I don't understand the new Compressor in 3.6.1 (Windows 10)

You had a great video on how to use the old compressor for new users: https://www.youtube.com/watch?v=WkPBWLmCv7c&t=427s

That was a great help for me. I record lessons approx 40-45 minutes in length. I would record it in 10-15 clips that were 3-4 minutes each.

I would run the NoiseGate to lower breathing noises across the whole 40-minute session.

I would then run the compressor across the whole 40-minute session to knock the highs down.

I would then amply each clip up to the desired level. That worked great for me, I was very happy. It was easy and fast.

I don’t know where to begin with the new compressor. the settings as you know are quite different. I’m not happy with the results I have gotten yet. I’m not able to to get the same results I was before. It was very easy before.

Can you please do a guide similar to the one I referenced above on how to use this? I understand this version probably has greater functionality than before. I need something simple like the prior version. That was great for me, but I’m lost now.

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Audacity! Do you have a reply?

I have the exact same issue. I don’t know how to use the new compressor and am getting results with which I’m not satisfied. I’d appreciate a new guide like the one OP referenced.

I haven’t tried it but it looks like a fairly “standard” compressor

Virtually all normal compressors have these 4 settings:
The Threshold is the level where it kicks-in and starts reducing volume. Above the threshold the volume is reduced. When the volume is below the threshold nothing happens.

The Ratio is the amount of compression (volume reduction). Zero is no compression and a high number is essentially a limiter where nothing is allowed to go over the threshold (after the attack time).

Attack time is how fast the compressor responds. A short-loud sound like a drum hit might not be affected. If a loud sound continues longer than the attack time, the compressor will kick-in and start lowering the volume.

A traditional limiter has zero attack time.

Release time is how long it takes the volume to return to normal once the loudness falls back below the threshold.

A traditional limiter has zero release time.

The additional features are:
Make-up Gain boosts the volume to make-up for the fact that regular (downward) compression lowers the loudest parts. (This may require some experimentation because depending on attack time some peaks may not be reduced at all.)

The Knee is the “sharpness” of the compression when you’re over the threshold. With a “soft knee” you won’t get the full ratio when you are just-slightly over the threshold.

Look-ahead sort of offsets the attack time (something like a negative attack time). You can start the compressor’s attack before the loud part comes-along. …Of course, you can’t have look-ahead with regular hardware compressor working in real time because it doesn’t know what sound is coming next, but it works with sound files where it can read-ahead.

Can you explain how to do this?

Everything I try with this new compressor just amplifies the audio in relation to Make-up Gain, except without anti-clipping safeguards. A compressor is supposed to make the waveform mostly uniform with its peaks and amplitude, to reduce the dynamics of audio volume.

Only with some rather extreme settings (threshold -45, gain 30, ratio 100, quick attack) can I get something that kind of simulates what the old effect did. But, it’s sounds like over-amplified, distorted garbage, even if the waveform doesn’t look like it clipped.

I’m glad they listened to their audience and brought back the older plugins. But, they are called “legacy” and that means they’re going to throw it back in the garbage in a later release.

Until they start migrating the features from that plugin to here, and fix it so it actually does what it’s meant to do, I’m going to consider this new compressor to be unfinished and alpha quality.

FYI - GoldWave (NOT free after trial period) has a compressor/expander with the option of (the usual) downward compression as well as upward compression (to boost the quiet parts with no effect on the loud parts).

It also has upward & downward expansion.

…GoldWave sometimes has the definitions of compression & expansion fouled-up. They consider any settings that work above threshold to be compression, and expansion for whatever works below the threshold. So you have to start with one of the presets, like “Boost Quiet Parts” (which will do what it says) and ignore the "Compressor/Expander" selection and you can experiment with the other settings from there.

Most compressors “push down” the loud parts (above the threshold), with the option of make-up gain so compression (or limiting) can boost the overall loudness without clipping.

But technically, dynamic compression is the reduction of dynamic range (or “dynamic contrast”) by pushing-down the loud parts and/or boosting the quiet parts.

There are free compressor plugins which work in Audacity 3 which can be adjusted in real-time … can you see the history of edits of a track after converting to mp3? - #4 by Trebor

Well, it doesn’t work in Audacity 3.6. Make-up Gain can and will clip the waveform.

Also, the problem with push down compression is that it’s bring the louder signals down to the noise floor, and then raising the entire noise floor (make-up gain) to compensate. The louder signals are already where they need to be. Only boost what needs to be boosted, and then there’s no need to make up the gain, because it’s already at the right level.

And upward compression exists in the “legacy” compressor. It’s the “Compress based on Peaks” checkbox. Except the Audacity team decided to replace this legacy compressor with their new one, they didn’t bother to implement this new checkbox.

There is also the “Make-up gain for 0 db after compressing” checkbox, which normalizes everything back to 0db and prevents clipping! Why fiddle with a make-up gain slider that could clip, depending on both the original waveform and other settings like threshold and ratio? But, again, another unimplemented feature in the new compressor.

They replaced the compressor with an inferior one with reduced features, and then wondered why the community demanded they re-instate the old one.

On the plus side, from hours of trial and error, I did finally get this compressor to emulate at least something that looks like the old one with:

  • Threshold = -30db
  • Make-up gain = 21db
  • Knee width = 5db
  • Ratio = 4:1
  • Lookahead = 1ms
  • Attack = 0.2ms
  • Release = 1000ms

The biggest difference from the old compressor is the Attack setting. The legacy version has it marked as “0.20 sec”, and using a setting like Attack=200ms for the new version completely blows away the amplitude, clips everything, and ruins the waveform.

So, I’m really wondering if that’s a multiplication bug.

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