Your monitors want to tell you something – but are you listening – and more to the point – is it the truth? Howard hacks through the monitoring myths to help you hear what’s really happening.
Your monitor speakers are the most important investment you can make in your studio. Really. Bar none. They are what let you judge your material; they are your quality control.
I’ve heard stunning recordings done on a cassette 4 track – with decent monitors attached. And I’ve heard the results of hundreds of thousands of pounds of gear and time ruined by reliance upon rough, or badly installed, monitoring.
It can be ProTools or an Edisonwax cylinder, Nuendo or Logic, but if you can’t hear what’s going on, then you’re up, as the German’s call it, ‘Scheissen Strasse’…
Studio Monitor or HiFi Speaker?
First of all, lets get one thing straight. Studio Monitors and HiFi speakers have very little in common other than being made of (mostly) wood and having wobbly plastic bits on the front. A HiFi speaker is usually built to the following brief; it must be:
- Flattering to the programme material – hide shortcomings.
- Sound rich and full (so it uses harmonic ‘tricks’ to make things sound good and to extend the apparent bass response).
- Be cheap to produce.
It also is never expected to have to playback anything other than nice, mixed, compressed finished material – no solo’d kick drums here!
As a result your average 100w RMS HiFi box has a tweeter rated at (if you’re lucky) 3 or 4 watts. This is going to burn out the first time a decent lump of feedback or high square-wavy synth is chucked at it! Also it was never designed to be run at anything like rated power for more than a few minutes at a time.
Your studio monitor is a different beast altogether, it’s design brief is to:
- Tell the truth, even when it’s painful.
- Show up every bit of programme distortion.
- Deliver accurate bass within the constraints of the cabinet size.
- Be able to survive feedback and high transient impulse noise.
- Be capable of running at rated full power for extended periods.
It’s also likely to have a minimum of a 50 watt tweeter in a 100 watt speaker.
By making everything sound ‘nice’ the HiFi speaker is making mixing almost impossible. And it’s going to blow up.
Now that those Japanese hifi wonders are safely in the dustbin, what sort of studio monitors are going to be best for you?
Nowadays, there are almost as many new manufacturers making monitors as there are producing microphones, and inevitably, some are great, some are not so great, and a few are little more than horrid HiFi speakers in disguise; beware! Buy with your ears…
Monitor speakers can be divided up in two different ways, firstly there are either 2 driver and 3 driver (or more) systems, secondly, but possibly even more importantly, there are either active or passive speaker systems.
Unless a speaker is tiny (and therefore very quiet) it is impossible to manufacture a single speaker capable of producing the raw energy required for bass reproduction (the cone needs to move a long way) and the fast changes of direction required for treble (transient) reproduction. Consequently speakers come with different drivers each coping with a small part of the frequency range, a great idea until we try to cope with managing how just the right part of the frequency spectrum goes to each driver.
Passive systems take a speaker level feed from a separate power amplifier. The signal is then split by a passive (unpowered) crossover to (hopefully) feed the right bits of the signal to each driver. As the whole splitting thing in a passive speaker is done with high(ish) voltage, high(ish) current speaker level signals, then the technology is of necessity crude and almost Victorian – all coils, fat capacitors and big wire resistors – impressive, but none too subtle when it comes to fine tuning the speaker to the room…
A ‘proper’ active system splits the signal at line (mixer) levels, with a great degree of finesse – the split signal is then sent to several dedicated amps each working with, designed for, and damping, it’s own driver. Accurate crossover control is therefore available with small line level signals easily being manipulated much like the signals in a mixer, and a good match to the room is easily achievable. Sadly a lot of passive speaker manufacturers have jumped on the active bandwagon by bolting an amp on the back of a passively crossed over speaker and calling it active – beware! If it hasn’t got an amp per driver – it’s not active – it’s a passive design in drag!
All those Drivers
The driver issue is one that also has great influence on the output of our studios. We are all used to the sound of domestic 2 driver speakers, which, as they crossover the sound between the woofer and tweeter at around 2 kHz, are consequently distorting the sound at this point, causing a blip in the frequency response curve right at the critical point where lies the bite of the snare, the rasp of the vocal, and the snarl of the guitar etc. As a result it is easy to overcook these things on a 2-driver system, resulting in mixes that are painful to listen to on car hifi, pa systems and the like. A 3-driver system with a midrange driver dedicated to these critical frequencies creates two crossover points one above and one below the critical 1-2kHz region, giving a more faithful reproduction of the important speech frequencies. This may well sound over-middly at first (to our ‘2 driver’ ears). We need to ‘unlearn’ the conditioning of listening to 2 drivers and start to listen to these 3 driver systems as though we are in the room with the musicians. Once you have acquired this ability – the difference in perception is astounding!
A natural extension of a multi driver system is to dedicate a speaker and amp to the frequencies that are too low for the main cabinets to handle – this is a Subwoofer, and (owing to the fact that we have a hard time telling where bass noise is coming from) this should be capable of being situated anywhere in the room. Realistically, the Sub still produces frequencies that yield some positional information, so sticking it anywhere is an old wives tale – you’ll need to place it centrally and at the front. With the advent of 5.1 surround monitoring systems, the sub has been pressed into use carrying the ‘FX’ or ‘earthquake’ information too, placing additional constraints on sub placement. 5.1 is a topic in itself, so discussion of surround monitoring will be the subject of another post in the future.
Amps & Cabling
If your speaker system is passive, or a big enough active system, then the amps (and in the case of the active system the crossovers too) will probably be mounted remotely in a rack somewhere. This helps get rid of fan noise from big amps, but it also raises two more issues; amp power and speaker cabling.
If you buy amp(s) separately from a speaker system, make sure they are big enough. In contradiction to the strange HiFi rule where the speakers should have twice the power rating of the amp, in studios we accept that the amp should have double the rating of the speakers! This is because if the amp goes into distortion, the majority of the distorted signal will route to the tweeter – probably frying it in the process. My old Phase Linear 400 pro amp from the early 70’s is 200watts RMS/channel, but when the meters read 0vu it’s pumping out just 45watts – the rest is headroom…
When the signal from an amp forces a bass driver forwards, it doesn’t want to stop when it gets to the other end of its travel. The cone over-run generates a small electrical signal, which gets back to the amp, which in turn generates feedback to suppress this over-run. If flimsy wires are used between amp and speaker, the resistance of the wires will hinder this damping, and the consequent cone overrun will make the bass sound muddy, so speaker cabling needs to be massive & low resistance. I’m going to be shouted at for the next suggestion, but having done many technical and subjective tests over the years, I can confidently assure you that in most situations the best and most cost effective cable to use between an amp and a speaker is 2.5mmsq T&E solid ring main cable. It ain’t sexy, but it’s cheap and it works brilliantly – in some cases noticeably better than some ‘audiophile’ products costing hugely more.
Stands & Soffits
When amps were weak, and speakers couldn’t handle the power, then the only way to get high volume at low frequencies was to ‘soffit’ mount the speakers actually in the monitor wall, which has the effect of lifting the bass end by some 6-9dB. Individual monitor walls tended to colour the speaker such that consistent results were rare. Nowadays this practice is only required in the largest and loudest pro studio installations. Elsewhere speaker and amp designs are now more than capable of producing the bass we need without help.
What we do need, however, is to support the speaker rigidly. If the room is well designed, then the speaker can be happily coupled to the room by a simple rigid, heavy stand; hollow timber filled with sand, a brick column or the like. If the room is resonant or leaky, then spikes must be employed to cut down structure-born transmission of bass.
Old fashioned speakers with horn loaded tweeters were designed to focus all the HF information into a ‘sweet spot’ where you HAD to sit to make any sense of the sound, and to get a stereo image. Engineers and producers used to have to fight to occupy that precious football-sized spot during a mix or a cut! Luckily modern dome tweeter speakers are designed for a wide, even dispersion of sound, allowing everyone in the room to hear something (tonally) close to what’s happening in the sweet spot, even if they don’t get the stereo, and also creating a much larger sweet-spot to boot.
For stereo, there are some simple rules regarding placement that will ensure you make the most of your speakers:
1) The speakers and listener should be at the 3 corners of an equilateral triangle. If the speakers are too far apart you will have a ‘hole’ in the centre of the stereo image. In fact with modern dome tweeters you can stretch this rule a bit. In the diagram below you can see that domes produce a decent sized elliptical sweet spot, so by careful placement you can put the engineer at the front of the spot and make room for others to squeeze in behind for critical listening.
2) The ‘virtual source’ of the sound should be at ear height. Yeah, but when you are standing or sitting? If you only ever sit to mix, then around 1300mm is a reasonable height (measure the floor to your ears if you’re not sure). If you mix a lot standing, then raise them up to an in-between compromise height (between 1500-1600mm for instance).
3) Keep the drivers vertically oriented to get the best stereo image. I know you like the look of them when they’re on their sides, but you’ll get much better stereo if they’re upright – trust me!
Virtual Source. A typical 2-driver monitor speaker in vertical orientation, showing the position of the virtual source (i.e. the position the sound appears to emanate from). (Image courtesy of Genelec).
Stereo Monitor Placement. Showing the equilateral triangle of placement and the elliptical ‘sweet-spot’.
Lend me your ears…
Finally, don’t forget that you never listen to your speakers alone. You always listen to them in a room. Consequently the design & layout of your control room can make, or ruin, the sound of your monitors. If you get a chance to listen to some professionally designed rooms, you will see just what I mean!
About the Author:
Howard Turner has over 30 years experience in the studio business, and for the last 2 decades, his Studio Wizard Organisation have been at the forefront of the development of effective & affordable designs and solutions for studios. We design and troubleshoot studios worldwide. Further information: +44(0)7803666789 web: www.studiowizard.com