Audio compression using UA’s 1176 peak limiter(Part 2)

There is some new gear in the Red studio at Musitechnic…

The 1176LN Peak limiter is a classic compressor designed by Bill Putnam and introduced in 1968 by UREI (now Universal Audio). Last time I looked at the history and features of the compressor. This time I’ll go through some different ways of using the 1176 and let you hear the results.

EQ mode

Some use the 1176 as a form of equalization. If you leave the “Attack” pot closed (fully counterclockwise) you effectively bypass the compression stage and the unit becomes an equalizer or a tone modifier. Without going into too much technical detail, the 1176 is based on the 1108 microphone preamp and gives a naturally edgy sound to whatever program goes through the unit.

I’ll let you judge for yourself with three audio examples: A drum room microphone, a DI bass and a speech track. You can hear the original non-processed and the modified (EQed) tracks. I purposely chose three different audio sources to process because certain characteristics of the compressor may not be obvious with some sources.

Drum Room Original:

Drum Room Comp Off

Bass Original

Bass Comp Off

Speech Original

Speech Comp Off

The 1176’s sound is partly due to the fact that, like the LA-2A, it is a program dependent compressor. The reaction of the attack, the release and the ratio depends on the materiel being played through it. The ratio you choose is applied on the transients of the source material being compressed and that ratio increases slightly after the transient. By how much? That will depend on the program, hence the term ”program dependent”.

“All-Button” mode

This is particularly true in the “All-Button” (or British) mode. In “All-Button” mode, the compression curve is changed. The attack times and release times tend to lag behind (what Universal Audio calls ”reverse look-ahead”). The ratio in “All-Button” mode is between 12:1 and 20:1, acting more like a limiter.

The limiting action can be clearly perceived in the following audio examples: the same drum room microphone, DI bass and speech used previously, but now in “All-Button” mode with a medium attack and release time (set at 12 o’clock). For comparison purposes I left the input knob (also acting as threshold) in the middle (12 o’clock position) for all three sounds. I normalized the files so the original and compressed sounds peak at 0dBFS.

Drum Room Ratio All Normalized

Bass Ratio All Normalized

Speech Ratio All Normalized

In “All-Button” mode the perceived level of distortion increases particularly in the lower frequencies making it an appropriate setting for drum overheads or a drum room microphone. The percussive nature and variety of frequencies present in a drum kit make it an ideal candidate for the “All-Button”. It is easy to understand why certain signal processing devices become favorites for certain sounds.

If the sound seems too processed to your taste, just tell yourself that you are not hearing the entire mix, you are hearing a single track in solo. In the case of the drum room microphone, it could also be used as the compressed track of a parallel compression setup. In addition, it should be noted that for comparison purposes, all my tracks are processed identically. The “All-Button” drum sound is even better with a faster release.

As an extra note. When exploring a sound processing device you are not familiar with, it may be a good idea to try bold moves. For instance, you are not sure what a certain parameter does, listen to the sound with the parameter potentiometer near off and then crank up the pot almost all the way and listen. Once you hear what is going on, then place the potentiometer in a more conservative position depending on what sound you are looking for. Remember that the brain gets used to little changes: as you change the parameter, your brain adapts to the changing sound and all you notice is a changing sound. If you let your brain listen to two blatantly different versions (pot open vs pot closed), your brain perceives the differences between the two with more ease. Psychoacoustics.

These are the settings I used for the audio examples. Every knob at 12 o’clock. Here a ratio of 4:1 is selected.

Compression

What about normal compression? Here are the same three audio examples with a compression ratio of 4, medium attack and release time (set at 12 o’clock). For comparison purposes I left the input knob (also acting as threshold) in the middle (12 o’clock position) for all three sounds. I normalized the files so the original and compressed sounds peak at 0dBFS.

Drum Room Ratio 4 Normalized