Ideas on how to use an "additional volume" for absorbers

[andymel]

Hi guys,

maybe someone wants to help me finding the right idea to use some volume under a staircase that was found during the build of a studio.

aditionalvol.png

unterstiege_700px.jpg

I don't know the exact size. At the moment I also can just guess from the pic that it is aroun 1m deep (from the studio...the right wall on the pic) and something between 1-2m3 volume.

Between this volume and the studio is a 25-30cm thick wall. My first idea was to just use the volume as a big helmholtz absorber and tune it to room mode(s) when the rest of the room is done. But with the volume being that deep it seems not to be possible to tune the resonance frequency to something high enough (40-80Hz).

It's a load-bearing wall so it's not easily removable. But holes could be made.

The problem that I see with anything absorbing to much >100HZ is that it looks like it is a first reflection spot so it could be a problem for the symmetry of the room.

The literature I know of writes for Helmholtzabs. the bigger the better. But regarding to the formulas I use this is just too deep?! The spring gets too weak => ResonanceFq. gets too low. I would need a hole with ~2m diameter (so basically a lamda/4th reflector?!)

With http://www.mh-audio.nl/acalculators.asp#showcalc I can design some slat resonators that could work but maybe that's outside of the calculators 'meaningful range'?! I prefer to check my calculations against scientific sources :/

Besides any science and calculations. Do you have an idea? How would you use it?

As a general info about the room a diagram of the first RT60 measurements (nothing done yet)

SamuelBern_ErsteMessungen_700px.png

Andy

[Soundman2020]

Hey Andy! Good to see you around again! You still have the best room mode calculator on the Internet! I still use it, regularly.

Here's a couple of ideas for your "cavity":

1) You could divide it up into a few smaller cavities, and tune those individually as Helmholtz Resonators. However, that would only work for modes that are associated with that location in the room (pressure nodes). It should be possible to tune them suitably.

2) Perhaps use it as an isolation "tank" for an electric guitar or bass cab? Put a thick, heavy trap door over it for isolation. Access might be coplicated...

3) Use it for rack gear that isn't needed very much. Eg amps, power supplies, or remote controlled outboard gear.

4) Fill it with absorption, so that it acts as a general deep bass trap.

Probably other things could be done as well, but those come to mind first...


- Stuart -

[andymel]

Hi Stuart,

I'm very happy to see you are still very active. Sorry I just saw your answer today!
Glad to hear you are still happy with my calculators I am actively working on the next one. I guess I will tell you here as soon as it's online as you are a perfect beta tester

Thanks for your tipps!
1) I thought about that as well. It would be a lot of work though.
Those relations to the mode patters!! Where did I already learn this?! Ah yes, this great amroc room mode calculators 3D view!

2) Perhaps use it as an isolation "tank" for an electric guitar or bass cab? Put a thick, heavy trap door over it for isolation. Access might be coplicated...
3) Use it for rack gear that isn't needed very much. Eg amps, power supplies, or remote controlled outboard gear.
Yeah, probably a good idea to simply think about using it as storage an forget about acoustics.

4) Fill it with absorption, so that it acts as a general deep bass trap.
It has to be coupled with the room volume though. The wall between is heavy weight.

Thanks a lot for your thoughts!
Andy

[Soundman2020]

I am actively working on the next one. I guess I will tell you here as soon as it's online as you are a perfect beta tester

Cool! You know I'm your number one fan, right?

Those relations to the mode patters!! Where did I already learn this?! Ah yes, this great amroc room mode calculators 3D view!

Absolutely! That comment was far more for folks following your thread than for you...

4) Fill it with absorption, so that it acts as a general deep bass trap.
It has to be coupled with the room volume though. The wall between is heavy weight.

No part of that is exposed to the room air? I guess I had the wrong impression: I thought it was inside the room, but now I guess it is outside the room?


- Stuart -