Reacomp Free Compressor- A Review

PLEASE NOTE: This article has been archived. It first appeared on in January 2009, contributed by then Editor Jeremy Dahl. We will not be making any updates to the article. Please visit the home page for our latest content. Thank you!

Pros:Free, very light on CPU, comprehensive features, easy to understand, good sound

Cons:For dirty, “colored” compression you might want to look elsewhere, doesn’t work in Wavelab.

Summary:An incredible value that dwarfs the competition, this is a stand-out track compressor in any arsenal. And did I mention it’s free‌?


Price- FREE

You may or may not have heard of Reaper, a remarkable sequencer that’s been gaining lots of ground over the last few years on its bigger competitors. But that’s OK, because Cockos Incorporated has been kind enough to release some of its basic DSP plug-ins for use in any VST host. The best part? They are free of charge.

Reacomp was one of the first to be released and the first one that I tried out as I’m always interested in a free compressor! It’s even better when released by an esteemed developer. So how does it stack up?‌ Let’s find out.

First Thoughts

There are two things that immediately occurred to me when I first opened Reacomp. One, it’s very clean and simple, and two, it reminds me of the old Sonic Foundry/Sony compressor. This is a good thing. I’m very used to Sony’s stuff from years of using Vegas, ACID, and Sound Forge (I wonder if Cockos were fans‌?). At any rate, I like how clear the layout is, and this would be a great compressor for beginners to learn with.

The Layout

I really like when compressors show you levels for your input, gain reduction, and output. It’s important to know what’s being done to your signal in case you want to figure out if your ears are fooling you, or if you need more accurate tweaks. It’s a snap with Reacomp to simply slide your threshold below your peaks and get going.

Now, I know that I said it is clearly laid-out, but there are a LOT of features packed into this little freebie; unmatched, I think, in the free compressor category. On top of the requisite basic features like Attack, Release, and Ratio, the long list of features are:

Pre-Comp: A look-ahead feature to decrease compression artifacts.

Knee Size: Allows the user to soften the transfer curve of the compressor.

Classic Attack: This sets the attack behavior back to the previous version’s character in case you liked that one better (personally, I found the new one a bit more effective).

Auto-Release: An always-welcome feature in my book, sets the release on”auto pilot”, adapting its length to the source material. This can be great for more transparent compression or different effects.

Side-chain Filter: Allows the compressor to only work at certain frequencies. For instance, this is very useful if you’re losing low end on the kick, but everything else is sounding super. You can preview the cutoff frequencies too, which is always a necessary feature so you can hear what the compressor is affecting.

Detector Input: Another feature here is the detector input, which lets you choose from typical stereo input or just left or right channels. Or, as is very in vogue right now, use the input from another channel to trigger the compressor for side-chain ducking and other neat tricks. You can even feed the output back into the compressor for “feedback” compression, which is featured on many popular hardware compressors of yore. And of course there are the Auxiliary inputs, which allow you to use another instance of Reacomp to trigger ducking-style compression, as is a popular feature nowadays.

RMS Size: This is a nice feature that allows you to switch from peak (zero) threshold detection to a more RMS, average detection. This can lead to a smoother sound and is used quite often in popular compressors.

Auto make-up: Always a convenient feature to have, this automatically raises the output level to compensate for the gain reduction of the compressor.

Limit Output: Another nice touch, this places a brickwall limiter over the output to prevent stray peaks from clipping. It’s a nice feature to have on for safety, or for peaks that just won’t stay down.

Oversampling AA: This is a bit of a surprise, and something I’m seeing more and more on today’s effects. You can multiply the internal sampling rate, forcing the plug-in to increase its processing power, thus becoming more accurate. However, this does increase the CPU. So be careful as you raise it. On my slow machine (P4 2.6ghz), the difference between zero oversampling and 64x made my CPU meter in Cubase jump from nil to about 20%. Multi-core users probably won’t notice much of a difference nowadays.

OK, enough! Use it already!

I decided to try Reacomp on a peaky drum loop that I keep around for just such occasions. Reacomp loads up zeroed without affecting the sound, which I like.  There’s nothing like having your track jump +6dB while you’re carefully mixing a multi-track project, so clean is good. I notice the ratio is set to 1:1, so I turn that up to 4:1 and turn the threshold down to get things going. I really like how you can see the left and right input below the threshold fader. This is perfect for beginners, as you can literally visualize what happens when the threshold goes below the peaks.

You can see in the gain reduction (GR) meter on the right when compression actually starts to happen (the top-most readout tells you how many dB of GR is occurring). This makes it extraordinarily easy for the user to control the amount of compression and identify problem areas, a real plus for this compressor.

As the threshold dips below the peaks, the worst of which are from the snare, the compressor starts reacting. This effectively catches the snare peaks without much change in the overall sound, apart from the expecting small reduction in volume. This is easily addressed with the output level slider, or you can elect to go with automatic gain make-up, which I do. This results in a significant output gain jump. But you can temper this again with the output slider, which is great. I prefer to match gain on my dry and affected signal so I can better hear what the compressor is actually doing to the sound. And to these ears, Reacomp seems to be applying some pretty transparent compression at moderate settings.

So let’s turn it up to 11:1!

…or infinity, rather. I’m curious to see what this sounds like at heavier settings, as I tend to not be so much of the 1970’s, 2:1 compression-type. I love to hear drums bleed, stomp, and thrash like a wild animal. So let’s see what happens when I lower the threshold to “pain”(shown on right).

I’ve really pulled it down now, and I’m reading an (un)healthy -12 to -16dB of GR. And although I like the crushed sound, I notice I’m losing a lot of the character of the attack. This happens on the first downbeat especially, which threatens to turn into a “pop!” instead of a happy kick drum. So I increase the Attack from 3 ms to 20 ms to try and remedy this, which it does.

The body of the attack has returned, and I’m pretty happy with the sound. I’d like to be able to take that attack lower without pinching the attack so much though. I should point out that this drum loop is particularly brutal on the first peak, but is ultimately a good test. Another solution to the “attack problem” is to increase the RMS size, which effectively switches the compressor from peak detection to RMS, or average level, detection. I lower the attack way down to 1ms and start raising the RMS slider; instantly, the compression becomes more transparent. I can hear more of the body of the drums, up through the highest levels, where it doesn’t sound like there is much compression at all. I found settings between 20-100ms to sound best as a compromise between clarity and character, but as always, experimentation is king.

Attack and Release my Knee

Reacomp also features detailed control over how the compressor responds to the input with advanced parameters for attack and release. The attack can be switched between normal and “classic” attack; “classic” being the characteristic from an older version of Reacomp in case one prefers it. This is not any kind of “vintage” modeled attack, as some may think though. Personally, I found the classic attack to be more frail than the standard and seemed to need oversampling to get to the same level of clarity. But it’s worth experimenting with.

The release features “Auto Release”, where the release time will adapt to the incoming signal to give you a more dynamic, natural response. I found the auto release sounded great at light-to-medium settings, but if you’re looking for big, pumping compression, it sounded more even with the auto release off. This makes sense as there’s no need to force your compressor to work hard, quickly adapting release times, trying to catch all the peaks when really all you want is a uniform, brutal compression. But this is a great feature to have, and something that I expect to see in much more expensive compressors, let alone a freebie like this.

Another welcome standard feature is a slider to adjust the knee curve so the ratio adjusts dynamically as the input nears the threshold, leading to smoother-sounding compression. This can be ideal for things like vocals and melodic instruments that tend to not have as sharp transients as percussion instruments. Many beloved compressors feature soft-knees by default, so this can be crucial in emulating the behavior of vintage hardware. Sure enough, increasing the knee on a peaky vocal track made the compression more fluid, and I could get away with some pretty fierce compression, which is sometimes needed in a modern rock mix.

Side-chain of Command

Now as I’m raising the compression levels, I’m noticing a familiar pitfall with compressors: the apparent loss of low end. The kick seems to be thinning out, and this seems even more noticeable in context of a mix, so what to do about it?‌ That’s where the side-chain filter comes in.

At the very bottom, in Reacomp’s Detector section, there are high and low pass filters which will prevent frequencies from triggering compression. This allows them to pass through and retain their original strength (as mentioned before, this is a commonly used technique in the circuitry of many hardware compressors). And by moving the highpass slider to 80 Hz, I can hear the kick drum bumping through at full force, retaining all its beefy glory. To really zero in on where you want the compression to act (or not act), you can switch on the Preview Filter and hear exactly what the EQ is doing; a handy feature that I would’ve missed had it not been there.

You can also use the side-chain EQ from the input of one instance of Reacomp to control the compression of another Reacomp. This enables you to do the infamous “ducking” effect that is popular in House music nowadays, scoop out room in conflicting instruments, or for creative endeavors beyond. You could also use the side-chain EQ for de-essing. The possibilities are endless, and it’s a great feature to have when one needs it.

Watching the Detections

To make matters even more interesting, the Input Detection features several different types of input signal. These include the stereo input, either side of the track, an auxiliary input signal, and one of my favorites, the feedback mode (also known as “Opto”), where the compressor’s output is fed back into the input. This can often create smoother responses with individual instruments. I found I could really lean on the compression in feedback mode, where content between the peaks didn’t leap out as much during heavy compression. So I’d recommend experimenting with this when crushing heavy objects.

Limiting Your Fun

So I’ve got a really pumping drum sound here. Nice and compressed, strong transients, solid low end, but the peaks have gotten away on me, and I’m going over 0dBfs – oh no!  But it’s all OK: Cockos has been thoughtful enough to include a limiter on the output to catch those stray peaks. So I switch this on. It doesn’t seem to impact the sound quality at all, and I personally love having a failsafe feature like this. I mean, sure, you could just turn it down. But sometimes limiting is just what the man asked for, and it’s nice to not change your overall level once you’ve got the sound you want.

Oversampling for Better Living

Now if all this isn’t enough, Reacomp features an almost unique feature called oversampling. Oversampling lets you increase the internal processing depth as if you were working at a higher sample rate, increasing the accuracy of the compressor. This does, however, come at a slight cost, which is an increase in CPU consumption. But once again, Reacomp provides a clever workaround to this. You can select from six different tiers of oversampling, so you can dial in only as much added accuracy as you require (or as your CPU can stand!), leaving it in your hands to decide what’s enough.

With my very heavy compression settings, I tried turning up the oversampling; first to 2x, then 4…8…but I didn’t hear too much until I got to 32x and 64x. At that point, the transients seem to just jump out at me and become a bit more defined – but it’s still rather subtle.

So I zero it and go back and increase the release time (which I had at very short). And at these settings, you can hear the compressor pumping a bit. So I increase the oversampling to 8x, and I can hear the signal tighten up and become more accurate. This is even more pronounced when using Auto Release, where the increased sampling allows the compressor to better read and anticipate the incoming signal.

The same should be true for the soft knee and RMS settings, and it’s best to experiment to get the best trade-off between transparency and resource hit. Ultimately, this could be the feature to take your compression setting from “almost…” to “yeah!”, if you can spare the overhead.

Final Thoughts

I have to admit that I was reserving a little skeptical place deep inside for this plain-looking plug-in that promised so much for so little. I’ve now let that place go and have given myself over to the bright, sunny world of free compression. This is one serious offering that has jumped to the top of my list as a first choice for track compression. Not only does it offer a myriad of features – the likes of which are often missing from expensive, high-end compressors – but it sounds great.

Reacomp is capable of a wide range of styles, from clean and transparent to pumping and squashing, with plenty of control along the way. Furthermore, it offers an extra degree of refinement over the sound with its detailed oversampling control, heretofore unmatched in the compressor world. And if there is any CPU used by this plug-in, it goes unnoticed by my CPU meter, which is greatly appreciated. It’s frustrating to see a compressor use 30 percent of your resources in this day and age when you may need to use it on every track in a complex mix.

The only real downside I can think of is that if you’re looking for really crazy, dirty, “colored” compression, then you’ll probably need to grab something else. But this can handle all your day-to-day duties quite well. Also, as of this writing, it does not work in Wavelab 5.

And Reacomp materializes astride a relatively new movement; a positive sign of what we can look forward to from small companies. They work closely with their clientele, often appearing on popular audio forums, keeping their ear to the ground, and hashing issues out with users and responding to customers’ demands. In fact, this plug-in is so “street” that it’s a little hard to find, even on the developer’s site (this could be both good and bad, depending on how closely you like to guard your secrets). But once there, you’ll notice this is part of a bundle of equally promising plug-ins which I encourage you to try. Possible reviews will come at a later date.

All in all, Cockos Reacomp is giving the Big Boys a real run for their money, and you owe it to yourself to check it out, be you beginner or expert.