DIY Mastering Part 4 - Mastering Speakers and Monitors

The most important tool a mastering engineer has (apart from his ears and expertise) is the monitoring, meaning the speakers, amps and converters. We debate all of these at great length between ourselves, in online forums and down the pub, but without question the speakers have the greatest impact on the sound. (They need to be well-placed in a decent treated room, but I already covered that in my third DIY post.)

This post won't enable you to choose a set of speakers by reading specifications or manufacturer's blurb, but hopefully it will give you an idea what you should be looking for, and why.

So, what are suitable speakers for mastering ? Well for example we have B&W Matrix 801s in Studio 1 at SRT, Genelec S30Ds in Studio 2 (In general I don't rate Genelecs, but the S30s have a ribbon tweeter and are in a class of their own). Other common names include ATC, PMC and Dunlavy. What all these monitors have in common (apart from costing at least as much as a large family car !) is that they have:

1. Flat, or neutral frequency response - meaning their response is very even over the whole audible range. So, for example, B&W 801s come with a graph measuring their response - it only varies by +/- 1 dB from 20 Hz to 20 kHz.
2. Acurate phase response - meaning that the stereo image is very detailed, giving an absolutely solid mono center image, but also a deep, convincing "three-dimensional" soundstage - at least, on a decent recording. The stereo imaging in our studios is so good that it's common for people to ask if some of the sound is coming out of the center speaker (used for surround work), even though they are listening to pure stereo. And on the occasions where a mix element is accidentally phase-reversed, it leaps out and draws attention to itself.
3. Clean, controlled dynamics - with only minimal distortion introduced, even at high listening levels. (Using a suitable amp is important for this, too, of course.)

Of course there are many other aspects of speaker's capabilities I could list, but it's almost more important to realise that these characteristics mean mastering speakers should be:

1. Revealing - allowing you to hear details you'll miss on other speakers - faults, like clicks, hiss and distortion; but also the positive sides of the recording - accurate stereo imaging, "depth" (meaning the impression of a three-dimensional sound field), impact and dynamics. Listening on a mastering system should almost be like wearing headphones, in this respect.
2. Clinical - Mastering speakers don't make things sound good. Unlike speakers for tracking or mixing, they shouldn't add "vibe", or "feel". Often they might be described as "bland", "boring", or at best "civilized". In fact, they are reliable and acurate. Only the very best recordings will sound good on them ! In fact that leads us neatly to:
3. Unforgiving - It's often shocking to hear how bad many recordings sound on a mastering rig - the uncompromising accuracy uncovers limitations masked by lesser reproduction systems. While this won't necessarily make for a very satisfying listening experience, it's essential for the mastering engineer to hear and correct any problems or limitations in the original mix.

Together, all these requirements add up to help the engineer achive translation - when it sounds it's best on the mastering system, it will sound great everywhere else, too.

So, if you've got this far, you're probably thinking "how the hell do I choose speakers which meet all those criteria ?". If you can't rely on printed specifications alone, this is a tough question. Until you're learnt exactly what a recording should sound like, it's hard to recognise a pair of speakers that make it sound that way.

Probably the first piece of advice is to get some recommendations. This post was inspired by a thread on the Gearslutz mastering forum asking about mastering speakers, and places like this or the SOS forums are good places to start - perhaps less than £500 isn't really realistic, though! Several of the speakers I mention above are available second-hand for "reasonable" amounts of money. My personal favourites, B&W, have ~35 staff working constantly on research and development, and the advances they make for their most expensive speakers always filter down to the cheaper models. I have Series 2 601s at home and am frequently amazed by how good they sound. Not that I'm suggesting you use them for mastering, but considering the difference in size and price, there's almost certainly something in the 600 range to suit.

Next - listen ! Find a showroom where you can test a few different speakers, ideally in the same room, and listen to various different tracks you know well. Even better, get some on demo and try them in your room. Remember you're looking for accuracy, not excitement - mastering monitors reveal limitations that others don't. Choose a range of recordings and be objective. "Sledgehammer" by Peter Gabriel is a great-sounding track, but it has very tight, controlled bass, so if the speakers give it a thundering bottom end, they aren't flat. "Dummy" by Portishead is a classic album, but it's almost entirely in mono - that should leap out at you. Maybe even take a CD with a few test-tones on it - for example a sine wave sweeping up from 20Hz to 20kHz will not only give you an idea about the speakers frequency response, but may also reveal a few buzzes and rattles along the way. (Don't play it too loud, though, or you may find yourself paying for some blown tweeters...)

Finding the right speaker in your price-range is a major challenge for a would-be DIY mastering engineer, but once you've worked with truly acurate monitoring for a while, you won't want to go back.

CD & DVD on the same disc

Richard Durrant's DAVD discs arrived today - CD audio on one side, DVD on the other of a single disc. This is a format I've been wanting to promote for years, back when the only option was DualDisc, but manufacturing costs plus licensing and compatibility issues put paid to that.

But all that is history now, and you can get a DAVD pressed up for only 60% more than a normal CD. That's incredible value, compared to a 2-disc CD and DVD package which costs more than twice as much, including the packaging. And as a format it beats Enhanced CDs hands down, if you ask me.

So, what are you waiting for ?!

And, speaking of Richard, here is a video of his single-handed live performance of one of my favourite things, Steve Reich's Electric Counterpoint, a piece for 12 guitars... prepare to boggle.

Next post DIY Mastering #4 - Speakers

Christine Tobin - The Secret Life of a Girl

An excellent (and well-deserved) review of Christine's new album which we mastered back in March, as I mentioned in my first post. It's always good to see one of your artists doing well - I love this record, and I wish Christine every success with it. Maybe this will be the breakthrough she deserves !

And while I think of it, Phil got a great review too !

Christine Tobin, Secret Life of a Girl

 (Babel) 

John L Walters
Friday May 16, 2008
The Guardian

Dublin-born singer Christine Tobin is a jewel of the London jazz scene, streets ahead of the pack, but she deserves better. She should be on a global stage, rubbing shoulders with fellow troubadours like Cave, Mitchell and Cohen. And while her current 15-date tour should help broaden her UK fan base, this is an album that could break through to a bigger, international audience. Tobin's eloquent songs are framed by masterful arrangements and beautifully recorded to make the most of the content. There's no self-indulgence: it's all about the songs. Dave Whitford's sonorous bass and Phil Robson's self-effacing guitar are the perfect match for Tobin's rich, dark-hued vocals.

Highlights include the swampy Bye Bye; the Corner of an Eye, with its archaic "spring reverb"; and a delicious cover of Cohen and Robinson's Everybody Knows. Yet it's a tribute to the quality of Tobin's writing that there are no weak spots in this excellent collection.

Mastering Software Part 1 - Metering Levels and Loudness

I mentioned the Orban Loudness Meter on the SOS forums, and thought it would be good to start a series of posts here on useful mastering software. So, first up - metering apps. Several of the best editing packages include decent metering, for example Wavelab, and Audacity, but here are a few personal favourites:

•  Orban Loudness Meter Great (free!) utility includes a PPM meter, VU meter, ITU BS.1770 meter and CBS Technology Center loudness meter - it's fantastic to have access to these less common metering systems, which offer measurements of perceived loudness, which can be more useful than pure RMS. (Plus it runs well under Parallels on my MacBook Pro ;-) 
• Pinguin Audio Meter Not free but comes in several flavours, the Pro version includes an incredibly detailed spectrum analyser, audio phase correlator (more in a later post), PPM & VU monitoring plus a specrogram. Interestingly, Pinguin have done research to suggest that RMS is the most reliable way of measuring perceived loudness.
• Speaking of Spectrograms, there's Spectrogram - and Audacity has this capability, too.
• Finally, the fantastic (Mac-only) AudioLeak - an Leq (Long-term Equivalent Level) Analyzer for audio files and sound input streams. Swiftly discover the average RMS of an audio file, and it's A-weighted counterpart. Just watch out - by default it displays a combined mono value which reads higher than other applications like Wavelab - I usually use the average of the left & right values - they should be almost identical if the L/R balance is right, anyway. Also great for DVD Producers wanting to find the right dialnorm setting for a Dolby Digital encode.
• Update - here's another one - the SSL X-ISM meter. This is useful because it includes checking for inter-sample peaks. This is well-explained on the page I linked to, but briefly: strange as it may seem, when audio has been heavily limited and is peaking at (or very near to) zero, it is possible that the reconstructed analogue output actually peaks above zero. (In theory, up to 6 dB higher !) In cheaper players, MP3 encoders and other utilities, there is often no headroom allowed for this situation, and unwanted clipping can result. This meter will help you watch for this effect and avoid it. As a rule of thumb, don't allow your audio to peak higher that -0.3 dBFS.

Coming soon - how to choose a mastering studio.