Summary

In this article Julian considers why, however effective the traditional solutions for acoustically treating mixing spaces might be, they are out of step with much of the audio industry as it exists today. Is there a better way?

Going Deeper

When one thinks of a recording studio, the chances are that you think of a purpose-built studio with the characteristic nonparallel walls, a large console and soffit mounted monitors which look closer to a PA system than to a pair of monitors designed for studio use. Beyond these immediate visual cues, a studio like this would also incorporate significant acoustic treatment in the large control room. These studios, which were far more common in years gone by, have defined our expectations. They were in buildings which were usually owned by the studio owner, and while refits and upgrades would occur during the lifespan of the studios, the location usually remained unchanged.

The recording studio landscape as it exists a quarter of the way into the 21st century serves an industry which has changed almost beyond recognition since those days. It is reasonable to expect studios to have changed with it and in many ways they have. Today studios are more transitory. The building may be owned by the studio owners but it is quite likely that the studio will be at the owners residence, either one of the rooms in the house, a garden studio or a garage conversion. If the building is exclusively used as a studio, it is more than likely rented rather than owned, and of the many bedroom studios which are doing serious work, many are in rented properties. In a situation where budgets have fallen dramatically and the costs of property have risen almost exponentially there is very little similarity in business terms between the studios on which our expectations are based and the studios which are a sensible fit for the industry as it exists today.

Other Equipment has Changed - Why Not Acoustic Treatment?

Examples of equipment moving with the times are easy to find. Consoles are something of an oddity these days with excellent virtual alternatives available for those who hanker after the sound of a mixer. Likewise tape machines are firmly in the territory of the committed minority these days. The need for instant recall has squeezed out nearly all outboard equipment from mixing. Plug-in alternatives, being cheaper, easier to live with and in all but the most exacting circumstances so close to the originals as to make little difference. Guitar amplifiers have also moved into the box with increasing numbers of players favouring the convenience and flexibility of modern amplifiers over the real deal. Even microphones have modelled alternatives which compete with their real counterparts in every way other than client wow factor.

Even the tracking spaces of big studios themselves occasionally show up in virtual form. The most notable example of which is the recent Sound City plug-in from Universal Audio although its Ocean Way predecessor has been notably popular for a very long time due to the relative scarcity of alternatives.

More common in virtual form are mix spaces. The ability to recreate approximations of specific mix rooms binaurally is very attractive to people mixing in less than ideal spaces, which is after all the majority of people. Waves NX and Slate VSX are notable players in this area. The desire for mixers working in repurposed domestic spaces to escape the influence of their rooms is strong.

Old Problem - Old Solutions

The reason for this is that, as R&D Director at Genelec Aki Makivirta wryly puts it “Physics always stays on version 1.0”. The sound of a loudspeaker is influenced by the room it is in, and not by a little. And until very recently there has only been one way to influence this - By physically changing the room.

To take tracking spaces as an example, the influence of the room is rather easier to deal with when capturing sounds. The trend towards closer and closer miking to exclude the influence of the room is widespread as is the popularity of reflection filters and portable vocal booths. The old fashioned approach of dealing with these issues by changing the position of equipment and ‘putting stuff in the way’ (my catch all description of passive acoustic treatment) has worked for years but the recent progress in AI and de-reverb technology as found in plugins such as Accentize DX Revive and Acon Digital DeVerberate does suggest that an alternative in-the-box solution for keeping the room out of recordings is on its way. The fact that we will probably be replacing them with another, better room using a plugin feels ironic but a common criticism of virtualised recording spaces is that unless the audio being processed is completely dry, the results will be compromised by virtue of there being the sound of two rooms present on a recording. Of course the best way to capture sounds is in a great sounding room but ultimately we have to work in the room we have access to.

Minimising the Influence Of The Mix Room

Keeping the sound of the room out of the equation when mixing is a more stubborn issue. The sound of your monitors and your room combine at your ears and in the smaller studios which are so prevalent today that means problems at the bottom end due to standing waves. Of course using headphones avoids this but if headphones were the complete answer we would have seen sales of monitor loudspeakers dwindle over the years. People clearly still use monitors!

When it comes to addressing a less than ideal mix room it had to be said that this is a difficult problem to fix. The issues are twofold. The first is issues above what is known as the Room Crossover, which is typically around 200Hz. This is where the behaviour of sound energy transitions from being velocity-based to being pressure-based. These can be addressed using the kind of absorption and diffusion products which are readily available. However they aren’t useful for the kind of bass trapping which is necessary to address the pressure-based issues at the bottom end which are so common in smaller control rooms and require much more effort to fix. Faced with this, many people do nothing.

It strikes me as odd that while so much effort is put into what happens once audio is safely in the box, what happens on the way in and out receives so much less attention. It’s understandable but anyone addressing the parts which are hardest to fix and make the most difference deserves our support.

Why Hasn’t Acoustic Treatment Moved With The Times?

Budgets have contracted, studios have shrunk and decentralised and everything in the studio has moved into the box. Why are we still using acoustic solutions from 50 years ago?

Soffit mounting of monitors flush with the wall has significant advantages when implemented in a purpose-designed room. But these days those rooms are fewer and fewer. This is reflected in the move towards nearfield monitoring. This is in itself a practical way to address the shortcomings of the mix room. The closer you are to the monitors, the less influence the room has on the sound. However this isn’t a free lunch. Bass issues remain and the sweet spot narrows. Many monitor manufacturers provide large, freestanding main monitors which are more flexible when it comes to placement and far easier to relocate in the event of a studio move. The larger models from PMC come to mind as does the new 8381A from Genelec which also has adaptive features which help it perform better in the room in which it is installed.

Keeping The Sound Away From The Walls - Controlling Dispersion

Controlling the dispersion of monitors is an excellent way of potentially reducing the influence of the room on the sound. Controlling dispersion becomes increasingly difficult as the frequency lowers and it is precisely these frequencies which are most difficult to address using treatment so the creation of monitors such as the Kii Three and the Dutch and Dutch 8c which create a full range cardioid response are an excellent way to address poor room acoustics at source. I know very little about the Dutch and Dutch 8c but I know the Kii Three well and can confirm that its ability to deliver in less than idea acoustic environments is remarkable.

Speaker Calibration Vs Acoustic Treatment

Far more accessible than cardioid monitors are speaker calibration products, from the hardware based Trinnov range through to software-only products such as Sonarworks, these products are easy to implement but unfortunately can only provide half the solution because, by their nature nulls created by room modes can’t be fixed with EQ. Adding more level to fix a null just results in greater but equivalent cancellation. 

To properly address low end problems in studio it has always been necessary to install adequate bass trapping, absorbent material which soaks up bass energy and converts it to another form, usually heat. Narrowband absorbers can be built to address specific frequencies or much thicker broadband traps can be installed, though to absorb deep bass these have to be so thick as to be impractically large in typical control rooms. This has been the way to do it for decades and it is still the best way to to it. But it’s expensive, takes up valuable space in the the room and is usually designed specifically for that room. Portable bass traps exist but when deployed in sufficient quantity to adequately address the issues they are there to fix, their size often makes them unattractive. The only alternatives to traditional treatment currently available borrow from the principles of active acoustics, using powered loudspeaker drivers to control the energy in the room.

Active Bass Trapping

The product I’m most familiar with is the PSI Audio AVVA C214, a unit which looks rather like a tall black cylinder which, when suitably positioned, uses information gathered from an integral microphone to move the driver diaphragms in such a way as to absorb bass energy rather than reflecting it like a static wall would. This absorption via a diaphragm also exists in passive form - A heavy, floppy membrane can be deployed as an absorber, these have to be carefully designed to absorb the correct frequencies but the active approach allows more efficient absorption allowing more energy to be absorbed while occupying less space. And the active approach is self-tuning meaning that if your landlord moves you on from your present studio, your bass trap is just as suitable in your next studio.

Active approaches to fixing room issues are efficient in terms of the space they occupy, they are adaptable to new environments and they don’t require the significant skill in measurement and the interpretation of the results of those measurements needed to deploy passive solutions. The best way to get monitors and room working together is still to use an acoustician and to build in acoustic treatment in accordance with their recommendations. But I think the most appropriate solution for most of the people working in our industry is to use what I hope will be a new generation of full range active products which are flexible enough to move with us from premises to premises, with speaker calibration working together with smart active acoustic products. After all, if the speakers and the room combine to create one single monitoring system, why not control them all together in a single, smart system?

Checking on headphones and explaining that you “know your room” isn’t really good enough but it’s understandable if the alternative is a custom built solution which will only ever work in one room. I’d like to see that fundamentally change and I suspect so would a lot of other people.