WHEN I FIRST laid eyes on the Mackie SR24-4 in late 1995, I thought I beheld the small-venue engineer's Holy Grail — and in fact I did. My eyes traced every knob, button, and slider, and each XLR and TRS connector. My mind ecstatically visualized the routing options and applications of this 31-inch-wide, 31-pound Goliath killer.
A decade ago, mixers with the SR24-4's features and quality cost several thousand dollars. Mackie included 20 mic/line inputs, 3-band EQ with sweepable midrange from 100 Hz to 8 kHz, 2 stereo line inputs and 4 stereo returns, 6 aux buses (2 prefader, 2 postfader, and 2 switchable, all accessible simultaneously), 4 pannable subgroups with adjustable 16 kHz Air EQ, and inserts galore.
Although only the left, right, and mono XLR outputs were electronically balanced, the impedance-balanced aux and sub outputs proved effectively hum-free in the field. Mackie even included the feature necessary to make a mixer a real recording console: a dedicated monitor section complete with source selection and control-room outputs, which can also be used to feed a cue wedge in live applications. The construction was rock solid, with metal everywhere except the end caps, all connectors solidly mounted to the chassis, and no breakable plastic ¼-inch jacks.
Was the SR24-4 perfect? No. It would have been nice to have long-throw faders, two mid sweeps, polarity reverse, direct outs, switchable pads on all inputs, and inserts on the auxes. However, for a $1,599 board with no real space for 20 more knobs and switches, the compromises made sense.
But there were also a couple of problems. First, the solo feature didn't function on muted inputs, requiring rerouting of the input and disabling the monitor feeds to line check discretely. Second, the headphone jacks were located below the jack field at the console's rear. They were hard to patch when the system was up and running, and the head-phone wire had to drag over important connections and controls or go under the board, all while eating up 20 inches of mobility.
The latest round of Mackie mixers, including the SR24-4 VLZ Pro, uses a combination of high operating current and low-impedance circuitry (VLZ refers to very low impedance) to reduce internal noise and channel crosstalk and to optimize microphone preamp performance.
THEM CHANGES
So what's different now that the SR24-4 has attained VLZ Pro status? The good news is that the Solo function now works on muted inputs, and the ¼-inch main outputs are now balanced. Other, if less significant, news is that a cooling vent now sits along the top surface. Mackie also claims improved RFI rejection.
The bad news is that the prefader auxes have changed from pre- to post-EQ. Some folks apparently like it that way, but when mixing monitors from the front-of-house position, I find it scary that any input EQ change will also occur in the monitor mixes and that I won't hear the effects until boosting some frequency pushes the monitors into feedback. (Mackie plans to offer a DIY modification to switch the prefader auxes to pre-EQ.) The headphone jacks are also still inconveniently located on the rear panel (see Fig. 1).
The VLZ Pro version features upgraded microphone preamps. Mic preamps are a hot topic as project recordists suffering from digital guilt look for that magic piece of gear that will breathe life into their productions. Mackie has responded by spending $250,000 to develop — and who knows how much to advertise — its XDR mic preamp, the jewel in the crown of the VLZ Pro mixer series.
PRE VIEWS
Mackie's previous preamp had little to apologize for sonically, but it was awkwardly implemented. Even with the Gain knob at the extreme counterclockwise position, the preamp was too sensitive for hot signals such as an AKG D 112 on a kick drum (especially when boosting bass at the input EQ). Because there was no input pad, I used the work-arounds of patching a pad in-line or using an XLR-to-TRS adapter to route the mic through the channel's (20 dB) less sensitive line input. Additionally, clockwise rotation beyond roughly four o'clock produced an abrupt increase in gain, with a corresponding increase in noise, which made the last few decibels of gain practically unusable.
The XDR addresses those issues effectively. The preamp's gain range has been widened from 10 to 60 dB to 0 to 60 dB, and the maximum input level increased from +14 dBu to +22 dBu. I've been using the SR24-4 VLZ Pro at Sweetwater (a Mill Valley, California, venue) mixing rock, jazz, bluegrass, singer/songwriters, and even a brass band, without reaching for a pad or adapter. Throughout the Gain knob's range, gain increases smoothly with gradual and acceptable noise increase.
QUIET ON THE SET
In addition to using the SR24-4 VLZ Pro at a live venue, I also conducted two listening tests in residential settings where it was quiet enough to listen attentively to the XDR mic preamp. I compared the XDR, the SR24-4 classic preamp, and, for perspective, an Aphex Model 107 Tubessence tube preamp. I used a Neumann KM 184 condenser microphone, an Oz Audio Q-Mix HM-6 headphone amp, and the ruthlessly revealing Sony MDR-V6 headphones.
In all instances, environmental noise was much more of an issue than system noise, which was completely masked by the sound of voices and instruments. I listened to fingerpicked flattop guitar through both Mackie preamps in a small garage. Both were extremely detailed, almost etched, and each clearly revealed the incredibly ugly room sound. Although the XDR sounded slightly warmer and made it easier to position the mic for good tonal balance, both preamps accurately rendered the sometimes painful finger squeaks and the grotesque sonic signature of parallel plasterboard walls. They were deadly accurate and offered no discernible coloration — for better or worse.
In an acoustically benign living room with the Aphex and voices added to the test, all three preamps produced usable sounds. Again, the XDR was slightly warmer than its predecessor, and the Aphex was warmer still, though a bit more liquid and a shade less detailed (as one would expect from a tube device). Both Mackie preamps accurately rendered the source sounds, including a particularly harsh female vocalist.
In all the applications, as well as during an outdoor neo-Celtic harp concert, the VLZ Pro's improvement in sound quality over the original SR24-4 was real but subtle. The differences will probably be audible only in the quietest venues for the most attentive audiences, and probably not for electric music. For recording applications, however, having the XDR preamps will definitely be an advantage.
GO PRO?
Overall, the SR24-4 VLZ Pro is a high-quality, feature-laden console that has been improved in a number of ways from the original model. From my perspective, the only change that's not for the better is the post-EQ aux sends. That said, if you're in the market for a full-featured, good-sounding, and reasonably priced 24-channel live mixer, the SR24-4 VLZ Pro is hard to beat.
