I have been a user and fan of Metric Halo's hardware and software for quite a few years now, having gotten my first Mobile I/O 2882 +DSP [Tape Op #34] almost a decade ago. My two 2d-upgraded 2882s are still the hub of my home studio setup and allow me to achieve superb sonics and complex routing scenarios with very little rack space needed. However, despite the excellent sound of the +DSP plug-ins, I found myself using them more and more rarely, since they run in their own accompanying software and not directly in Pro Tools. Metric Halo recently released a seven plug-in bundle for both AAX (Pro Tools 10) and AU formats, so now I can get the best of both worlds - MH sound directly within my Pro Tools work environment.
ChannelStrip 3 is the new version of Metric Halo's long-revered flagship plug-in. There are four separate sections available in ChannelStrip, each individually activated through nice, big, square buttons at the top of the GUI - gate, compressor, EQ, and hard (brickwall) limiter. Sidechaining capabilities on both the gate and compressor are extensive, either from an external source or a filtered version of the signal itself. You can open up a window to the right which gives you a graphic representation of the adjustable compressor knee and EQ/filter curves being applied to the sidechain. The compressor has four curve settings: smooth, warm, fast, and "MIO", named for the hardware box that runs the +DSP plugs. I found myself preferring the MIO setting most often for its flexibility; it sounded really good whether it was set to be grabby or to be smooth. Look out for auto-gain on the compressor, by the way! It can make your signal very loud very quickly if the threshold gets set low.
ChannelStrip's EQ has six bands, each of which can be switched to one of six filter types (high shelf, low shelf, high cut, low cut, band-pass, or peak). The peak setting is fully parametric, and you can change the slope of the band-pass and shelf curves, but I was a little disappointed to discover that you can't change the high or low shapes - they are set at 12 dB per octave. Over in the display graph pane (which can be hidden to save screen real estate), clicking on the magnifying glass icon switches on a very accurate real-time spectrograph overlaid on your filter curve, with different colored traces showing post-EQ peak and average frequency analyses of each channel. This is one area where it is evident that this bundle was designed by the guys that made SpectraFoo, one of the best software tools available for analyzing audio.
At the end of the plug-in's signal path, the peak limiter has a simple threshold control, which effectively makes your audio louder as you decrease the value, by chopping off the peaks and raising the average level.
Bluntly put, ChannelStrip 3 just sounds incredible. Each of the sections does what it does so effectively and flexibly that I feel like if I lost all of my other dynamics and EQ plug-ins somehow (unlikely, I concede), I would be perfectly happy using ChannelStrip for all of my gating, compression and EQ needs. It's extremely transparent when necessary, but the compression section can be made to impart various colors by tweaking the knee and curve settings. The EQ is both surgical and musical - and extremely responsive even at relatively low dB settings.
One more thing that I think is worth mentioning is that the interface of ChannelStrip is remarkably elegant. It isn't a skeuomorphic representation of some classic piece of gear, but it is highly intuitive, and honestly, it's just plain beautiful to look at. The use of color is more functional than flashy, and parameter values are easy to read and enter manually. My only small complaint is that the "shadow" of some of the knobs slightly covers the knob's label, making it a little tricky to read everything clearly. However, since you can resize the window in a way that actually enlarges all of the controls (a unique function I hope to see in more plug-ins in the future), this becomes less of an issue. Plus, in addition to mouse scroll-wheel support, all of the functions of the Production Bundle plug-ins are very well integrated into both the HUI and Eucon protocols, so control surface users can take advantage of physical knobs and labels.
The two plug-ins in the bundle that share the most GUI- wise with ChannelStrip are Multiband Expander and Multiband Dynamics. Each of these split your signal into three bands at crossover points of your choosing - frequency-dependent expansion or compression can then ensue. I found the interface of both of these plug-ins extremely straightforward and was able to use them very effectively. In addition to plenty of finely-tunable gating use, I used Multiband Expander as a noise-reduction tool by tweaking the crossovers to only let through the business frequencies of a noisy guitar amp track. Multiband Dynamics was great for quasi-EQ'ing a dull drum-machine track, bringing it to vivid life. I also effectively employed it in a couple of mastering projects and found it easier to wrap my brain around than other multiband compressor plug-ins that I own. Part of it is that it's a manageable three bands, and also the extensive graph displays help you understand exactly how it's affecting your audio. There is a brickwall limiter at the end of the circuit as well, to get the overall volume up, but I found I liked bypassing this and using one of my other mastering limiters slightly better. If you don't have another mastering limiter, though, this one will most certainly do the job.
Precision DeEsser is another frequency-dependent dynamics processor, and its functionality goes way beyond taming vocal sibilance. It excels at that, but the range of controls, from width and sharpness of the detection band to the time constants of the compressor circuit, allow for some seriously effective and transparent de-essing. I also used it to tame hi-hats, remove some midrange harshness from a questionably-recorded trumpet track, and soften the attack of a very bright piano. I do wish the center frequency went lower than 2 kHz, but for grabbing specific lower frequencies, you can always use Multiband Dynamics instead.
TransientControl will be familiar to anyone who has used the SPL Transient Designer [Tape Op #21], but it gives more advanced control over the detection of the transient and sustain envelopes. It also shows a process meter, providing a graphic idea of how the processor is treating your signal. The basic controls are Transient and Sustain - the former increases or decreases the amount of attack the signal has, and the latter lengthens or shortens the tail of the sound. You can get similar effects using standard compression and expansion, but this sort of processor has its own sound, and is great for easily adding a little more punch to a bass drum or sustain to a snare track, or for taking the pick noise of a plucked bass track down a little. A comparison to the UAD SPL plug-in is inevitable, since the basic controls are identical, and I have to say I find the UAD more effective. Also, interestingly, I found Metric Halo's +DSP version on the hardware box to sound a little better, partly because the range of the Sustain control goes down to -1000% instead of the -300% on the Production Bundle version. That extended range allows for much more effective envelope shaping, allowing you to almost eliminate any room sound or printed reverb on a track, for example. (Metric Halo reports that this is a bug and will be fixed with the next update.)
Another plug-in ported over from the +DSP suite is Character, which emulates the saturation imparted by various tubes, tape types, transistors, and transformers. However, whereas the +DSP version doesn't give any control over parameters, the Production Bundle version provides Drive and Gain controls, in order to fine-tune the gain-staging and saturation level of the emulated circuit. The differences between many of the 20 models are very subtle and only start becoming apparent when used on many tracks simultaneously. In this way, you can simulate using a certain console or tape machine across your entire session. The less subtle models are the Soft Sat settings, which head into actual audible distortion of a very pleasant, analog-sounding nature.
Finally, HaloVerb is another +DSP offspring, and it is an algorithm-based reverb of the utmost quality. The main control may have a confusing label to some people - RT60, which is a way of measuring the length of decay in a room or reverb tail by determining how long it takes the sound to fall below 60 dB. Just think of it as reverb time. Damping and diffusion respectively control how much the reverb feeds back into itself and how dense the reverb tail is. There are high and low-shelving pre-filters, a predelay setting, a wet/dry mix, and a width control for stereo instantiations. There are also graphic displays of your filter curves and reverb impulse tail. Altogether, this gives you an extremely natural sounding reverb that has the capability of sounding like a tiny room or a cavernous cathedral, and everywhere in between. I would place HaloVerb into the category of reverbs that effectively puts your music into a space, as opposed to sounding like an effect. I haven't mixed a session since I got the Production Bundle that didn't employ at least one HaloVerb instantiation; it has in fact been more common that I have used two or three separate HaloVerbs for various instrument groups, which always sound extremely coherent with each other within the mix.
I really can't recommend Production Bundle highly enough for anyone using a compatible DAW on any level. The value is phenomenal, given the amount of care and expertise that went into designing these plug-ins. On a personal note, the timing couldn't be better for me to have access to such a high-quality processing suite, since I recently relocated to Brooklyn and have temporarily lost access to most of my hardware, which stayed behind at my studio in Oakland. I still look forward to getting back to using hardware while mixing, but in the meantime, this bundle gives me plenty of confidence that I'm not cutting any sonic corners while working primarily in-the-box.