Another studio bass taming post

[ore_terra]

hi all

I'm moving the studio out from home. I got a room aproximately 5,5 x 4 x 2,5 m.

the room is fairly well treated already. it has copopren 5 cm foam all around. it's in the end of a big hall and does not share any wall with another room. inner walls are double, with another layer of 5 cm copopren in between.

I set the desk and speakers in one of the 4 m ends and measured with Sonarworks software before stickying anything else to the walls. I got (among other "minor" things upper in the freq range) 2 dips of about 6 db's around 80 and 150 Hz.

I then placed 4 small commercial bass traps I had at home in the 4 corners, of about 120 cm long (plus a few 5 cm thick absorber tiles in the mirror points that helped with that "minor" stuff I mentioned above) and the 150 Hz dip improved considerely (no more than 2-3 dbs), while the 80 Hz one remains the same.

I'd also like to have some consistency out of the listening spot, as it's an all in one room installation. moving out of the spot while playing well known tracks on the speakers it feels more or less quite evenly, except in the very center of the room where there's an obvious bass level increment.

now - finally - the questions:

1. regarding the listening spot, should I just leave Sonarworks do its thing for that remaining 80 Hz dip, or try to tame it with additional treatment?
2. if the latest, what density and thickness of rockwool should I use? do you think I'd get away with only wall absorbers for 80 Hz? - I rather not to add anything bigger to the corners.

[Hugh Robjohns]

1. regarding the listening spot, should I just leave Sonarworks do its thing for that remaining 80 Hz dip, or try to tame it with additional treatment?

Tame it with additional treatment.

The dips are, apparently relatively small (and way better than most domestic rooms already), but even so if the problem is physical acoustic cancellation due to standing waves (which it undoubtedly is) Sonarworks can't 'fix it'. All SW can do is ask the speakers to produce a lot more energy at those frequencies -- robbing them of headroom and potentially degrading the monitoring quality significantly. And even if they do produce more welly, the same standing waves will still be generated and will still interact and cancel it all out... so you'd be no better off.

A subwoofer or two in different locations might well help... but then you have the very high expense of decent subs and the hassle of setting them up accurately ... and still no guarantee of success.

What is really required is some proper bass trapping which is genuinely effective down at 80Hz. And that means pretty big and DIY. if the problem really is confined to a couple of specific frequencies then smaller tuned traps might be a more practical solution... but they are a bit harder to design and build.

2. if the latest, what density and thickness of rockwool should I use? do you think I'd get away with only wall absorbers for 80 Hz? - I rather not to add anything bigger to the corners.

60kg/m3 (RW3) is what most would recommend as being a good compromise between effectiveness and workability, but it also depends on the form of construction you plan to use. You can try wall panels... but people put bass traps in corners for sound technical reasons (see what I did there? )

It really depends what the modes are and which boundary reflections are causing the problems. I'd try using one of the online room mode calculators to find out which modes exist at which frequencies. That will give you a much better idea of how to target your treatment most effectively.

[Drew Stephenson]

Remember that sound pressure builds up in the 2-surface corners as well as the 3-surface ones. Can you add something in the wall-ceiling or wall-floor corners? Your wavelength at 80 Hz is 4.25m so you'll still need to be getting fairly deep to control it. Have a think about those wall-ceiling corners. Also, have you got a cloud set up yet? At 2.5m height you could get something a fair distance from the ceiling without affecting headroom.
Unless you're really, really tall.

[EDIT - I see Hugh has got in first!]

[DanDan]

The Minimum treatment many of us recommend is the 1200 x 600 x 100 mm semi rigid fibre trap. Best to use about 100KG to prevent sagging , particularly overhead, and to avail of a damped panel resonance, which is very significant especially straddling corners. For those on the wall and ceiling a 100mm airgap delivers free lunch. Increased LF absorption to a lower frequency. The solidity of your boundaries will determine how strong your modal and SBIR issues are. But there is a case to be made that the Back Wall is the dominant boundary in terms of wrecking FR. Probably best to say 'All Factors Matter' but again, the boundary mass and rigidity will prioritise.

https://realtraps.com/art_modes.htm

https://www.hunecke.de/en/calculators/r ... modes.html

[CS70]

the 150 Hz dip improved considerely (no more than 2-3 dbs), while the 80 Hz one remains the same.

Keep in mind bass traps tend to be tuned - so they absorb better in a band around a specific low frequency. You can probably add some that are tuned to 80Hz..

[Philbo King]

For my bass trapping I picked up 2 full sized sofas and a love seat (a small 2 seat sofa) and put them at places where measurement indicated a maximum null or peak. Worked very well.

They were used, so they were quite inexpensive.

[DanDan]

Tuning Bass Traps is difficult. Most of the commercial corner traps tend to be 'broadly' tuned. But....the semi rigid 4"x4'x2' fibre trap has a sort of damped resonant bonus straddling a corner. By a lucky coincidence it is around 80Hz where many of us on this side of the atlantic have our worst issues. Straddle properly touching the wall at the edges and go floor to ceiling to get the maximum effect. http://forum.studiotips.com/viewtopic.php?f=8&t=534