Mastering compressor ... free and paid GE edition...

TDR Kotelnikov is a wideband dynamics processor combining high fidelity dynamic range control with deep musical flexibility. As a descendant of the venerable TDR Feedback Compressor product family, Kotelnikov has directly inherited several unique features such as a proven control scheme, individual release control for peak and RMS content, an intuitive user interface, and powerful, state of the art, high-precision algorithms.
With a sonic signature best described as “stealthy”, Kotelnikov has the ability to manipulate the dynamic range by dramatic amounts, while carefully preserving the original tone, timbre and punch of a musical signal. As such, it is perfectly suited to stereo bus compression as well as other critical applications.
The concept is “proudly digital” in the sense that it doesn’t try to emulate any previously existing device. This is the original!

Key specs and features

• 64bit floating point precision for all relevant calculations
• Multi-rate processing structure for highest accuracy
• “Delta” oversampled signal path (bit transparent at 0dB gain reduction)
• Super fast, yet natural sounding compression
• “Crest factor” based control scheme offering independent release controls for peak and RMS events
• Flexible sidechain highpass filter
• Advanced stereo linking options optimized for the stereo bus
• Delta preview mode to preview the difference between compressed and original signal
• Latency compensated parallel bypass (i.e. processing not interrupted) 
  

http://www.tokyodawn.net/tdr-kotelnikov/

Definitely going to give this a try. We'll see how "intuitive" the UI is...the feedback compressor was somewhat less than intuitive. But once I figured out how it worked, it did a fine job even though I have other compressors that are faster and easier to dial in, and more CPU-efficient. The TDR Feedback Compressor never quite made it into my first-string lineup, but it's good. I expect Kotelnikov will be, too. (But jeez, they could have come up with an easier-to-remember name.)

I love TDR's other stuff and bringing in Vlad G was a very smart thing to do. I'll try the demo.

Initial experiments are promising. At first I saw "mastering" in the name and assumed it was a limiter, but quickly found out that it's a bus compressor and suitable for drum and other submix busses as well as inserting on the master in front of your limiter.
 
Just like TDR Feedback Compressor, there are separate peak and RMS thresholds, and you adjust their relationship via a "crest factor" knob. Like TDRFC, it's no dumbed-down one-knob effect - you have to think about what you're doing, understand the difference between peak versus RMS compression, and have a peak-to-average goal in mind before you start.

My first trial ended with a crash. I right clicked in the fx bin to remove it and....crash.

Now I can't seem to get it to crash...Let's pretend it didn't happen then. The comp itself sounds great to me, I love the added features such as the HPF and the stereo thingy.

The first time I tried Feedback Compressor it crashed SONAR. I didn't revisit it until version 2, after which the problem never reoccurred. It happens with new products, and for the price nobody's complaining.

Downloaded...   I'm curious to mess with the peak/RMS aspect.
 

Toneboosters is about to upgrade their (or his) Buscomp too and Klanghelm is working on another as well. These independent guys are knocking it out of the park!

TDR/Fabien have become one of my favorite devs, because a) Fabien really knows his sh*t, and b) the products are being actively developed and improved, despite being freebies. With some further optimization and some tutorial documentation these could easily become successful commercial products. But for $0 I'm willing to accept the extra CPU cycles and having to figure it out for myself.
 
The key to understanding this plugin is that there are two separate detectors, one looking at peaks and the other measuring RMS. With most compressors, you're either looking just at peaks or you have a choice of peaks or RMS. This results in the common practice of using two compressors in series on busses, one to contain peaks and the other for leveling. With Kotelnikov, one plugin handles both. Separate release times for peaks and RMS means you can let transients reset quickly while smoothing the overall volume with slower RMS release times. Or do the opposite for things you want to pump to the beat. Many combinations, but I haven't tried them all yet.
 
The trick is getting the peak and RMS detectors to not fight one another, e.g. when you have large peaks but low overall average values. The "crest factor" knob handles that, by setting the relative influence of the peak and RMS detectors. Turn crest factor down to raise RMS (loudness), turn it up to mainly just control excessive peaks.
 
In this way you are able to decide how much punch you're willing to sacrifice in the name of loudness, or vice versa. Turn it fully counter-clockwise to turn the plugin into a plain peak compressor. Turn it fully clockwise to make it straight RMS compressor. Set it to around 3dB to give peak and RMS equal weight, a good place to start on the master bus.
 
You'll also want to adjust the Knee parameter depending on how the compressor is being used. For leveling, turn it to 12 o'clock or more. For peak limiting, turn it fully counter-clockwise.
 
Even though it's intended as a mastering compressor, the plugin's minimum attack time of 20 microseconds puts it in 1176 territory in terms of ultra-fast clamping/clipping. I haven't explored this aspect yet, not generally being a fan of very fast attacks except for specific remedial situations. But I think it's pretty cool that one plugin covers so many bases.