Tools of the Trade: Portable Mixing Consoles

October 26, 2001 at 5:17 pm

(Originally published in Audio Media Magazine USA)

In this volume: Cooper CS-208 & CS-106; Sonosax SX-8; Zaxcom Cameo; Audio Developments AD-146, AD-147, & AD-149; PSC M8.

For Film and Television production, these portable mixing consoles (or for our European colleagues, desks) pick up where even the best ENG (electronic news gathering) mixers leave off. Compact size is still important, but the assumption is made that these mixers will be operated from the flat surface of a cart or table instead of from a pouch hanging from the shoulder, so the strap is replaced with a handle. The basic criterion remains the same as their ENG little brothers, i.e. battery powered, compact, and quiet high gain mic preamps, but a greater importance is given to features which allow more control, inputs, outputs, monitoring options, and versatile signal routing. And, as always with location sound equipment, these mixers will often be exposed to the elements and constant relocation, so ruggedness is a big plus.

Location sound recordists are at an advantage today because there are a number of high quality portable consoles designed specifically for their profession, in a wide range of prices and capabilities. Several of the new choices in portable mixing consoles are evidence of the fading reliance on just 2 tracks and the growing trend in 4 track recording by offering 4 or more output busses.

While some are slightly better than others (+/- a couple of dB), all of these mixers have high quality specs in terms of signal-to-noise, distortion, and frequency response, which is not uncommon today with analog circuitry. The differences that remain result from the competition to create the best balance of size, reliability, desirable features, and cost. The prices in this class range from $4300 to $14,500+. So there’s a choice: You can buy a mixer and a car, or just a mixer.

Cooper CS-208 & CS-106+1 (www.coopersound.com)

Cooper Sound Systems’ slogan, "Sonus Clarus" could just as accurately be "No Nonsense". Everything about the Cooper mixers has a purpose, and all of the functions of these mixers work together for a single purpose that can be boiled down to a single word: Professional. These mixers are designed and over built to stand the rigors of location production for people who rely on them to make their living as location sound engineers. I can attest to their success with this goal because I have used a CS-106 for the last 8 years on all types of location production, and the sizable investment has proven profitable. Cooper edifies the "form follows function" engineering creed. A novice who might gaze for hours in wonderment at a Mackie mixer would likely walk right past a Cooper, unimpressed. Audio quality, logical layout, simplicity, and specific function have always been the hallmarks of the Cooper mixers, which is very impressive to the professional.

Still available is the mixer that made the Cooper company famous: The CS106+1 ($11,600), which was also once available in an otherwise identical 8-frame version called the CS108+1. The CS106+1 has 6 mic/line inputs while the CS108+1 had 8. The "+1" is for a blank module that can be left blank or fitted with either a 7th (or 9th) input module, a stereo mic/line input module, or an AUX module. While the CS-106 and CS-108 are basically 2 channel consoles, the AUX module provides two additional mix busses, effectively converting these consoles into 4 output mixers capable of tracking to the Nagra D or Deva 4 track recorders. Cooper uses a sturdy gauge anodized aluminum chassis and ultra precise fitting modular top panels to allow easy removal for servicing, reconfiguring, etc.

From the back of CS-106+1’s input module working forward, there are XLR inputs, balanced and isolated with Jensen transformers. These inputs can be anywhere from mic to +4 line level, and mic powering options are available for 12V & 48V phantom, as well as T power (also known as A/B, and Tonader). Each input module has its own unbalanced, post fader, -10dB, direct output, and each input also has a pre-fader unbalanced insert jack. It is recommended that the input portion of the insert jack be used for line level inputs (by passing the mic pre) to achieve best signal-to-noise, though I’ve always found the XLRs satisfactory.

Features on each input module include pre/post AUX send, PFL, peak limiter, overload LED, 3 band EQ with sweepable midrange, T and phantom mic power, 83mm Penny & Giles faders. Output and monitor features include balanced L/R outputs, unbalanced outputs on RCAs, balanced AUX out, and three separate monitor outputs.

While Cooper mixers have also won a deserved place with location music recordists, the original primary intent still remains: location recording for film and television production, as the following list of specific features suggests:

  • Standard PPM meters with markings and ballistics similar to the Nagra modulometer (-8dB = 0VU) (but VU meters are available at special request.)
  • Huge amounts of available microphone gain (85dB) with very low noise. (CS-106: -128dB; CS-208: 129.5dB)
  • Nagra standard Tuchel connectors for direct interface with mono and stereo Nagra recorders, complete with remote roll and automatic end-tones.
  • Integrated talkback communications module for off-line, private, two-way communication between the Mixing Engineer and the assistant (typically the boom operator).
  • 3 separate monitor outputs (typically used for Mixer, Boom Operator, and Director)
  • DC power input (12 – 24 VDC) on a standard 4 pin XLR, and internal battery compartment that holds 12 D cells to power the mixer for, at minimum, a full production day.

Occasional complaints heard about the Cooper CS-106 include input overload sensitivity, noticeable action of the input peak limiters, and the row of connectors on its right side. The first of these, input overload, is explained by operators trying to hard keep the mic pres completely noise free, where the tendency is to not use the 20dB pad for condenser mics in order to keep the input trim (gain) pot as low as possible. The result is ultra quiet tracks, but when the unexpected shouts come from actors, the inputs will sometimes clip. The remedy is to normally use the 20dB pad and increase the gain as needed. Regarding the peak limiters, the thing to keep in mind is that these limiters are intended to control surprise peaks only, and not to be relied on for use a compressor. The connectors on the side? Well, they’ve got to go somewhere. However, the raised meter panel on the CS-208 added sufficient back panel area to allow Cooper to finally locate all connectors where they belong: on the back.

The CS-106 & CS-108 were quite sufficient when they were introduced in 1985, and remain a mainstay of serious professionals today. But film production is becoming more complex, and often requires 4-track recording and a host of AUX sends and monitor mixes. The most limiting features of the 106/108 mixers is a single AUX send, and only 2 main output channels. Though the optional AUX module squeezes this mixer into the 4-output channel category, it is a bit cumbersome to use. So, Andrew Cooper went back to work.

Cooper’s brand new flagship, the CS-208 ($14,000), has a definite family resemblance to its older brothers. So much so that it includes every feature of the CS-106, but brings it up to date to meet the increasing demands of modern film production with increased outputs, more monitor options, and improved noise specs (-129.5dB), achieved while still using input transformers. After all of this, the CS-208 somehow still managed to reduce battery consumption. With the same unbeatable, rugged, precision, construction as the CS-106, the CS-208 has 4 main output busses, 4 meters, and 2 AUX sends, making it a top choice for the Nagra D and Deva digital recorders.

After all is said and heard, even as other manufactures are offering close competition, the Cooper mixers are always included when comparisons are made.

SonoSax SX-S (www.sonosax.com)

When the Sonosax SX-S series mixers were introduced in 1983 they instantly became recognized as "THE" mixer to have for film production. With a modular configuration, these mixers from Switzerland are rugged, compact, are very quiet (-129.2dB), all of which is reflected in its price tag. Even when introduce nearly 20 years ago, the price was an amazing $9,000. Today’s price for the basic configuration is $11,600, and with a full compliment of options, the price can easily exceed $15,000 for an 8 input mixer.

The "SX-S" is always followed by a number representing the number of input channels, i.e. SX-S8, SX-S10, etc. Starting at the top of the input modules, it is first noticed that there are no pads on the new versions. Using transformerless balanced inputs, the SX-S mixers control the input range simply by changing the amount of amplifier gain, which is done with 3 range selections plus a variable gain trim pot. The range selections are HI for line level signals, LO for mic level, and CAL (gain by-pass) for unity gain when the faders are set to 0dB. The HI and LO ranges give the gain trim knob a total range of 70dB. With the P&G faders at the full up position, there is a total possible input gain of 85dB.

Next on the input module is a compact 3-band EQ section with a sweepable midrange from 200Hz to 8kHz. Instead of low cut switches, the Sonosax uses a sweeping low cut pot, cutting 12dB/oct from 20Hz to 500Hz.

Discussions amongst those who are familiar with the Sonosax always include approval of the limiters, which are on each input. In fact, they sound so good that Sonosax decided to make them impossible to turn off, giving each module an additional 6dB of overload protection when the alternative would be clipping. For more active limiting, a threshold control knob increases the sensitivity.

Sonosax’s original space saving design placed the PAN, AUX, and Limiter Threshold knobs just to the left of each fader. This was always a peeve of mine because my fingers usually managed snag them when changing faders, and they made one-handed gain riding on more than one fader at a time seriously difficult. To Sonosax’s credit, they have now recessed these knobs, so I guess I now have nothing to poke at.

Except: Compactness is a mixed blessing, and to help the SX-S be the smallest in its class, Sonosax opted for numerous "TT" tip-ring-sleeve jacks on the rear panel for utility in/outs. These connections include a prefader insert and unbalanced direct outs for each input. The direct outs can be either pre or post fader, determined by using the tip or the ring of the jack. While these jacks are certainly a common standard in patch bays, they require a bag full of adapter cables to connect other equipment in the field.

The two-channel master output module is simple with only basic stereo/mono monitoring ability, AUX master level, and a level control for an unbalanced stereo TAPE insert. Alone, the master module is no doubt too simple for most film production today, so Sonosax came through again with the "Extension Module", often referred to as the "Film Module. This optional module is very comprehensive and adds a multitude of features including off-line communication, tape return monitoring, separate output for video assist, MS decoding, remote roll, Mid/Side monitor decoding, and to supplement the standard LED bar meters: very nice analog meters that are switchable Peak or VU. When the meters are switched to mono mode, the left meter indicates phase correlation while the right meter displays the greater of the two channels. A very nice touch of class.

The SX-S mixers are adaptable to 4 track recording by adding the optional matrix module, which assigns up to 10 inputs to any combination of 4 additional outputs while retaining the master module’s 2 track mix outputs. This is ideal for film production when recording to both a 4 track main recorder and a 2 track backup recorder.

It’s no wonder that Sonosax SX-S mixers are adored by their professional owners and, if they are willing to add the optional modules and boxes, these mixers are quite capable of continuing to serve their owners into the coming age of more complex requirements and 4 track recorders.

Audio Developments AD-146, AD-147, & AD-149 (www.audio.co.uk)

I first became aware of the Audio Developments mixers in 1984, soon after the AD-062 and AD-145 were introduced. Internally battery powered with conventional layout and communications modules, they were well suited for location film production. I opted for the more compact AD-145, which became my primary mixer for the next several years. Using modular input assembly then and now, Audio Developments’ more recent versions include up to date refinements in construction, layout, features, and audio quality, and are showing up more often on some very notable productions. Available in four models that are well suited for film production, they are priced a little bit easier than the Cooper and Sonosax brands.

The Audio Developments line starts with the AD-245, a great little mixer priced at $4300 for the 6 input version, and $5155 for the 8 input version. Largely a refinement of my old AD-145, it is a fairly simple stereo board with no AUX sends. The things it does have, though, are very nice: Transformer balance inputs and L-R-SUM outputs, 80dB gain mic pres with noise specs of -126dB, long throw (100mm) Penny & Giles faders, 3 band EQ, 48Vph and T power, PFL, off-line boom operator communication, analog meters, and something every mixer should have: stereo linking output limiters. If I were starting out on a budget but refused to go the Mackie route, or needed a back up to a more capable mixer, I wouldn’t hesitate to go for the AD-245.

The AD-146 ($8300) was one of the first location mixers suitable for 4-track location film production. It’s similarities to the AD-245 are undeniable, but the AD146 is more mixer than that would suggest.

There are separate XLR connections for Line and Mic on the inputs, selectable from the module’s top panel. Each input has 4 output assign buttons (A, B, C, & D) and a pan pot that affects channels A & B only. There are no AUX sends, but when 4 tracks are not needed, the remaining channels would function very well for utility. It has the standard PFL button, but also a button labeled "MON" (for monitor), that follows the Pan Pot (post fader). A very nice feature that is ahead of its class is the ability to decode MS stereo at the outputs (or convert stereo to MS). Stereo, whether its M/S or L/R, is becoming more and more requested in film production, and having an on-board decoder is a real plus. The 4 main outputs are transformer balanced.

Other features include 4 channel return monitoring, off-line communication, several days of power from 10 internal "C" cells, and standard 4 pin external power input. The console has only 2 analog meters, an obvious limitation for a 4-output console, but they are managed well by the different metering combinations available through the meter switches. There is a rear mounted, buffered, accessory output connector that can feed the 4 separate outputs to an external meter bridge.

Again, the AD-146 is an excellent way to stretch a dollar and have a very nice, high quality, very portable mixer for 4 track recording, or for 2 track recording when additional utility outputs are needed.

The AD-147 ($6785, 6 inputs; $8239, 8 inputs) is a stereo mixer that picks up where the AD-245 left off. Ergonomic styling has improved with a reverse printed Lexan overlay, which incorporates pastel blue shading to visually separate control functions and signal flow, as well as guarantee the immortality of the labeling. The addition of 2 AUX sends that appear on balanced outputs make it reasonable to stretch this mixer into use for 4-track recording.

Other additions to the input modules are: 2 AUX sends (pre or post fader), post-fader stereo soloing (labeled MON) Pan Pot and Assign switches. The master module followed the lead of the 4 output AD-146 by adding an M/S decoder matrix, which is also found on the monitor module. A remote roll switch controls a Nagra IV-S through a standard rear mounted 7-pin Tuchel connector. To help control weight and cost, Audio Developments opted for electronically balanced inputs and outputs and abandoned their transformers, the loss of which will normally go unnoticed. Like the other AD-x mixers, 10 internal "C" cells power this mixer for at least a couple of days. Rounding out the "location specific" features is a 6-pin boom cable connection for 2-way private communication.

The AD-149 ($10,165, 6 inputs; $12,212, 8 inputs) is the flagship in the Audio Developments line ($10,169, 6 inputs; $12,212, 8 inputs). It is largely an AD-147 on steroids, as feature of the AD-147 is included on the AD-149. It is a 2 channel stereo mixer with 2 AUX sends, and the top panel looks nearly identical to the AD-147 except for the pastel red tinted Lexan overlay.

However, there are some important additions that explain the higher model number and the higher price: The AD-149 adds direct outputs and insert jacks to each input, and a more agile EQ section with peak/shelf choices and mid range sweep. A 10-pin multi-connector allows quick hook up of the main outputs and returns, and a 6-pin multi-connector with buffered unbalanced outputs and returns for use with, for instance, a backup DAT recorder.

Finally, there is a 15-pin "D" connector for monitoring all outputs with an external meter bridge.

Audio Developments is the only manufacture in this list that offers a range of professional portable consoles that span from entry level to advanced master level. There is something to be said for continuity and brand loyalty and it makes sense that some will see value in staying with a familiar company as they advance in their careers. Audio Developments is well suited to this set of values, and for decades they’ve been making fine audio equipment for location sound.

PSC M-8 (professionalsound.com)

The PSC M-8 ($10,250) is Professional Sound Corporation’s (PSC) current entry into the portable console category. Introduced in 1992, PSC’s goals were to offer a high quality, self contained, portable mixing console for 4 track recording with all of the features desired by location film sound recordists at a price lower than the Cooper and Sonosax mixers. They obviously did a lot of homework by asking professionals what they would want in a mixer, and their goals were largely achieved.

An 8 input 4 output mixer whose introduction was well timed a couple of years after the 4 track Nagra D, the M8 is designed specifically for location film production. It meets the requirements of internal battery power with ten "D" cells that power this mixer for at least a full production day, and can take external power on a standard 4 pin XLR. The physical profile is kept very low by extending the front surface beyond the bottom of the 83mm P&G fader travel, which also gives a nice place to rest your wrists while mixing. This "wrist rest" is a windfall of its economical non-modular top panel, which is well protected with a reverse printed Lexan overlay.

Starting at the back panel input section, there are the expected XLR inputs, plus direct outs and insert jacks on 1/4" tip-rig-sleeve connectors. Other features include 3 band EQ with sweeping mid range, 2 AUX sends (pre or post), T or 48Vph power, input limiters with controls for ratio, threshold, and bypass, remote roll switch.

Two additional features which are a combination unique in portable mixers and very much appreciated by the location professional, are: 4 separate monitor mixes labeled Mixer, Boom 1, Boom 2, and Director, and stereo cue speakers flush mounted right on the chassis. Each monitor mix bus has independent assign switches to dictate what does and does not go to the intended listener. The only mixer in this list with integral cue speakers, they are a major convenience for recordists who, when cabled away from the film set, allow them to stay in touch without wearing their headphones.

2-way off-line communication with the boom operator is well thought out and easy to use. Each boom operator has their own talkback input on the console, which has preamp for mic level signals. The recordist selects either or both boom operators to listen to and has separate level controls for talkback signal.

The all-important tape return monitoring is accomplished via 4 simple push buttons for tracks 1, 2, 3 & 4. Even when recording only 2 tracks, a 2 track backup recorder is often used, and this system allows confidence monitoring and playback of the back up machine as well.

The most comprehensive metering of any of the mixers on this list, the M8 has three stereo LCD bar meters, allowing six busses to be monitored at once.

With clean, logical, layout, 4 track recorder-ready, noise specs of -128.5dBu, the most self contained utility features of any other analog mixer in this list, and a very competitive price, the PSC M8 is definitely one to consider.

Cameo, by Zaxcom (www.zaxcom.com)

And now, for something completely different. The Cameo ($11,400) by Zaxcom, the same company that blazed the portable hard disk trail to the film production world with their Deva recorder, is the first portable 24 bit digital mixer built for location film sound production. At first glance, it resembles the other mixers in its class: Input trim and gain switches, Penny & Giles vertical faders… But a closer look will tell you it’s very different. For instance, there are no master faders. There are no EQ knobs on the inputs. And, what the hey… Yipes! There’s a mouse! But possibly the most distinctive part of this mixer is the glowing display that is, among 30 other things, a peak meter for all 8 inputs and their limiters, all 6 mix busses, and both AUX busses. Construction is economically simple but adequate, with a non-modular top panel with reverse-print Lexan overlay labeling that will last forever.

Briefly, the Cameo has 8 mic/line inputs with T and 48ph mic power, 6 main outputs, 2 AUX outputs, and 2 "COM" outputs for Boom, Director, or whoever. The inputs can be a combination of analog or digital signals, and all 6 mix buss outputs plus the 2 AUX outputs are available in digital and analog at the same time. There are no master faders because, well, who needs them? Sure there is the odd occasion, but during a film production the masters always remain wide open anyway, so: no masters. There are a total of 3 EQ knobs for all 8 inputs because, being a digital mixer, knobs can control the EQ of whichever inputs the microprocessor tells them to. The mouse is there for the same reason it’s found with nearly every computer used today: It saves time and effort.

Starting at the top of the input module, the user selects digital or analog input, then a toggle switch selects the input level which is fine tuned with the input gain trim knob. Next, there is a bank of switches to assign the input to any combination of the 6 main outputs. These switches have a center position that routes the input signal to a knob just below the switches labeled "Variable", for sending different levels to the mix busses chosen. The "Variable" knob can also be selected to function as a PAN pot. Below this knob is a group of switches for phase, EQ on/off, compressor limiter on/off, 2 notch filters, low cut, and PFL. At the bottom is the P&G fader.

The display has eight screens to choose from. The main screen (home) is mostly used for level indicators displayed as high-resolution vertical meter bars. On the top of the screen are meters for the 8 inputs, which is very useful in taking the guesswork out of optimizing the input trim. If the phase reverse switch is selected, an obvious "X" appears on meter for that input (very cool). Next to each input meter is a shorter meter that shows compressor/limiter gain reduction. Below the input meters are larger meters for the 6 main mix busses and 2 AUX busses.

As mentioned earlier, there are only 3 EQ knobs (High, Mid, and Low) on the entire board. Here’s how they operate: Pressing the EQ button on the input needing adjustment causes the EQ knobs to affect that input. Press the EQ button again, and the screen changes to a spectrum analyzer which displays the EQ curve. In this display (here’s where the mouse starts to come in handy) the frequency, width, and type of EQ (shelf/peak) can be selected and manipulated, as well as the parameters of the low cut and notch filters. As if that’s not enough, 5 presets can be stored for each input. Hit the EQ button again to return to the HOME screen.

Pressing the AUX button on any input changes the screen to a matrix that displays all of the signal routing which shows, at a glance, exactly which input is assigned to which output. Supplementing the "hard" input assignment switches on the top panel, additional routing is done through this screen by clicking on the matrix display with the mouse. With the click of the mouse, the inputs, Tone, Slate, AUX IN, and Talkback are assigned are assigned to (or removed from) all 6 main outputs, as well as to the Boom, Com, AUX 1 and AUX 2 outputs. For once it is easy to take the tone away from anyone (everyone) who doesn’t want to here it.

To list all of the Cameo’s signal routing and processing possibilities would take up too much space here, but suffice it to say that it is extremely versatile and the display allows it to be easily managed.

A unique feature of the Cameo that could exist only on a digital console is its Delay feature, which gives the user the ability to delay any input in increments of meters, feet, or samples. I have only used this mixer on two different productions, but, to my surprise, I have found an interesting and very useful way to use the delay on both of them. Often, because of either a wide shot, lighting, or high ambience, it is impossible to use the preferred boom mic, so a lavaliere must be used. The problem is the lav’s close sounding perspective may not jive with the camera’s picture. The remedy often used is to mix in a distant boom mic to add ambience or "fill", but the problem with that is the difference in microphone distances causes slap-back or irritating phase cancellation. Using the Cameo, I found that I could delay the close lavaliere by the difference in distance between the ambient boom mic and the lavaliere, time-aligning the two signals well enough to mix them together without the phasing problems. I was able to very closely approximate the sound of a single boom mic being used.

There are plenty of situations involving multiple mics and multiple actors that the delay tool would not be helpful, but so far, I’m two for two on productions when it was very beneficial. In my opinion, the delay feature is a revolutionary tool for location mixers that will really catch on as more Cameos are used.

The Cameo works very well with digital as well as analog location recorders, but it was certainly designed with Zaxcom’s Deva recorder in mind. There is a port dedicated for direct interface with the Deva’s 422 port for remote roll functions, metering, and return monitoring. The Cameo even has a text entry screen that allows scene, take, and title information to be recorded along with the Deva’s program material.

Other features of the Cameo: Fully variable compressor limiters for each input, with five storable presets. Direct digital outs for feeding, for instance, a DA-98. Off line communication to Boom operator and two others. Tape return connections for digital and analog recorders, switching from one to the other.

Because it is a digital mixer, it can always be considered a work in progress, and improvements can be made, functions can be tweaked, and features can be added without changing any of the hardware. Zaxcom has already made some adjustments and added some features suggested by Cameo users. Just pop in a new EPROM, and viola – your mixer has new abilities.

So, the Cameo is very different, just like our standard technology once was. Since more than adequate audio quality has been achieved by every mixer in this list (all within a couple of dB), the race now is for features and signal routing, and microprocessor driven digital mixers do not have the limitation of analog mixers. Assuming that reliability is adequate, sooner or later Cameo’s digital format is what we can expect the future to be in mixers to come.

Summary

When I was a kid I would tell people, "When I grow up I want to own a Nagra recorder and be a Location Sound Mixer, if my grades are good enough".

Back then you could use any recorder you wanted, as long as it was a Nagra III — there was only one choice. But that’s no longer the case with location mixing consoles today. As indicated in this list, there are a number of very good ones to choose from, and all are valid as professional tools. Budget, technical requirements, portability, etc, can be figured in to the decision making process. Fortunately, we have the option of choosing one that fits us just right.

– Glen Trew