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Mackie LM3204

Stereo Line Mixer By Paul White
Published March 1995

Paul White gets his hands on Mackie's long‑awaited 3204 line mixer and discovers that it has hidden potential.

It is widely held that in the UK we produce some of the best and most competitively priced mixing consoles in the world. According to the pundits, that's because it rains a lot in England, and there's nothing better to do! By a strange quirk of fate, one of the few industrialised cities on the planet where it rains even more than in the UK is Seattle, USA, and just outside Seattle, in the sleepy hamlet of Woodinville, Mackie have taken advantage of the inclement weather to develop a world‑beating range of mixers of their own.

Line level sound sources went stereo several years ago with the arrival of stereo synths, samplers, drum machines and so forth, but it seems that Mackie are one of the first mixer companies to acknowledge the fact by introducing a 6U rackmount mixer comprised entirely of stereo, line‑level channels. By switching to surface‑mount electronic component technology, Mackie have shoe‑horned 16, stereo line‑level channels into 19 inches of rack space, and they've included enough Mackie‑esque wrinkles and quirks to enable the 3204 to function as a basic multitrack console, as well as a live and studio keyboard mixer/submixer.

The Concept

Some of the 3204's features have obviously been culled from previous models — for example, the combined muting and routing system. Instead of separate routing and muting buttons, a single button routes the channel signal either to the main stereo buss or to a second stereo buss (Alt 3,4). If you don't need the Alt 3,4 buss, then you simply leave it disconnected, which means the routing buttons effectively act as mutes — but if you need to use both lots of busses, then there's no muting. This arrangement is obviously a compromise, but whether you look at it as a cop‑out or a neat bit of lateral thinking depends very much on what kind of facilities you'd normally expect on a line mixer, and on your own requirements.

Unlike basic line mixers, which feature little more than pan and level controls, the 3204 also has a three‑band EQ and two Aux Sends (one stereo and one mono) on every channel. The Aux Sends, which are both post‑fade, may be switched as a pair to feed Aux busses 1 & 2 or 3 & 4. Though Mackie are normally quite keen to encourage hot‑rodding, they point out that in this particular case the very dense circuitry precludes home‑brewed post‑fade to pre‑fade conversions. In any event, most users are likely to want to use the sends for use with effects, and in this case the lack of pre/post switching won't be a problem.

Because of the lack of panel space, the familiar channel fader is replaced by a rotary pot with Mackie's familiar centre detent at the unity gain position. There's no input gain trim control, but simple ‑20dB and Overload LEDs on each channel help you optimise the gain structure. There's also a Solo button for each channel, which works pretty much like the solo function on a studio desk, in that, in addition to isolating the solo'd channels in the monitors, it also meters the solo'd channels so that you can set the input level to make the best use of the available headroom. As there's no input gain trim control, this means adjusting the output level of the synth, drum machine or whatever feeding the mixer.

Because all the channels are stereo, there's no need for a pan pot, but what you do get is a balance control (which can be thought of as the stereo equivalent), which is used to change the balance between the left and right channel signals. All the channels have balanced inputs, which may also be used unbalanced, presented on pairs of stereo jacks. Channels 1 to 4 also have (pairs of) insert points, and of course there are also insert points for the main stereo output. As with earlier Mackie mixer designs, the insert points can be coaxed into a number of functions, depending on what kind of plug you stick in there and how far in you push it! For example, a stereo jack works as a conventional insert, but a mono jack pushed all the way in provides a direct out, while killing the channel signal. On the other hand, a mono jack pushed halfway in doesn't disturb the channel signal but does provide you with a direct output. Again, some people criticise this type of approach, but let's face it, you wouldn't normally get discrete direct outputs on a mixer of this size anyway, and at least in this way you can fake them if you need to. Also on the rear panel is a multi‑pin expander socket marked for use with the 3204E expander module, so now you have some advance warning of what Mackie will be building in the future.

Naturally, you wouldn't expect mic inputs on a line mixer — but Mackie provide them anyway. On the rear panel are two high‑quality, balanced XLR mic preamps with switchable (as a pair) 48V phantom power and individual gain trim control, but these preamps are quite separate from the rest of the mixer and have to be patched in using jack leads. In practice this is very useful, as you can patch them into any line input you choose and is far more flexible than a fixed routing arrangement.

Master Section

The Master section of the mixer is rather like a mini studio console master section, and it's here that you find the four (stereo) Aux return master level controls, the metering, and short faders for both the main Left/Right output levels and the Control Room level. There are no aux send master level controls and no level control for the Alt 3,4 stereo buss output, but as most outboard gear has its own input level controls, this isn't really a problem. The peak averaging, LED ladder meters follow the Control Room/Phones signal, unless Solo is depressed, and (both jack and phono) connections are provided for a 2‑track recorder, with a Tape Return button routing the tape outputs to the monitors in the usual way. Unusually on a mixer of this type, a Solo level control is fitted, and when Solo is operated, the channel overload LED stays illuminated, while a bright, flashing red LED in the master section leaves you in no doubt as to what is going on.

In the Aux Return section there are two switches that require a little explanation. The Source/Alt 3,4 switch affects only Aux return 3, and with the switch up, Aux 3 functions normally. With the switch down, the Aux 3 inputs are turned off, and instead, the Alt 3,4 stereo buss is routed into the main stereo mix via the Aux 3 control which makes subgrouping possible. There's also a button relating to Aux return 4 which says 'AUX RETURN TO CONTROL ROOM ONLY'. Not surprisingly, the title says it all, and the reason for putting this in is so that you can have a nice wet control room mix without the effect going into the main mix — great for giving vocalists a false sense of security! Finally, the Phones outlet carries the same signal as the Control Room output and has its own level control.


Mechanically, the 3204 has the Mackie family feel, which somehow manages to combine a utilitarian, robust feel with attractive panel styling. The choice of knob colour, the design of the silk screen and the metallic grey base colour lend the unit a confidence‑inspiring appearance, and most of the ergonomic factors also make sense, apart from the positioning of the mic amp trim controls on the rear panel, which was, I suspect, dictated by lack of panel space.

The Aux Send switching worries me a little, because both sends are switched as a pair, so if you want to use a common background reverb on all channels, you can't combine this with effects on the other pair of effects busses. There are ways around this, such as plugging sends 2 and 4 into the two inputs of the same digital reverb, but a front‑panel switch linking sends 2 and 4 might have been useful. Still, considering what you do get for your money, any complaint of this type must be judged as pretty minor.

When it comes to sound quality, the 3204 is reassuringly clean and performs very much like Mackie's original 1202, other than having the benefit of a Mid EQ control. The EQ is generally effective, though too much in the way of boost, especially in the mid or high bands, can make the sound a touch aggressive. The mid control is fixed to operate at 2.5kHz (or 2kHz if you prefer to believe the spec page in the otherwise excellent manual) and has a maximum range of plus or minus 12dB, which makes it ideal for fine‑tuning what I call the 'presence' region of sounds, and while it doesn't offer anything like the scope of a sweep mid, it's far better than simply having a 2‑band EQ, as many rack line mixers offer.

Having the Alt stereo buss does mean you can do simple multitrack recording with the 3202. For example, signals sent to the Alt buss could be recorded to tape while the normal stereo buss is used for monitoring and mixing. Working in this way limits the number of separate signals you can record at any one time to two, but with a little imagination, this can be extended by using the 'mono jack all the way in' direct output dodge to provide extra tape inputs. And, because the mic amps aren't routed anywhere, these could be patched straight to tape too. So as long as you're prepared to put up with a little patching and you never need to record more than two mics at once, you could easily cope with the needs of an 8‑track recorder, and if you're really brave, you may even manage 16.


As we have now come to expect from Mackie, the 3204 is a very competent, nice‑sounding mixer offering a huge number of inputs (40 including the stereo aux returns) in a compact and attractive package. The odd little excursions of lateral thinking that have gone into the design make most things possible, even if they're not quite as easy to achieve as with a dedicated studio desk, and in true Mackie style, each channel has bags of extra gain to cope with wimpy input signals. Equally traditional is the fact that every pot has a centre detent position, whether it's EQ, gain or even phones level, and though rotary controls aren't quite as graphic as faders, this mixer can handle a range of functions, including small‑scale studio recording.

If you're a live musician who uses lots of instruments, or even a few instruments with multiple outputs, the 3204 will appeal, not least because it has proper mains power rather than the dreaded wall wart, while in the studio, it's just the job if your synth rack has got your regular console outnumbered in the sockets department. The quality is certainly good enough to use in a serious recording environment, and I see the future of analogue mixing as a combination of this type of mixer plus a smaller multitrack console, rather than one huge multitrack console with all the redundant facilities that implies. An all‑stereo‑channels line mixer was, in many ways, an obvious product to develop but Mackie got there first! Having said that, we've had a very wet winter so don't be surprised to see some interesting British mixers appearing over the next few months!

Brief Specification

  • Stereo line inputs: 16
  • Stereo aux returns: 4
  • Mic preamps: 2
  • Frequency response: 20Hz to 50kHz (+0dB, ‑1dB)
  • Noise: (unity gain settings) ‑84dBu
  • THD: 0.0024% or better
  • Maximum levels: Mic preamp +14dBu, all other inputs and outputs +22dBu
  • Equalisation: Lo 80Hz shelving, +/‑ 15dB; Mid 2.5kHz peak, +/‑12dB, Hi 12kHz shelving, +/‑ 15dB
  • Mic preamp noise: EIN ‑129dB with 150 ohm termination
  • Weight: 24 lbs
  • Power: 240V (UK)


  • 40 Inputs (20 stereo) including aux returns.
  • Two high‑quality mic amps included.
  • Useful routing and switching facilities.
  • Clean sound.


  • Effects send system may be limitingfor very serious applications.
  • Insert points on first four channels only.


On balance, a well‑conceived mixer that has a multitude of uses, from the obvious keyboard mixing applications to multitrack home recording.