Compression/sustain

moosy1

Inspired
This has been discussed many times, but I'm left with a lingering question regarding the single Threshold setting on all compressor models:

Setting the Threshold determines when sound is too loud (at the top) and then reduces it; but shouldn't there also be an option for a second threshold setting "at the bottom" that determines when the sound is too quiet and then increase it?
Especially because the volume trails off after you hit a note, a "bottom" threshold could keep increasing, ie, sustaining that note to prevent it from fading away. Compressors are often called compression/sustain, but doesn't it really need that second lower Threshold option - to raise the disappearing sound. Without the bottom threshold, how is a compressor helpful to sustain a fading note?

ps, I've found the Make-up toggle helpful (it's supposed to do what a bottom threshold would do), and also the Repeat/Hold toggle on Delay is helpful, but still, logically, shouldn't there be a bottom threshold option when the sound is too low (as opposed to too loud) to help sustain a note?
 
Without the bottom threshold, how is a compressor helpful to sustain a fading note?
I'm no expert / others may correct me, but I think the concept is that by squashing from the top (downward compression - lowering sounds over the threshold), quieter sounds are brought forward in relation to the reduced louder sounds, and so, with makeup gain, there is a perception of more sustain. Some compressors like the Studio FF Compressor 2, and Studio FB Compressor 2 Axefx3 models work in reverse and raise quieter sounds below the threshold (upward compression), so are more directly raising quieter sounds for more perceived sustain. I'm saying "perceived" because the quieter sound was always there, the compressor is just making it louder either directly (upward comp), or in relation the lowered louder sound (downward comp).

I never really bonded with the name "sustainer" for compressor pedals as it suggests to me that some sort of extended sound is created where none was before - to me the "sustainer" name is more suited things like sustainiac pickups, ebow etc but whatever - just a name.
 
You can try having the envelope controller increase compressor (or any block) level when your input level falls below a certain value. Or for the same idea on the grid, use a gate on a parallel signal that's been inverted with a filter block. Turn the gate level down a bit so it doesn't mute the signal completely when gain reduction is at 0. Level at -6 dB will provide 6 dB of level variation. -2.5 dB would give 12 dB. Remember this just reduces level without doing anything else, so you'd probably want to turn the level up somewhere after everything, or in the compressor.

I've found the Make-up toggle helpful (it's supposed to do what a bottom threshold would do)

Auto makeup doesn't really do anything like this. It just applies a hidden level adjustment when threshold or ratio is adjusted to (maybe) keep the average output level more consistent. Needing to increase level after the gate in the example above is the same idea.
 
This has been discussed many times, but I'm left with a lingering question regarding the single Threshold setting on all compressor models:

Setting the Threshold determines when sound is too loud (at the top) and then reduces it; but shouldn't there also be an option for a second threshold setting "at the bottom" that determines when the sound is too quiet and then increase it?
Especially because the volume trails off after you hit a note, a "bottom" threshold could keep increasing, ie, sustaining that note to prevent it from fading away. Compressors are often called compression/sustain, but doesn't it really need that second lower Threshold option - to raise the disappearing sound. Without the bottom threshold, how is a compressor helpful to sustain a fading note?
No, there is no need for a second threshold. When you use a compressor, the trailing part of the sound is louder relative to the earlier part of the sound due to the level being turned down for the earlier part of the sound. So, you turn up the make up gain so the entire signal is about as loud as it was without the compressor. The end result is a louder trailing part of the sound, which effectively increases the sustain.
 
Thank you all for your replies; there are some ideas i'll try.
But my (FX2 Mark 2) Owner's Manual says (p.53) "While a compressor reduces the volumes of loud sections, it can simultaneously boost overall level for greater perceived sustain." That's the line that I don't get.

MAKEUP gain is supposed to "automatically" compensate the output level "to maintain perceived loudness at the current threshold and ratio" but it's a simple toggle on/off with no parameters, compared to the multiple parameters for the volume reduction function.

Unix-guy says that compression by definition means reduction. But that works contrary to the need to increase the volume of a fading signal. So, apart from the magic on/off Makeup button, I don't see how a compressor helps emulate sustain. So why is sustain commonly included as a function of compressors?
 
Thank you all for your replies; there are some ideas i'll try.
But my (FX2 Mark 2) Owner's Manual says (p.53) "While a compressor reduces the volumes of loud sections, it can simultaneously boost overall level for greater perceived sustain." That's the line that I don't get.

MAKEUP gain is supposed to "automatically" compensate the output level "to maintain perceived loudness at the current threshold and ratio" but it's a simple toggle on/off with no parameters, compared to the multiple parameters for the volume reduction function.

Unix-guy says that compression by definition means reduction. But that works contrary to the need to increase the volume of a fading signal. So, apart from the magic on/off Makeup button, I don't see how a compressor helps emulate sustain. So why is sustain commonly included as a function of compressors?
This is an oversimplified example, and the numbers are not exactly correct (it’s probably logarithmic instead of linear) but this is how I interpret it personally.

Let’s say we have a hearing range of 1 - 10.

The loudest you play guitar is a 10, and you can still hear your guitar at a 1.

a ringing/fading chord may start at 10, then naturally fall to a 1. But the difference between 10 and 1 is so great that if you back to back played at 10 then at 1, your ears may not perceive the 1 volume because it’s so quiet and your ears were just shot with a 10.

Add a compressor and we’ll set it so that it compresses that 10 volume down to 5.

Now the loudest volume you can produce is a 5. But now this is too quiet because you’re used to hearing a 10 - but we can’t produce a 10 because the compressor is forcing it to stay down at 5.

So we increase the make up gain so that compressed 5 now sounds as loud as 10 sounded before.

Since the makeup gain was increased so a 5 is now a 10, that 1 is now also louder - we turned up, so it’s louder too. THAT is where the sustain part comes in.

We hit a hard chord. It’s compressed and is “limited” to a 5, but sounds as loud as a 10. As the chord naturally fades out

original 10 = new louder 5
original 9 = new louder 5
original 8 = new louder 5
original 7 = new louder 5
original 6 = new louder 5
original 5 = new louder 5
Now we’re going to cross the threshold and
original 4 = new louder 4
original 3 = new louder 3
Etc.

Because volumes 10, 9, 8, 7, 6 and 5 are all compressed to sound the same, it seems as if the chord is "sustaining" - meaning staying the same loudness - because it is at the same loudness (the new louder 5) the entire time. it's not getting quieter gradually as it did before without a compressor.

Because volumes 4, 3, 2, and 1 are turned up due to makeup gain, this also seems like "sustain" because those originally quiet volumes are louder than before and everything sounds more even.

Hard to put into words but hopefully that makes sense. Again, it’s a simplification and how I interpret it in my head.

if you want to approach it from the other direction conceptually, increase the make up gain until your quiet playing is loud enough. Then adjust the compression amount to tame the loud parts that are now too loud.
 
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Thanks for that full explanation, Chris.
I'm starting to understand from you (and others) that's it's a relative gain that helps create perceived sustain.
I was just hoping for a dial called "sustain" inside the compressor that would just sustain the notes.
ps, i've found certain amp models have better built-in sustain than others, and again, that Delay Repeat/Hold toggle seems to help.
thank you all
 
This is still compression, upward compression instead of (or in addition to) the downward compression from the compressor block.

https://en.wikipedia.org/wiki/Dynamic_range_compression#Types
Thanks Bakerman; in the link it says: "Upward compression increases the loudness of sounds below a certain threshold". That's exactly what i'm looking for, but the problem is there's only 1 threshold setting (for downward comp) but there's nowhere to set a threshold "below a certain threshold".
It's that 2nd threshold setting I'm looking for. All we have is a on/off Makeup that automatically sets a lower threshold, but I don't have any control over where to set it. That's the problem i'm trying to solve, getting some control over the lower threshold, so as the signal fades it keeps getting pushed back up over that lower threshold.
 
So we increase the make up gain so that compressed 5 now sounds as loud as 10 sounded before.

Since the makeup gain was increased so a 5 is now a 10, that 1 is now also louder - we turned up, so it’s louder too. THAT is where the sustain part comes in.
OK, bingo, now i'm getting it; but where exactly do I control the "make up gain"? Is it just the overall Comp block Level?
 
Adding makeup gain (via level or auto-makeup, which accomplish the same thing) won't specifically add this type of upward compression with a second threshold.

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Looking at the blocks guide I see now that Studio FF 2 and Studio FB 2 types use upward compression. If you want upward compression of low levels along with downward compression of high levels (and some range of no compression in the middle), you can try two compressors in series instead of the alternate approaches I mentioned in post #3. First, maybe just try downward & upward types separately.
 
There's also the Dynamics type which per the manual "allows compression or expansion with a single control".
 
I can confirm a system that these compressors dont compress... the signal is not sustaining.. (thats the first block I always use after the input one). The compressors just squash the entire signal into deadness when turning down the threshold on all these compressors. Turning down the threshold should give loads or sustain when squashing, especially when the auto gain makeup is on.
 
K nevermind, it was only doing it on Mark amps.. i dont understand why. on other presets its working fine. It felt like a temporary glitch on one preset where thresholds were acting like levels.
Also not a fan of going into a gate before the compressor. This input gate is screwing me up sometimes. you want to compress your signal for high gain leads immediately, then you want to go into a gate after that. You don't want to gate any of your signal before the compressor because the compressor will then have less signal to compress. For me, gate works much better after the compression.
 
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