Building a studio within steel framed + sheet metal shed

[epemusic]

Hi guys, Matt here from Adelaide, Australia, first time posting.

I have searched the forum but can't seem to find anything about my particular scenario, I'm sure somebody will point me in the right direction if I have missed it.

...

I have a steel framed shed, thin sheet metal (steel?) walls and roof which measures roughly 9000mm x 7500mm total. The roof studs begin at a height of 2940mm on the edges and rise to 3600mm at the highest point dead centre of the shed. The floor is an ~2 foot deep concrete slab.

There is a steel C channel single stud wall virtually dead centre through the middle of the shed and the studio will be on the left hand side only, leaving me with around 4490mm x 7500mm (with an additional 75mm from the inside edge of the horizontal steel wall studs to the sheet metal walls on the other 3 sides).

There are also two 200mm wide support beams beginning from the floor and continuing along the roof on the 7500mm side, located 2400mm from the short sides.

I am aiming to create a 2 leaf MSM system and have 2 ideas to have picked apart by John Sayers and the other professionals here.

First; am I able to utilize the sheet metal screwed into the steel 'C' channel shed frame as one layer of the system, then improve it by;

A. Sealing all the air gaps to the outside
B. Spray some sort of sound dampening onto the sheet metal + frame
C. Add RockWool, leave a 300mm~ air gap, then build the second layer with RockWool, wooden studs and a 16mm+12mm layer of gyprock?


Second; will the better option be to build the two leafs independent of the steel structure, leaving the steel structure unsealed so it does not act as a third leaf? My issue with this option is I will loose ~0.5 meters of floor space from the 7500mm face (leaving 200mm for support beams + 10mm clearance, then ~400mm for the double stud assembly).

Thank you very much for this extremely valuable resource
I look forward to hearing your replies

-Matt

[Soundman2020]

Hi Matt. Please read the forum rules for posting (click here). You seem to be missing a couple of things!

Quick answer: unless the metal is reasonably thick and massive, it won't be much good as your outer leaf. However, it can still potentially be a third leaf, and/or resonate sympathetically, so there's an issue there. Several other forum members have run into the same situation, and have taken various routes to overcome the problem.

Second; will the better option be to build the two leafs independent of the steel structure,

If you need high levels of isolation, then that's what I would do.

...leaving the steel structure unsealed so it does not act as a third leaf?

That won't stop it from acting as a third leaf. It does not need to be sealed in order to do so. Have you ever noticed that an acoustic guitar resonates at some frequencies in sympathy with music played nearby? It has a huge hole in the front, so it certainly isn't sealed, yet it still resonates...

My issue with this option is I will loose ~0.5 meters of floor space

Why so much? Studs measure 9cm when laid flat. Drywall takes up another 2 to 5 (depending on thickness and number of layers), so figure average 13cm for each leaf. Figure a 1cm gap between frames: 1 + 13 + 1 +13 = 28 cm. Maybe a bit more if you want to go crazy on the gap size and number of drywall layers, but I can't see you needing 50 cm unless you have outrageously extreme isolation needs.

- Stuart -

[epemusic]

Rules read, thanks

I will be using the studio as a recording space, mixing space and a rehearsal space for many styles, rock bands being the loudest. I ideally want a control room and live room out of the space, however I do realize room volume may be an issue. My budget is yet undecided, I have $2500 to spend on the frame/isolation phase of the build, however I will rather wait for funds than skimp on the build . We live on a suburban block, with neighbors backyards surrounding the shed. The nearest neighbors house is roughly 20 meters away, although this may change with one neighbors house being replaced with two town houses (damn new age living). All homes in the area are solid brick construction, although the new ones probably won't be.

Why so much? Studs measure 9cm when laid flat. Drywall takes up another 2 to 5 (depending on thickness and number of layers), so figure average 13cm for each leaf. Figure a 1cm gap between frames: 1 + 13 + 1 +13 = 28 cm. Maybe a bit more if you want to go crazy on the gap size and number of drywall layers, but I can't see you needing 50 cm unless you have outrageously extreme isolation needs.

I made a sketchup of the floorplan. The 75mm measurments around 3 sides of the room refer to the existing horizontal studs the sheet metal is screwed to. Building the new 2 leaf system with a ~10mm gap after the two structural beams is my reasoning for loosing 0.5m of floor space. Is it possible to build an effective MSM system around these beams instead? Will the depth lost at the beam locations effect the air spring negatively?

On another note, I notice many (all?) of Johns studio builds use odd shaped rooms rather than parallel surfaces. I have a superficial understanding of flutter echo but want to know more about the reasoning behind this room shapes. Can anybody suggest further reading about the advantage of designing such rooms?

Thankyou!
-Matt

[epemusic]

After spending my day whole day trying to figure out how to design this studio as well as I can, I have partially answered my own question about odd shaped rooms, RFZ's it seems.

Can anybody help or help me help myself with creating a LEDE/RFZ room with my dimensions (~5 x 7.5 x 3 meters)? I am still in the planning stages so this zone can be built right in.

Primary concern is being able to record a good drum track in the live end of the room. Guitars and bass can be recorded DI and Re-amped/close mic'ed in the RFZ later, vocals can also be re-recorded within the RFZ

Any thoughts?

[xSpace]

"I have a superficial understanding of flutter echo but want to know more about the reasoning behind this room shapes. Can anybody suggest further reading about the advantage of designing such rooms?"

Yep, continue to read the threads in this forum for about six months. You answered your own question, flutter echo.

[epemusic]

Thankyou Xspace.

Bump. Can anybody help?

If my questions are too stoopid to be rewarded with an answer I will appreciate being told so I can move on and not bother anybody

thanks!

[Soundman2020]

Is it possible to build an effective MSM system around these beams instead? Will the depth lost at the beam locations effect the air spring negatively?

Entirely possible, yes. MSM is a tuned system, and the equations for calculating the tuning are fairly simple. Basically, the more mass you have on each leaf, the better. And the bigger the air gap between the leaves, the better.

I notice many (all?) of Johns studio builds use odd shaped rooms rather than parallel surfaces. I have a superficial understanding of flutter echo but want to know more about the reasoning behind this room shapes. Can anybody suggest further reading about the advantage of designing such rooms?

For many of his designs, John uses the studio design technique known as "RFZ" meaning "Reflection Free Zone". With that, the walls are carefully angled to force all reflections to go around the mix position, thus creating an area right at the engineer's chair where there are no first-order reflections at all: only direct sound from the speakers. The reflections are sent to the rear of the room where hey are partially absorbed, partially diffused, and only get back to the engineers location after a delay of at least 20ms (ideally) and at a level that is 20 dB below the direct sound, before fading out smoothly across the spectrum, and also in time. That's the reason for the angled walls. Yes, they also do deal with flutter echo, but that's not the major reason. RFZ is. Flutter echo can be dealt with using angles of 6° or more on each side wall (total 12° difference), but RFZ usually needs much more than that.

- Stuart -