Thursday, 25 July 2013

Speaking of Speakers Part 1

Over the last few weeks we have been looking closely at music gear and working our way from the most important equipment in your sound system (cables) down to the least important (speakers).

A lot of people remain surprised at this however there is some quite simple logic behind the argument.
Firstly we must differentiate between the two parts of a speaker system. The speaker is the device inside that actually moves. The speaker enclosure is the cabinet that encloses the speakers. Arguably, the design and build quality of the cabinet is far more important than the speaker itself.

Speakers by their nature are a mechanical device, the fundamental design of the modern speaker has not changed much in the last 100 years.

There are only two major differences between a cheap speaker and expensive speaker.

  • The speakers ability to handle a lot of power
  • The type of magnet used.
    • Old school Iron Ferrite magnets = heavy
    • Modern Neodymium magnets = light
The actual sound quality difference between old and new magnet technology is negligible, the only major difference is the weight of the resulting speaker. Therefore an expensive Neodymium based speaker cabinet may not actually sound any better than a low cost Iron Ferrite speaker cabinet. However, you will notice a major difference when you are loading your van.

Modern speakers may also incorporate improved cooling technology to enable them to handle more power. In practice, this technology makes no difference to the sound quality, it just costs more and means the speaker can go 'louder for longer'.

So, if you have a healthy bank balance or are going to be lugging lots of speakers around 5 nights a week, then it may make sense to invest in some high end speakers, but if you are just doing the odd gig here and there and weight is not a big issue for you, save yourself some serious coin and buy some cheaper speakers.

Next week I'll look more closely at the different types of speaker and also the properties of a speaker we might be interested in.

Thursday, 18 July 2013

Mixing Magic Part 4

This week we take a closer look at some of the more important features on a mixing desk to consider during the purchase process.
  • Pre-Amp - Every desk needs a Pre-Amp section on each channel, this is the input to the desk and is controlled with a gain knob. High quality Pre-Amps are desirable, but a wide gain range is more important. Another useful feature in the Pre-Amp section is a PAD button which reduces the input signal by 20dB or more. The Pre-Amp section is also key in determining the Headroom a desk has. Lots of Headroom is desirable and is measured in the amount of signal a desk can handle above full volume or 0dB. This might sound a bit odd, most people assume that 'Full Volume' is the loudest a piece of equipment can go and that it can't go louder than that. Without getting too technical, here it is in layman's terms.
    • 0dB is reference point that all audio equipment uses to determine the maximum level of a signal. In theory, if everything in the system is at 0dB then its all running at full power.
    • Quite a few components in an audio system are capable of handling more than 0dB, this is a good thing, because sometimes things might spike up for a split second or maybe are turned up for a blazing guitar solo, you wouldn't want the whole system to melt down in a blaze of distortion every time the guitarist turns up.
    • The more Headroom you have over and above 0dB the better. Some mixing desks only have 6dB of headroom, which is not much. Others go as high as 16 to 24dB above 0dB. This doesn't mean that your system will be any louder, it just means that it will cope if individual instruments suddenly get loud. Generally we use compressors and limiters to prevent the output signal from going over 0dB and damaging your amplifiers and speakers.
  • Noise Floor  - The noise floor of a desk works in conjunction with the noise floor of your amplifiers. Noise is additive, so that the noise from your mixing desk, instruments and amplifiers is added together to get the total noise for a system. This is why there is no point investing in one high quality component when the rest are crap. The noise floor of a mixing desk should be at least -100dB or better (-105dB would be better), avoid desks with a noise floor in the 90's.

Connections - The industry has standardised on the XLR connector for audio. To save cost and space, some mixers use Jack inputs and outputs with TRS connectors instead of XLR connectors. Avoid mixers that use this, they are designed so that you can also use unbalanced Jack to Jack cables, which if you have read my previous Blog, you would never do would you? Stick to the tried and tested XLR connector pictured and you can't go wrong.

Powered or Un-Powered - Never buy a powered mixer, they are heavy and if the amplifier section in the mixing desk dies or no longer suits your setup, then you have a big heavy mixing desk that you have to cart around everywhere. The amplifiers that are built into mixing desks are rarely any good.

Reputable brands of mixing desk include Allen and Heath, Soundcraft, Midas, Yamaha and Digico

Thursday, 11 July 2013

Mixing Magic Part 3

Whether you go digital or analog, the equalisation features of your mixing desk are critical to achieving a great result. Equalisation consists of different types of filters.

High Pass filters cut out bass below a certain frequency ie they let high frequencies pass through.
Low Pass filters cut out high frequenceis above a certain frequency ie they let low frequencies pass through.
EQ or Equalisation, allows the boosting or cutting of specific frequency ranges.
  • High Pass Filter - Most desks will have a Hi Pass button on them, this basically cuts out the bass below a certain locked frequency (often 100Hz). Really good desks replace the High Pass button with a sweeping high pass filter that allows you to choose the frequency of the high pass filter. This one feature is often the difference between a horrible muddy mix and a great sounding mix. I would pick a desk that had a sweeping high pass filter over a desk without it at the sacrifice of just about any other mixing desk feature. It really does make that much difference.
  • EQ - The number of bands in the EQ section are not the only thing to look out for

    • 3 Band EQ - most desks will have at least a Bass, Mid and Treble control. You simply boost or cut the knob to add or remove what you want around an arbitrary set of frequencies. This is a bit like using a "Cluster Bomb" to shoot an apple. Sure, it totally destroys the apple, but it also takes out everything else around it for miles.
    • 4 Band EQ - This splits the mid EQ into two separate knobs, one high mid and one low mid. Its better than a 3 Band EQ but is like using a cannon to shoot an apple. Again, you kill the apple but also take out things around it that you don't want to.
    • 3 Band Swept EQ - The next tier up of desks will have a sweep control on the mid section, this will appear as 4 knobs but it is still only a 3 band EQ. Don't get fooled by the middle two knobs as I have seen many people do. The bottom of the two knobs controls the frequency the Mid EQ operates at and is a different colour, the top knob controls how much that frequency is boosted or cut by. This is fantastic when you are trying to get on top of troublesome feedback. The Bass and Treble knobs are the same as the 3 Band EQ cluster bomb scenario and the two Mid controls are more like a grenade. The Apple is destroyed along with a few things around it but damage is limited to the surrounding area.
    • 4 Band Dual Sweep EQ - This adds in another band with a sweep control, so there will be 6 knobs to control the 4 bands of EQ. A high mid and a low mid gives you fine grain control over specific frequencies. This allows you to gain fairly precise control over feedback. Its like using a shotgun to shoot an apple. The apple is obliterated along with anything else right next to it.
    • Adjustable Q Control - Adjustable Q gives you additional control over the sweep control by allowing you choose a wide Q or a narrow Q. If you chose a narrow Q centered on 500Hz then it would just affect 500Hz and nothing else. As you widen the Q control then this extends the range of frequencies the sweep control affects allowing you to take out a big chunk of frequencies or narrow in on a very specific range. The Q control usually comes in the form of an outer ring knob on the sweep knob so its two knobs in one. Its the Rolls Royce of EQ and is the artillery equivalent of shooting a fruit fly on the surface of the apple with a bow and arrow.
Happy apple hunting

Thursday, 4 July 2013

Mixing Magic Part 2

Digital vs Analog

The debate over digital vs analog consoles has well and truely been won by digital at the high end of the spectrum.  The days of large outdoor concerts using heavy copper snakes are well and truly over due to the massive cost and time savings that can be made with digital consoles.

At the lower end of the market, in the pubs and clubs across the world, the war is still waging and manufacturers are still churning out millions of analog desks every year. The scales are certainly beginning to tip towards digitals favour, but there may still be times when an analog desk is the best solution for the job.

Digital desks have gotten a lot cheaper over the last couple of years, but when should you consider one?
In my view, there is a relatively simple answer to this question...

Whenever you think you might need to connect more than two external processors to a mixing desk, a digital desk will likely be a better and cheaper option. If you just plan on using the desk as is with no external devices and maybe a few on-board effects, then a good analog console may be your best bet.

However, if you plan on connecting more than two of the following devices (collectively referred to as "outboard) then digital may be the way to go.

Examples of external outboard include:
  • More than one Effects processor
  • Noise Gates
  • Compressors
  • Graphic Equalizers
Digital mixers have these external devices built in and as a result can save you a lot of money when purchasing a system. The total cost of the actual mixer is often more than an analog one, however the cost of the outboard devices often tips the equation back into digital's favour.

Aside from cost, if you ever use a "Soundman" out the front in the audience, a digital desk with a digital snake may save you hours of setting up and pack-down time.
Other advantages of digital desks include:

  • Recall - you can save your settings and recall them whenever you want.
  • Security - you can lock the desk, or portions of the desk to avoid tampering.
  • Control - You can often mix using an iPad or laptop for monitors or for "walking the audience"
  • Weight - Digital systems are usually pound for pound lighter than the equivalent analog feature set
  • Space - Digital systems are usually much smaller saving on truck space
  • Updates - Manufacturers release new features regularly as firmware updates.
  • Flexibility - Digital systems can often be configured and optimised for different tasks.
Some of the disadvantages of digital mixers include:

  • Failure points - there are usually fewer individual failure points, but more catastrophic points of failure. With digital if something fails, generally the whole system dies.
  • Old School Factor - Some people (typically older sound engineers), think Digital does not sound as good, or prefer the highly tactile and proportional interfaces of analog systems where each knob has one function and one function only.
  • Obsolescence - With analog, a 20 year old desk can still be plugged into a 2 year old sound system. In the future, as Digital becomes more ubiquitous, new digital interfaces may not be compatible with old ones.
There is currently no right or wrong answer on whether to go digital or not, there are still some great analog consoles out there and users need to choose the right tool for the job and that suits their own working preferences and budget.