Monthly Archives: January 2013

Music via Ambisonics

Late last year I was playing around with some songs I’ve recorded and doing some quick 3rd order Ambisonic mixes. It got me thinking about what I wanted to use Ambisonics for and how best to present my songs using it.

[Just as a side note, I’m talking here about “pop” music mixes, not electro-acoustic music where use of spatial audio is much more widespread.]

For example, do I want to use the full 360 degrees (or full sphere if were doing 3D) for the sounds or is it better to stick with a frontal sound stage and just use surround for ambience, which is common in 5.1 music mixes?

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Ambisonic Decoder Progress Update

There’s not been much in the way of news about the VST plugins recently so I thought I’d post a quick update. I’ll make my excuses and then say what I’ve been working on.

First comes the excuse. I’ve been busy. I know it sucks as an excuse. The problem is that the VSTs are a side-project for me that can be useful for my PhD but when they’re not they have to go on the back burner. Unfortunately I’ve been very busy designing an experiment involving Ambisonics to work much on the VSTs.

But aside from that I should give a quick update of what’s to come. My plan is to release an Ambisonic decoder to go with the two encoders. It’ll allow loudspeaker position selection, choice of listening options (with 1 or 2 bands with user selected crossover frequency) like Basic, Max rE and in-phase, up to 5-the order decoding, stereo bounce down, near field compensation and selection of the spherical harmonic weights used (eg N2D, SN3D etc.).

I’m sorry about the delay but I’ll try my best to make available as soon as possible. If I’ve missed any essential features then let me know d I can try to work them in. Until then, if anyone is dying format decoder, you can send me an email and I can send you a copy of my old decoder. It’s basic and a bit cumbersome but does the job.

Acoustic Panels (On the Cheap)

Over the last 2 weekends I’ve been building some acoustically absorbing panels to supplement the ones my department has purchased. They’re needed to absorb as many of the first reflections in the studio as possible during an experiment I’m doing in a couple of weeks.

They were make out of Knauf Rocksilk RS45 (100mm thickness) and I went with 10 slabs in total. This was by far the material with the best absorption properties I could find but it is rather bulky. The manufacturer lists the absorption as:

Freq (Hz) 125 250 500 1000 2000 4000
NRC 0.80 1.15 1.20 1.15 1.10 1.16

[Note: the Noise Reduction Coefficient can go beyond 1 due to the way it’s measured. I don’t expect these panels to absorb 80% of the sound at 125Hz but it’s should kill a decent amount of it].

Knauf RS45 100mm

Knauf RS45 100mm Universal Slabs

The panels are 60 x 120cm (that’s 2×4 ft for the non-metric) and even though they’re slightly rigid they needed some sort of frame to help them maintain their shape (especially if they’re being handled). Various online DIY guides recommended using wooden frames and they probably would have been best. However, I was working on a tiny budget and had access to a large amount of corrugated cardboard for free so opted for that. I also made a back for them to provide some extra support for the structure. It’s strong enough to do what I need and it also has the added benefit of being lighter than it would have been with wooden frames. I’m not planning on hanging these with a picture frame hanger otherwise I might have opted for the sturdier frame.

Corner2

Cardboard overlaps for extra strength.

Once the frames were done they were wrapped in hessian (aka burlap) to keep them all together. I didn’t worry much about the overall appearance because I’m not planning on having them up in my living room or bedroom. Some of them did end up being a nice red colour because the shop didn’t have enough natural coloured hessian to let me do all the panels. I used carpet adhesive on the cardboard frame and that seemed pretty strong. I also used duct tape to fix the edge down and hopefully stop the fabric coming loose over time. If I’d wanted something more aesthetically pleasing I’d have spent a bit more time when affixing the hessian to the frames, making sure all the joins were not visible by putting them round the back.

All done!

Some finished panels

They ended up being very cheap (approximately £6 each) and I think they should do the job for my experiment. But I don’t think I’ll be doing this again. Not least because I don’t have room to store the 10 panels I have currently but also because it’s a fair amount of work. It’s still a good option for the cash-poor and time-rich and probably saved me £250 over buying equivalent professional studio-foam. That fact makes it all worthwhile.

They’re not pretty, but they were cheap.

New Year Goals

Following the advice of Kim Lajoie about resolutions vs. goals I’ll set out what I hope to achieve this year. I’ll not go into massive detail in this post (that’s for my own private notes and is probably a bit boring) but I’ll give the broad outlines.

Now, I’m not normally one to make New Year’s resolutions because I’ve always wondered what was the point of making them only at one time in the year? However, this year I’ve got a lot going on and now is as good a time as any to set goals and organise myself. They’re in a few different sections – PhD, Music, VST plugins and Misc.

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