Mic Preamps

I didn't have time to really work with the mic preamps, but I listened to a number of mics, including my B&Ks, my Schoeps tube mic, some ATUS condensers, and some dynamic mics, through the preamps, auditioning a variety of barnyard noises and other rural Foley. I also did a differential null of a couple of different preamps to see how well they matched (-50 dB, a very good match). One problem surfaced here: when splitting a mic feed to two channels with polarity reversed on one of the splits, at maximum gain the preamps went into oscillation. I suspect this is inherent to the active differential amp design, and it's not a big problem, but it means you need to be careful with mic trims if you are using such a splitter to do Middle Side stereo miking. Better to split by sending the Direct Out of L channel to the Line In of the R channel, inverting as you patch. (If you don't understand what I'm talking about, don't worry about it for now.) Listening with my Etymotic in-ear headphones (which are essentially lab-grade instruments with some serious resolution), the preamps sounded excellent, with little hiss and great resolution and clarity. Noise, with the mic preamp cranked, was at least 70 dB below nominal level, which is plenty quiet - with a normal dynamic mic the noise floor would be equal to about 30 dB SPL. With a more sensitive condenser mic, the noise floor would equal about 20 dB SPL. This is plenty quiet for all but the fussiest classical work where you are trying to record soft instruments from some significant distance away. These are transparent mic amps, and you will find them easy to use.

EQ

Mackie has emphasized the equalizers in their advertising, and its clear some effort and thought has gone into their design and execution. There are five EQ elements: an 18 dB/octave high-pass filter fixed @ 75 Hz. for removing LF garbage (trucks, AC, the stray Concorde lost in space over your town, etc.), Hi and Lo shelving equalizers with the shelves set at 12 KHz. and 80 Hz. respectively, a semi-parametric (fixed bandwidth of 2 octaves) Lo-Mid equalizer ranging from 45 Hz. to 3 kHz.) and a full parametric (bandwidth from 1/12 octave to 3 octaves) sweeping from 500 Hz. to 18 KHz. These work just fine, are quite accurate and very consistent from channel to channel, praise be! When you set the knobs for 1KHz. boosted 6 dB, that's what you really get. Great for developing your Golden Ears. Thanks, Mackie! Personally, I need to work with variable bandwidth at frequencies lower than 500 Hz. (particularly on vocal tracks) and so I got a little frustrated by this limitation. Nonetheless, the EQ sounded quite good and was very flexible. The real sleepers of the EQ were the Hi and Lo shelves. Think of them as spectrum tilt controls, hinged around 1 kHz. Boosting the lows, for instance, has an audible impact out through 800 Hz. The result is a smooth, broad and musical capability to tilt the response of either or both halves of the spectrum to suit your needs. They did a whole lot for me. Sounded great!

Pol Rev

The ability to reverse polarity is, to me, essential. It is one of the fundamental tools of stereophony, and as fundamental to the mixer's craft as EQ. I seem to remember that early ads promised it, but it wasn't here. I suspect the mic/line switch, added late in the game, used to be the pol rev switch. This is a major disaster to my way of thinking, and it made me gnash my teeth for about 20 minutes, moan 'n groan and seriously reconsider the status of contenders in the Dave Moulton Console Sweepstakes.

I'm morally certain Mackie is aware of this, because there is a work-around available to handle this problem. It's simple if a little clunky, and it largely obviates the problem. For Mic inputs, a pol rev mic cable adapter (see my A+B/A-B article for details) inserted in between the cable and the XLR takes care of pol rev. For the 1/4" Line inputs, it is really simple: you just push the plug just far enough into the jack to engage the tip of the plug on the ring of the jack and voila, you have achieved pol rev.

Given the simplicity of this solution, I think Mackie's present configuration is manageable, if not optimum - a reasonable cost compromise. I wish they had discussed it in the manual (hear that, Minister of Propaganda? - believe it or not that's really his title - strange place, Mackie).