Mixbus Compressors

I have some questions about the Mixbus compressors. The only (free) documentation I know about Mixbux is Mixbus_Install_QuickStart.pdf which does not have much detail on the compressors. Perhaps there is some other documentation I am not aware of?

Here are my questions. I am familiar that a compressor may have the following parameters: threshold, compression ratio, attack time, release time, make-up gain, shape of knee (maybe more?).

It would appear that the Mixbus compressor allow modification of only threshold (via slider), attack time (via rotary knob labelled “FAST SLOW”), and make-up gain (via panel activated by the tiny button). I guess (?) the compression ratio is not settable? If so what
compression ratio is used (probably different for Leveler, Compressor, Limiter)?

Also, I’m not completely sure what the difference is between Leveler and Compressor. My guess is that Leveler is based on RMS level, and Compressor on peak value.


The actual allgorithms used are slightly different IIRC, but don’t quote me on this.

The leveler is closer to the LA2 leveler, while the Limiter I have been told is closer to the 1176. Not sure on the compressor, but really the main thing you are choosing with all of these are the characteristics defined by the attack and release, where the speed control modifies both at the same time I believe. Leveler tends to be a slow attack and release, whereas compressor is a much faster attack paired with a faster release(Though not necessarily a linear correlation). The leveler uses a pretty light ratio, while the compressor has a much heavier ratio as well.

To give examples, I use the compressor on drums etc. whereas I use the leveler on bass and vocals often, along with sometimes on acoustic guitar as well.


also , when klicking on the very small button right from the harrison logo below your faders, you open up the channel strip editor, i m not sure,but i think at least compression make up is only changeable here (or not??), … but its also unusual to me to not know the compression ratio, or at least something like “soft”," a little more" and “very much” :wink:

Leveler = Soft
Compressor = More
Limiter = Hard

In all honesty I generally find one of two things true with Harrison’s Compressor[s]. Either they work for the material I am doing(Most of the time) or they don’t (Not often). So in general I don’t use other compressors, but on occasion I might. For any of this though I use my ears to decide and don’t worry about the numbers;) Been pretty happy that way to tell the truth.


yeah of course, the ears should judge, thats a good point! and thats generally how i see the mixbus effects; (just started with mixbus on linux…) to have kind of a analog live feeling twisting the nobs till it sounds decent…

While I see that you’re on Linux, I have found that I prefer the sound of iZotope’s Alloy compressor when you need something more than the built-in Harrison compressor. If you want controls, it has them, just not the ‘knobby’ kind.

For linux, I’d recommend the LinuxDSP suite of dynamics plugins; see www.linuxdsp.co.uk (linked to from the Ardour.org news pages) for a wide variety of choices.

There have been a few things I’ve wanted to do with the sound on a track that the otherwise superb Harrison compressor would not do; those things have been handily dealt with (in OS X) using Alloy’s dynamics module. Including taking a very long sustain electric bass and making it sound almost like an old Kay upright… with a bridge mic, at that. I used all three slopes in both of Alloy’s two stages, but I didn’t actually have to use the multiband feature, although I might get slightly more realistic sustain fade (where the lows fade out before the ‘gongish’ higher frequencies do) if I were to go multiband.

Although using the Harrison leveler, driven rather aggressively and with the speed timed to the beat of the track made what Alloy did a lot more consistent.

And I’ll agree with Seablade; the Harrison leveler sounds a LOT like a UREI LA2; I had a real LA2 several years back, and have some tracks recorded through it, with both wet and dry versions for comparison; I loaded the dry pre-LA2 version into Mixbus and compared the leveler output (after finding the closest ‘speed’ match) with the wet LA2 output, and it was very close indeed.

I say had: the LA2 stopped working shortly after those tracks were done, but I found a buyer willing to give me a rather nice sum even with it in ‘broken’ condition (yes, I told him exactly what I thought was wrong with it…). Because of the agreement with the client involved with those tracks I can’t post them (or excerpts of them) anywhere, sorry, and while I might wish I had less encumbered tracks in both dry and wet forms through the LA2, I don’t…and that has been quite a while back, fifteen years or more, since I sold the LA2 ‘for parts’ for a very tidy sum.