Upwards Compression

[Dubuyu]

Hi, I just recently bought a Line 6 HX Stomp and was wondering how I can achieve upwards compression. This is my first guitar pedal board and as an acoustic guitarist have never previously used pedals. 
Thanks,

Dubuyu

[bassbene]

There is no direct option to apply an upward compression. You may check if the Noise Gates (Noise Gate, Horizon Gate) can do the trick. If they can operate in an "attenuation" mode which does not cut the complete signal below the threshold. However, it is likely that the ratio is to high.

If you are really fresh to the world of pedals and fx, I would start "simple" and go for classic downward compression instead. Plenty of options and in most (live) situations, the difference is neglectable. 

[Schmalle]

Try a compressor with mix parameter - start with 0% mix and then increase. That will add sustain and body while maintaining the acoustic guitar's transients.

The Ampeg Opto Comp is my fav for that.

[Dubuyu]

I read before that threshold on most compressors only reduces the volume of notes above the threshold, not raising the ones below. Is this not true?

[Schmalle]

On 2/10/2024 at 7:47 AM, Dubuyu said:

[...] threshold on most compressors only reduces the volume of notes above the threshold [...] Is this not true?

This is true.

[craiganderton]

On 2/10/2024 at 12:47 AM, Dubuyu said:

I read before that threshold on most compressors only reduces the volume of notes above the threshold, not raising the ones below. Is this not true?

 

Basically, yes, but there are two fine points. If a compressor has a soft knee, compression actually begins below the threshold, and doesn't reach full compression until a point above the threshold. Also remember that in most cases, people apply makeup gain due to the level loss caused by compression. So, this brings up all audio. The audio under the threshold isn't compressed, but it is louder than it was originally. That's why some say that technically speaking, as soon as you apply makeup gain, you're raising the level of audio below the threshold. This is how compression brings up low-level sounds, like room sound with drums.

 

As to upward compression, there is a workaround for Helix but it's a little touchy to set up. Insert a Studio Comp set to Limiter mode in Path B, with Mix set to 100% wet, in parallel with your dry signal. Invert Path B's polarity. If you get the balance of the two just right so that audio below the threshold cancels partially with the dry audio, then when the compression kicks in, there will be less cancellation between the two, and the dry audio will be louder for as long as the compressor is above the threshold. This isn't as precise as proper upward compression or transient shaping, but it may do enough for what you want. Good luck!

[Schmalle]

@Dubuyu

Why is upwards compression desirable to you?

What are you trying to achieve?

[lou-kash]

On 2/9/2024 at 11:25 AM, Dubuyu said:

how I can achieve upwards compression […] as an acoustic guitarist have never previously used pedals

 

I would check out the Blue Comp in the "Legacy" section. It's supposed to be modeled after the Boss CS-1. 
I've never had a CS-1 but I have been using a Boss CS-3 since the mid-1980s, in recent years particularly for acoustic slide guitar, until I bought the HX Stomp.

"CS" stood for "Compression Sustainer", and sustain is apparently what you want.

[Dubuyu]

On 2/12/2024 at 12:03 AM, Schmalle said:

@Dubuyu

Why is upwards compression desirable to you?

What are you trying to achieve?

I do a lot of tapping heavy stuff, and find my tapping is often significantly quieter than other elements. I'm sure bringing everything down to the level of tapping volume would work, but that does not seem optimal.

[lou-kash]

On 2/13/2024 at 11:40 AM, Dubuyu said:

I do a lot of tapping heavy stuff, and find my tapping is often significantly quieter than other elements.

 

Then you need very short attack times in the compressor to tame the loud transients that occur when picking a string regularly, as opposed to the very soft transient when tapping.

[Schmalle]

On 2/13/2024 at 3:27 PM, lou-kash said:

Then you need very short attack times in the compressor to tame the loud transients that occur when picking a string regularly, as opposed to the very soft transient when tapping.

That's a nice suggestion. The Deluxe Comp is great for that. Ratio 10:1, Attack 0.1ms, Release 200ms, Mix 50% seems a starting point to me. 

[craiganderton]

Okay, what you want is very different from what's commonly called upward compression. With upward compression, the signal increases at a faster rate above the threshold, rather than decreasing above the threshold. Very different things! I use upward compression with acoustic guitar to emphasize attacks and strums, so I thought that might be what you were trying to do. Since your main issue is reducing peaks, try the Studio Comp in Limiter mode.