Making an acoustic ‘gobo’

Having taken the decision to take VO more seriously, after completing Gary Terzza’s excellent VO Masterclass, my ‘recording studio’ has taken a number of forms incorporating blankets, quilts, cushions, towels, the side of a wardrobe – in fact there weren’t many bedding items left in the house to put on the actual bed!

My room of choice was always a good starter as it is acoustically pretty good, and nice and quiet. However it’s also my daughter’s bedroom when she comes down, and so it was a case of regularly dismantling the pile of quilts, in order for the room to be habitable (and so she had something to sleep in)!

Eventually things morphed into something semi-permanent, resembling something like a Bedouin tent, constructed in part with an up-ended sofabed, and a collection of quilts, cushions and blankets.

(Where did I park my camel?)…

Tent-2Tent

Totally effective, but not the best use of an otherwise perfectly good sofa-bed. Out of shot is the mattress ‘gobo’ which stood behind me – again another element to be returned to its rightful place when my eldest is in the house.

So it was time to do something more effective. I had been spending time researching my options, and had settled on a ‘bi-fold’ door solution where I was going to fix acoustic foam to three pairs of doors which I could fold away when needed. This was inspired by Brian Thon’s video here https://www.youtube.com/watch?v=q0Uflof369A

However, bi-fold doors in the UK are not cheap, and neither is the foam. Whilst I was happy to invest – I wanted to be sure it was going to work for me, and I wasn’t in the position to chuck a couple of hundred quid away as an experiment.

Keeping my eyes open for second hand room dividers, bi-fold doors, acoustic foam, even considering making the doors myself from MDF I started to see some of the YouTube videos made by people who create proper ‘acoustic panels’ – and became interested in this option.

I looked at LOADS of forums, AVS Forum, Gearslutz to name two, and I stumbled on a video by a guy call Larimarmusic who showed how to construct a ‘gobo’ which seemed to make sense – his construction is here https://www.youtube.com/watch?v=x65he5FbbAU and it was posted a few years ago.

The challenge is that the ‘magic ingredient’ 703 isn’t available here in the UK, so I needed a low cost alternative, and I found it in ‘RockWool RW3’ (or SL930 as it is called now).

You can’t buy it from DIY stores, you need to get it from a specialist insulation supplier – I used CCF. This material has a GREAT capability to absorb sound. Some independent detail was to be found here http://www.bobgolds.com/AbsorptionCoefficients.htm and the manufacturers numbers seemed to stack up to. As well as being effective, I like the fact that it’s not glass fibre too.

So I bit the bullet, and went for it.

Here’s how it looks

RW3-pre-2

I ended up making two pairs of panels, which I can effectively use as a booth, they fold away in a jiffy, and I can adjust them to make the sound ‘dead’ or more open by literally opening them up.

The cost was £86 a pair, but I made one pair first in order to test it, before I went ahead and made the second one.

This was what I bought for each pair:

  • One pack of Rockwool SL 930 – 50mm thick, pack of 8 slabs (enough for two pairs)
  • 4”x2” wood  – 4 pieces at 7’ long, 4 pieces at 21” long (sorry – old money, old bloke!)
  • Hardboard backing – 3mm, one piece 244cm by 122cm. Cut 32.5cm cut off the end and then split in two
  • Felt fabric – 152cm by 5m (I bought mine from Fabric Warehouse at £9 per metre)

I chose felt because it has good acoustic ‘transparency’ but is stronger than muslin, looks better than Linen AND it stops you from seeing the insulation inside. Plus it comes in FUNKY Colours! The eighties are back – I promise you!

Felt

In addition to the above I needed to raid my toolbox for:

  • Panel pins
  • Long screws for the frame (I used 2½” drywall screws)
  • Small brackets
  • 4 hinges
  • A staplegun and plenty of staples
  • Gloves for handling the rockwool

Here’s the various stages of construction, and how the finished items look – and I went for red and black so I can change my mood depending on the read I am doing! Black for calm – red for passion!

Four long pieces of wood and hardboard – on the bedroom floor ONLY for photos, and I had permission J

Four-lengths

 

Check twice, cut once!…(see Dad, I did listen to you):

Length-long

Four smaller pieces next:

Length-short-2Length-short

Lining up the pieces, the two small sit in-between the two long:

Frame-end

I stapled the pieces together first before screwing to hold them in place:

Staple-frame

At this point I asked Dave if he was going to help…

Dave-2

Hmmm, ok well back to doing it on my own then, so time to screw the pieces together. I drilled the holes first, and used three screws on each corner for stability:

Screw-2Screw

Once I had put three screws in each corner, then I fitted a bracket inside the joints, again to keep it all sturdy:

 

Bracket

Once that’s done, voila you have your first frame:

Frame

Repeat the process for the second panel – and then you got two!

After that, it’s time to apply the fabric, but first, I wonder if SPUD is going to be more helpful than DAVE?…

Spud

Clearly not.

Ok so having cut the fabric in half, you simply lay the frame over it, and then trim off the excess:

FabricTrim-2

 

 

 

 

 

 

 

Having done that, then it’s time to get stapling – Dave, do you wanna help with the stapling?

Dave-3

Fine. Ok pull the fabric nice and tight, stapling opposite sides first, then working your way around:

Trimstaples

Once the fabric is trimmed and stapled (and cats removed from the room) it’s time to go outside, gloves on, and cut the RW3 to size. Once cut, simply place it into the void:

RW3-intRW3-full

 

 

 

 

 

 

 

Then you lay your hardboard over the top shiny side up. You should find it just sits nicely inside the edge:

hardboard

And then it’s time to got those panel pins out – and nail it all down. I started at the corners, and put three in each as the fabric is folded there and I don’t want it coming away mid recording!

Panel-timePanel-corner

So I had the hardboard on, time to stand back and admire my first panel:

Single-panel

Then have a cup of tea

Cup

 

And full of energy, it was time to do the second panel – Taa Daa!

Two-panels

Then it was time for the last two things. Firstly, after laying the panels face to face on their side, you screw home two hinges:

Hinge-2Full-with-hinges

 

 

 

 

 

 

 

I used the type with a removable pin, as you can separate each panel to make it easier to move them around – they are HEAVY! (But you don’t want them falling over do you?)

Hinge

 

After the pins, I stand them up to ensure they are all square, and then tack some hardboard cut to size on the bottom to protect the fabric:

Feet

And that’s pretty much it! Here are the panels in place of the Bedouin tent:

ClosingClosing-2Half-open

And you can adjust to get the comfort/sound right, and once not needed, simply fold away

Folded-away

Acoustically they really are superb, when folded around you the sound is entirely dead – it doesn’t even seem to matter that there is nothing on the top, The sound gets ‘sucked in’ so well and the height helps.

Now, who moved that blanket which was down the back of the tent?…

Dave

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5 thoughts on “Making an acoustic ‘gobo’

    1. steveoneillvoice Post author

      Thank you.

      Ha ha – if I could make a business of it I’d consider taking orders! That sounds like an excellent option using a wardrobe, they’re almost purpose made aren’t they? My wardrobes have been fabric covered rails until recently – #perilsofmovinghouseeachyear!

      Reply
  1. Carrie Afrin

    Hi Steve,
    I came via Twitter for a nosey at the site and it is looking great but I am VERY impressed with the DIY studio! I have finally got my hall cupboard the way I want it but it feels like it has taken forever. I’ll try and send a pic via twitter but it has been lined with thick underlay using double sided carpet tape, shelf above me included (only short people can use this one! ) and then my dad stapled thick duvets into the wall. I’ve ordered some accoustic tiles that should arrive tomorrow but to be honest I’m perfectly happy with the accoustics without them. (I too live in the sticks so that is a bonus 🙂
    Happy ‘studio’ time 🙂

    Reply
    1. steveoneillvoice Post author

      Hi Carrie,

      Thank you so much for replying to the blog – really makes it feel worthwhile doing it.

      I know we exchanged Tweets late last night – but I struggle with 140 characters.

      Your arrangement sounds really good, and if your demos on your site were recorded there they sound excellent!

      Whereabouts in the highlands are you? I lived in Scotland for a while and really miss it! 😦

      Happy ‘studio’ time to you too!

      Steve

      Reply
  2. Pingback: Steve O’Neill – PES 066 – Podcast Engineering School

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