Mackie's HR624 powered studio monitors build on the success of the company's HR824 monitors, which were immediately successful due to their accurate response,

Mackie's HR624 powered studio monitors build on the success of the company's HR824 monitors, which were immediately successful due to their accurate response, wide dispersion, and affordability. The HR624 is smaller, designed primarily for use with a subwoofer and in multichannel monitoring setups. But don't let the smaller size fool you — the HR624 also delivers great sound in a standalone stereo setup.

The HR624 is not simply a smaller version of its predecessor: it has been modified to optimize its sound quality. One of the benefits gained from the new design is a more accurate transient response. Also, the cabinet is not being pushed to the limit to reproduce low frequencies. Overall, this yields a more accurate midrange response; inaccurate midrange response was one of the few criticisms I had of the original HR824. When used without a subwoofer, the HR624 still disperses a smooth, accurate frequency response from top to bottom. However, the bass frequencies obviously don't dive as low as the original HR824.

Mackie provides several options for customizing the monitor's response in order to complement the monitor's location in your listening environment. A three-position switch allows you to tailor the bass response by cutting either 2 dB (which helps if your monitors are against a wall) or 4 dB (which helps if your monitors are in the corners of your room) at 400 Hz and below. The low-frequency rolloff filter can be switched to 49 Hz (normal) or 80 Hz (THX mode). Additionally, the three-position high-frequency switch allows you to boost or cut the treble response by 2 dB at 10 kHz.

The HR624 has XLR, ¼-inch, and RCA inputs to accommodate a wide variety of setups, and the input sensitivity control allows you to tweak the basic volume response of the monitors to your liking. I wish that the input sensitivity pot were notched and better marked — that would make it easier to match levels between speakers.

An auto-on power mode allows the HR624 to sleep when it is idle for more than eight minutes. That conserves power and reduces heat buildup in your room. The amplifier wakes up when audio signals are detected at the input.


As I mentioned before, the HR624 provides a smooth frequency response from top to bottom. According to the response graph in the manual, the HR624 is nearly ruler-flat from 60 Hz to 20 kHz, and the manufacturer says it tests each speaker to make sure it has an accurate response before shipping. The goal is to make it possible for any two HR624s to be put together for critical monitoring without the user having to spend time searching for a matched pair.

Specs aside, the HR624 sounds great. With new monitors, I typically begin by listening to a wide variety of very familiar prerecorded material. I was very happy with my findings, as all of the material that was well recorded sounded excellent on the HR624s. But what I loved about the HR624s was that the marginally recorded material did not sound great — exactly what I want from a set of monitors.

Monitors that make everything sound great are not what you want in the studio. You need to hear the flaws, frequency imbalances, compression artifacts, and so on without a speaker covering up these sins. As it turns out, the HR624 is not a forgiving monitor.

For example, I rushed out to buy the new album from a very successful crossover country artist I work with occasionally, but I was disappointed as soon as I heard the CD. The HR624s revealed just how overcompressed either the mixing or the mastering was, which killed all the vocal dynamics that I know this artist has.

Further listening tests revealed more of the same: if a record was well recorded and mixed, the HR624s sounded stunning. On the flip side, I easily heard bad balances; overuse of de-essing, compression and EQ; and sloppy editing on a number of commercial CD releases. I'm sure they sound fine on the radio or on car speakers, but the HR624s revealed flaws I had never heard before on these familiar recordings.

When put to the test on my own material, the HR624s were equally brutal. True to form, the good stuff sounded good and the bad stuff sounded bad. Over the course of a few projects with quick deadlines, I had an initial tendency to rely on my older, more familiar monitors, working on the Mackies only occasionally. It was a little disconcerting at times: I would be quite happy with the way a mix was progressing on my other sets of monitors, but when I would pop the mix over to the HR624s, my heart would sink. The mix would pretty much stink, and I knew that I still had a lot of work ahead.

As I became comfortable with the HR624s and started to rely on them more, my mixes got better. The trade-off was that I had to work a little longer and harder to get them right, but I never experienced a situation where mixes that sounded good on the HR624s did not sound good on other monitors. In fact, I found that minor tweaks that were necessary while listening to the HR624s were sometimes largely unnoticeable on other speakers. Again, that's the way I like it.

I've now settled into a critical-mixing system using the HR624s, an alternate set of midfields, a pair of Apple powered speakers, and a mono cube. When I get a mix that sounds good on all four setups, I know I have a mix that will translate well pretty much everywhere.


The HRS120 subwoofer rounds out the bottom end for those who need the extended low frequencies or are mixing 5.1 surround material (see Fig. 1). The HRS120 is a beast, weighing in at just under 100 pounds. But with its monster size comes monster sound — the HRS120 totally rocks with the HRS624s.

Setting up the HRS120 with a stereo setup is a breeze because it has built-in stereo bass management. Just send your mix to the subwoofer, which uses a built-in active crossover to split the signal. The outputs from the subwoofer are then sent to the inputs of the satellites, and the frequency response is spread between the speakers and subwoofer appropriately. In this configuration, the HRS120 and the HR624s are perfectly suited for each other, and I would have no problem at all mixing a record with this setup alone.

I managed to borrow an SUV and haul five HR624s and an HR120 down to the studio and set up a temporary 5.1 system using Digital Performer and a MOTU 1224 to route the multichannel mix appropriately. Here I ran into a problem: the built-in crossover of the subwoofer only supports two channels. If you plan on building a 5.1 mixing setup, you will need to purchase an additional bass-management solution for controlling the crossovers between the five satellite speakers and the subwoofer.

For my testing, I initially ran the front-left and -right speakers through the HRS120 crossover and connected the center and rear speakers directly to the MOTU audio interface. That gave me a great sense of what the surround system is like, which is stellar. However, I suspected that running just the front speakers through the crossover would introduce misalignments in timing, so I decided to wire all the satellite speakers directly from the audio interface. The result was, I felt, a more cohesive sound.

Of course, that didn't give me a proper bass-management solution: all I could do to tame the overall response was tweak the low-frequency filters on the individual satellites and the response of the subwoofer. Still, the Mackie system sounded great in this context, and I would not hesitate to rely on it for a surround mix.


Mackie has yet another winner on its hands. I have come to depend on the HR624s as a dose of sobering medicine with my mixes. When a mix sounds great on the HR624s, it's usually a good sign. When it sounds bad, it's time to roll up my sleeves and keep working.

As a standalone set of stereo speakers, the HR624s are great. Add the HRS120 subwoofer and you have a fully professional mixing setup. Add three more speakers, and you have a fantastic surround-mixing environment.

ProducerRob Shrockhas worked with Burt Bacharach, Elvis Costello, Dionne Warwick, George Duke, Leann Rimes, Faith Hill, Isaac Hayes, Wynonna Judd, Sheryl Crow, David Foster, Stevie Wonder and a host of others. He currently serves on the Board of Governors for NARAS.


Mackie Designs
HR624 High-Resolution Active Studio
powered monitor
HRS120 Active Studio Subwoofer


PROS: Smooth, balanced frequency response. Excellent transient response. Wide sweet spot. Response can be tailored to your environment. Great value.

CONS: Additional bass-management system required for using HRS120 subwoofer in 5.1 surround setup. Subwoofer is expensive compared to the satellites.


Mackie Designs, Inc.
tel. (800) 898-3211 or (425) 487-4333

HR624 Specifications

AUDIO Frequency Response52 Hz-20 kHz (±1.5 dB)High-Frequency Equalization±2 dB shelving @ 10 kHzLow-Frequency Equalization80 Hz/49 Hz second-order Butterworth, switchableAcoustic SpaceEQ 3-position switch: -4 dB or -2 dB @ 400 Hz (and below) or flatPeak Output112 dB @ 1mResidual Noise< 8 dB @ 1m

Power Rating (@ 1 kHz with 1% THD)40W (HF amplifier); 100W (LF amplifier)Signal-to-Noise Ratio> 93 dB unweighted (HF); > 101 dB unweighted (LF)Input Impedance20 kž balanced; 10 kž unbalancedTotal Harmonic Distortion< 0.035%Power Consumption12W standby; 20W idle; 105W loud program

High-Frequency Driver1" aluminum domeLow-Frequency Driver6.7" mineral-filled polypropylene coneInput ConnectorsXLR; ¼" TRS; RCA

Crossover Slope24 dB/octave @ 3 kHz, active

Material0.625" MDF with 1.000" MDF front panelDimensions8.25" (W) × 13.00" (H) × 12.50" (D)Weight25 lb.

HRS120 Specifications


Frequency Response21 Hz-150 Hz (±1.5 dB)Low-Frequency Cutoff-3 dB @ 19 HzSubsonic Filterflat @ 15 Hz; 18 dB/octavePeak Output100 dB @ 1m

Power Rating400W, 8ž load (500W peak)Signal-to-Noise Ratio> 107 db @ 350W into 8ž

Low-Frequency Driver12" RCF PrecisionInput Connectorsbalanced combo (XLR and ¼-inch TRS); RCA

Crossover24 dB/octave, 55 Hz-110 Hz

Material0.750" MDF with 1.125" MDF top panelDimensions18.0" (W) × 21.0" (H) × 21.3" (D)Weight94 lb.