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Review of the Mackie ProFX12 audio sound mixer

Introduction

Because we undertake a lot of audio production work including internet broadcasting, we make heavy use of an audio sound mixer. For those who don't know, very briefly a sound mixer allows you to mix several audio sources together, such as microphones, the output from soundcards, musical instruments, CD players and so on. Not only can you do this but you can also vary aspects of each individual sound, such as its volume level and audio quality.

I do particularly like the sound quality of my radio shows to be as professional as possible with no distortion and minimal background noise. While we have had a mixer for the past year, the background sound emitting from it was quite significant due to the cheaper components within it. I wanted to purchase a mixer we could use for our current projects while leaving room for expansion. Having done a lot of research on the internet, I finally settled upon the Mackie ProFX12 unit.

Description of the Mackie ProFX12

This unit is built to last. It is constructed to withstand a good deal of transport and its chassis is made of steel and consequently is quite heavy. Certainly it won't be falling off a desk onto the floor!

The ProFX12 is known as a 12 channel mixer. Channels 1 through to 4 can accommodate either 4 microphones (with XLR inputs) or 4 mono line-in devices (with quarter inch jacks). Channels 5 through to 8 are two stereo pair of line-in (quarter inch jacks) or 2 additional microphones (again with XLR inputs). Channels nine through to 12 are two sets of stereo pairs with line-in quarter inch jacks. In practice, this means you could use four stereo devices and a mixture of mono inputs and microphones as a typical example. You can use a combination of any of these.

The mixer contains the ability to accommodate microphones with phantom power for those needing it. There is a "low cut" switch for each microphone input so as to reduce specific frequencies which may be helpful in some situations.

Each channel has a balance control. This may be useful if two microphones were being used and you want to have one speaker in the lefthand channel and one on the right (although I personally do not like this arrangement). Each channel also has a monitor control (described later), a gain control (for applying additional volume), three band graphic equaliser for changing the sound characteristics of the channel, a mute switch (for removing the channel from the main mix) and a level to control the effects (such as reverb). These are all rotary dials. A tactile arrow is contained on each rotary dial with a definite "click" resistance to denote the midway point. Finally, each channel has its own slider fader, situated at the point closest to you.

The graphic equalisation for each channel is particularly important as it is unlikely that two devices are going to sound the same. Even using two identical microphones, the way each person speaks may sound different requiring changing of the graphic equalisation for each one.

There are two additional functions for input I have not mentioned yet. A pair of phono sockets accommodate an additional CD player (or tape deck if you have one). However more usefully, (and very exciting), the mixer includes USB connectivity both in and out. What this means is that you can connect the unit to the computer via the USB port. You can either then send out the main mix to the computer (so as to provide internet broadcast streaming or recording), but very usefully, you can send the input from the computer back to the mixer. So if you want to record Windows sounds or internet content such as video, this can be set to be part of the main mix or bypassed if required. Alternatively, this is seen as a separate sound source in StationPlaylist Studio and so for example you could assign this internal soundcard to your cart player for jingles, as I do. Naturally, this input also has its own fader control for changing the volume.

Turning now to the righthand side of the mixer, you have outputs for a tape deck (phono), headphones (quarter inch jack with independent level control), a foot switch for controlling the effects (quarter inch jack), and sockets to send the output to various devices such as soundcards or another external recording devices (quarter inch jacks). There is also a "monitor send" described shortly and a switch to stop all output apart from the tape deck or CD player.

The mixer contains a series of 16 audio effects which can be selected by using a rotary dial. As you move the dial carefully clockwise, you feel a slight resistance notch when denotes that a new preset has been switched to. While it is true that turning the knob anti-clockwise to the left does not provide complete resistance when the first effect is reached, they do not wrap. So, turn the dial anti-clockwise enough times so as to be sure that you are at the first effect and work from there, turning the knob clockwise through the notches. A table of effects is provided in the PDF User Guide (downloadable from the company's website) and they can of course be applied either to the main mix or monitored separately.

The other item of note on the front face of the mixer is a seven band graphic equaliser to change characteristics of the main mix after it has been processed by the other controls. This (if necessary) can be bypassed entirely or used in conjunction with the monitor.

This mixer emits very little background noise which really is not noticeable except if the volume is turned to an exceptionally high level and if you possess sensitive hearing.

Monitoring

One notable feature on some mixers is called pre-fade. This allows you to listen to one of the channels without sending it to the main mix, such as a microphone or even your screen-reader if you have one. The latter is important to enable you to search for tracks or read email and twitter activity for example while a radio show is progressing. However, as to how mixers handle pre-fade when using headphones is different in all cases. Some mixers allow you to hear the desired channel or channels for monitoring cutting the main mix entirely, while some allow you to hear them in addition to the main mix.

We wanted to use pre-fade in two ways. First, we wanted to be able to vary the volume level of listening to the main mix without disturbing it going to air. In other words, we want to be able to hear what is going to air very much in the background. Secondly, we wanted the ability to be able to talk to each other through the microphones and to be able to hear each other through two sets of headphones and have a simultaneous conversation.

For these reasons, I purchased a mixer which had a "monitor send". Traditionally, this is used for sending the output to monitor speakers, perhaps when mixing the performance of a band and vocalists on stage. But we will use it in a very different way.

For some time, I have used a Belkin Rockstar Multi-Function Headphone Splitter. This is a device costing about seven pounds and allows for five devices to be connected via 3.5 MM jack plugs. The combined output of the five devices is sent to one pair of headphones.

So, the sequence is as follows. Connect the headphones to the splitter. Connect a cable from the splitter to the headphone socket of the mixer. Connect the splitter to the "Monitor Send" facility on the mixer.

This gives us what we need. It ensures that the main mix can be heard through the headphones and the volume can be varied according to our listening preference. However, it will also be possible to monitor other events at varying levels, such as a screen-reader and microphones. It also means we can talk to each other and hear that conversation through the "Monitor Send". It is worth saying that the "Monitor Send" has its own overall fader as well as individual faders for the different channels you wish to monitor.

Practical Scenario

What all this means is that we have an ideal broadcast setup. StationPlaylist Studio can now send the output of two internal players for playing alternate tracks to different audio sources. So I have two soundcards, each of which outputs to a SPL Studio player and controlled on different faders. This means that the output of the programme is more polished as there is no substitute in my view for decisions being made by a human as to when songs play. The timing is far better using this method.

The mixer's own internal soundcard I use for the playback of the jingles. Again, this is preferable to having it assigned to one of the other two cards used for the playback of music, since effective mixing of dry jingles and station idents can be achieved without loss of music volume.

A further soundcard is used to output my JAWS screen-reader for monitoring. This could also be used for Skype calls without a problem, although there is plenty of expansion available to accommodate a separate card for that if desired.

Conclusion

While the above might sound complex to setup, you can use as much or as little of this configuration as you like. But assuming everything was correctly configured, there is no doubt that everything available to you should give your programmes or productions an extremely professional sound indeed!

In terms of where the main mix is sent to, to repeat, you have a choice as to whether you connect the mixer to a recording device not associated with a computer, an external soundcard or via USB. There are no specific USB drivers for the device as it just relies on Windows "plug and play". The soundcard is displayed in the Windows Volume Control. From there, you can select the mixer's soundcard for input and output. You will want to pay careful attention to the output level in the Recording Properties of Windows so as to adjust it to something which suits the mixer's output and which will not distort. You should then subsequently test with your recording and broadcast streaming software (if you use it), such as StationPlaylist Streamer.

I hope you have enjoyed reading this review. If you live in the UK, you may like to consider purchasing the mixer from Gear4Music as they always give an excellent standard of after-sales service and prompt delivery.

In conclusion, I should say that a smaller version of this mixer exists, the ProFX8, which is identical in functionality with the exception of having eight channels as opposed to 12.

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