ELC-0 beta is live: an Equal Loudness Contour plugin for mixing/listening safely at low volumes

[gcordova]

Ear fatigue is a real cost for producers and engineers and protecting hearing over a long career is something I care about deeply. Some say to monitor at around 85 dB to get a flat representation of the sound, but that's too loud to be healthy. If you lower the level you lose the fun part of the frequency spectrum and it's harder to work on stuff that will translate.

I found a couple of plugins with compensation features, but they simply use approximation shelves (like the "loudness" compensation often present on hifi stereo systems). So after a few years of trying to match the Equal Loudness curves with a simple EQ, I decided to create a plugin that would make it quick, easy, and as accurate as possible.

ELC is an Equal Loudness Contour compensation plugin inspired by the ISO 226:2023 curves. ELC-0 (the beta version) is now live, donationware for the next 30 to 60 days, while I gather final feedback from working engineers before ELC-1 launches.

Looking forward to hearing thoughts from the community.

In case you're interested in the topic, I wrote some more:

Long Article (11 minutes read): Low-Volume Mixing and the Case for ISO 226:2023 Equal-Loudness Compensation
Shorter Article (4 minutes read): Nobody Was Fixing This, So I Built My Own Audio Plugin

 

[Fletcher Munson]

flipping awesome ! i was sitting here talking to claude , asking is if there was a simple one knob AU plug in to simulate feltcher munson curves, he said no, i asked if he could help me write one lol
And ere you are lol
Works well dude. its too quiet of course. have to turn the gain right up in the host but the curve adjustment work really well and seems reliable, im on your list

 

[gcordova]

That's great to read, thanks a lot!
Yes, ELC-0 (beta) has a "safety" input trim at -24 db. The compensation will boost significant low end risking to clip the output if starting from "zero". With -24db you're safe but I understand it's frustrating if added on multiple tracks for creative purposes. This is already sorted in ELC-1 (still unreleased) where I unblocked the trim option. Other ELC-1 features are the linear phase module (useful for parallel stuff) and an unlink option that splits the compensation at 1kHz and allows to set high and low range compensation individually. Did you find anything else that could be improved? Curious to hear real user feedback.

 

[olieb]

I, too, have been looking for a plugin to have loudness compensated volume control.
So I checked your solution and this is my feedback.
I would be great to have such a plugin and thank you for your work.
I do not know how others want to use this but for me it is not working well.

My expectation:
A volume control (+10dB/-30dB or less) with a loudness compensation filter that can be switched on and off. The “reference level“ ( which would have a flat filter and correspond more or less to 85dBSPL at -20dBFS) can be calibrated either independently in the DAW/chain or, more conveniently, this could be integrated in the plugin.

When I opened the plugin there were two sliders whose functions were at first unclear to me. (Your webpage did not exactly clear anything up). I had to find the graph drop down and play around with the sliders to understand the way this works.
Maybe I missed something essential, but it seems to me that to adjust volume/level more than ±4dB (which is very narrow), I would need to use another plugin to adjust level and then compensate the loudness by setting the left slider to the appropriate value.
Not exactly the automatic solution I would be interested in.

My idea: make the right slider available for a reasonable level variation and get rid of the left slider [what is it for?] or hide it in another tab. The input trim could then (if it were variable) be used to calibrate to “reference level“.
The GUI ,too, would be even better, if it were only half as wide.
Then this would be a simple but great solution for my (and other peoples?) use case.

Observation
When I configure the ELC plugin in HLHost (accuratesound.ca) for multichannel input and output (7.1.4) only the channels 1+2 get loudness compensated. All other channels remain untouched. How about compensating all channels?

 

[gcordova]

I, too, have been looking for a plugin to have loudness compensated volume control.
So I checked your solution and this is my feedback.
I would be great to have such a plugin and thank you for your work.
I do not know how others want to use this but for me it is not working well.

My expectation:
A volume control (+10dB/-30dB or less) with a loudness compensation filter that can be switched on and off. The “reference level“ ( which would have a flat filter and correspond more or less to 85dBSPL at -20dBFS) can be calibrated either independently in the DAW/chain or, more conveniently, this could be integrated in the plugin.

When I opened the plugin there were two sliders whose functions were at first unclear to me. (Your webpage did not exactly clear anything up). I had to find the graph drop down and play around with the sliders to understand the way this works.
Maybe I missed something essential, but it seems to me that to adjust volume/level more than ±4dB (which is very narrow), I would need to use another plugin to adjust level and then compensate the loudness by setting the left slider to the appropriate value.
Not exactly the automatic solution I would be interested in.

My idea: make the right slider available for a reasonable level variation and get rid of the left slider [what is it for?] or hide it in another tab. The input trim could then (if it were variable) be used to calibrate to “reference level“.
The GUI ,too, would be even better, if it were only half as wide.
Then this would be a simple but great solution for my (and other peoples?) use case.

Observation
When I configure the ELC plugin in HLHost (accuratesound.ca) for multichannel input and output (7.1.4) only the channels 1+2 get loudness compensated. All other channels remain untouched. How about compensating all channels?

Thank you for taking the time to give your feedback.

The output compensation already has an "auto" button. I will consider raising the range from 4 dB up to a higher number (main concern here was again safeguarding the headroom). I'm also thinking about removing the graph dropdown completely and having just a single compacted version of the curve somewhere near the slider. The multichannel part is already in the works.

The "compensation" setting can be used both as:
- A monitoring tool (you lower the monitoring level on your headphones and compensate until you can hear the full spectrum).
- A creative/action tool (for example, if a song was mixed with too much low end, you can compensate in a very natural way with the negative settings of the compensation slider. Or, if there is too much proximity effect on a vocal, same thing).

I'm realizing from your comments that the uses can be wider than I expected, and that's definitely motivating.

 

[olieb]

The output compensation already has an "auto" button. I will consider raising the range from 4 dB up to a higher number (main concern here was again safeguarding the headroom). I'm also thinking about removing the graph dropdown completely and having just a single compacted version of the curve somewhere near the slider.

Yes, the auto button is exactly what I meant with on/off for the compensation. This is the part that works as I expected, only ±4dB is way too narrow.
I do not understand your safeguarding idea. The boost form compensation will only happen to the degree the signal is attenuated, so there is no problem at all. Only if you “compensate“ without attenuation the boost makes problems, but that is the other slider.
I found the graph instructive to understand what the sliders do. More information about that (compensation and level calibration) could make this unnecessary, I agree.

The "compensation" setting can be used both as:
- A monitoring tool (you lower the monitoring level on your headphones and compensate until you can hear the full spectrum).
- A creative/action tool (for example, if a song was mixed with too much low end, you can compensate in a very natural way with the negative settings of the compensation slider. Or, if there is too much proximity effect on a vocal, same thing).

Ok, I understand that. (Though I do not see the specific advantage of a loudness compensation type filter over any other filter for creative purposes. But that could be, because I am not into that.)
But these are two very different use cases that would probably have the plugin placed at different spots in the DAW.
So maybe that could be a reason to make two plugins, or at least two modes/tabs inside the plugin. That would be more compact and clearer.

I'm realizing from your comments that the uses can be wider than I expected, and that's definitely motivating.

I would say the latter is exactly my use case.

- A monitoring tool (you lower the monitoring level on your headphones and compensate until you can hear the full spectrum).

I would only use “listening“ instead of “monitoring“. And that includes to use the slider in the plugin as the primary/only volume control. So sometimes at “reference level“ and sometimes attenuated to “room volume“ and then it would be great to be able to use the slider to attenuate even further to “whispering“ in some situations without using another control knob in the chain.

The multichannel part is already in the works.

Great.