting and doing some testing and comparing more to old measurements I'm not so sure it has done that much, but they're made and mounted at least.

Not entirely sure what to do next. Currently it looks like this:

Front wall:
Right and left corner above speakers - 100 & 60x45x25 cm (only covers about 30%)

Back wall:
20 cm trap ceiling corner - 150x45x25 cm

Side Walls:
Absorbers first reflections - 100x55x12 cm
Traps ceiling corners front to back - 200x45x25 cm

I could move back the mix position, which is currently at ~35%, closer to 50%, which is not ideal but it would allow for full trapping in the front corners.

Broad band absorbers could also be fitted on the side walls further back, but I feel like the front wall is causing most of the issues.

 

[ddude003]

I might be off on my math here... Please forgive me if I am... And your front wall surface area is approximately 52.7 sqft... I averaged the front height with the back height times the width... And your absorbers are approximately 5.9 sqft... I would suggest that you need 1/4 to 1/3 coverage which would be 13 sqft to 17.5 sqft of absorbers...

I would also try 75dB to 80dB SPL when doing your frequency sweeps... You don't really listen above 75dB do you?

 

[fiskmaas]

Approximately yes (4.5 sqm, 49.2 sqft). Current ones are not taking up much due to lack of space and mounting options. Window, speakers, speaker stands, computer screens, ventilation hole are the biggest problems.

I think moving back both speakers and desk would help free up some space.

On another note I am noticing things sounding a lot clearer and detailed though, so there's that.

 

[ddude003]

Have you thought about making an absorber that fits into the window frame and can be removed when not in use, maybe?
And I would think, at this stage, that things are starting to sound a little better... Good job...

 

[fiskmaas]

Thanks!

Yeah, I tried fitting something in there a few posts back but could give it another go for sure.

 

[fiskmaas]

Built one to fill ~80% of the window. No way I'm getting it in and out easily, but hey, winter's coming. I won't need open windows for another 8 months anyways.

Filtered IR looks better? Had some big dips before I feel which have been smoothed out.

The general curve looks a lot flatter too now. Comparing 70hz to 130hz it's the same as before (which is what I'm usually comparing to), but comparing it to 350 it's a lot lower. Maybe it is getting better after all.

Added an image comparing to no treatment. (Green is current treatment)

 

[ddude003]

I imagine your right on that borderline where with additional absorption your will see more improvements... What is the total surface area of the room? All 6 sides... Front, back, left, right, floor and ceiling... Now figure 1/4th to 1/3rd of that total surface area needs treating... And if you are going to flatten that room mode at 70Hz and 130Hz you will need to go thicker still or look into other design types of absorbers/traps... Oh, and like I said above, you can put 1/8 inch thick plywood or peg board on the front of the bass absorbers...

 

[fiskmaas]

Cool, exciting. I'll have to shop for more rockwool, almost out. Figure I'll make a small one for the front top corner with what's left.

Here's what it looks like atm, not the prettiest but functional will have to do for now. Kinda like how the window one turned out, better than the curtains.

 

[ddude003]

Oh, that's a block wall? Get some absorption behind those speakers... Lol... I'll agree, its not so pretty... And it is the function that counts... Sounding better all the time, yea?

 

[fiskmaas]

No it's all pressed wood panels I believe. Yeah that was what I was referring to earlier about moving back the mix position so I can fit traps behind the speakers. Might not look like it from the picture due to wide angle lens, but there's not much space behind them unfortunately.

Yeah night and day difference from when I started.

 

[DanDan]

Sorry just tuned in and skimmed the thread.....
Speakers with multiple drivers work better vertically.
130Hz is often the peak of the ceiling floor mode.
A flat response as shown in your first post is highly undesirable. It is skewed, tilted, 6-9dB away from normal domestic listening responses, including cars and headphones. Check out the Harman Listening Curve or the Bruel and Kjaer.
Traps behind the speakers can do more harm than good.

 

[fiskmaas]

Sorry just tuned in and skimmed the thread.....
Speakers with multiple drivers work better vertically.
130Hz is often the peak of the ceiling floor mode.
A flat response as shown in your first post is highly undesirable. It is skewed, tilted, 6-9dB away from normal domestic listening responses, including cars and headphones. Check out the Harman Listening Curve or the Bruel and Kjaer.
Traps behind the speakers can do more harm than good.

Hi DanDan, thanks for the info. Is that true for slanted ceilings aswell? I did try putting absorbers on the ceiling but didn't find it did all that much. Maybe they need to be thicker.

 

[fiskmaas]

Ok, so I measured and held a big absorber in the ceiling and now it made a big difference actually. Shaved another 2 db or so off. Going to mount it and make some proper measurements.

I also tested to turn the speakers vertically, it made a big dip in the 1-2khz range, but maybe there's other benefits.

Edit: Mounted the absorber in ceiling, definitely helping. (test and test2.jpg = 5.2 and 8.2 db respectively.)