In the never-ending quest for good monitor mixes, engineers field a steady stream of requests and/or complaints from instrumentalists and vocalists alike. “More piano, please.” “I can’t hear myself at all!” “Did you just turn down the CD track?”
In an effort to lighten the engineer’s load (and leave performers with only themselves to blame for a bad monitor mix), several manufacturers have developed personal monitor mixing systems. These so-called “More Me” systems place a small mixer right by the performer. Instrument and vocal signals come to this mixer individually (or in small submixes), allowing for personal control of instrument blend and overall monitor level. When properly implemented, personal monitor mixers can spell the end of grueling monitor checks, too few monitor sends and disgruntled performers.
The TDM-16 system from Boling Engineering gives performers control over up to 16 discrete input channels, plus overall monitor volume, from a compact on-stage mixer. Up to 16 mixers can be connected to the TDM-16; expander and extender modules are available to increase both the maximum number of mixers and the maximum working distance between console and mixers. The TDM-16 Main Console ($2,700) is also available in an eight-channel version (TDM-8, $1,700), which will support up to eight mixers. Output Mixer Stations are also available in 16-channel ($350) and 8-channel ($290) versions.
A Closer Look
The TDM-16 Main Console is a free-standing unit held at a useful angle by two sturdy legs. The front of the console is simple by any standard—it sports just 16 input level control knobs with signal present and peak LED indicators for each, and a single power LED. All inputs and outputs are on the back panel, including an XLR in/out for each channel, 1/4-inch in/out per channel and 16 mixer output connectors. Each output is hard-wired to its corresponding input, insuring no loss of signal level or quality.
Thanks to its loop-through connectors, the TDM-16 can intercept mic and instrument signals before they get to the snake. This is probably the simplest setup, with the Main Console taking the place of a traditional monitor mixer. Another option is to route signals from the house mixer to the Main Console, which opens up the possibility of submixing certain channels before they return to the monitor system (i.e. drum set, brass section). A hybrid of the two approaches will also work, where some channels are captured on-stage and others return from the house mixer.
You can think of the TDM Main Console as the system’s input, with the appropriately named Output Mixer Stations being the system’s “business end.” These compact mixers connect to the TDM Main console by a somewhat unorthodox means: standard coaxial TV cable (i.e. RG-59). Because it has just one large conductor, the TDM-16 can use “cable cable” only by combining all input signals into a single multiplexed signal. This composite signal travels to the mixer in the digital realm, where it is converted back to analog before hitting the headphones or monitor.
As evidenced by the many Ethernet digital snakes available today, sending audio around in digital form is becoming more common. Boling’s approach is a little different. By using RG-59 instead of CAT-5 Ethernet or fiber optic cable, the TDM-16 can route a decent amount of power to the mixers. How much power? Enough, it turns out, to place a small power amp inside each mixer. This amp will churn out 7 watts into a 4 ohm speaker, which can drive a very efficient speaker into the 100 dB SPL range. This is a best-case scenario— most passive monitors aren’t this efficient, making the TDM-16’s power amp of use only where stage volumes are very low.
The TDM-16 mixer’s headphone output is far more useful, coming in both 1/4-inch and 1/8-inch varieties. With low-impedance phones (the most common type) or in-ear buds, the TDM-16 mixer puts out plenty of crisp, punchy sound. Only when you exceed the recommended 100 ohms impedance for headphones does the output suffer. Even with volume maxed, the TDM-16 mixer wasn’t able to drive my favorite AKG- 240 headphones (600 ohms) to a high enough level before distortion set in. I was warned.
Another option is to feed the TDM-16 mixer into a self-powered monitor or external power amp/speaker combo. For whatever reason, though, the mixer does not have a line output for these situations. Instead, you have to use either the speaker or headphone output. The manual is mum on which output to use for a line-level signal; both seemed to work fine in testing. This omission of a bona fide line output is unfortunate, especially considering how many selfpowered monitors are now in use in churches across the country.
What you plug into the TDM-16 mixers also affects how far they can be from the Main Console. With a passive speaker attached, loss of power in the cable limits length to 50 feet. Low-impedance headphones double this distance to 100 feet; high-impedance headphones can sit a full 150 feet from the Main Console. If you need greater cable runs, two options are available that add 500 feet to the lengths listed above. The TDM EXPander ($450) boosts one coaxial input and splits it to eight outputs, while the TDM EXTender ($150) extends a single cable run. Both require AC power.
More Me, Please
Once you have channels patched into the TDM-16, it’s a simple matter to set levels with a twist of the input level controls. The TDM-16 has gain galore, easily handling even less-than-sensitive mics and very quiet electronic instruments. Each channel has a green LED indicating signal present and a second red LED to indicate the onset of clipping. These lights are very bright, which is a blessing when trying to keep an
eye on things from across the stage. With signals dialed in to correct levels, they’re off to the Output Mixer Stations. Operation of these mixers couldn’t be simpler. Each input channel has a blue knob to control its level, while a single red knob controls the overall monitor volume. There are no switches, buttons, signal LEDs or meters to be found. The only trick is keeping track of which signal is on which knob—the mixer’s front panel doesn’t have channel numbers.
Labeling is a problem area with the TDM system. Knobs don’t have dB markings (yes—some folks use them); input level knobs have numbers 0 through 10 on their perimeter. Channel numbers don’t appear on any part of the Main Console or Output Mixer Station, front or back. Likewise, mixer outputs are not numbered on the Main Console. This can make troubleshooting a bad cable or connector unnecessarily complex.
Speaking of cables, anyone who has worked with TV cable knows it can have a mind of its own. It can be stiff and stubborn, and almost impossible to keep flat on the floor (especially if it came off a small roll). RG-59 was meant to be run out of sight, underneath a structure or inside a pipe, and most churches would be wise to keep it there. Plan on running the TDM’s thick coaxial cables under the stage as much as possible. If you’re needing to run cables on-stage, cable from a large spool will give you fewer stubborn bends. You will be supplying your own cable with the TDM system, as it’s not included.
Sonically, the TDM system sounds good. Frequency responses seems broad, and coloration and distortion are not a problem when input levels are properly set. Where the TDM system struggles is in the area of noise. The manual describes the prominent “scratchy” sound of the mixer knobs as normal, and it’s not really a problem as you only hear it when a knob is being turned.
What is a problem is the self-noise—hiss—that the system generates. With all knobs down, input and output alike, the noise is noticeable. Bring several channels and the output level up at the mixer, and the noise jumps considerably. With all mixer channels at a normal level, the system’s self-noise is downright loud. All the noise seems to be on the output side, as it remains basically unchanged regardless of input level settings.
Though clearly the product of a small company, the TDM system appears to be very well made. Main Console and Output Mixer Stations are sturdy and solid-feeling. Boling Engineering backs the TDM system with a one-year warranty.
The Boling TDM system delivers on the personal mixer promise with no-brainer simplicity and a few added niceties (like the built-in power amp). Unfortunately, noise mars the TDM system’s otherwise clean sound. The noise is a result of the design of the TDM system, and no revisions are planned to eliminate it. You can either live with the noise or you can’t—I’d recommend you try before you buy (or at least talk to someone currently using the system first). Personal monitoring systems can solve a host of problems, and few churches ever switch back to the “old way” once they’ve tasted the freedom of individual monitor mixers. If your church is plagued by stress and strife where monitors are concerned, you may find your solution in the Boling Engineering TDM system.
