Equal Loudness Countour (ISO 226 / Flectcher Munsen Curves) Suggestion

[danmarell]

Hello

 

I recently got a Denon Reciever/Amplifier. One of its feature is something called Dynamic EQ. What this does is compensate for the way that the human brain hears different frequencies at different levels. Eg when volume is quiet, bass and highs roll off and mids are pronounced. When music is loud, Bass and Highs are heard louder and mids are reduced.  This is a psychoacoustic thing and happens in our physiology not actually anything that happens physically to the sound wave.

 

This hearing response is represented by a specification/standard called ISO 226 and also known as The Fletcher-Munson curves based on a study done to measure the perceived volume of frequencies at different levels.

 

So...... this brings me to my proposal for Helix (in my case I have a Helix LT). 

 

I use my helix as my PC sound card as well (so that I have high quality output to my monitors and can also play guitar that is mixed with the output which is is a very nice thign to have).

What I would like is exactly what the denon has which is a compensation curve that is tied to the hardware volume knob of the helix. I don't know if its possible to 'read back' the volume level into the software but if that was possible, we could potentially have a global EQ applied to the output of the helix (including PC output) to apply the inverse ISO226 curve. 

 

The result of this would be increased bass and highs at low volumes and increased mids at high volumes. In the middle would be flat.

 

This is actually a feature of some room correction monitoring/mixing softwares that are on the market. Would be a cool feature to have on the helix built in. I imagine that it would be semi trivial to implement ( as long as the hardware volume knob level is readable).

 

Failing that, a manual 'loudness EQ' might be doable? This is actually something that used to ship on a lot of old classic stereo integrated audiophile amplifiers. The downside of that is that it would be a manual tweak each time you change volume to balance it out and I imagine that non technical users would be confused by it and maybe even make their sound worse if they don't know what they are doing.

 

The other hurdle is that with the Denon feature, it uses a calibration microphone to measure the speaker level to set the right 'reference level' for how much correction to apply. I think with the HELIX, that wouldn't be feasible to it might have to be a manually set reference level (or pick some value of the volume knob which is like 65% or something that approximates the 85SPL standard where the frequency response would be flat and use that as the centre point (and hope that speakers are set appropriately as well).

 

I'm keen to hear people's opinion on this. It is an amazing feature that makes speakers sound great at low (and all) volumes and would be great as a PC processing effect (or even as a manual EQ just for guitar after the Cab IR).

[DunedinDragon]

I'm not sure I'd get any particular benefit from it.  I can't even remember the last time I played anything through my Helix that wasn't at or above 90dbSPL where the Fletcher Munson curve starts to flatten out.  In my studio I do occasionally play at lower volumes, but if I'm going to be doing it for the purpose of mixing I'm again going to be in that 90db range or on a headset with the volume at that range.

 

In addition to all of this, my Helix master volume knob is always disabled as many do because I always go direct to the mixing board from my Helix so I control my levels from within my presets so I can count on them to be gain staged equally and correctly going into any mixing board despite using different amp models and such.  If I did want to play at a lower volume such as early in the morning I'd just turn down the master fader on the mixer and not worry too much about Fletcher Munson.

[rd2rk]

On 3/21/2024 at 3:42 PM, danmarell said:

Hello

 

I recently got a Denon Reciever/Amplifier. One of its feature is something called Dynamic EQ. What this does is compensate for the way that the human brain hears different frequencies at different levels. Eg when volume is quiet, bass and highs roll off and mids are pronounced. When music is loud, Bass and Highs are heard louder and mids are reduced.  This is a psychoacoustic thing and happens in our physiology not actually anything that happens physically to the sound wave.

 

This hearing response is represented by a specification/standard called ISO 226 and also known as The Fletcher-Munson curves based on a study done to measure the perceived volume of frequencies at different levels.

 

So...... this brings me to my proposal for Helix (in my case I have a Helix LT). 

 

I use my helix as my PC sound card as well (so that I have high quality output to my monitors and can also play guitar that is mixed with the output which is is a very nice thign to have).

What I would like is exactly what the denon has which is a compensation curve that is tied to the hardware volume knob of the helix. I don't know if its possible to 'read back' the volume level into the software but if that was possible, we could potentially have a global EQ applied to the output of the helix (including PC output) to apply the inverse ISO226 curve. 

 

The result of this would be increased bass and highs at low volumes and increased mids at high volumes. In the middle would be flat.

 

This is actually a feature of some room correction monitoring/mixing softwares that are on the market. Would be a cool feature to have on the helix built in. I imagine that it would be semi trivial to implement ( as long as the hardware volume knob level is readable).

 

Failing that, a manual 'loudness EQ' might be doable? This is actually something that used to ship on a lot of old classic stereo integrated audiophile amplifiers. The downside of that is that it would be a manual tweak each time you change volume to balance it out and I imagine that non technical users would be confused by it and maybe even make their sound worse if they don't know what they are doing.

 

The other hurdle is that with the Denon feature, it uses a calibration microphone to measure the speaker level to set the right 'reference level' for how much correction to apply. I think with the HELIX, that wouldn't be feasible to it might have to be a manually set reference level (or pick some value of the volume knob which is like 65% or something that approximates the 85SPL standard where the frequency response would be flat and use that as the centre point (and hope that speakers are set appropriately as well).

 

I'm keen to hear people's opinion on this. It is an amazing feature that makes speakers sound great at low (and all) volumes and would be great as a PC processing effect (or even as a manual EQ just for guitar after the Cab IR).

 

First, WELCOME and just FYI, this is a user-to-user support forum. Nobody from L6 hangs out here. You should post this (very good) suggestion here:

 

https://line6.ideascale.com/c/

 

I'd vote for it!

 

Now that the boilerplate is out of the way, Helix has a Global EQ which can be setup to accommodate the F-M curve.

It is very manual and needs to be set for each situation/level change, but it's very easy to use.

[PaulTBaker]

Yes, that would be nice. Be quite complicated to implement.  There have been many posts on the Fletcher Munson effect on this board, some go dig deep into the science, which is very interesting to me.  Some people posted an EQ block they created to "similate" the FM effect.  they would turn it on when playing softly, off when loud.

 

I tweaked the block some and used it for a while and it did help in creating patches that sounded good at "live" volume.

[mustafai]

can you share that global eq setting?