Working with opto-style compression (1): bass

Opto compressors are said to sound very musical, especially when used with bass instruments and/or vocals. In my live rig, I’ve been using an opto compressor pedal for quite a while now, it makes my bass or guitar sound thick and warm, while preserving the punch of the instrument.

ONE LA500In the studio, I’ve recently had the opportunity to work with the IGS ONE LA500 (see picture), which is a single channel optical compressor just like the “good old” Teletronix LA-2A, a compressor heard on countless records since the 1960’s.

Soon, I’m going to post a mix I finished a few days ago. While mixing that song, I was using the ONE LA500 on every (!) track just to figure out what it sounds like, or what it adds to the sound. More about that mix project soon.

For today, I’d like to share some sound files which have been processed using the ONE LA500 by IGS Audio. Being sort of a descendent of the classic LA-2A, it naturally shares the same sonic DNA, and that’s why I used it on bass in the following examples.


1. Electric Bass

My first example features a short slow bass groove. (Don’t forget to use good earbuds or speakers.) The first audio clip is the unprocessed bass track, in the second clip, the bass track was processed through a ONE LA500 with about 7 dB gain reduction. Both clips have the same peak level, but the compressed bass track of course has a higher RMS level.

Unprocessed electric bass (D.I. signal):

Processed electric bass (compressed):

You can clearly hear the punchier attack and the longer sustain of the notes. Also, the shorter notes are much more balanced in volume. (That doesn’t excuse sloppy playing, but helps if you’ve got a sloppy bassline …) The makeup gain circuit, too, helps the track sit well in the mix, since it’s a tube design and adds nice harmonics if you crank the knob. If you don’t exaggerate, it adds some classy, elegant texture to the signal.


2. Double Bass

A short demo of an acoustic, upright bass. Again, the following examples have the same peak level.

Unprocessed double bass (mono track, 1 LDC mic):

Processed double bass (compressed):


Here, the original track was compressed using a ONE LA500, with about 6 dB gain reduction. Usually I wouldn’t use that much compression, especially if it’s a sparse arrangement. Instead, I’d process the track first (with dynamic EQ, gain automation etc.), AND THEN send it to the optical compressor, so I could dial in less (audible) compression and benefit from the sound of the unit (which there is, even at small gain reduction amounts). But that’s just me. To others, it might still sound great (which it does), and they’d dial in even more compression (which the LA500 is totally capable of).

Anyway, this example should demonstrate what the unit sounds like. Similar to the electric bass example, it adds some nice attack and sustain to the notes. Moreover, the musical phrases don’t die away at the end (listen closely to the length of the long notes).


Hope you like the clips! As these examples show, optical compressors are great for processing tracks with long, dynamic musicals phrases. To some, the differences might be subtle, but these subtleties will stack up in the end, over a whole mixing process with lots of tracks. Your bass or vocal tracks will sit incredibly well in the mix. For me, as a singing bass player, the only thing that’s better than an opto comp is two of them! But that’s another story …

More examples coming soon! Cheers, Tim

Comments are closed