In the first picture, you’ll see 4 colored bands on the analyzer. The red band is the noise floor of my interface, and it’s reading down around -110dbfs.
The dark orange band at the very bottom is where the expander is pushing that noise floor to, down around -170dbfs.
I usually use HoRNet Track Utility to bring the overall level of my DI’s up to -6dbfs after I’ve passed my converters, that way the signal hitting the amp sim is hotter. The dark green band right above the orange one at the bottom is how high Track Utility brought up that noise floor.
Then you’ll see a brighter green band that’s being pushed back up to near the original noise floor. That’s how much JST Gain Reduction is bring up the noise floor. Since there is no signal, and it’s all noise, this is to be expected.
With the expander in the picture, even after being heavily compressed the noise is only reaching back up to the original noise floor level.
I’ve bypassed the expander, and now you see our original noise floor is the lowest signal on the analyzer. Right above that is the 7db boost provided by HoRNet Track Utility. And reaching to just below -80dbfs in a manner that is audible at mixing volume, you see how high the compressor brought up the noise floor.
With the expander pushing down the noise floor to such a low level, it takes a lot more heavy handed compression to make the noise floor of our converters become a problem. Anyone who has used JST Gain Reduction knows that the default setting is quite loud and quite squashed, so this would be a good emulation of what a guitar amp sim would do to the noise level when you’re not actually playing any notes.
With the expander in the picture, it practically eliminates the need for gating on heavily distorted guitar tones. That’s because it drastically increases the signal-to-noise ratio in our favor. The noise level has a much further journey to travel to become a problem.
The Nomad Factory AS Gate-Expander, with a preset I made just for guitar DI’s. You can download the preset in the files section of Nomad Factory Audiophiles! on Facebook, or try your own expanders to achieve the same result. Be warned though that not all expanders are created equally. Some will create weird glitching artifacts as the signal nears the threshold. This is one of the few that I’ve tried that does not do this, which is why I use it religiously now on guitar DI’s.