Thoughts

Merry Christmas. I do believe this is the first I’ve ever spent entirely alone.

I suppose seeing Andy Bell’s “Just Post” (via Blake Watson’s “omg.lol: an oasis on the internet” via Hacker Newsletter #681) prompted me finally to post something here. I might as well: I pay for the domain name, after all….

To be clear, this post has no detailed instructions on how to actually build an acoustic panel — you just make a rectangular frame, stuff it with rockwool, and wrap the whole thing in acoustically transparent fabric (secured with a staple gun). It’s not complicated at all, and there are tons of actual tutorials out there.

Rambling background

My journey to building these simple panels — there must be thousands of guides both written and visual on how to make these — probably started 10 years ago. To express the significance of this project requires to some extent telling the history of my journey with music.

I grew up with Western classical music — especially the Three Tenors — and, like so many children growing up in my context, started taking violin and piano lessons from a pretty young age (4?). Unlike many in my context, my parents ever forced me into anything: they put me into those lessons primarily in the belief that it would give me a more rounded experience. To some extent, I suspect they also did it because it was and is the norm for all children where I grew up.

I could have quit at any time (I didn’t) and, to a great extent, was never even that engaged: I don’t remember ever practicing either instrument seriously¹ before the age of 18…after I’d moved halfway across the world for university and had stopped taking lessons entirely. In fact, I’m quite comfortable suggesting that I passed ABRSM grade 7 on piano, and grade 8 on violin, by spending just 1 hour per week with each instrument: the hour I had my weekly lesson. Talk about getting away with it.

I have often wondered, actually, to what extent the structure of my lessons caused me not to practice. My teacher wasn’t the most active in my journey of discovering musical styles, with lessons largely focusing on technique and (ABRSM) exam syllabi. To some degree, I must have categorised those hours as “more lessons, just outside of the school building and not in uniform”. From that perspective, and yet given my unwavering love for music, it should be no surprise that I soon found a separate outlet for my musical energy, outside of the reach of any lessons or teacers: voice.

I’d always sung — even kindergarten made sure of that, and I was involved in choir as well as orchestra in both primary and secondary schools — but in 2007 seriously started exploring my voice as a real instrument. It developed very naturally: getting home after school, I would put some music on and would just start singing along; indeed, I’d been doing this for years prior, but it was only around this time, inexplicably, that I started to really focus on the quality of my own singing, rather than just going with it.

The earliest recording I have of myself dates back to 2008-08-02: “Amor ti vieta”. It is objectively awful in every way imaginable:

• My early attempts to imitate operatic technique involved the retracted tongue technique, which is widely held to be unhealthy technique and actually restricts projection. It over-darkens the voice — but that sounded right to my teenage self, because I was singing along to Plácido Domingo’s far more mature voice.
• Because I was using the retracted tongue technique, I had no access to my head voice, and so could not actually sing anything for the bass-baritone repertoire: I was just singing tenor lines an octave lower.
• I made my early recordings either by singing into whatever crappy microphone dad picked up from the electronics market that week — often these were mics designed to be put on a lectern for public speaking, though he did eventually give me a battery-powered shotgun mic that I used until finally buying myself an Audio Technica AT-2020 in 2014 — or, worse, recording the entire room as I sang along to a full recording; effectively recording a karaoke session, but with the original artist’s voice at full volume too.
• “Recording”, back then, meant pressing the “record” button on Quicktime Pro (I miss that application still). No EQ or anything, and I had no idea what a compressor was (other than as an app that came with Final Cut Pro).

Yet something in me never gave up on this. There was, undoubtedly, an element of self-delusion and massive arrogance — I sincerely thought I was a pretty good singer! — but also, I think, something much deeper: passion unmarred by a classroom focused on grades and exams. No one to tell me what to do; unlimited freedom to explore. And a separate (but tightly related) obsession with European languages, which classical music allowed me to spend more time with.²

I don’t think I attempted anything along the lines of recording to a backing track before 2011, or even 2012. I certainly remember the immense frustration with a school assignment when I had to record a violin duet alone: because I didn’t have a proper USB audio interface, there was a lag between audio output and input, so it was impossible to record over myself and the whole exercise was a disaster.

Yet I persisted, and in late 2013 or early 2014, when I moved to Paris for university, and got my own apartment and had much more space than my 2.5 x 2.5 m bedroom (approx.), and also no parents to scrutinise my spending³, I bought a Behringer 502 mixer/USB audio interface and and Audio Technica AT-2020. In conjunction with my Shure SE205 and Logic Pro, and the pop filter my parents had gifted me for my birthday(?) in 2009(?), I finally had a primitive, but genuinely workable, recording setup.

By that time, my technique had improved markedly (I’d been allowed to sing at secondary school graduation just a year prior: Schubert’s “An die Musik”) and so I was, perhaps for the first time, actually able to start picking out the technical reasons I sounded “off” versus professional recordings. Days of reading up on recording and mixing technique ensued⁴: microphone positioning, room treatment, EQ settings, what a compressor is and why it matters….

It was at that time that I discovered the idea of acoustic panels to reduce reflections from walls. Now, professionally made acoustic panels are pretty expensive — Panelscreens.co.uk seems to be selling the “Abstracta Soneo Acoustic Wall Panel” for GBP 78.08 per piece after VAT (dimensions unclear, but up to 100 x 100 cm at 100 mm thickness offered) as of 2023-12-25 — yet I was completely hopeless at anything DIY and it seemed inconceivable to me that, even if I did have all the materials magically to hand (i.e. no hunting around shops), I would be able to produce anything like an acoustic panel.

So for the next 9 years, I improved my recordings by doing things like hanging heavier curtains, closing the curtains, tenting a duvet around the microphone, placing pillows and cushions along the wall, and opening the bookshelf doors so the uneven texture of the books and the paper could absorb some sound: informal, somewhat-effective remedies to unwanted reflections. I also spent quite a bit of time envying those who could seemingly record in any environment and get a decent sound, principally those whose technique was more grounded in the soft (or even whispery) pop singer-songwriter approach.⁵

In early 2023, I picked up a shipping pallet from the nearby garbage collection depot during a walk. Actually, someone had thrown out about 20 pallets, but since I had to move it by manually about 1.5 km I could only take 1 (and even that was a serious struggle).

Breaking it apart into planks in my tiny studio apartment rekindled a joy I’d once felt more often, but never really nurtured: working with my hands. (Growing up in a city of tiny apartments really discourages that kind of hobby, especially growing up in a time when home computers were booming.)

Nothing really came of that project: the wood was too soft and thin and I simply ended up damaging a lot of it using crowbar and nail puller. A combination of both poor quality and inexperience.

About half a year later, I moved halfway across the world again, and somehow had it in my head that this time I really wanted to make some acoustic panels such that, whatever apartment I ended up renting, I could have a good acoustic environment. The Covid-19 pandemic and the working from home that accompanied it made me appreciate just how sensitive I am to sound. Here I was in a city with slightly larger apartments and, well, less energy: smaller population, fewer tourists, fewer shops, weaker infrastructure — the kind of place where you have to keep yourself busy to be entertained, rather than being able to stand on the street and just absorb the energy from everything happening around you.

The project

Purely by chance, around 2023-11, I came across a pretty sizeable pallet on the street, about 100 m from my front door. I walked past it initially, but then it occurred to me that the pallet actually seemed to be of pretty decent quality, and I wondered if I might actually be able to make use of it. I rang the doorbell and got permission to take it — something my personality makes me very nervous about and which I’ve been working on slowly (“The worst they can say is no.”)

Dragging it back even that short distance was no easy feat: this was much denser wood than my first pallet.

Over the following weeks, I bought various tools to complement what I already had: a crowbar, a sledgehammer, an orbital sander, and a circular saw. I managed to salvage almost everything from this pallet, with only a few minor splits and one completely broken plank.

YouTube videos make recovering pallet wood easy and indeed prying the planks out isn’t necessarily the hardest job, but coming up with workable plans without a planer is pretty tiring: endless chiselling of crumbling/rotting wood and untold patience with the orbital sander.

All this, too, in my studio apartment: I moved to a particularly rainy city and so, even though I have access to the communal garden, there are vanishingly few days in which I can actually do woodworking outside without getting everything wet, and wet power tools tend not to be happy power tools.

I quickly developed a strategy for dust management: to avoid dust getting everywhere (notably my computers and bed), I needed the only enclosed space available in is 30 m^2 apartment: the approximately 1.2 x 1.2 m hallway. So I put the planks there — which, by the way, measure just about 1.2 m! — and did all my messy work there (with the ends of the planks sticking through the bathroom doorway: tiled floors there, so easy cleanup). The challenges were real: I didn’t even have a workbench, so everything was done at floor level, and I simply hadn’t spent so much time squatting down in all my life; nor was I particularly at ease using power tools (especially a circular saw) in such cramped conditions, and I was constantly aware of my “escape plan” in case I lost control of the saw, to make sure that I at least wouldn’t drop it on my foot.

Safety equipment was essential: boots and glasses, of course, but also hearing protection, which should always be worn but especially in such a confined space, and working hours were severely constrained to avoid noise complaints from others in the building.

Having recovered the planks at full length, I realised something very convenient: standard Rockwool slabs are 1.2 x 0.6 m, with many thicknesses available; I was able to find 35–100 mm quite easily. These planks were 1.22 m long, around 100 mm wide (an approximation as, after removing the damaged wood, the long edges were simply not straight on many planks, and I had no inclination to try to make perfectly rectangular planks), and around 22 mm thick (again, variable after removing all the defective wood).

So all I needed to do was trim some planks to 1.2 m, and trim some planks to 60 + (2.2 * 2) = 64.4 cm for the short sides of the frame. Then I could avoid cutting the Rockwool at all — something I was quite keen to do because I don’t feel I fully “understand” Rockwool and best practices for working with it.

Then I’d need some cheap fabric to hold the Rockwool in, and some prettier fabric for the top layer: these are big and visually dominant panels in an apartment and aesthetics do matter. I settled on weed blocking membrane for the former, and found some cotton-polyester fabric for the latter.

Costs

All converted into USD and rounded to the nearest dollar:

• WorkZone circular saw: USD 5 from eBay (collection)
  • Yes, five dollars, fully working apart from the laser guide.
• Sledge hammer (1.8kg): USD 19 from Amazon
• 24-inch wrecking bar: USD 8 from Amazon
• Bosch Profi PSS 230 orbital sander: USD 24 from eBay (including shipping at USD 9)
• WorkPro set of 4 5 m rolls of sandpaper (60, 120, 180, and 240 grit): USD 18
• Zinc-plated steel corner brackets, pack of 30, with accompanying screws: USD 8 from Amazon
• 6 m of cotton-polyester fabric, 45 inches width: USD 22 from eBay (including shipping at USD 5)
• 15 m of weed membrane, 1 m width: USD 9 from eBay (free shipping)
• Rockwool slabs, 100mm, pack of 4: USD 47 (including shipping at USD 9)
• Staple gun with assortment of staples and brad nails: USD 10
• Wood: free plus time

Things I already had

• Drill
• Drill bits
• Saw and mitre box
  • I’d bought this a long time ago for another project. It came in handy because the circular saw’s blade got pretty dull near the end of my cutting, evidenced by the ridiculous kickback I started getting, and I decided I was so close to finishing I should just do it by hand.
• Assorted screws
• Safety glasses
• Leather gloves
• Respirator
• Earplugs
• Safety boots

Build notes

• The corner brackets are indispensible for building frames using roughly-shaped wood because you can actually achieve a sturdy structure with known 90º angles.
• Corner brackets alone are not enough to make a sturdy frame: you need to drill long screws into the wood itself; the combination of long screws directly into the wood plus corner brackets makes for a very solid structure.
• Since these frames aren’t going to be wall mounted, I may eventually add little nail-in feet to the frames so I can rest them on the floor without wearing away at the fabric. This will also help the frames stand more sturdily: because these salvaged planks aren’t entirely flat, there is at least one frame which, if rested on one of the short sides, will simply tip forward. Feet might allow for small adjustments in this regard.
• Avoid U-shaped staples into wood: they won’t fit in flush without extra hammering.
• Brad nails are aesthetically attractive, but painful to make a mistake with since they’re so much harder to pull out. The shape of the head can cause fabric to pucker: the staple gun, sends this further into the wood than crown staples on an equivalent spring setting.
• Weed membrane is too porous for brad nails.
• Weed membrane is wonderfully transparent, but tears ridiculously easily, whether by stretching it too tightly over a sharp corner of the wood, or even just regular wear-and-tear from moving the panel around or resting it on a surface. Covering the whole with the cotton-polyester fabric is essential and I have ordered extra fabric to cover the back fully as well, so that the membrane’s only job is to hold the Rockwool in and give an initial barrier against any fibres escaping.
  • It is debatable whether weed membrane was necessary at all if I’m just going to wrap the entire thing in the nicer fabric. I suspect some people use weed membrane for the backing because it’s so much cheaper than nice fabric. Ultimately, I feel some comfort knowing that I have 2 layers of fabric separating me from the Rockwool fibres, even if my concerns about Rockwool exposure may be completely unfounded.⁶
• When attaching the fabric to the frame, you always have to maintain tension, otherwise the Rockwool will flop around and cause the frame’s surface to bulge (ultimately placing extra wear on the fabric at the stapling points) and the fabric will look wrinkly.
• In the interest of being a little safer from Rockwool fibres escaping, I decided to use weed membrane on both the front and back of the frame, such that the cotton-polyester fabric would only be for aesthetics (and, I later learnt, to protect the weed membrane from tearing). This means I had a lot of staples going into a very limited surface area (the back of the frame). Attention is needed to minimise the chance of overlapping staples and blow-outs. (Overlapping staples isn’t bad per se, but staping over an existing staple can prevent the top staple from actually going into the wood as you intended.)
• A manual staple gun — the spring-loaded kind — can actually be very loud. Earplugs welcome, but perhaps not strictly needed(?)
• Orbital sanders are way louder than I thought they would be.
• If you can have 2 drills for the project, do it: keep a drilling bit in one, and use the other as as screwdriver. Changing bits every few minutes is absolutely no fun, especially on a keyed chuck, but using a manual screwdriver is out of the question as that really is a recipe for RSI, especially with the longer screws at 4 cm and up.

First day of usage

I have these just leaning against the wall either balanced on top of the radiator or on the various tables I have in the apartment: this is a rental and picture nails won’t support the weight of such big panels, and I feel rather disinclined to use my hammer drill on walls I don’t think will be constituting my main shelter for much longer.

I also want to keep them mobile to give myself the flexibility to play with their configuration whilst recording.

I haven’t actually tried recording with these yet — I only stuffed and wrapped the panels last night (taking care to avoid making them look like stockings) — ultimately working from around 16:00–23:00 (I was ridiculously picky about having even the ugly underlying fabric neatly folded with sharp edges, straight lines, minimal puckering, etc.). I did just have a call with my hard-of-hearing grandpa though, to wish him a merry Christmas — not the kind of conversation where you have to shout down the phone, but more one where you need theatre-style projection with crisp diction — and I was acutely aware throughout the conversation how much less of myself I was hearing. An incredible improvement.