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Fletcher Munson correction IR pack

Would you be willing to pay for a Fletcher-Munson correction IR pack?

  • Hell yes! $50 seems about right

    Votes: 4 7.7%
  • Sure! $20 is good for me

    Votes: 11 21.2%
  • No, but I want it for free (it's only software, right?)

    Votes: 4 7.7%
  • No. I'll wait until someone shares the IRs and steal them

    Votes: 1 1.9%
  • No, this doesn't sound like something I need / I've solved it another way

    Votes: 32 61.5%

  • Total voters
    52

ML SOUND LAB

Cab Pack Wizard
This is once again one of those things where you'll find a lot of misinformation. Let's start by talking about the approximate dB levels you'll hear your guitar in. I would say strumming your electric guitar acoustically can go up to 70-80dB. So any guitar sound you'll ever amplify will be around 90dB at its lower volume. A loud gig will be around 120dB. Okay well let's look at the Fletcher-Munson graph between 90-120dB loudness. A guitar tone will usually range between 125hz-4khz with rolloffs at both sides of those frequencies.


125hz stays pretty much the same between 90-120dB loudness. The middles (around 750hz) will be the biggest difference between 90-120dB loudness where there can be a few dB difference. The high curves are not that different between 90-120dB. Sure this picture is a bit hard to read with a 20dB difference between each line but the point I'm trying to make is that if you are subtracting 7.4dB at 125hz because of Fletcher-Munson to simulate things at 120dB loudness you would've had to tweak your sounds at about 50dB loudness which is lower than normal speech volume and your acoustic strumming is most likely louder than that. So I repeat what I said in the beginning you're most likely listening to your guitar sound always at around 80-90dB minimum and the main difference in Fletcher-Munson will be in the middles around those playing volumes so run a wide EQ at 750hz to fine tune yourself to fit the occasion. That would be my advice.

For the business side of things, who knows? Maybe some people are interested in this. I know there are some plugins that simulate this and they're usually all free or about $10. Here's one: https://www.noisebud.se/?page_id=2685
 

Joe Bfstplk

Inspired
I wouldn't use BMT as much as a Filter block at the end of the chain that makes the changes you need.

IMHO, this would ideally be a block in the AxeFX itself. We'd just have an Equal-Loudness block with a couple of knobs to dial in the amount of forward or reverse correction. You could try to be exact with it, or use it as an effect.
Exactly this ^^^^^^

The curves are well-known, and were shown in F & M's original work for many different volume levels, so the rate of change in each frequency band relative to the others and to the perceived volume change should be a doable bit of math.

One knob for +/- 100% EQ curve ought to do, though a second knob with a 0-200% volume adjustment would be helpful in some cases, no doubt. If nothing else, it would provide one more place to control volume with controllers....
 

fractalz

Veteran
Exactly this ^^^^^^

The curves are well-known, and were shown in F & M's original work for many different volume levels, so the rate of change in each frequency band relative to the others and to the perceived volume change should be a doable bit of math.

One knob for +/- 100% EQ curve ought to do, though a second knob with a 0-200% volume adjustment would be helpful in some cases, no doubt. If nothing else, it would provide one more place to control volume with controllers....
The actual math is "impossible" since it requires two point measurements of loudness (to, from).

That said, the curves remain very similar for different volume deltas and , in my experimenting, an approximate curve produces great results.

The +/- % knob is exactly right. You'd basically dial in the dB diff between reference (loudness making the patch) and current (loudness playing patch).
 

Joe Bfstplk

Inspired
The actual math is "impossible" since it requires two point measurements of loudness (to, from).

That said, the curves remain very similar for different volume deltas and , in my experimenting, an approximate curve produces great results.

The +/- % knob is exactly right. You'd basically dial in the dB diff between reference (loudness making the patch) and current (loudness playing patch).
The curves are mostly similar, so going "up" in volume relative to the volume which the sound level at which the sound was dialed in, one would need would subtract a fair amount of bass and a little bit of the very high end. The 1k - 6k range part of the curves stay relatively the same shape all the way from 0dB to 120dB, so the main adjustments would be outside that range. The ear is poor at picking up bass until sound is fairly loud, so the rate of change in the correction would be fairly steep on the bass side, as the required bass output level for perceived equal loudness only changes about 20dB between 0db and 80dB. The very high treble has a smaller change in slope above 6k, possibly almost negligible, but if we're in there and adjusting EQ, might as well adjust that too in order to keep things sounding as "flat" as possible with the volume level changes.

If we ignore the range below 40dB, which is pretty quiet, really, we could get a bit finer control over the range of 40-120dB. Things in the 40dB-ish range: "Library, bird calls (44 dB); lowest limit of urban ambient sound" per the site http://www.industrialnoisecontrol.com/comparative-noise-examples.htm.

The change rates in sub-1k and super-6k ranges are close enough to constant rate on either side of the 80dB curve as to make it a good compromise middle value for the "do nothing" flat curve, and more realistic for a bogey "bedroom" volume starting point. By way of comparison, here's what the previously-referred link has as examples of things in the 80dB-ish range: "Garbage disposal, dishwasher, average factory, freight train (at 15 meters). Car wash at 20 ft (89 dB); propeller plane flyover at 1000 ft (88 dB); diesel truck 40 mph at 50 ft (84 dB); diesel train at 45 mph at 100 ft (83 dB). Food blender (88 dB); milling machine (85 dB); garbage disposal (80 dB)."

And, perhaps reinforcing the choice of 80dB as "middle", typically 85dB is what is recommended for mixing music, as the changes in frequency response as you deviate from that are least detrimental to most mixes, per what I learned when studying studio music recording and audio engineering half a lifetime ago.

Really, though, the whole idea is more at having one knob you can tweak to "un-FUBAR" your tone at a gig or at home (depending on where you dial in the sound) than an exact "this to that" conversion, I think. One could even have the EQ delta curve to correct from 80 -> 120 and the other EQ delta curve to correct from 80 -> 40 stored, and simply blend in either curve with flat, depending on how the knob was turned. Then it's simply a balance pot taper for each direction deviating from "0" that needs to be worked out to give a smooth transition....
 
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200man

Veteran
... or an eq built in , that is a dial for a fm curve.
+1 on this...one knob that controls the FM curves...then add to the new performance feature in the axe 3...easy.
Although you would have to dial in your presets based on the initial curve setting...which would be required.

But perhaps the global eq would work as well if you created 4 FM curves and then used channels to switch?
 
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