FM Effect in Patches vs Music

So in preparation for my AX8 (expected Monday) to replace my HD500x, I ordered a nice pair of studio monitors. I've been retweaking my patches in the Pod to get used to my new room arrangement and work flow, while also doing some serious music appreciation - I've never had anything that resembles a nice pair of studio monitors and the sound and enjoyment is incredible. It truly is like I've heard these albums for the first time again.

I've been curious about the FM effect, so I would play some patches with the Pod master volume set relatively low and then play them at gig volume, and then slightly higher than gig volume. The highs as the volume increased became piercing! However, I didn't seem to notice that same effect whenever I would go through an album. I could listen to an album at low or high volume and it was pleasing across all sound levels. What gives? Is it more noticeable on the Pod just because I'm only working on one instrument as opposed to hearing the whole context of an album?
 
FM isn't the massive "issue" its become on forums as of late for one thing. Its a real effect, but its more significant with regards to very high and low frequencies, so within the range of most guitar tones, its fairly minimal. Something to keep in mind when adjusting patches, but nothing to obsess over. I did a pretty extensive experiment on minimum human auditory perception in grad school, and unless your talking about things in the 20 Hz range, there just wasn't a huge difference in what test subjects perceived across more typical ranges. Just look at the curves and you can see where it starts getting really steep, even at low intensity levels, and where its far flatter. This is all assuming you've got normal hearing sensitivity too, which a lot of musicians don't.....

Second, your program music has been EQ'd and mastered to sound best at most any volume. Your going to low and high pass things like guitars when recording them as you don't want too much bass muddying up the drums, bass guitar etc, you don't want too much highs getting shrill, competing with the hi-hats and stuff.

Last but not least, most studio monitors (unless you dropped a ton of cash) aren't going to put out anything close to "gig volume", and if you push them that hard, your not longer getting a very linear response and probably introducing a lot of clipping and distortion into the sound. Any speaker is going to sound like crap if you push it too hard, the bass farts out, its gets shrill and unmusical etc. That isn't so much FM as it is an overdriven speaker.
 
I've been curious about the FM effect, so I would play some patches with the Pod master volume set relatively low and then play them at gig volume, and then slightly higher than gig volume. The highs as the volume increased became piercing! However, I didn't seem to notice that same effect whenever I would go through an album. I could listen to an album at low or high volume and it was pleasing across all sound levels. What gives?
The Fletcher-Munson effect is the same, regardless of whether you’re listening to a single guitar or an entire band. As you turn down the volume, the highs of the guitar get reduced. But so do the highs of the cymbals and everything else. So the balance between instruments stays the same.

On a record, the guitar was recorded loud. They already dialed it in so the highs wouldn’t be pricing at high volume.
 
Its actually the lows that present the most problem in terms of FM. If you look at the curves of minimum human auditory perception, very low frequency tones are simply not audible to the human ear until they are at a higher intensity than sounds at higher frequencies, around 1-3 kHz range, which is so happens coincides with typical speech sounds. If someone is mixing or sound designing at very low levels, such as late at night, and trying to dial in a deep subbass synth line etc, they are likely going to increase the deep bass levels much higher to make it perceivable, yet, when played at more normal levels, say 70-80dB, its going to be absurdly bass heavy. This is basically compounded by most studio monitors having less than flat response for low tones as well. Most monitors are pretty flat from about 60 Hz to 16,000 Hz, maybe +/- 2dB (which isn't really all that flat, but better than nothing) but at the extremes the monitor just can't reproduce a 30 Hz subbass tone, which isn't suprising of course, given many people are using models with a 5 or 6" woofer. As such, combine that with reduced auditory perception, and you get a very muddy mix at normal volumes.

There are FM effects, and speaker effects at higher frequency, that is true, however, guitar really isn't into that range. Most people tend to high pass their amp or cab block around 6 kHz. There just isn't much guitar context at 12,000 Hz in order to not hear, regardless of FM etc

As I've mentioned before though, hearing loss is a far bigger factor than FM for most folks. I have a doctorate in audiology, so my day job is testing peoples hearing, and its frankly pretty rare to find many adults still perceiving those high frequencies normally past age 40 or so, and younger if there is a history of noise exposure. You may have heard of those "teenager repellents" that play high frequency sounds, not audible by adults, but teens, with their good high sensitivity, supposedly still hear it, and don't want to hang out.... or so the installers of such products always claim

Bottom line is don't make critical mixes late at nigh at whisper volume, and if you've spent 3 decades in front of 100 watt stacks, you probably shouldn't be making mix decisions at all, but otherwise, don't worry too much, guitar luckily falls into the range of sound that our ears are most sensitive to, and the range that typically isn't as affected by hearing loss.
 
When mastering, a good engineer listens at three volumes. First, there is the normal volume, full but not overly loud (to avoid ear fatigue). Then at loud volume to hear how it sounds with FM, Third, turned down to a very quite volume (makes some things stand out). Also typically, through very cheap speakers, briefly (to hear how the less privileged will hear it). Each volume level the overall eq is tweaked until it sounds good at all three levels. I have worked with engineers that have mixed and or mastered albums that have sold in the millions (George Horn, Jeff Sanders come to mind). The process was the same.

If you think about it, we do pretty much the same thing with presets. I create my presets in my home studio, usually at a normal volume. I occasionally crank them up to hear how they sound at gig volume. I tweak accordingly.
 
You don't really need to get super loud, the human ear is at its most linear frequency response at around 80-90 dB, with I believe 87 dB said to be the "ideal" volume for accurate perception.
 
Its actually the lows that present the most problem in terms of FM. If you look at the curves of minimum human auditory perception, very low frequency tones are simply not audible to the human ear until they are at a higher intensity than sounds at higher frequencies, around 1-3 kHz range, which is so happens coincides with typical speech sounds. If someone is mixing or sound designing at very low levels, such as late at night, and trying to dial in a deep subbass synth line etc, they are likely going to increase the deep bass levels much higher to make it perceivable, yet, when played at more normal levels, say 70-80dB, its going to be absurdly bass heavy. This is basically compounded by most studio monitors having less than flat response for low tones as well. Most monitors are pretty flat from about 60 Hz to 16,000 Hz, maybe +/- 2dB (which isn't really all that flat, but better than nothing) but at the extremes the monitor just can't reproduce a 30 Hz subbass tone, which isn't suprising of course, given many people are using models with a 5 or 6" woofer. As such, combine that with reduced auditory perception, and you get a very muddy mix at normal volumes.

There are FM effects, and speaker effects at higher frequency, that is true, however, guitar really isn't into that range. Most people tend to high pass their amp or cab block around 6 kHz. There just isn't much guitar context at 12,000 Hz in order to not hear, regardless of FM etc

As I've mentioned before though, hearing loss is a far bigger factor than FM for most folks. I have a doctorate in audiology, so my day job is testing peoples hearing, and its frankly pretty rare to find many adults still perceiving those high frequencies normally past age 40 or so, and younger if there is a history of noise exposure. You may have heard of those "teenager repellents" that play high frequency sounds, not audible by adults, but teens, with their good high sensitivity, supposedly still hear it, and don't want to hang out.... or so the installers of such products always claim

Bottom line is don't make critical mixes late at nigh at whisper volume, and if you've spent 3 decades in front of 100 watt stacks, you probably shouldn't be making mix decisions at all, but otherwise, don't worry too much, guitar luckily falls into the range of sound that our ears are most sensitive to, and the range that typically isn't as affected by hearing loss.

You don't really need to get super loud, the human ear is at its most linear frequency response at around 80-90 dB, with I believe 87 dB said to be the "ideal" volume for accurate perception.
Quit it! You're slowly taking away an argument a lot of forumites like to use to sound like they know what they're talking about when someone can't quite get the tone they want!:D
 
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