Crushed To Hell: My Thoughts About Mastering

For the second time in my life I have realised that reaching out to a mastering studio to put the “finishing touches” on my music is completely pointless.

Allow me to explain…

Mastering recorded audio became its own discipline after the Second World War, when a “dubbing engineer”, secondary to the recording/mix engineer, was tasked with transferring the recorded audio from tape to a master disc, which served as the template from which all following vinyl discs would be pressed. This was a purely technical procedure, whereby the dubbing engineer’s job was to ensure that the final recording, which had been signed off by those creatively involved with the production of the music, was faithfully duplicated onto its designated medium.

Early vinyl records tended to be dogged by various inefficiencies in the tape-to-disc transfer process, not least that the dynamic range of the recorded material could be too large, resulting in the cutting of unplayable waveforms where the needle would actually pop out of the grooves, or even burning out the disc cutting head. The use of compressors and limiters in the mastering process became widespread in the 1960s, to cap the dynamic range at a particular threshold and thus ensure that such problems could be avoided. However, because this process was automated, often the dynamics processing employed was not sympathetic to the fidelity of the original material, and so over-compression would sometimes squeeze the life out of it, making everything sound consistently loud in a way that dishonoured the integrity of the original tape master. Some records ended up sounding particularly nasty due to this pitfall at the mastering stage.

And so, the solution to this problem?

Enter the mastering engineer.

By the 1970s, dedicated mastering studios had been established, staffed by sound engineers using high-end equipment. These “mastering engineers” were incredibly adept at finalising tape masters in an artistically satisfactory way, establishing mastering as a new artistic discipline that could actually make the final result sound “better” than the original recording.

Throughout the 80s and 90s, music production was revolutionised by digital technology, and CDs became the darling format of the music industry. To this end, the significance of mastering for vinyl became less prominent, as the problems incurred by analogue playback were no longer an issue in the digital domain. Mastering engineers, however, did not disappear, and instead their role migrated into audio specialists who serve as the last step in the production process – the guy or gal who collates all the final mixes for a particular release, and applies their technical wizardry to ensure that program volumes and tonal balancing are consistent throughout the entirety of the album. This is arguably of particular importance given the infinitely flexible DIY audio production world in which we now live, where track one may have been recorded and mixed in your bedroom, and track ten is a live recording from that gig you played last year – a far cry from the rigidly calibrated standards of professional audio recording of the 60s and 70s – the mastering engineer can be an invaluable specialist who coalesces all of these final mixes, “topping and tailing” each song to run seamlessly from one to the other, and thereby creating a pleasingly consistent album.

So, what’s my beef with mastering then? Why the need for such cynicism over a specialist process that seems so necessary?

Well, as we have seen, the discipline of mastering has migrated away from being a technical necessity, and has reinvented itself as an artistic process that seeks to “correct” and “improve” audio recordings. It seems to me that underpinning this is an assumption that all recordings require “correction” and “improvement”, such that it has now become an almost unquestioned assumption that recordings must undergo such processes before they are properly finished, regardless of the fact that 99% of all recordings these days end up uploaded onto Soundcloud or YouTube, and as such have absolutely no technical requirement for any fiddling at the final stage. I have had this demonstrated to me twice in my life, and both times I reached the conclusion that mastering is really only necessary if identifiable problems are present with the final mixes. In short, if your final mixes sound great to you, and you are satisfied that they translate well across systems, then you really have to ask yourself what the point of having it mastered actually is.

Case in point, I recently finished working on two songs of my own, and rather than do my normal thing of using some light compression, adding a little sweetening EQ and then normalising the result, I decided that it is high time I found myself a decent, trustworthy mastering engineer to whom I could reliably outsource any material recorded at my studio – for both myself and my clients – to put the “finishing touches” on the mixes. The icing on the cake. The cherry on top. The sachet in the pot noodle. The mayonnaise on your kebab. Whatever your favourite culinary analogy, that’s what I thought. And so I touched base with several mastering facilities, both home and abroad, each of whom did a test master for me of one of my songs.

The result?

In each instance I found their work to be a terrible detriment to my original mix; crushed with compression in a way that seemed to me to be horribly distasteful, and accompanied by notes claiming things like “I tried to make it a tad warmer and kill some spikiness in the guitar”. This seemed to me to be slightly presumptuous – perhaps I like the spikiness in the guitar (I do). But of course, how was he to know otherwise? He is not familiar with my style, my artistic preferences, or what I consider important about my mixes, and so he was just trying to rectify the problems in the mix, as he perceived them. Attempts to articulate my preferences via email just leads to a cumbersome back and forth whereby words prove to be an inefficient medium in which to convey the subjective pleasure of ambiguous terms such as “guitar spikiness”, let alone any other of the myriad things that I neglected to mention. I actually work hard to capture a wide, natural ambience in my music, especially in the drums, and I feel that, in this current age of “loudness war” style over-compression, excessive limiting of transients in order to push up the aggregate volume of the music actually works against this kind of production style, and forces a kind of “breathlessness” in the music, where everything becomes squashed into a mulch of muddy sounding loudness.

Let’s take a closer look…

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The image above depicts a stereo waveform representation of my original mix (red), followed by two subsequent masters from two different studios. In both cases we see that the audio peaks have been truncated in order that the aggregate level can be further maximised. The blue-backed waveform represents an attempt by the first mastering engineer – this waveform is a real sausage! Obviously hugely compressed (oddly more so on the right hand side than the left), which manifests as very noticeable “gain pumping” (sharp volume rises and falls) when listening. Detailing this concern to the second mastering studio, they returned their master, which is the yellow-backed waveform above. Noting that I was not a fan of excessive compression, they opted to still squash the mix, but just not as much. The result was a slightly less severe but still noticeable and ugly compression.

It actually seems to have become second nature to mastering engineers to simply make everything as loud as possible, because, hey, louder = better, right? We can see this trend towards excessive loudness by comparing two more waveforms, this time from Nirvana’s song “Smells Like Teen Spirit”, recorded in 1991. The image below depicts the original 1991 master (blue), and the 20th anniversary remastered “Special Edition” from 2011 (green):

2

It is interesting to note that the blue-backed waveform clearly shows Nirvana’s signature loud-quiet-loud song structure represented as an actual change in peak volume between the verses and the choruses. Cut to 2011 and this natural dynamic has been crushed in order raise the aggregate level of the song, arguably sacrificing one of the very trademarks that made Nirvana such a dynamically versatile and intense band in the first place. So no, louder is not always better.

But here’s another reason to be wary of excessive compression. Look what happens when we truncate peak waveforms in this way:

3

The above image shows a close-up of my original mix (red) side by side with the first master (blue). What we see is that, by truncating audio transients we are actually sacrificing audio content that would otherwise have been present. The detail displayed in the red wave has been totally lopped off and replaced with something resembling a large square wave. Square waves actually introduce odd-ordered harmonics into the signal, which manifests to our ears as rather ugly distortion.

So it seems to me that we are somewhere close to the old days of ramming final mixes through limiters at the mastering stage simply as a matter of course rather than because the music actually warrants it. Indeed, when I suggested to subsequent mastering engineers that I don’t wish to overdo the compression, they still felt inclined to push it somewhat, rather than to err on the side of subtlety. It’s curious why this has become the norm, and of course the much discussed “Loudness War” of the 2000s has impacted significantly upon the industry, such that it seems as though a mastering engineer doesn’t feel he is creating value for money unless he is seen to be mastering for “competition volume”, or else tampering with the mix to some significant and obviously noticeable degree. But for me, this is not actually the job of a mastering engineer. It seems to me that a principled mastering engineer should not be afraid to listen to a mix and decide that nothing needed to be done to it. And to that end, their job is done, and they are still every bit as entitled to be paid as if they had actually decided that there were real tonal balance problems that needed to be rectified. The mastering engineer is your last line of defence against actual technical problems, not a dude who can make your mixes sound “shit hot”. Working under that preconception actually encourages sloppy mixing, because it’s okay – the mastering guy will fix it!

So, where does this leave me?

Well, just to be clear – I am not a mastering engineer, and I do not claim that I can adequately do the complicated job of fixing the technical problems of someone else’s mixes. This task is for dedicated mastering engineers who are good at what they do and conduct themselves in a principled and agreeable manner. But I would urge you, if you’re happy with your mixes and you love the way they sound, please ask yourself – what exactly is the problem that you’re trying to solve? Personally I can only conclude the same point that I reached several years ago when I went through a similar experience: I seem to be trying hard to locate a mastering engineer to whom I can pay money in order to fix unidentifiable problems. All they seem to do – inevitably – is fail to align with my artistic vision and return results that I actually think make my mixes sound worse, not better. And so, being that I do not wish to employ someone to make further creative decisions on mixes that I am already satisfied with, it seems to me that I should take my cue from my previous decision on this matter, and that is that the person best placed to put any “finishing touches” on my music is me.

Hopefully, in a few years from now, when I have again forgotten why I don’t use mastering engineers and I find myself once again looking for that special someone who can put the awesome “finishing touches” on my music, this blog post will serve as a reminder of just how pointless that pursuit is.


The Bullshittery Of Audio Jargon

The topic of audio recording is vast and open-ended, and discussion about associated equipment in particular often gives rise to much heated debate with respect to perceived differences in the sonic performance between devices. It is not uncommon for hostile discussions to be waged pitting the minutia characteristics of this device against that, with all parties using increasingly elaborate language to define their subjective auditory experience, yet in the process obfuscating any real scientific analysis in favour of regurgitating “buzz” words that, when examined, actually fail to reveal anything helpful about the nature of the device in question. “Warmth”, “openness”, “air”, “punch”, “creaminess”, “sheen”, “silkiness”, “purpleness”, “dogturdidness”; fluffy terminology of this nature can often be observed in industry magazines (as some notable culprits are particularly guilty of), where vast word salads are served up in an attempt to suitably bewilder the reader into believing some imposed perception about a given piece of equipment. Whether it is an industry effort to create brand association with generic “good sounding” Barnum statements, or simply sloppy journalism in which authoritarianism comes from using words that everyone is too confused to question, the amount of bullshit I witness people talking on a regular basis goes to show how successful this method is.

I find language of that nature problematic for several reasons, not least because it denies us, as students of audio recording practices, access to scientific truths with regards to our field, where discussion of imparted harmonic content via signal distortion is much more helpful than fogging the issue under a linguistic cloud of subjective terminology and thereby propagating marketing myths about the necessity of over-priced equipment. It is no doubt a valuable weapon across all levels of the audio equipment industry, each brand justifying the apparent necessity of its newest model by using words that no one really understands. It’s interesting how readily we accept this lack of clarity in the discussion of audio, and how encourageable everyone seems to be to jump on the bullshit bandwagon. Note how we don’t accept this terminology in discussion of equipment where the scientific validity of their specifications really matters – I’m sure no FMRI scanner was sold on the basis of the “punch” of the scan or the “warmth” of the images produced. We can more readily accept fuzzy jargon in that context as obviously ridiculous and unhelpful.

“Brilliance”, anyone?

One of my audio recording heroes is Ethan Winer – musician, acoustician, and owner of the acoustic treatment company RealTraps – Ethan is somewhat notorious for his efforts to debunk tenacious myths prevalent among recording enthusiasts, whilst grounding his discussions in empirical scientific analyses, thereby abstaining from and often criticising the use of ambiguous subjective terms. I highly recommend his book “The Audio Expert” in which he talks about this very topic:

“Some of the worst examples of nonsensical audio terms I’ve seen arose from a discussion in a hi-fi audio forum. A fellow claimed that digital audio misses capturing certain aspects of music compared to analog tape and LP records. So I asked him to state some specific properties of sound that digital audio is unable to record. Among his list were tonal texture, transparency in the midrange, bloom and openness, substance, and the organic signature of instruments. I explained that these are not legitimate audio properties, but he remained convinced of his beliefs anyway. Perhaps my next book will be titled Scientists Are from Mars, Audiophiles Are from Venus.”

With this in mind then, allow me to demonstrate the principle of audio bullshit in action. As I came to undertake an investigation into the sonic differences between several different microphone preamps (post on that soon), I encountered a 2007 article from Sound On Sound in review of the Neve Portico 5012 Dual Microphone Preamp. As my curiosity led me to probe how such a device can justify a £1,400 price tag, one sentence in particular proved to be such an excellent demonstration of the ambiguity of industry terminology that I was inspired to finally write this blog post, hailing my discovery as a gold standard of audio bullshittery. Let’s have a look:

“The 5012 […] has a full bodied, solid sound that gives that slightly larger-than-life character that is the trademark of a really top-class preamp. It sounds clean and detailed in normal use, without that edgy crispness that can detract in some designs…

When the Silk mode is switched in, the sound becomes a little smoother, rounder, and sweeter still in the upper mids. The high end gains a little more air, and the bottom end becomes a tad richer and thicker.”

Terms like “larger-than-life” and “edgy crispness” are rampant when describing microphone preamps, analogue-to-digital converters and other studio essentials, yet they say nothing useful whatsoever about the actual, verifiable sonic characteristics of the device, instead simply propagating the usage of these vague terms and using them as flimsy justification for impressionable enthusiasts to feel anxious about the “below-par” consumer grade equipment they are currently using, and therefore encouraging them to unnecessarily part with not insignificant sums of money, thereby continuing the trend. That’s not to say of course that there is no value in “high-end” gear such as this, however I would prefer that its usage could be justified in more certain terms than these floppy, nothing words that we all have to keep grappling with. In my experience it’s always worth pushing for clarification via language that is arrived at through scientific consensus so that we can all be on the same page in terms of our expectations. This is the best prophylactic available against the tech-heads who claim authority by asserting that their £X,000 device sounds “sweet”. Chances are, they’re talking bullshit.


Stereo Recording Techniques On Test

Often in recording scenarios it is necessary to implement a stereo miking technique. Usually this is employed to capture room ambience at a distance from the originating sound source, by which I mean the reverberant field of an acoustic environment – anywhere where the late reflections are of greater intensity than the direct sound. Whether it’s for drum kit ambience, concert halls or choirs, ambient stereo miking provides a way of adding depth, width and general realism to the recording that is not possible through close-miking alone.

However, there are numerous stereo mic techniques and it struck me recently that I had never undertaken a direct comparison of them. This realisation in fact struck me with such vigour that I felt moved to instantly rectify the situation, spontaneously leaping up from my seat, screaming “STEREO MIC COMPARISON!!”, and bolting, arms flailing and screeching like a girl, towards the door. The other cinema-goers were somewhat bemused.

And with that I decided at once to trial four different stereo mic techniques over a few different scenarios. These are techniques that any good engineer should be aware of, but perhaps not all have actually directly compared. Well, in the name of science I hereby rise to the challenge.

Yes, that’s right… science.
 
 
So the four techniques on the menu today are the following:

  • #1: XY
  • #2: ORTF
  • #3: Blumlein
  • #4: Mid/Side

stereo-mics

I won’t go into detail about the configuration of these techniques here, largely because it’s late and I can’t be bothered, but if you’d like to know more about their implementation, please follow this link.
 
 
The purpose of my trials would be to answer the following questions:

  • Which technique captures a more effective and balanced stereo image?
  • How well does each technique collapse to mono?
  • How rich is the tonal balance?
  • Which one do I like best?

 
 
I chose to make these comparisons under 3 different scenarios: a large, reverberant concert hall, the drum recording environment in my studio, and with a moving sound source in a small room, which in this case was me wandering around and talking. The tests employed two sets of microphones – two AKG C414s for Blumlein and Mid/Side, and two AKG C451s for XY and ORTF. This selection was imposed due to equipment restrictions, otherwise identical microphones would have been used for all applications, thereby eliminating the variable of the sonic performance of the different mics. Nevertheless the comparisons should allow us to draw some reasonably solid conclusions.
 
Listed below are the recordings. Click each one to listen for yourself and see if you agree with my analysis:

 
stereo-mics-2
 
stereo-mics-3
 
 
So, based upon these recordings, along with a whole load of other tests I carried out which are not listed above, here are my answers to the aforementioned questions:
 
 

  • Q: Which technique captures a more effective and balanced stereo image?
  • A: Mid/Side.

The weakest stereo image seemed, across the board,  to be XY. It has a strong centre but very little width. This is unsurprising, since the capsules are so close together that it seems illogical to expect anything more. This is as I had always suspected, and why I never really felt tempted by this technique. The lack of movement in the voice recording is particularly noteworthy. My next preference is ORTF due to its much wider stereo image and strong centre point, followed jointly by Blumlein and M/S, both of which clearly exhibit a wide, detailed image. If I had to pick a winner, I’d go with M/S. The movement may not be quite as authentic as Blumlein, perhaps due to the trickery involved in the M/S configuration vs. the fairly organic method of Blumlein, however for the capture of room ambience for a static source, M/S just seems to have a special kind of something about it – a width and depth that to my ears is incredibly realistic.
 
 

  • Q: How well does each technique collapse to mono?
  • A: ORTF & Blumlein win.

The mono drum recordings reveal that no technique has any particular issue or phase weirdness occurring when collapsed to mono, however in terms of preserving the fidelity of the ambient field that we are attempting to capture, Blumlein and ORTF seem to have it over M/S and XY. With M/S this is due to the cancellation of the side mic so that we are left with only one microphone pointing at the source, and XY had the weakest stereo width anyway, so this result is unsurprising.
 
 

  • How rich is the tonal balance?
  • A: Mid/Side wins.

We have to be a little careful here when we start using ambiguous terms like “richness”, “warmth”, “creaminess”, “silkiness”, “moistness”, “purpleness”, etc, etc, because these aren’t exactly scientific words. However, what I intend it to mean in this instance is how well expressed are the bass, middle and treble parts of the frequency spectrum, subjectively speaking. In my view, M/S clearly trumps all others in terms of its pleasing bottom end yet detailed high frequency reproduction. This was deduced by looping small parts of the drum and concert recordings and directly comparing each technique. ORTF is also very good in this regard, followed by Blumlein and finally XY.
 
 

  • Which one do I like best?
  • A: Mid/Side!

Yep, it would appear that M/S is awesome. Science says so. Well, to my ears at least. My science ears. It adds something magical to the recording and is extremely pleasing to experience, especially on drum recordings when combined with the close miked signals. Here is a demonstration of that:

 
 

Blumlein and ORTF are still excellent techniques though, offering a nice, solid centre and plenty of detailed width, which is certainly bad news for the XY technique, which has since been strapped to a rocket and jettisoned into the centre of the sun.
 
It deserved it, too.
 
 
That is all.

 


Comb Filtering In Drum Overhead Microphones

Recording drums in a small room is a problem that any engineer not blessed with an infinite budget must deal with at some point. Among the difficulties inherent in this scenario is the problem of comb filtering in the audio signal due to the microphone’s proximity to a boundary, i.e. the ceiling or a nearby wall. For example, if a singer sang into an omni-directional microphone placed 1 metre from a reflective wall or surface, the sound of their voice would hit the mic but also carry on past it, hit the wall, rebounding back and re-entering the mic about 6 milliseconds after the direct signal.

boundary

 

This is exactly the right amount of time for the frequency components around 85-86Hz to come back close to 180° out of phase with the direct signal. There will not be total cancellation, since the rebounded signal will be weaker and because the sonic characteristics of the singer’s voice are constantly changing, but the effect may still be significant.

frequencies

 

Rounding down to 85Hz, at 170Hz the reflection will come back in phase and reinforce the 170Hz components within the direct signal. At 255Hz it will be out of phase again, and at 425Hz and 595Hz, and at intervals of 170Hz all the way up the frequency spectrum. This is known as “comb filtering”, due to the regular series of peaks and notches across the spectrum. It sounds phasey and generally undesirable.

This effect is demonstrated in this video, where a drum overhead microphone is moved towards a nearby boundary and back again. The comb filtering artefacts are clearly audible in the recorded signal. The first microphone – a Royer R121 ribbon mic – clearly suffers from this effect with great prominence given it’s bi-directional polar pattern, and thus greater susceptibility to rear reflections. The second mic – an Audio Technica ATM450 – reveals itself to be less harshly affected due to its cardioid polar pattern. This then demonstrates the importance of microphone selection with regard to its placement within a recording environment, as well as the importance of placing the mic as far from boundaries as possible, or, when this is not feasible, treating nearby surfaces with good quality acoustic absorption in order to eliminate as many reflections as possible. A combination of absorption and diffusion is most effective.

 

Many thanks to my beautiful assistant, Bebe Bentley, for helping me with these tests. Check out her excellent work in film and moving image on her Vimeo page.


Impulse Responses & Convolution Reverb: How To Sample An Acoustic Space

Those familiar with audio production probably know that there are two types of digitally synthesised reverb effect. The first, and generally most popular given its byte-sized (heh) use of computer resources is known as “algorithmic” reverb, where the incoming signal is, sample by sample, multiplied by a factor dictated algorithmically by various twiddly knob-like parameters. Such reverb types, although efficient on resources, can be less than convincing upon application, especially when applied to particularly exposed instruments or voices; unsurprising since they are merely a mathematical approximation of the kind of thing reverb should probably sound like.

 

1A twiddly knob algorithmic reverb unit.

 

The second, more sophisticated type of reverb is known as “convolution” reverb, and it is this type that is the focus of today’s brain spillings.

 

You see, convolution reverb more precisely replicates the acoustical properties of an actual real-life environment by manipulating the original recording via a method similar to the algorithmic reverb technique, but crucially different in a very specific way. This time instead of relying on a mathematically produced set of rules to determine the multiplication of the incoming signal, an “impulse response” – an actual recording of an actual real-life actual environment – is used.

 

Actually.

 

2

A convolution reverb unit.

 

“Impulse response” is just a fancy way of saying a “recording of a signal processed via some system”. In the case of convolution reverb, the system is the reverberation of a physical space. Stick a microphone in the middle of the Sydney Opera House, record the sound of a balloon popping plus the ensuing room acoustics, and, hey presto, you have yourself an impulse response. An accurate impulse response must feature all frequencies within the audible spectrum (20 Hz – 20 KHz) in order to be effective for use as convolution reverb, which is why a balloon pop makes for a fairly commonly used source, especially given the ease with which such a scenario can be set up. Generally speaking, a sudden burst of white noise of this kind contains spectral content of sufficient bandwidth to be practically useful.

 

There is however, as impulse response elitists never tire of pointing out, a problem with this method, since no two balloon pops are exactly alike, and the intensity of frequencies across the spectrum may vary wildly. A higher intensity at 500Hz than 2KHz will bias the response of the room in favour of 500Hz. Therefore, for the sake of accuracy, a frequency sweep played back through a flat response studio speaker is considered the definitive method of sampling an acoustic space. This way it is ensured that all frequencies are played at equal intensity. Of course there is then some deliberation about the quality of speaker, microphone and preamp used, however it is claimed that a fairly modest system can at least produce a very reasonable approximation.

 

I should point out at this juncture, ladies and gentlemen, that I did, in order to look clevererer than I necessarily am, try to find a more detailed explanation of the process of multiplying the input signal by the impulse response at a sample level, but my efforts merely resulted in my being sick on my desk. So forgive me if I quietly refrain from that, and instead offer that I think it might have something to do with very, very tiny squirrels.

 

I think.

 
 

Isn’t it?

 
 

Well, okay – here, I drew a picture. I think it’s something like this:

3

Make of that what you will.

 
 

Anyway, so far, so good – find a sonically interesting environment, record a frequency sweep, run it through some jiggery pokery to create a usable impulse response, load it into your favourite convolution reverb plugin – I will be using Cubase’s inbuilt REVerence – and marvel at your digital recreation of your original environment. Sounds like fun to me.

 

So, choosing two sonically interesting spaces at the University of Sussex, I put it to the test. The Meeting House is a large, circular, chapel with a domed roof, apparently designed in the midst of a fairly potent acid trip, whilst the drama studio is a much smaller, enclosed room, yet of equivalent acoustic interest.

4

The Meeting House.

5

The Drama Studio.

 
 

Within these environments I set up a Genelec 8030A for playback of the frequency sweep, a pair of AKG C451Bs in ORTF configuration on the far side of the room and then, to the bemusement of any passing visitors, recorded the signal. Then, in the same positions, I recorded a short segment of acoustic guitar for reference when assessing the authenticity of my resultant convolution reverb. For completeness, I also recorded balloons popping, so that a true comparison could be conducted.

6

7

8

 
 

So then, once all the data had been collected I could return to the lab to analyse the results. Some subtle treatment of the recorded signals was required to eliminate ambient noise where possible, always ensuring never to damage the fidelity of the actual recordings. Once the material had been analysed, treated and turned into usable impulse response files via Voxengo Deconvolver, I could load them into the REVelation Convolution Reverb unit, apply the plugin to a source signal (in this case a dry recording of the guitar riff I had played in each environment), and cross my fingers that it had worked.

 
 

Here are the results. Click to listen.

 

#1: Meeting House
— Guitar in Room / Frequency Sweep Reverb / Balloon Pop Reverb.

The results here are actually pretty good. Firstly it’s noteworthy that the frequency sweep does indeed produce better results than the balloon pop. The balloon pop has a deficit of high end information and a swelled, rather ugly middle. The frequency sweep on the other hand does a reasonably good job of replicating the guitar test recording. Both however produce a reverb tail that is fairly authentic. I am pleased with these results.

 

#2: Drama Studio
— Guitar in Room / Frequency Sweep Reverb / Balloon Pop Reverb.

A generally brighter reverb this time but the results are consistent with the previous environment. Again, the frequency sweep method has produced a far more convincing result.

 

So, all in all, that seems to have proven very successful. It is worth noting that, as well as actual physical environments, the frequency sweep method can also be used to sample hardware or software reverb FX units. By processing a frequency sweep with an interesting reverb unit and then generating an impulse response from the resulting file, a startlingly accurate clone of the original effect can be made. Here are two examples of such a practice, whereby the previous dry guitar recording has been processed first by a dedicated reverb unit, and then by an impulse response clone of that unit:

 

#3: Spring Reverb
— Original Reverb / Cloned Reverb

 

#4: FX Reverb
— Original Reverb / Cloned Reverb

 

So that’s it. Impulse response generated convolution reverb.

Lawks a lordy.

 

I’m going to eat some chicken.

Ta-ra.

 


Binaural Recording

Have you ever wondered how it is possible for the human brain to so accurately detect the location of a perceived sound? We only have two ears, yet somehow we are able to discern the differences between sounds originating from any direction within our 3-dimensional environment – in front, behind, above, below, left or right. How is this possible? And can we therefore simulate this effect in order to artificially reproduce the experience of perceived 3-dimensional sounds, as opposed to the normal left/right experience we are accustomed to in traditional stereophonic speaker set-ups, without simply adding extra speakers?

The answer is yes we can. Directional perception of sound occurs by our brain’s ability to decode the subtle differences in information received by our in-built stereo receivers – our left and right ears. Binaural recording is a recording technique that uses two microphones to mimic the human auditory system, utilising the exact same conditions that create the phenomenon of binaural localisation in humans. And so, with the acquisition of a pair of binaural microphones, a portable Tascam field recorder and a dummy head named John, film maker Bebe Bentley and I spent one evening carrying out some binaural recording tests at the University of Sussex. Here are the results (please note that headphones must be worn in order to perceive the effect):

#1: Binaural recording in a dead room.

#2: Binaural recording in a live room.

#3: Binaural recording of James with a guitar.

NEW-2NEW 1 NEW-4

In the directional perception of sound there are two phenomena at work: Binaural and monaural localisation:

Binaural Localisation

Binaural Localisation refers to the discrepancies in the characteristics of a sound wave arriving at the closest ear, and then the farthest. Your brain is sensitive to the discreet time difference between a sound hitting the nearest ear and the farthest ear – referred to as the Inter-aural Time Difference (ITD) – as well as the slight change in volume between the two ears – the Inter-aural Intensity Difference (IID). If sound originates to your left, your head acts as a barrier or filter and reduces the level of sound heard in the right ear.

Monaural Localisation

Monaural localisation mostly depends on the filtering effects of physical structures. In the human auditory system, these external filters include the head, shoulders, torso, and outer ear or “pinna”, and can be summarized as the head-related transfer function. Sounds are frequency filtered specifically depending on the angle at which they strike the various external filters.

binaural
Binaural recording of the kind Bebe and I carried out works by the use of two omni-directional microphones fitted to a dummy head, thereby simulating as realistically as possible the actual physical location of the human ears, combined with the filtering incurred by the human head. The same effect would be achieved by placing the microphones in your own ears, which would make for an interesting audio experience were you to then simply walk around an urban environment or visit a concert. In these instances it would be possible to accurately record exactly what you heard in these situations, complete with directional perception of the ambient noise, in order to later recreate that exact sensation through a pair of headphones. This, however, is perhaps a test for another day. Here we simply affixed the microphones into John’s ears and proceeded to move objects around and make various noises such that the illusion of directional perception is created.

It is however important, for the effect to be fully realised, that headphones are worn. This is because, on replay, the left ear must receive only the signal recorded by the left microphone, and the right ear only the signal from the right microphone. Playback through speakers destroys this effect by obscuring the stereo field emitted by the left and right speakers.

What strikes me as odd about the experience of listening to this recording is the realism it invokes. When hearing Bebe and I running around the room it is as if ghost figures are appearing in front of you. With your eyes closed you can almost “see” the people. This demonstrates just how unaware we are of the subtleties of our sensory information in building our picture of the world. The next time someone supposes some supernatural bullshit to describe how they “felt a presence in the room”, remind them how easily our senses can be fooled.

So there we are. Artificial directional perception by binaural recording. Now, if only I could find a practical application…


Eliminating High-Hat Spill

When recording a drum kit one of the most perennial problems encountered is high-hat spill on the snare microphone. Some engineers claim to have made peace with this issue by utilising the signal as simply “part of the drum sound”. This doesn’t do it for me since, among other problems, it ruins my stereo image of the kit, placing the hats immovably in the centre. Others aim their microphones such that the null in the cardioid pattern (i.e. the rear of the mic) is directed at the hats. Others even suggest using a figure-8 mic such as a ribbon, which has deeper nulls in its off-axis response, placed so that the side of the capsule looks at the hats.

None of these solutions provide suitable buoyancy to float my little boat. For a start, dynamic mics – especially the SM57 – do not, in my opinion, sufficiently capture the snap and sizzle of a snare drum, and besides, positioning one so that its rear is pointing towards the hats without disturbing the drummer is a tactical nightmare. Ribbon mics are scarcely much better, since there is no one location where the rear of the microphone is not detecting an unworkable amount of the tom behind it. And I don’t even want to think about the consequences of the inevitable battering it is going to take from the drummer. In any case, microphone positioning of this nature when in such close proximity to other undesirable sound sources is purely a hypothetical exercise. In the real world the results achieved by nit-picking in this manner are more or less negligible. The harsh spill from a close set of loud high-hats is simply not going to be significantly reduced by inching a microphone on its axis one way or another.

When I record snare drums I generally like to use the very tiny Shure Beta 98 microphone. It sounds absolutely excellent, gives great top end crack, has very fast transient response, and is so physically small that it can be positioned anywhere around the drum without getting in the drummer’s way (it also has great mounting hardware so as to clamp rigidly onto the side of the drum, thus eliminating the requirement of yet another mic stand). Then when I mix the snare I like to take a good, transparent EQ and make it extremely bright. That’s how to achieve a good crack that pierces like a razor blade though the mix. However, in order for this to work the snare must be as isolated as possible from the rest of the kit, and the high-hat above all must be eliminated as much as possible from the signal, or at the very least its high frequencies significantly reduced.

So. We have a conundrum on our hands. If we can’t budge on mic choice and we can’t solve the problem through placement, the only other alternative is baffling. With this, I set to work.

Now, I have read several times on forums and in textbooks such as Bobby Owsinsky’s “The Recording Engineer’s Handbook” that a good method of baffling ambient sound from a drum mic is to cut a hole in a polystyrene cup, poke your microphone through the middle and then tape the contraption together. Dubious, I gave it a try, suspecting that polystyrene does not present a suitably absorbent or reflective material to deflect close proximity, high intensity sound. As it transpires, I was right. Not only this, but I couldn’t imagine actually putting this into practice in a recording session without feeling like the dickiest of amateur dicks: “We’re all miked up lads… now, get me a paper cup and some gaffer tape!”. However, somewhat inspired by this idea I thought that perhaps I could build a contraption out of a more rigid material, take some steps to furnish it with some proper isolation material and then affix it retractably to the microphone, thus making for a more professional, more effective baffle and thereby solving our problem.

The idea? Tennis balls! One tennis ball, in fact. Cut in half, a hole cut in the middle, the outside covered in tin foil and the inside stuffed with acoustic foam. As I sat in one sunny Saturday, craft materials sprawled everywhere and glitter all over my face, my train of thought pulled in for a long stay at Genius Junction. This, I knew, was the solution to all my high-hat woes. I was indeed a genius. The result looked like this:

Tennis Ball

I thought it looked pretty smart. But did it work? Well, let me tell you…

No. It was shit. Not only was it absolutely ineffective, it also turned the source, i.e. the snare, into a tonally retarded shadow of its former self. And this makes perfect sense too – if you place a microphone within the confines of a cavity, then the acoustical properties of that immediate boundary are going to wreak havoc on the direct source you are trying to capture. The resonant frequency of that cavity combined with the filtering artefacts incurred by the boundary (the boundary effect) are going to dick with your source sound in a totally undesirable way. To see for yourself, just cut a hole in the bottom of a paper cup and put it up to your ear while listening to some music. Sounds awful, doesn’t it? If more proof were needed, here are the results of my tests:

Snare Test 1: Shure Beta 98, close, no baffle
Snare Test 2: Shure Beta 98, close, tennis ball baffle

So I think we can safely say that forming any kind of cavity immediately around a microphone is definitely not a good idea. This means that we have to find some other non-intrusive way of baffling the high-hats. Since the tennis ball idea not only sounded bad but also did very little to reduce the harsh frequencies of the hats, it seemed to me that we needed to think bigger to think better. I know from experience that an extremely good source of acoustic insulation is Rockwool, due to its high absorption coefficient, especially in the high frequencies – exactly where the harshness of the hats resides. So if we could somehow fashion a non-intrusive baffle out of four inches of Rockwool, then maybe we would be on to something. I immediately got to work on some leftover sound insulation with a Stanley knife. After many hours chopping, changing and inhaling an ever increasing quantity of microfibres, I discovered a solution that created no cavity around the microphone and significantly reduced the harsh top end of the hats in the snare mic. That solution was to raise the hats such that a four inch thick slab of high-hat shaped Rockwool could be installed beneath them, with the snare mic tucked underneath. It wasn’t pretty but it worked a treat:

Rockwool

For those of you with anxieties about raising high-hats, I should point out that this approach really is the first port of call when attempting to reduce high-hat spill. The further away you can move a source from the microphone, the less intrusive it will be. With the hats this carries the added bonus that it moves the drummer’s point of contact to the less clangy side of the hats, as opposed to the harsher top.

Finally we’re getting somewhere. For good measure, and simply because it seemed like it was something I should do, I added a chunk of acoustic foam underneath the Rockwool, just to see if I could knock off that spill a little more:

Rockwool + foam

The results were excellent. The high-hat spill was becoming reduced to a much more manageable level:

Snare Test 3: Shure Beta 98, close, Rockwool + foam baffle

The only remaining problems now were a) how to make this monstrosity more aesthetically pleasing, and b) how to not disrupt the drummer by its presence. Both of these concerns were addressed by cutting the Rockwool down to exactly the size of the high-hat (generally 14″) and taking one extraordinarily tedious afternoon to assemble a small pair of trousers in which to house it all:

Trousers

The Rockwool was inserted into the black cotton trousers, with the foam glued to the underside. By clipping this to the stand immediately beneath the hats, the microphone can can be tucked discreetly underneath, also then protecting the mic from an accidental battering from the drummer.

And there it is! This is how to eliminate high-hat spill without ruining your snare sound. And it just goes to show – don’t just believe what the textbooks tell you. Try it yourself, and if it doesn’t work, get creative.

hats


Thread Adapters And The Pain Of Existence

My sound engineering brethren, I feel your pain.

I do.

And for years I have been struggling just as you have, coerced into climbing that familiar mountain, bravely embarking ‘cross the bridge of despair, a spirit yearning for freedom, thoughts mired in the darkness of a wilderness within which only fools and heroes tread, all the while wondering, ever wondering, “does a man dare dream?”

I know, friends. I know.

I feel your pain.

 

It’s those bloody thread adapters getting stuck in mic clips. Ooo, they’re a nightmare, aren’t they?! There’s simply nothing worse. And what has always surprised me, right, is that they make them with small grooves cut into the top to aid their removal, yet no one has ever bothered actually manufacturing a tool for it! Tsk! My eyes are virtually rolling out of their sockets right now. So we’re all left, apparently “experienced” engineers, fumbling and bumbling around the circumference of the thread with a screwdriver, carving chunks out of it, only to inevitably utter the immortal line “anyone got a 50 pence piece?”

It makes me feel like a right willy.

And that’s of course if the adapter isn’t screwed so far in that no coin can achieve sufficient purchase. What happens then?! DOOM, that’s what. DOOM, right in your stupid, beardy face.

fig. 1: An example of the worst thing to ever happen:

thread 1

 

Well NO MORE!

That’s right, my friends, I have solved the problem, and I expect to be showered in riches and have commemorative statues erected at your earliest convenience.

All you need to do, right, is get yourself down to your local key-cutting establishment – usually a cobbler, (but please, let’s not use this as an excuse to engage in a protracted debate about the unexplainable relationship between shoe repair and key cutting. Not here. Not now.) – and ask of the clerk that he or she furnish you with a blank mortice key, one with a head no longer than 15mm (although my proud 13mm seems to do the job nicely, thank you very much). If they enquire, suddenly panicked, why you could possibly need such an object and threaten to throw you out and call the police, please, friends, do try not to spit at them or burst into flames. It contravenes almost all of section 6.4 of the cobbler code. I assure you they are merely afraid and mean you no harm. Instead just politely explain that you are staging a miniature all-key production of Othello and, having utilised all other options, a spare is needed to play the part of Roderigo (Othello of course being the production of choice for the annual cobbling society Christmas ball, staged in Whitstable). They will understand.

Now, with your brand new, uncut mortice key, you should find yourself in possession of the perfect thread adapter removal device. It’s rugged enough to resist contortion, has a big extendy handle for extra leverage, and a head deep enough to resolve even the most embarrassing of thread adapter misdemeanours. Perfect!

fig. 2: An image which could single-handedly have eliminated the need for this entire rambling post:

thread 2

 

So there you have it. Problem solved! No self-respecting sound engineer’s keyring should ever be without their very own thread adapter remover! That’s James’s top tip of the day, and if I ever hear any engineer ever again asking to borrow a 50 pence piece for this purpose, so help me I will personally burn their house down along with everything in it.

 

Fantastic! Well, I’m off to work on making blog posts, which could easily be summarised in two sentences, sound less like irritating Radio 4 light comedy shows.

No hesitation, repetition or deviation.


Achieving Nirvana

When I heard that Nirvana, or at least what remains of Nirvana, were to reunite this year to perform for the Rock & Roll Hall Of Fame, my excitement was inevitable. But a recent email conversation with a friend gave me pause to reflect upon the genesis of this excitement, and whether or not it is truly justified.

 

Turns out it is.

 

So rather than attempt to recreate that verbose justification for you here, it’s much more economical for me to simply repeat our exchange. I think I did a fairly good job of summarising my feelings. Interesting perhaps to see which camp you fall into…

 

James:  You’ve seen this, right? http://youtu.be/Ag643ahnUC8

 

Friend:  Yes I had seen various offerings over the last couple of months of the Hall of Fame thing.. Personally I wish they would never play as Nirvana sans Kurt no matter how great Lorde is or anyone else might be.. It usually just sounds wrong to me and I can’t enjoy it.. What are your opinions on the matter?

 

James:  I’m glad they did it. I wanted them to do it. I thought the whole affair was a magical and fitting tribute to a gifted songwriter and performer who truly deserves this recognition.

I just really wish it was better.

 

Friend:  It’s nice to have a fitting and uplifting tribute and all but I’d much rather see a bunch of people play their own songs that were perhaps inspired by Kurt Cobain/Nirvana.. Or perhaps original songs by people who were inspired to make music by the music of Kurt and Nirvana.. Like yourself..

I have to call you up on this line man: “I thought the whole affair was a magical and fitting tribute to a gifted songwriter and performer who truly deserves this recognition.”

Really? Being inducted into the Rock and Roll hall of fame.. I am probably considerably less clued up on his feelings about fame than you but my gut tells me Kurt would have baulked at the idea of being included in a hall of “fame” no matter how well intentioned a tribute it was..

Kurt Cobain truly deserves what recognition man? He’s dead..I’m not sure how this is getting him anything that he deserves.. I doubt very much he was presiding over the event from the heavens and if he was I’m sure he spent alot of time cringing! I’m not sure who that thing was for really.. I’m sure dead folk don’t give much of a damn and I can’t help but feel a little cynical regarding the motivations behind alive folk doing such things.. Unless of course it’s not really bad.. But then it was bad wasn’t it?

I may just be a very cynical human being but I can’t help but think that this was a moneymaking promotional event and nothing much more.

 

James:  First of all man I think it’s wrong to assume that what a drug-addled mind perceives as cringeworthy at 27 still holds quite so true by the time you reach middle age. The anger and blind resentment fades. Even Steve Albini is no longer the rasp-tongued abusive punk elitist he was in his more naive youth. And so too have Krist and Dave found a more mature approach to navigating the injustices of the world rather than spitting venom at anything even remotely regarded as “commercial”, whatever that word actually means (in any case, this event seems to have honourable enough intentions). So would Kurt be, if physical laws permitted, sat on a cloud cringing? If of the same mind as at the time of death then yes, probably. But that was a mind that elected to shoot itself, so I’m not sure how ethically reliable that opinion may be. Maturer minds may perhaps see the worthiness of such an event. One of life’s ironies is that we all grow, in one way or another, into the establishment. That’s not necessarily a bad thing man.

As for me, I loved that band. They meant so much to me. They inspired my life, for better or worse. And watching that video made me cry for reasons I couldn’t necessarily control or articulate. Repeatedly. I found it moving. I heard Michael Stipe’s brilliantly articulated speech speak to me on such a personal and profound level, as a quiet person who struggles with emotional difficulties, constantly feeling ousted from a world I simply don’t know how to access. It made me realise that it is no coincidence I took that band to my heart. And likewise I found the image of Kurt’s friends and family united on a stage to celebrate his life and works to be utterly, utterly moving, and yes, magical, particularly the very last song – all the Nirvana players united for a last stand beneath his angel winged torso, singing his words one last time, bringing him to life once again. From each artist to the next, our life and influence is passed down, and it’s fucking incredible. I am right there celebrating that.

So can Kurt comprehend that? Of course not. He’s, as you rightly say, dead. But we, the living, where his memory and his music still lives on, can. His mother can. His wife and child can. His band mates can. And his millions and millions of fans can. The people, just like me, that he has reached with the power of his music, who would never ever otherwise see a current performance from a band so fucking important to them, if they can see past their blind cynicism for just a minute, can appreciate that tributes are there for the living to celebrate those lost. To remember them. And to be thankful for their gift to the rest of us, lest you cancel remembrance Sunday and tear down war memorials in defence of your all-pervasive quest for literacy. I’m surprised at your opinion here.

So what’s a good celebration of a talented songwriter? Play his fucking songs. Who is best placed to play them? His fucking band.

Did they sound like Nirvana from 20 years ago?

No. There’s a myriad of reasons why not that should be too obvious for me to spell out here. But did it bring joy to his fans to see his name indelibly etched amongst the upper echelons of musical talent? From a one-person field study, I conclude yes. Call that cheesy if you like. But, in words that are sadly not my own, you know what goes well with cheese? A glass of red wine.

Right, I’m off to bed.


Mics Or Mikes?

Studio engineers, recording enthusiasts, musicians and journalists. I hereby call your attention to an issue of utmost importance. It is something that has niggled for as long as I have been writing about studio recording techniques, and I have yet to find a solution to it. I call upon us, here, now, to finally clean up this ambiguity once and for all, lest I never sleep a good night’s sleep for the rest of my days.

Friends, what exactly is the appropriate abbreviation of the word “microphone”? Is it mic? Or mike? My sense of rationality dictates that a suitable abbreviation for a word does not incur a re-imagining of the word itself, and therefore renaming it to “mike” seems faintly ridiculous. And so I much prefer “mic”, despite its erroneous phonetic pronunciation. But then we run into trouble as soon as we start talking about “micing”, or “mic’ing”, or “miking” – a non-OED word invented by sound engineers to describe the act of shoving a microphone some place, which incurs a total overhaul of the original word in order to scan properly. The word “micing” looks wrong, feels wrong and almost suggests some kind of bizarre cooking reference, “mic’ing” forces a descent into the kind of apostrophe retardation normally reserved for market stall sellers of “CD’s”, and “miking”, although phonetically accurate, declares an abandonment of the convention of the word microphone. In all recent writings I have taken the reluctant decision that the only logical interpretation of this chaos is that microphones are “mics” and drums are “miked” in the process of “miking”. However, I am in no way satisfied with this maverick approach to spelling, and find myself on occasions such as this wasting everybody’s time in an unwitting fit of grammatical anxiety. So, can we please – please – have some consensus on this? If the “they” committee would like to organise a board meeting regarding this important subject, I think it would be beneficial for everyone.