Summing mixers. They really weren't considered a decade ago, and now it's one of the main product areas that seem to have constant growth and development. Although the debate rages on, many feel that the sonic benefits of analog summing are well worth the extra expense, as opposed to just mixing in-the-box. Still, it seems as though bringing such a product to market has the potential to be a fairly frustrating experience. No matter how much thought is put into the functionality and design, it's likely that as a designer, you would never be able to please everyone. Anytime a summing mixer is released, there's usually a chorus of, "Oh man, I can't believe they left out that feature!" Or, "Why would I want to pay for that feature? I'll never use it!" So, we have companies that design to satisfy a specific type of user and workflow with the features they include.
One product that appears to cover a lot of ground from a feature standpoint is the Great River MixMaster 20. It not only provides a wonderful sounding summing mixer with up to 20 inputs, but also offers four mic preamps for tracking as well. Also included is a basic monitor controller that allows for A/B speaker switching. A stereo bus insert can be engaged from the front panel controls. Another "control room" type feature is a talkback input with a level control. For adjusting the overall output, a 100 mm master fader is horizontally mounted on the front panel. Also - and this one's a biggie - there is software for instantly storing and recalling all panning and levels for inputs 5-20.
To understand why the store/recall software only applies to inputs 5-20, a bit more detail on the layout is required. The MixMaster 20 seems to be aimed at those who want great sonics, with "a little bit of everything" included from a feature standpoint. As such, inputs 1-4 serve a dual purpose. They have both mic and line inputs with independent level controls. While tracking, these inputs provide four high-quality mic preamps. Unlike the "soft" controls of line inputs 5-20 (that are programmable), inputs 1-4 use traditional hardware knobs that are completely manual. This isn't an issue while using the mic preamps to track, but since these four inputs can also be used as transformer-isolated line inputs during mixdown, you would need to manually document the pan and level setting when recalling a mix. These four inputs also include phantom power, polarity reverse, and insert enable switches. There is also a solo button, as well as a button that assigns inputs 1-4 to the mix bus. Additionally, two aux send knobs can be routed to any of four aux buses, selected by pushbutton switches. This is a bit of an interesting feature, since they are only available on inputs 1-4 and only apply if that channel is routed to the mix bus. These preamps are not exactly like those in the wonderful ME-1NV and MP-2NV [Tape Op #28], although they do share the transformer and discrete three-transistor output stage. The input stage differs, however. It uses a transformer- coupled input which is then followed by an LM4562 op- amp, which provides most of the gain for the circuit. So while tracking, the signal hits two transformers on its way to the recorder.
The controls for the dedicated summing mixer inputs, 5-20, are a little more unconventional. With the wonderful feature of programmability and instant recall comes an "encoder" approach to adjusting level and panning settings. There is a row of LEDs which light up under a channel number, indicating which channel is selected. The selection is made by turning an encoder knob, and then pressing the knob to engage that selection. Then, by selecting either "level" or "pan", the encoder knob adjusts the selected parameter. Multiple channels can be selected to assure accurate level-matching between pairs or groups of channels. This process seemed a bit more fiddly at first than I wanted it to be, being just a bit less intuitive than I wish it were. However, I did get used to the procedure fairly quickly and was able to navigate without too many wasted steps. My biggest problem was in accidently erasing my settings due to forgetting to "take" them before moving on to other channels. These channels can also be soloed.
The rear panel is a sea of DB25 connectivity. Although some may groan at the prospect of DB25s being the only type of connectors used, it is the only way the vast array of I/O could fit on this 3RU-space chassis. There are XLR jacks for the four mic inputs, and also a 1/4'' used for connecting a remote talkback switch. All other connections are DB25. These include 20 line inputs for mixdown; inserts for channels 1-4; inserts for the stereo bus; a 2-track "tape" playback input that can be routed to the monitors via a front-panel switch; cue outputs; and direct outputs for channels 1-4.
I had the pleasure of speaking directly to Dan Kennedy on the phone after I had spent a little time with the unit. I asked him what the intended design goal was for the MixMaster 20, and his answer was "to attain the sound of a big console." Although I'll go into more detail, let me initially say that I feel he has been successful. The mix bus is a passive design followed by a discrete gain stage providing 30 dB of makeup gain. The summing and line drivers are both transformer-coupled, so the signal hits two pairs of transformers on the way out. Now, those who prefer a super-clean, transparent signal path will likely not favor that approach. The debate rages on about the benefits of in-the-box summing versus an analog summing mixer, and also clean signal paths versus ones that provide coloration. My experience has led me to believe that if you're going to use a summing mixer, some coloration is beneficial. The "straight wire with gain" approach to summing seems to have less benefit to my ears. So if you prefer some character being added, this is the box for you. Not to say that it is at all muddy, or even a one trick pony. Not at all, but rather, it fits Dan's design goals perfectly. To me, it sounds like a good console.
Although I mainly mix using a console, I have a second mix room that uses an in-the-box and hybrid approach. I used a couple of projects that I was working on as test cases for the MixMaster 20. Although these mixes were originally done ITB, they were mixed using the Metric Halo console, which is an 80-bit virtual summing mixer within their interfaces. You route your DAW outputs via FireWire to the interface, and sum them together in the digital domain using mixing software in the interface. I have found the MH summing to be a bit better than what I can get with straight ITB summing. Also, it was easy within the software to then route buses at unity gain to physical outputs, and then send those to the MixMaster 20.
With the inputs on the MixMaster also set to unity in stereo pairs, I was able to get a fairly direct comparison between the ITB mixes and ones summed through the MixMaster. In this test, the difference was noticeable. Forgive my somewhat imprecise and trendy descriptions, but things just sounded more real. The kick drum had a quality to the low end that sounded more "right." The attack on the snare sounded more like what I wanted to hear, with a little more clarity and harmonic content. I liked the midrange of vocals a little better, as they seemed to sit better in the mix with a little better feeling of substance. The bass guitar seemed to have more content on the lower octave, and the guitars had a slight bit more girth. The soundstage wasn't vastly different, but there was a degree of added depth. It was interesting; in directly comparing the mixes, there was absolutely nothing wrong with the ITB mixes. However, my reaction to switching to the MixMaster 20 mix was a feeling of things being improved, that I didn't realize needed improvement. Everything just hung together in a more musical way, in my opinion.
Now, I did this unity gain test to compare the straight summing functions. This is probably not the way this unit would be used in the real world. So, I then rebuilt the mixes using the MixMaster from the start, applying the sort of channel gain-staging that would occur in a real-world mix. I sent things out a little hotter from the DAW and used the MixMaster's level controls for balance. With this approach that more accurately emulated the gain-staging on a "console" mix, I was able to attain a small margin of improvement over the unity-gain mix. The differences were not staggering, but absolutely noticeable. The straight ITB was my least preferred mix and the "from the ground up" mix using the Great River was my favorite. This was true across genres, from a jazz mix to an alternative rock mix, to a country mix. The actual passive summing function itself may or may not have too big an impact, but the transformer coupling and active discrete gain stages sure seem to. At any rate, it made my mixes come closer to my desired sound.
One quick comment on the mic preamps - don't be put off because they aren't completely Class A. As I mentioned, they are transformer-coupled with a discrete output driver, and they sound wonderful. The op-amp used on the front end offers great performance, and the preamps sound great on snare, guitar, vocals, and whatever source I threw at them. The mic preamp has a ton of headroom and will accept a signal of up to +15 dBu before crapping out. And that's the feeling I got while using the whole unit, including the mic preamps. Headroom. High current. Dynamic range. Wonderful sonics from front to back.
As far as the store-and-recall software, it is completely "no frills" but does exactly what it says it does. Install the software on Mac or PC, connect the USB cable, and select the USB port. That's it. An unassuming green circle "lights up" on the software to let you know it's communicating with the hardware. Then, you can select two tasks: send settings to the unit, or store settings from the unit. There's no offline editor or even a way to graphically see what the settings are. Instead, multiple "scribble strips" are provided, allowing notes and documentation to be typed in and stored with the file. It takes only a moment to re-instate a saved file back into the hardware. And this is a good thing, since the early MixMaster units have no non-volatile memory, so all settings have to be restored from software when the unit is powered up. This has been changed in current units; settings are saved on power-down.
Speaking of powering up, it's quite a procedure. After flipping the switch on the large external power supply, you wait - more than just a few moments. I've seen NASA countdowns that were faster. Please understand that this is not a criticism, but rather a statement of admiration. It speaks to the attention to detail and build-quality that is demonstrated throughout the unit. Power isn't just thrown at the circuits all at once. Care has been taken in ramping up power to specific circuits in a specific order, to extend the life of the components. It takes about 30 seconds for the sequence to complete, ending with slowly rising illumination from the two massive analog VU meters, letting you know the MixMaster is now ready to accept your audio.
So we have a high-end unit that tries to do a little of everything. It sums 20 inputs. It provides four great-quality preamps for tracking. It has four aux sends. It includes an A/B monitor selector and also a talkback and cue system. And it sounds great every step of the way. Add (almost) total recall, and it becomes quite a desirable package. At $7000, it is certainly not for the low end of the market, but when you consider the sound, build-quality, and total functionality, it gives you a lot for the money.