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Mackie Onyx 4-Bus Series Analog Mixer

The folks at Mackie Designs are good at a lot of things. First and foremost, they are deservedly well known for their abilities to design/build very good mixers.

(click thumbnail)The folks at Mackie Designs are good at a lot of things. First and foremost, they are deservedly well known for their abilities to design/build very good mixers. Also, it is clear that they are willing to sell these mixers at very reasonable prices. After all, there is a reason why — no matter where you go as an audio professional — you will find (and happily use) a Mackie: it’s there, and it works.

The ubiquity of Mackie mixers throughout our industry is no fluke; this company intimately understands the various ways average American audio professionals work. We want intuitive, flexible gear that won’t fail and sounds very good.

In this review, I will detail my nearly year-long experience with the Mackie Onyx 4-Bus – a multipurpose analog mixer, which, most notably, features Onyx microphone preamplifers, Perkins EQ circuitry and a subtle analog stereo compressor/limiter. Simply stated, the Onyx 4-Bus ($2,049.99) is a workhorse, and more than a good analog live mixer; this console is a no-brainer for those who need a solid analog desk comprised of affordable, good sounding components.


The Onyx 4-Bus Series offers two models — the 24-4 and 32-4 — whose only differences are in total number of channels. The 24-4 has 20 mono channel strips and two stereo channels; the 32-4 has 28 mono channel strips and two stereo channels. I used a 24-4 in preparing this review.

The 24-4 measures 31.2 x 21.9 x 7.3 inches, and weighs in at 39.5 lbs. Power consumption is rated at 100 watts. Its steel chassis is solid and offers well-placed, recessed handles at either end. Designed at Mackie HQ in Woodinville, Washington, the Onyx 4-Bus is manufactured in China.

According to Mackie, technical specifications of the Onyx 4-Bus are as follows: its frequency response (mic input to main output) is +0, -1dB, <10 Hz – 80 kHz; distortion (mic input to main output) is 0.007 percent, 20 Hz to 20kHz; and signal-to-noise is -89 dBu (ref. +4 dBu, Mic In to Main Out, 24 channels and Main Mix levels at unity gain).

Each mono channel offers a mic and line input connector and insert jack for the connection of external processing. Starting at the top, these channel strips offer a -20 dB pad switch; a Low-Cut (high-pass filter) switch, cutting frequencies below 100 Hz at 18 dB per octave; a 48V Phantom Power switch; and a rotary gain knob (unity to +60 dB) for the “studio grade” Onyx mic preamplifier (more on the amp later).

Next, the Perkins four-band EQ section on each mono channel offers sweepable mids with an EQ bypass switch for true hardware bypass. (According to Mackie, the EQ is based on the designs of Mackie Designs’ collaborator Cal Perkins and is a “neo-classic” design with “British EQ” musicality.) The High EQ knob allows +/-15 dB adjustments at 12 kHz; High-Mid and Low-Mid EQs offer two knobs each — one for +/-15 dB adjustments and one for frequency adjustments at 400 Hz – 8 kHz and 100 Hz – 2 kHz, respectively; and the Low EQ knob offers +/-15 dB boost/cut, fixed at 80 Hz.

At its bottom, each mono channel offers six pre/post-fader AUX Send knobs, a pan knob (with “Constant Loudness” for maintained apparent loudness), a mute button with LED, and a smooth, “long-throw” infinity-to-Unity-to-+10dB fader — the de facto fader for the 4-Bus. At the very bottom of the channel is a PFL Solo (pre-fader listen) button with green LED. On the right of the fader, four small LEDs indicate channel signal level after gain and EQ, marked -20 dB in green, 0 dB in green, +10 dB in yellow, and OL (overload) in red. Finally, three rectangular buttons for buss/main mix assignment (1-2, 3-4, Main Mix) are arranged vertically just below the signal level LEDs.

The 24-4’s two stereo channel strips are similar in design to the mono input strips; however, they vary as follows, starting at the top: a -20 dB to +20 dB Gain knob adjusts level of stereo line inputs; and the Perkins EQ section features four fixed-EQ knobs, -15 dB to +15 dB, at 12 kHz, 2.5 kHz, 400 Hz and 80 Hz.

Next, at the far right of the desk, is the Matrix, Compressor and Metering Section. In the long, skinny Matrix sub-section, 14 “infinity to max” knobs are arranged vertically in pairs (indicated A and B per seven), and are labeled GRP 1, GRP 2, GRP 3, GRP 4, Left, Right and Master, each for the creation of separate mixes. At the bottom, two AFL (“After-Fader Listen”) solo buttons are paired with one LED indicator each. In the stereo Compressor/Limiter sub-section are three knobs and two buttons arranged vertically: a -30 dB to +10 dB Threshold knob; a Ratio knob ranging through Off, 2:1, 5:1 and Limit settings; a Comp Assign knob switch for Main Mix, Group 1-2, Group 3-4 and Off assignments; and the buttons for Fast Attack or Bypass Comp (with LED indicator) selection. This section also features a multicolored 24 LED Compressor meter — 12 for input signal level and 12 for Gain Reduction level. Finally, a 24 multicolored LED Left/Right Level meter offers 12 LEDs per side, ranging from -30 dB to +20 dB (CLIP). Also present are two Rude Solo LEDs (PFL and AFL, respectively), a 1/4-inch headphone jack, 12V lamp connection and a power-on LED.

The Phones/Monitor, Solo, Mono and Talkback Section offers level adjustment knobs for Phones (at the stereo headphone output), Monitor output and Mono output, plus Talkback levels routed to the AUX or MAIN L/R outputs. The Main To Mon button routes the stereo L/R Main Mix (post-fader to both Monitors and Phones outputs), and four buttons grouped as a TB Assign sub-section routes talkback to AUX 1-2, AUX 3-4, AUX 5-6 or Main Mix outputs.

The Auxiliary Section boasts six Aux Send Masters and two Stereo Returns featuring a level adjustment knob and a pre/post, AFL (with LED), and Mute (with LED) button per send. Both stereo return channels offer three knobs: one level adjustment per 1/3 and 2/4 returned signals (each with a shift button/toggle), and overall level adjustment per return. Also present per return is a PFL button with LED indicator. Above the two stereo returns is a CD/TAPE level knob with To Mon/Phones and Break (Tape To Main) buttons. When depressed, the Break button’s LED glows a unique blue.

Finally, in the Group Section, four faders reside with the same signal level LED arrangement as the console’s input channels. Per Group fader, a Mute switch, Pan knob, Main Mix assign switch and AFL Solo Switch are available. On the far right is the Main Mix fader with a Talkback switch (and Talkback LED indicator) above it.

As you would expect, the Onyx 4-Bus’s rear panel I/O is comprehensive. Each mono channel offers (top to bottom) a 1/4-inch Insert, 1/4-inch Line and XLR Mic input; both stereo channels offer two 1/4-inch inputs. On the far left, 1/4-inch inputs are present as stereo Returns, stereo Main Inserts, four Group Inserts and six AUX Inserts; 1/4-inch outputs are available via stereo Main Outs, two Matrix Outs, stereo Monitor Outs, four Group Outs and six AUX Sends. Very usefully, three DB-25 (TASCAM) connectors offer 24 channels of direct outputs, ideal for inputting post-gain/pre-EQ signal directly to an external recorder/DAW. Three Main Balanced Outs (Right, Left, Mono) are provided via XLR. An XLR talkback mic input and Stereo RCA I/O is also available. Last, but not least, the rear panel’s bottom left side provides the requisite IEC power connector and power switch.

In Use

As I mentioned above, I have had the Onyx 24-4 in near-constant use throughout the past year, and it has served many purposes. It mainly served as a front-of-house mixer, both with and without an attached digital recorder, though other roles served by the 24-4 included rehearsal mixer, monitors mixer (for a couple of large multi-band gigs) and a DAW tracking front-end (thanks to its incredibly handy DB-25 direct output connections).

Knowing PAR’s readership — professionals and semi-pros that have had their hands all over multi-purpose analog desks — I won’t detail all the configurations that this particular 24-4 has been in. Simply by analyzing the above “Features” section, it should be clear to all PAR readers that this particular Mackie can sufficiently serve many masters and can be routed to do most anything. Further, Mackie Designs is notorious for crafting pro audio gear with intuitive work surfaces, not to mention incredibly well written (but rarely needed) user’s manuals. So, as a result, you really don’t need me to tell you how easy this desk is to use.

Fast FactsApplications
Live, Theater, Houses-Of-Worship, Mobile Recording, Project Studio

Key Features
24 channels, 4 busses, 20 Onyx microphone preamplifiers, Perkins four-band EQ per channel, stereo compressor/limiter featuring a THAT Corporation chip, 24 direct outputs via DB-25 connectors


Mackie Designs | 800-898-3211 |



  • Impressive microphone preamps
  • Smooth, sonically pleasing EQ
  • Incredibly flexible
  • Good build quality


  • One minor build flaw

The Mackie Onyx 24-4 tops its product category in sound, features, build quality and price.However, I will note what I found to be the console’s three most appealing features, and why I think that anyone needing an mid-sized analog mixer should consider the 24-4 over most every similar product on the market. First off, the Onyx microphone preamp simply stunned me. Over the past 10 years, I have used all sorts of mic amps: big flagship console channel amps, esoteric/boutique standalones, cheapy “it’ll do” standbys and, of course, all those Mackie amps (the original Micro Series, VLZ, VLZ-PRO and now, the Onyx). So, I’ll have to say that this desk — featuring 20 of these Onyx babies — is a bargain considering the amps alone. The included Onyx amps truly do rival amps that cost thousands of dollars more … and if you don’t trust me, just consider Tom Jung’s own review of the amp (via the Mackie Onyx 400F product he spotlighted earlier this year in PAR). Our golden-eared expert called it as he heard it: “clean and uncolored.” ‘Nuff said.

Second, if you do need some “color,” you may look no further than down the same channel strip to the Perkins four-band EQ. It worked incredibly well for me, either as a surgical tool for removing offensive frequencies at concrete/cinderblock/beer-bottle club venues, or when using the Onyx 24-4 as a post-DAW studio mixer for drums, bass, electric and acoustic guitars, vocals, acoustic piano and various synth-based tracks (all of which were originally recorded on location at 96 kHz to an Alesis HD24XR via various pres — everything from Earthworks amps to the desk’s own Onyx offerings). More than a half-dozen musicians in live, rehearsal, and tracking/mixing situations specifically commented on the complimentary sound of the Perkins EQ. One particular guitarist, who has used every studio EQ under the sun on his tracks, was amazed that we got what we did via the Mackie EQ. His exact words: “Wow, I can’t believe that. How much did you say that was?”

Third, the stereo compressor/limiter in the master section sounds very good (or, more accurately, doesn’t sound like anything, except subtle dynamic control when used with care). As we all know, good gear is made of good components, and it’s assuring to know that Mackie took the initiative to incorporate a comp/limiter chip from THAT Corporation, a respected name in audio IC manufacturing.

Because of the affordable per-channel price point of the Onyx 24-4, I was never afraid to throw it in the back of a van or whatever I was traveling in. I find this to be an incredibly important quality in any affordable analog mixer. After all, workhorse gear is of no use if it cannot take abuse, and, ideally, such gear should perform as well as the gear that you wouldn’t consider pitching around.

On this particular Onyx 24-4, one minor build flaw was present straight out of the box: its chassis wasn’t square (i.e., it rocked on flat surfaces like a table with a slightly shorter leg). While annoying, it’s far from a deal-breaker. Maybe this happened in shipping; you can’t be sure. However, if that’s the case, I would recommend that Mackie consider slightly sturdier packaging for its mid- to upper-cost mixers to prevent this sort of thing from happening in the future. Other than this, the build quality of the 24-4 is superb: no wobbly pots, no junky-feeling faders.


If you’re in the market for a 24-channel analog mixer to serve many purposes — live, in the studio and all those locales in between — you truly can’t go wrong with a Mackie Onyx 4-Bus. Considering its low price point, all the included goodies, and its incredible flexibility, you just can’t go wrong by purchasing it. If you decide later that you don’t want it, somebody will. After all, it is a Mackie.