Tagged music production

The Rules of Digital Audio

Digital audio is a very different beast to its analogue forefather. Cleaner, colder, trickier. The science behind it is enough to make most people’s eyes glaze over, but there are some important rules that are often broken by those who’ve not taken the time to look into it.

To save you the time, here are the fundamentals of digital audio (without the number crunching).

Levels and clipping

The most common digital mistake is inheriting the ‘run it hot’ mentality of an analogue engineer. Under no circumstances should you run a digital signal into the red. Unless you want your audio to sound edgy and horrible, which you might. (There are always exceptions).

Analogue clipping makes a pleasing distortion that if used sparingly can really enhance a sound, digital clipping is an audio error code. If any digital clipping is to occur, it should be left to the mastering engineer to make it happen. Even then, it’s fraught with controversy, and we avoid it as much as possible.

The rule of thumb when recording is to keep it clean, firmly in the green. If recording in 24 bit, hitting somewhere around -18dB on your VU meter will give you plenty of signal to work with while giving you plenty of headroom for peaks.

Sampling rates

The sampling rate for CD quality audio is 44.1khz. Therefore lots of people work at that rate. However, DVD quality is 48khz, presenting a good reason to record at the higher rate.

It is generally a good idea to record and mix at higher than CD quality as any processing you do will degrade the original fidelity of the signal to some extent. Some plugins also work better at higher sampling rates (also why many now internally upsample). The higher the rate the better, so work at the highest rate your processor can handle.

But, keep downsampling to the mastering engineer. Using sub-par converters can cause undesirable effects when converting sample rates, so if you’re not sending it out for mastering, you might be better off sticking to 44.1 all the way through. Check out http://src.infinitewave.ca/ to see where yours stack up (pictured).

Bit depth

CD quality audio works at 16bit (as does DVD) so this is definitely the end goal. However, as with sampling rates, using a higher bit depth during tracking, mixing and mastering will help preserve fidelity and often improve processing quality. There has also been talk of the introduction of 24 bit downloads so it’s a good idea to make sure you’ve got the audio to back it up – you can up the bit rate, but all it’s doing is adding 0s on the end.

Dithering

Dithering is a fairly counter-intuitive process that involves adding a layer of distortion to smooth out any errors made in chucking away 8 bits of information (when downgrading from 24 bit to 16 bit).

Again, this is something that should be left to the mastering engineer, but if you are mastering at home then make sure you always dither last – that includes after changing sample rate. So, if you recorded in 48khz/24bit and you’re exporting to 44.1khz/16bit you will need to first export at 44.1khz/24bit and then separately dither down to 16bit. Putting a dithering plugin on your post-fader master channel and then going straight to 44.1/16 puts your sample rate conversion before your dithering. Your audio will suffer for it.

Also try out as many dithering algorithms as you can, they do sound different. Noise shaping algorithms generally work best, but it is entirely subjective. My personal favourite is Izotope’s Mbit+ algorithm but I will always audition different noise levels and shapes for each project.

Follow these rules and your sound will come out cleaner, sharper and, well, better.

Great Free VST Plugins

The maxim ‘you get what you pay for’ holds true for most pro audio products, but I’ve recently been pleasantly surprised at the quality of some free VST plugins. Most useful are the free utility plugins used as loss-leaders, but there are also some really talented bedroom programmers out there.

I’ve tried out quite a few over the last few months, and these are my favourites.

Analysis tools

Some people find needle meters somehow easier to understand than the bar meters most DAWs use these days (myself included). If that’s you, PSP Vintagemeter could be the answer for you. Useable in either PPM or VU mode, it’s a nifty way of getting needles into a digital environment.

Voxengo SPANBlueCat FreqAnalyst is a fully customisable spectrum analyser that even lets you zoom in on a particular frequency range for more detailed inspection.

Voxengo’s SPAN is a great all-in-one analysis tool that gives you metering of almost any kind you could want – from standard VU and PPM to different K weighted scales, average values (RMS and crest factors) as well as a very useable spectrum analyser. The only problem is it does seem to colour the sound a little bit when switched on…

Utility plugins

BlueCat’s Gain Suite contains a number of very simple plugins that literally do what you’d expect – adjust gain. This is actually more useful than you might first think, particularly for optimising gain structures when running outboard gear as external plugins from your DAW.

Anyone interested in mid/side processing would do well to download Voxengo’s MSED. Although it’s not too difficult to manually set up a mid/side chain if you know how, this is a great time saver.

The Audiocation Phase AP1 is great for sorting out phase relationships in your mix.

Character

Voxengo’s Tube Amp is great for adding crunch to a signal, particularly when run hot and in parallel. It’s actually surprisingly tube like as well.

The excellent Bootsy over at Variety of Sound has put together three brilliant saturation plugins: the Ferric TDS tape simulator and the Tessla SE and Tessla PRO transformer saturators. The Tessla PRO is particularly interesting as its transient aware.

What free VST plugins can you recommend? Leave your answers in the comments.

The Biggest Mistake Home Producers Make

We’re big advocates of home production. The falling cost of music technology has democratised the process of making music enormously, which can only be a good thing. However, there remains a substantial knowledge gap between most home producers and those working in ‘traditional’ facilities.

Here at Brighton Mastering, we get sent a lot of tracks that were recorded in home studios, and the biggest mistake we come across is not a lack of creativity or ideas, but not understanding the science behind music production.

Covering the Basics

One thing we’re often surprised by is a lack of understanding about the basics of recording. We have often been sent tracks that have the odd tell-tale crackle of digital clipping and have even been sent mixdowns in low quality mp3.

What this demonstrates is a fundamental lack of education about music technology. The problem is that any Apple Mac comes with a copy of Garageband that anyone can use, but without knowing what a compressor is actually doing (beyond some vague understanding of ‘punch’), or what different frequencies sound like you don’t have a hope of making a commercial sounding recording. And that doesn’t come in the manual.

Tilting at Windmills

There is a lot to be said for learning by experimentation, and that’s certainly how I got started. However, everything in music production is physics. Knowing that physics makes the whole process much more practical and less the quixotic pursuit of mythical qualities that frankly may be unattainable with what you’re working with.

Knowing the physics can actually plug a lot of the holes in the equipment you’re dealing with, as Mike Senior aptly demonstrates every month in his Mix Rescue column for Sound on Sound. Want to compress only a particular frequency range but don’t have a multiband compressor? Get out your broadband compressor, an EQ with high and low pass filters and away you go.

It may not be fun (well, depends what your outlook is) and it may not be rock ‘n’ roll. But all music technology is physics at work. Making that physics work for you is the creative bit.

Educate Yourself

Mike Senior's Mixing Secrets for the Small StudioDon’t think that you have to go on an expensive music production course to learn the science – after all, almost none of these courses existed until a few years ago, and people still made great records.

Buy a couple of books. Get a subscription to Sound on Sound. Subscribe to a few RSS feeds. If you can, get some work experience at your local studio (although these opportunities are drying up in the face of home studios).

Learning the science behind the faders is like learning scales. Sure you can write a song by ear, but it’s a lot quicker if you know which notes fit together.

What books can you recommend to other readers? Leave your suggestions in the comments!

Photo credit Creativity103