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Australian Monitor ZRM4 Zone Mixer

Zone mixers are a staple of install work. They are essential to routing signals to places like bars, dining rooms, classrooms and conferences rooms.

Zone mixers are a staple of install work. They are essential to routing signals to places like bars, dining rooms, classrooms and conferences rooms. It seems that some manufacturers are now moving toward DSP power-based versions for this class of product, but many still manufacture non-digital products. These enduring analog products seem to be very competent and comprehensive or somewhat budget oriented. On first glance, the ZRM4 appears to bridge this gap with a host of handy features and a price of only $650. This, coupled with my lack of familiarity with the folks at Australian Monitor, piqued my curiosity to examine this mixer.


Fast FactsApplications


Key Features

Six inputs; four outputs; 15V phantom power; bass and treble controls; high-pass filter; matrix style routing; onboard alerts and tone.




Australian Monitor/Sennheiser USA | 860-434-9190 |

The ZRM4 has a single space chassis that weighs in at 6.4 pounds. The mixer accommodates six input channels and can redirect those inputs to four separate outputs. The inputs arrive via XLR (mic/line) and dual RCA (line) while the outputs show up on balanced XLR. In addition, the outputs can be individually controlled by remote VCA (for instance, if a bartender might want to lower the music volume at the bar without leaving his/her post to make that adjustment) that can be actuated by a remote wall mounted volume control. Other notable features include onboard alert, evacuation, bell and pre-announce tones, as well as a high-pass filter and 15V phantom power.

The front panel is home to the control area while the back panel is home to the previously mentioned I/O connectors. Each input channel has a potentiometer for volume control (±15dB), mini recessed pots for bass and treble, and output assignment buttons that can route that channel’s signal to any of the four outputs. In addition, each channel has a status LED that glows green for signal present and red for clipping. Channel one has the ability to be designated as the priority channel (nice for making sure the big cheese or moderator gets his/her point across). The rear of the unit has the previously mentioned I/O connections, a power switch, and block connectors for triggering of the alert tones and control of the VCAs.

In Use

My first use of the ZRM4 was at a committee meeting at the National Institutes of Health. The meeting consisted of a facilitator and a number of scientists who would comment on agendas presented by the facilitator, including a guest on the telephone. In the past, I have used a small format mixer (like a Midas Venice 160) and had to ride herd over the proceedings. With the ZRM4, I was able to designate the priority channel for the facilitator and, once reasonable levels were established for the other participants (including a mix-minus for the telephone interface), the event mixed itself. The room had a lot of HVAC noise, so I opted for some dynamic hypercardioid mics on tabletop stands. The ZRM4’s mic preamps had no trouble providing the extra gain required to get voices to an acceptable level and, I might add, with a minimal amount of self-noise. Listening to the recording from that meeting and comparing it to previous recordings made on the Midas (with the same microphones) led me to feel that the ZRM4 has some decent mic preamps for a piece in this price range.

Later, at an event on Capitol Hill, I used the ZRM4 in a similar situation for a forum featuring some members of the Indiana Congressional delegation. Again, I assigned the priority channel to the moderator and, once reasonable levels were established on the other inputs, the event went very smoothly. The room for this event, like so many on the Hill, was all marble and there were some challenges getting ample gain from the system, especially given the unit’s modest channel EQ. Therefore, I had to rely more heavily on my system EQ for feedback suppression.


My experience using the ZRM4 was a very positive one but I was left feeling that I wasn’t giving the unit the opportunity to reach its full potential. While it has a number of features and characteristics that made it pleasurable to use in portable sound reinforcement, it seems like it would really shine in the confines of a fixed installation. I could envision it being very valuable at a school, restaurant, or other institution where public address, multiroom music or meetings may occur. It seems to have a better build quality and sonic capability than other similar models in this price range and it feels very rugged. It actually does seem to bridge the gap between competency and affordability, offering a distinct alternative to those DSP products on the market.

Review Setup

Audio-Technica AE6100, U857RU microphones; Rane EQs; Sabine Navigator; JBL SRX712 speakers.