Construction of mobile studio on caravan chassis

[Rod Gervais]

Originally Posted by adamski

I am designing together with a friend who is an accomplished eco-carpenter and builder. The aim is to be achieve a balance of lightweight construction, strength and soundproofing. Lightweight is needed so the unit is towable, so total weight should not exceed around 1500 kg. The lighter the better in terms of towing. However it will not be moved a lot, I imagine around once every 2 months or so.

Lightweight and soundproofing do not belong in the same sentence - one does not work with the other.....

In order to soundproof to any real degree of efficiency you have to have mass - this on all 6 sides of your enclosure.

I'd like to describe the current design to see if anyone can lend some advice or suggestions.

Walls:

• 2x3" stud frame
• outer wall sealed with waterproof membrane, cladded with weston red cedar which becomes very light when dry. my friend suggests waterproof breathable membrane for this but I am thinking about changing this to some kind of rubber matting to add some extra sound absorption, although this will add more weight.
• 60 kg/m3 rockwool stuffed in the frame
• inner wall attached to resilient bars - 6mm ply with spruce cladding.

Roof: curved ribs supporting 2 layers of 6mm ply glued together, with fibreglass coating to seal and strengthen.

Ceiling: Resilient bars from which 1 layer 6mm ply hangs down. 60 kg/m3 rockwool between the roof and ceiling.

Floor - 18mm ply base with sheepswool /rockwool in between slats and another layer of ply on top (maybe only 9 or 12mm)


We are trying to go for the lightest possible structure with adequate soundproofing, for low to moderate sound levels with the ability to be a small distance from any neighbours. The main concern is to be isolated from outside noises which is mainly birds and nearby traffic, plus occasional motorised tools nearby. I do not have data in dBs atm! [/quote]

I don't see this design achieving any real level of isolation, birds are the least of your worries.

However - a bigger problem is fuzzy specifications - you have to clearly define the level of sound you need to deal with - along with the level o isolation you want to achieve in order for us to make any real sense out of this.

Another consideration is splitting the space to have a small recording booth, and getting the length + width ratios right to reduce unwanted resonances... I am going by this diagram: Acoustics Forum • View topic - ROOM RATIOS: M.M. LOUDEN ANALYSIS

This you may as well forget - in a space this small sub-dividing it into even smaller spaces is going to make it extremely difficult for you to treat the space. Heck - even with one larger space you are going to be faced with a very difficult task making this acoustically workable.

Rod

[adamski]

OK thanks Rod - I was half expecting a response like this... I know that mass = isolation, but since the structure is not touching any other then less isolation will be needed.

I also realise that lightweight and soundproofing do not generally work together... however the challenge here is to make compromises so that the trailer remains towable but also has a degree of isolation so that low-to-moderate outside noise can be kept out.

I do not have the means to give measurements is dB of the levels of isolation needed atm (I should be able to in a few days) but the idea is to keep ambient noise out. I will be working at low to moderate levels most of the time (I wont be able to measure this for a while as I'm without a studio now). I am looking to be able to record low-level instruments such as flute and percussion, not drum kits or amps.

I think the next step is to work out how much the building materials will weigh in total and try and reach a compromise - basically the total weight should not come to more than 1700kg including all my gear.

Any help with this would be much appreciated! Thanks
Or am I totally barking up the wrong tree?

[Rod Gervais]

Adam,

Personally I think you are barking up the wrong tree - especially if you are looking at low level instruments.......

With loud instruments you can lose low level background noise (to some degree anyway) through gating - however this is not going to work with a flute - what is going to happen is that you are going to pick up everything in the background - - and then when you bring compression into play you are going to bring everything to the surface........

Road noise and power tools can be pretty high in amplitude.

I just don't see this happening........

Rod

[adamski]

Originally Posted by Rod Gervais

Adam,

Personally I think you are barking up the wrong tree - especially if you are looking at low level instruments.......

With loud instruments you can lose low level background noise (to some degree anyway) through gating - however this is not going to work with a flute - what is going to happen is that you are going to pick up everything in the background - - and then when you bring compression into play you are going to bring everything to the surface........

Road noise and power tools can be pretty high in amplitude.

I just don't see this happening........

Rod

OK - by road noise, I mean in the distance... the nearest country lane is around 50 metres away.

Power tools are use only occasionally, mainly to cut the grass, and I can ask them to be stop for a bit if need be.

Given the situation, is there a way to make this work better? A compromise that could be made?

Thanks for your time

[Rod Gervais]

Again, there is no way to determine this without you first making some determinations as to levels - both those you will encounter and those you wish to isolate - however - as mentioned - it would take very little background noise to screw up a recording of a flute - violin, harp, etc., etc., etc........ so you are really talking about achieving good isolation here -

I would also point out that you are talking about taking this on the road - how is it that you know that the road noise will always be that distance away - the way you are talking now is as though this will always be at a particular location on your property........

[adamski]

The background noise to block out, would most of the time be around 50-60dB, occasionally up to 70, measured where I am at the moment..

The main aim of this is to enable me to make music where I am currently living, and to learn about the possibilities and challenges of off-grid living - without committing to a place (I have built two studios in the past and left them).

The possibility of taking it out on the road is a nice idea but not the main aim.

Also - most of the time I am using electronic gear, samples or pre-recorded material. Recordings can be made when things are quiet, if need be, or else I know a couple of people in town with super-isolated recording rooms if I need that.

In terms of upgrading the design, to try and balance weight, towability and isolation:

I am thinking of using a double layer of plywood, perhaps just 9mm for the walls with green glue in between. In this case, would using resilient channels be worth the extra effort?