Five-band Digital Signal Processor Review
ã 1999 by Eddie Ciletti
| MANUFACTURER: TC Electronic; 790 Hampshire Road, Suite H; Westlake
Village, CA 91361-9773. Vox:805-373-1828 Fax: 805-379-2648
APPLICATION: (Not "limited" to) Broadcast audio signal processing SUMMARY: Five band compression, limiting and expansion with presets. STRENGTHS: Each band has independent threshold, attack, release, ratio, range and output settings. Manufacturer and user presets. "Wizard" mode helps you get started. WEAKNESSES: Attack and Release ranges (for the compressor), should be interchangeable. LIST PRICE: $ 3995.00 |
Your stereo mix is the biggest challenge for any dynamics processor. That’s why it’s so difficult to find the right one. Processing just a kick, vocal or bass track is easy, but you can never fully optimize the attack and release parameters for full-spectrum audio program.
ADJUSTABLE COW
When you hear or read the hyper-raves about a vintage Neve or Fairchild compressor / limiter, keep in mind that while these boxes have a certain "Magic," they aren’t perfect for all mixes. And you can’t just take a piece of a circuit, like the gain reduction device — optical or FET or variable-mu — and surround it with opamps. The full-monty magic is the combination of transformer saturation, the characteristic tube or transistor overload plus your mix. Translation: You can tune your mix for a specific compressor but the reverse is not always true.
GROVELLING FOR BEADS AND OTHER TRINKETS
If all of this "sonic voodoo" sounds like a bit of a crapshoot, it is! To increase the odds you have to be either very rich, very knowledgeable or have a multi-band compressor. The latter is what made the TC Finalizer successful. By splitting the signal into three bands — low, mid and high — each compressor / limiter can be optimized for that specific frequency range. It’s not magic. It’s multitasking for audio.
That’s why I was thrilled to snag the broadcast version of the Finalizer,
DBMax,
after seeing it at the TC Electronic booth at last year’s AES show. It
looks like the Finalizer because it’s the same basic hardware but with
software optimized for Broadcast purposes. Instead of three bands, the
audio spectrum is now divided into five bands. This is not new for broadcasting,
but doing so in the digital domain means you can save settings. Considering
how bad commercial radio sounds, anything that motivates broadcasters to
attempt improvement should be encouraged.
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CROSS DRESSING
Why review a broadcast product in a project studio magazine? Well, a microphone designated as being "perfect for guitar" can be used on other instruments, so too can the DBMax find life in other environs. Splitting the audio into five bands works great for the Expander. Funny isn’t it. Here’s a box that can bring back The Dead (hello, Jerry?) and I’m getting my jollies playing with the expander…
By choosing the fastest release time on the "ring" band (centered at about 430 Hz), the DBMax effectively killed the ring in a snare drum without sucking the life out of it. Slower release-time settings on the other bands let the "good leakage" through — the upper-frequency "air" and that dirty low-down womp! I also used the multi-band expander along with the equalizer to "denoise" some old AM radio broadcasts.
Figure Two: Threshold, Release, Range, Ratio and more can be independently set for each band
PAYING HOMAGE TO THE MASTER(S)
The biggest chunk of my time was spent using the DBMax to master a demo for a friend, Dina Regine. Every time she fills up an Adat tape, I throw it into my Soundscape workstation and make a slave reel. Some of the mixes she’s been able to do at home, others were done at my place. Her varied material and our very different approach to mixing yielded a wide range of tracks.
To start, all of the mixes were transferred to one DAT in the sequence requested by the composer. I then listened to each track to determine which needed tweaking. I did nothing to the best sounding mixes — three out of twelve — the other nine got very special treatment, each saved as a preset and detailed in a log. Like Roger Nichols said in his February column, "Documentation, documentation, documentation!"
TRIMMING THE FAT
One track sounded perfect in the verse but the chorus had been over compressed, especially obvious on the lead vocal. For that track I used just one mid band of the expander — 630 Hz to 3.15kHz — setting the threshold to trigger expansion in the chorus.
On another track, I needed to extract some high frequency intelligibility without making the track too bright. There is high frequency pre-emphasis for FM broadcasts along with a limiter to keep it under control. After turning it on, I then went into the compressor and trimmed away the excess brightness by pulling the level down on the upper frequency bands.
Please note: On some of the songs, I did also use the "Pentode"
feature of the Crane
Song HEDD, to warm things up.
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| Figure Three: Using the high-frequency emphasis along with its dedicated limiter to improve intelligibility. | Figure Four: Using the individual output level controls to undo the emphasis EQ |
SHEEP DOG
After listening to the whole CD burned from the DBMax’d DAT, all of the songs now feel like they came from the same neighborhood. My sonic herding instincts were good, even though I burned the oil that night. Had I made a big mistake, my notes and the presets were all in order. I know what I did!
TAKE ADVANTAGE OF TECHNOLOGY
Now more than ever, I understand why mastering engineers are up in arms about the excessive use of compression. Listening to all the mixes, with fresh ears, on great monitors — Dynaudio BM15As — excessive processing is more than obvious, it’s annoying. If you’re guilty of dynamics abuse, the ability to record 24-bit could change your life. (Check out the Tascam DA-45 review also in this issue)
Rather than play the carnival game of trying to get as close to 0dB Full Scale without hitting the "over" gong, you can now be more conservative during the mixing process. Unlike the magic processors of old, TC’s DBMax (and Finalizer) can be tuned to your style of mixing — after the fact — so that you can comfortably record to 24-bit without relaying on a dynamics processor to maximize the signal. Then, use the DBMax during the pre-master phase, customizing it to the specifics needs of each piece, then, if necessary, use it to dither the 24-bit mix down to your 16-bit destination of choice, allowing you to keep a clean hi-fi master.
Granted, broadcasters will assume the lowest common denominator — a car stereo with 5 watts per channel (plus wind, engine and road noise) or a similarly powered boom box. "Radio" needs to squish your 16-bit mix into about 3 bits, 4 bits on a good day.
DIGESTING CROW
I often listen to Sheryl Crow’s Tuesday Night Music Club while writing. Sure, it’s a bit over compressed and that is part of her sound, even several albums later. Just for fun, I put the CD through the DBMax and "expanded out" some of the compression. The results were surprising. All of a sudden, ear-tickling transients gave localization cues — I could here space in the mix — instruments seemed more present and three-dimensional.
I know it must seem odd to take a device designed to make things as loud as possible and go the other way, but the DBMax is surprisingly effective in both directions. If you need a stereo signal processor that can be transparently gentle or seriously aggressive, the DBMax can live in both worlds making it both a sonically and a monetarily effective solution.
FINAL-IZED COMMENTS
I love the power of mulit-band processing so it’s a no-brainer to say the DBMax is a powerful tool that can help make things sound better and/or more consistent. You know, I didn’t even open the manual! That’s one of the things I like about TC products, ease of use. While I have a few functional preferences (mentioned below) there is only one comment about the way the DBMax works out of the box.
The Bypass switch (naturally) does not "hard wire" the input to the output. Doing so could actually cause major glitches because this is a digital box and clocks get upset when they get interrupted! Instead, it makes a "soft" transition from "Process IN" to Process OUT." My beef is that the transition time is too long and that the "sound" of the transition is too obviously "digital." It should be faster and, if real estate permitted, I’d like to see a real BYPASS switch and the current switch relabeled as "Process: In / Out."
SIDE DISH: SAFETY FIRST
It’s easy to over-use any dynamics processor, but here’s one tip that might help you become a "safe" operator. It seems that modern design engineers have this preconceived notion that compressor attack time should be faster than release time. The Finalizer and DBMax are both guilty of this as are many other compressors. I don’t feel it should always be the case. ( There is a power-assist "Wizard" mode, but I'm a hands-on guy! )
Try starting out with a slow attack time (50mS to 70mS, if possible) and a faster release time (10mS to 20mS) to preserve the ear-tickling transients while smoothing out the dynamics. That’s what a compressor should do. DBMax also has what all digital compressors should have, the ability to "look ahead." (The TC Dynamizer plug-in for Soundscape also has this feature.) One of three tweaks I'd make to the DBMax would be to correlate the "look ahead" value with the attack time. Whatever value Attack is chosen should (at the user's option) bump the "look ahead" to that value.
Tweak Number Two would optimumize the Attack and Release range for each
of the five EQ bands. Tweak Number Three would integrate the Attack
and Release sliders into one control so that there would never be a "bad"
setting. (Attack and Release can't both be as fast as possible because
doing so yields about the most awful sound since four-bit digital audio
hit the toy market!)
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