Review of a Yamaha MG 12/4 audio mixer

(picture of the mixer)
Picture of the mixer

There's a bizarre breakthrough of the signals from other channels if you unbalance an input (e.g. if you ground one of the signal legs in the XLR input sockets by connecting pin 1 to either pin 2 or 3), then audio being fed to other input channels of the desk can be heard, and at a surprisingly high audio level.  It wasn't just a faulty input channel, all the input channels exhibited this strange behaviour.  I've never seen any other mixer do this.

Awful metering, it rapidly flutters about without giving any sort of useful display.  It's next to useless unless you're mixing pre-compressed audio.  It's some kind of peak reading meter, with unknown ballastics, and without enough peak-hold to let you read the meter properly.  Straight audio goes into a BA682A LED driver IC, without any time constants being applied to the signal.  At best, you get some sort of indiction you might be able to use to avoid overdriving the output stage, if you can manage to see the LEDs ever-so-briefly light up, but nothing that helps you set a volume level.  It's also nearly impossible to view the meter when under bright lighting.  I ended up modifying the metering circuit (putting in a capacitor to give a bit of hold time to the LEDs).  While far from being calibrated, at least you can now read the metering to make an educated guess at the signal levels.

Tape record out is pre-master-fader.  I don't know who wants that.  It means that you can't record a master fade in or out, and it means that if you adjust the master fader, your metering gives you no clue about the level being recorded.  If you're one of those people who're recording a mix being sent out somewhere else at the same time (e.g. to PA speakers), you really want to be recording the main, controlled, program output, and have a separate monitor feed level controller.  You really need several monitor feeds—control booth (headphones and/or speakers, preferably both separately), remote speakers (e.g. front-of-house amplifiers), and one or two foldback feeds to performers.

Surprisingly susceptible to EMI pick-up in the mixing desk.  The power supply is external, and needs to be kept well away from the desk.  Other mixers manage an internal power supply, and without any noise from it.

Irritating mixture of different input and output levels and three different connector types (XLRs, ¼″ jacks, and RCAs), and an annoying mixture of balanced, unbalanced, and impedance balanced, wiring of the ¼″ input and output jacks.  RCA connectors are the almost the worst type of connector to use (worse would be the 3.5mm mini phone jacks), don't put them on a mixer.  Stick to XLRs and ¼″ jacks on the mixer, I'll use a cable with different connectors on each end, if I have to plug anything into the mixer that uses RCAs.

Stupid position for where the headphone connector is, it means that you have a headphone cable trailing across the top of the desk, over the middle of the controls.


Written by Tim Seifert on 29 September 2022, and last updated on 10 October 2022.