Rickresource Rickenbacker Forum

How would you define compression, as in what happens in a tube amplifier? It doesn't seem to me to be the same as the compression that is used for vocals. The definition I am familiar with is it reduces the dynamic range.

I was playing my Blackheart the other day, and I cranked it, and a fairly knowledgeable guy said, wow that's compressed! He has been out of town lately so I haven't asked him exactly what he meant. Can someone shed some light? I didn't find out if he thought that was a good thing or bad either!!


Thanks

Ok, I guess it's good we have a studio at work. I asked one of the guys, and he explained: Vocal compression when recording is clean, no distortion, tube compression turns the sine wave into a square wavy(distorted) thing as you push the output, but does not get louder, thus "compression".

The difference is clean versus dirty compression. Now I know.

I'd call that "clipping" not "compressing."

"Square-wavy" = extra harmonics = "distorted" sound (in quotes because any deviation from the original sound wave is by definition a "distortion" of the original sound but in this case we mean that classic "distortion" sound). Compressing my bass does NOT result in distortion unless I want it to.

Right! The "sweet" sound of the guitar comes from the output tubes squaring off the wave a tad. The bass, not so much.

Compressing is taking the dynamics of the waveform and boosting the lower levels and lowering the higher levels dynamically, to make the range of the signal more constant in level, determined by how you set the controls.

Radio stations have done it for decades to make their station appear louder while staying within the frequency constraints of their channel.

Which is why recording off the radio sucks!

Technically, compression does not boost lower levels. Simply put, compression reduces the dynamic range of an audio signal so levels do not go above a set threshold. This allows you to boost the entire signal level.

Erik, I know you are correct in the sense of audio compressors used for recording. In the broadcast industry, it is as JA says, IIRC. They compress and muck with the signal for power purposes.

blueflamerick wrote:Technically, compression does not boost lower levels. Simply put, compression reduces the dynamic range of an audio signal so levels do not go above a set threshold. This allows you to boost the entire signal level.

Erik, what you describe is a limiter. A compressor , ANY compressor used for recording OR broadcast, does in fact raise quiet audio and lower the louder audio, reducing dynamic range but raising the average sound.

Here is an explanation of a compressor from the Tweakheadz site:
"OK, Imagine you had a vocalist who would whisper words quietly and then belt out some loud screams. You, the engineer, has to record such a take. You find the whispers are too quiet unless you boost the fader and the screams require you to quickly lower the fader so you don't overload the recorder. That is the time-honored technique called "riding the gain" (gain is another word for volume). A compressor is an audio circuit that automatically rides the gain. It pumps up the volume when things get quiet and slams down the peaks when they get loud. The goal of the compressor is to achieve a more uniform, more consistent audio signal that is optimum for recording and listening."

Even simpler from xowave.com:
"Compression works by reducing the volume of loud passages and increasing the volume of quiet passages."

What he said............. my recaller is a little fuzzy. I have to say I knew the compression thing, from years ago when recording stuff like King Biscuit. There was insufficient dynamic range on the radio recorded stuff compared to an album, and it seemed bassier. I am talking reel to reel, not those chintzy little plastic thingys.