Re: Using An Outboard Compressor with XD-Vs
on 2013-01-05 20:23:41
I happen to be a big fan of the Behringer Multicom MDX4600, provided an inexperienced operator has the patience to experiment and/or rehearse with it (or any other similarly versatile outboard gear) PRIOR to using it in front of an audience.
I've found that it's a worthy descendant of Klark-Teknik's similar, but much earlier and ground-breaking DN504 single rack-unit quad compressor. I also think that both are very versatile, have proven to be "roadworthy" and are excellent value for money.
"Will this truly benefit me?"
Careful use of compression is indeed one of the best ways of taking full advantage of the XD-V systems' clean delivery, but it's important to note that outboards such as this CANNOT simply have a mic (be it wired or a "cabled-mic-replacing" XD-V wireless) plugged into their XL inputs ahead of a mixer.
They're all essentially "line level" devices, which finds them EITHER being "jack-inserted" (be it via separate "Insert In" and "Insert Out" jacks or via a single TRS jack "y-cord" to those "In" and "Out" jacks) into the "channel strips" of individual mixer inputs,
being cabled via their balanced XL line-ins and line-outs to facilitate longer cable runs and/or the control of individual amplifiers such as can be found when using powered speakers.
The beauty of devices like the Multicom is not only that they allow each of the four processors they contain to be individually wired for its own application, but also the ability to very easily either "stereo link" pairs ...or even to "daisy chain" several should a "weird" special effect or very precise dynamic control be required.
I've taken the liberty of adding "Ron's Introduction To Compressors & Limiters"
...Which starts with this link to a great “getting started” document from Sean Vincent:
(I think it’s the best and plainest “non geek” guide I’ve yet seen.)
It’s only short and I’d suggest that what follows may make more sense after you’ve read it.
So What Exactly ARE Compressors & Limiters?
Here’s where I’ll revert to my usual gross over-simplification that really annoys the self-appointed “Purist Police”.
(“Oh dear, ...what a shame! ...There, there, never mind...” etc. etc.)
Regardless of how these devices are “packaged” or the means they use ...and whether they’re digital, analog or powered by teams of trained mice on treadmills, they’re essentially THE SAME device.
Think of them as an amplifier which has the invisible hand of a “phantom” operator continuously clutching its “volume” control, ...poised and ready to “tweak” it up or down as required, with all the mind-boggling speed and precision of a road crew attacking free drinks.
When the input signal rises above a pre-set threshold level, the “phantom’s hand” turns the volume down, when it drops below that threshold, the “phantom” restores the volume to “normal”.
With that in mind, it’s possible to imagine a limiter as being a version of that arrangement, but a version that’s fundamentally intended to spend most of its time dealing with signals that come in below that set threshold,
...whereas a compressor is the version of the same arrangement that’s designed to spend most of its time handling input signals that are above a pre-set threshold.
From that we can readily imagine that a limiter gets its name from only “limiting” (turning down) the loudest (above its relatively high threshold) peaks, whereas a compressor “compresses” by not only “turning down the volume” of the loud stuff, but also by “turning up the volume” of the quiet stuff.
Slowing the attack time tells our “phantom” to allow more of the initial “peaks” through before turning the volume down, similarly slowing the release time is an instruction to be more gradual with a slower “fade back up” to the “normal” volume setting.
Think of ratio as the “harshness” of the gain-reducing “twist of the volume control” that we’re demanding from our “phantom”.
A 2:1 ratio demands that a 2dB rise above our input’s threshold only yields half that amount of signal gain (1dB) at the output, whereas setting a ratio of 20:1 will only yield the same 1dB of gain at the output from a (relatively huge) 20db gain above our input threshold.
Limiters, intended to operate below their relatively high thresholds, (as they’re mainly employed for protection from peak overloads) typically employ ratios higher than 15:1, with some (like the Behringer MDX4600 in question) even offering a so-called ∞:1 (“Infinity to One”) “brick wall” setting.
Compressors, on the other hand, being mainly employed as “gain riders” or “sound fatteners” (hence operating above their relatively low thresholds) typically run to ratios from 1.5 to 10:1.
A compressor, therefore, has our “friendly phantom” continuously holding louder signals back with the volume control, all the while “turning it back up” in humanly impossible microseconds, thereby “catching and boosting” every softer sound.
This is why the device’s “gain reduction” indicator is nearly always active when compressing, but only “flickers” occasionally when limiting.
Here’s the “catch” with compressors. “Gain reduction” means exactly what it says. Operating above the threshold as we are, our “phantom” is indeed dutifully “fattening” and “riding” our sound, but by being always above the threshold, we’ve lost gain.
That’s why our compressor also features a “gain” knob. (Its full name would be “Gain Make-Up”, but the Registrar couldn’t fit that onto the birth certificate.)
With some devices the gain control provides just that, a fixed boost to compensate for compressor-induced gain reduction.
Others have the effect of making our “phantom” ambidextrous, with the one hand instantaneously varying the boost to compensate for the gain reduction “dialled down” by the other.
Some can even “instruct” our “phantom” to disregard the signal at our device’s input and to perform all “tweaking” in response to a different (and/or differently equalized) signal that’s known as a “sidechain”.
Whatever device is involved, ALL are dependent on the intense scrutiny and analysis that can only be provided by the finest instruments the Audio World has to offer.
These generally come in pairs and are to be found on either side of the human head, ...except possibly when dealing with the occasional painter of masterpieces.
The information above may not be current, and you should direct questions to the current forum or review the manual.