LFO2 covered here along side new timing feature:

https://yamahasynth.com/learn/montage/mastering-montage-the-extended-lfo-in-os-v3

Depth means how much of the dry signal vs signal with filter is mixed. So cutoff and resonance would stay put but modulated would be how much of this filtered version is in the audio path.

If you need the cutoff to be modulated then Motion Sequence would be used assuming it is a parameter that can be a destination.

If not, cutoff is a common MIDI CC that can be modulated using a control ARP. There's probably a preset which demos this. CC #71 is resonance ("harmonic content" in the data list) and #74 is cutoff ("brightness" in the data list). Searching the data list for "CC#74" will return an extensive list of Control Arpeggios that modulate cutoff. There are more that contain more than just cutoff. These list 74 without the # because only the first CC number is preceded by a pound sign.

I'm only mentioning control ARPs and Motion Sequence as a reminder of the other LFOs available.

I'm on mobile so my search capabilities are somewhat diminished.

[quotePost id=116656]LFO2 covered here along side new timing feature:

https://yamahasynth.com/learn/montage/mastering-montage-the-extended-lfo-in-os-v3

Depth means how much of the dry signal vs signal with filter is mixed. So cutoff and resonance would stay put but modulated would be how much of this filtered version is in the audio path.

....

I'm on mobile so my search capabilities are somewhat diminished.[/quotePost]

When you get back, make some extreme examples... my take on the documents is that they're talking about what was planned, not what got coded.

There's seemingly (to my ears and how I'm using it) definite cutoff movement occurring, at the very least.

Fair warning... messing with the Filter and its envelopes and the 2nd LFO in FM-X are the easiest and most reliable ways to crash (it's a freeze type of crash) the MODX. Hopefully less so in the Montage.

Also, the Sine wave shape is out of phase with triangle and drop down saw, which is super annoying, as it has to be shifted to 270 degrees to get the same transition each time you want to compare it with the triangle and drop down saw.

This is another one of those things that clearly indicates there's no serious user as product manager.

Sorry, one more thing... I use the Res 1 & 2 "oscillator shapes" of FM-X, a lot, mostly with Resonance of 1 through to about 7, and a skirt of 1 or 2, sometimes higher for crispy noise.

Doing a lot of this reveals there's a delay glitch/bug in the Resonance setting; sometimes changes back to 0 aren't immediately registered, or it seems to go to a "minus" value that's very resonant, but in a deeper way. Jogging the jog dial again, when this happens, clears this.

[quotePost id=116655]

I had previously thought only the cutoff,

Can we assume you have read the extensive documentation on page 153 of the Reference manual?

Filter Modulation (2nd LFO Filter Modulation Depth)Determines the amount (depth) by which the 2nd LFO waveform varies (modulates) the Filter Cutoff frequency.Settings:0–99

Oops - sorry - did I say 'extensive'? I meant 'minimal'.

but recent adventures tend to indicate it's doing (and/or blocking Motion of) more aspects of the filter.

Any simple example 'adventure' you can post that we can try?

Another good example of 'functionality without explanation'.

I looked at the Six part article series and they barely mention the LFOs
https://yamahasynth.com/learn/synth%20-programming/fm-101-part-six-complex-systems

No mention at all in the three part series either
https://www.yamahasynth.com/learn/modx/mastering-modx-fm-x-exploration-part-i

Manny's 5 part series doesn't go there either.

I wonder if Bad Mister knows anything about that? Maybe his replacement will chime in when they see the thread.

[/quotePost]

This is the third time I've not seen one of your replies, despite it being earlier, until much later.

I think your posts might be getting vetted for later approval.

--------------

What I'm hearing is mostly cutoff movement and that horrid squelch on resonance if that's part of the filter, but what I'm seeing and sensing is that there's more being controlled by the "Filter Modulation"... but I can't quite put my finger on what it is. Sorry for being vague. If I had more, I'd have dropped it in here.

What you've dug up, in terms of there being very little about the LFO activity in documentation and commentary, is amazing. That's a definite pattern of avoidance, I'd say.

Quite odd.

Though, there are times when my more cynical side thinks that the whole SuperKnob and Motion Sequences were really just glamming up primitive LFO modulators as something special so that the Montage had a gimmick other than FM-X and AWM2 with 2 effects slots each.

[quotePost id=116670]
Being a fellow software developer ...
[/quotePost]

Do you ever get the feeling the Montage/MODX OS was outsourced via a spec sheet to folks with low level coding skills [for those of you not familiar with coding, this is a compliment] but little to no interest in sound synthesis and design

There's a nation the other side of China (from Japan) that has a veritable sea of programming talent that fits this description. All other havens of programming talent don't have the same quality of low level coding (for the dozens of gripes I have, I have as many compliments about the performance given the hardware!) and too much experience and familiarity with iOS to have gone the many odd and inconsiderate ways the UI/UX operates.

And Japanese coders revere everything iOS, so there's no chance it came from them.

From single paragraph functional query to full-blown Yamaha denigration in under a Page, and less than 24 hours.

In the absence of anyone else's thread to hijack, just create your own Trojan Horse.

I, for one, was expecting an intelligent discourse on the use of FM-X functions, but alas. Hope springs eternal.

Done some experiments with offensive levels of resonance to hear better what's happening. It's definitely modding the cutoff. Can't detect any wet/dry mix modding.

Also can't tell what the order is, of this "scaling" of the cutoff vs other mods and assigns adjusting the cutoff.

Antony, it's spelt "denigration". But that's not what's happening in the above commentary, even if you "feel" that it is.

Jason, does one of the ways of dynamically adjusting the FM-X Filter Cutoff operate on a per unit (note instance) of polyphony usage rather than across the whole Part?

Depth....

in this case is setting the amplitude of the LFO.

Which means the total amount by which the Cutoff is varied/changed/modulated.

If for example the Cutoff value is set at 160,

A low Depth may vary the cutoff by +/- 5.

So the Cutoff would "swing" back and forth between 155 and 165.

A high Depth may vary the cutoff by +/- 60.

So the Cutoff would swing between 100 and 220.

In FM-X test, 24A LPF, a Max Depth of 99 will swing the Cutoff between 0 and 255, so you get a faux "Tremolo" effect.

How noticeable (severe) the effect of an LFO on Filter Cutoff largely depends on:-

a) The Harmonic Spectrum of the "Dry" input sound.
b) The set Cutoff value.

Obviously the greater the Depth, the more noticeable the changes (modulation), because the LFO is sweeping the Cutoff through more of the Harmonic Spectrum. A lower Depth will have a less drastic effect on the Timbre.

Example: If the Dry sound has very little Harmonic Content in the High Frequencies, and the Cutoff is set to a High Frequency, then small changes to the Cutoff (Low Depth) will result in little or no noticeable change in the sound.

The most dramatic changes in sound, when varying the Cutoff, occur where Harmonics are most dense. Typically, in music, this will be in the "Mid" Frequencies.

Regardless of AWM2 or FM-X, you will find that in most cases, with most of the available MODX Filter models, there are "Dead Zones", where manually varying the Cutoff value seems to have no discernible affect on the sound.

I assume this is because, being Digital, the Filters can have a lot wider range (Bandwidth) than you could achieve with a typical Analogue (real) Filter.

Moreover, Analogue Filters were likely designed to have a bandwidth that closely matched the actual bandwidth of the Oscillators in the Synth. Therefore, on an Analogue Synth, sweeping the Filter (knob) through its whole range, usually resulted in at least some detectable change in Timbre.

By contrast, a Digital Synth, such as the MODX may have hundreds, if not thousands of different sound sources, not limited to 2 or 3 VCOs. Therefore the Filters need to cover a lot wider Bandwidth. So depending on the source sound, there is an increased probability of finding "Dead Zones", usually in the Upper values (at least for a LPF).

The critical factor therefore, is the actual "starting" Cutoff Value.

Good practice on the MODX,
before experimenting with Filter ADSR, LFO or other forms of Cutoff modulation, is to manually sweep the Filter Cutoff and discover its "most active" zone. Then set the Cutoff Value within the extremities of that Zone. Then set your Modulation values accordingly to move (limit) within that zone.

This method is particularly valuable when setting ADSR, to avoid any puzzlement.

Well done Antony, you've described depth, as it pertains to this, quite well.

Which was covered by the first phrase of the second sentence in the original question.

Is the Filter Modulation doing anything else, that you're aware of?

[quotePost id=116681]Well done Antony, you've described depth, as it pertains to this, quite well.

Which was covered by the first phrase of the second sentence in the original question.

Is the Filter Modulation doing anything else, that you're aware of?[/quotePost]

No, there are no "extras", and this would be true of probably all "classic" synths.

However, the audible results of Modulating Filter Cutoff may vary considerably based on what I described above, but there may also be other considerations.

To define, the Type of Filter, the Resonance and other potential settings, the original "make up" of the Harmonics and any other external, non-filter, factors at play such as Pitch and Amp EG.

A "classic" synth will likely have basic oscillators (Saw, Square, Triangle etc) plus an LPF, and maybe a HPF.

The MODX has quite a large array of different Filter, including "exotic" filters. The LFO still only affects the "Cutoff Parameter", but you have the ability to manually adjust other significant parameters.

For example, a Dual LPF has two Cutoffs. The secondary cutoff is defined as a "distance from" the Primary Cutoff. So if you vary the Primary, you are also varying this "distance", resulting in a Formant Filter for (human) voice like sounds.

It is possible to modulate the "exotic" Filter parameters with Control Assigns and Motion Sequencing.

Anyways, as I have learned, the functionality of Filters is not always, immediately (audibly) apparent.

I recommend using classic VCO type Elements (Saw etc) when testing/experimenting with Filters. These will give you a cleaner picture.

If the 2nd LFO's filter === (current_cutoff+lfo_offset), then one wonders why setting the cutoff to 64 ("middle" ) and applying the LFO2 filter doesn't sound like turning off LFO and using modulation using the mod wheel as the source and cutoff as the destination (still 64 nominal). With a bidirectional curve and maximum ratio - this should sound similar if LFO2 was as described.

As you listen to the LFO2 you'll hear the fundamental without filter adjustment and then as you increase the depth - you still hear the fundamental without any filter difference applied and a differently filtered version "mixed in". Somewhere around the middle of depth's range - you stop hearing the "fundamental" (sound without any filter difference) or the balance is so faint it's difficult to hear. And between 0 and this crossover point, you can still hear a this "fundamental" get softer and softer.

So, to me, there's an element of "depth" as first described by me. Although what's going on with say the LFO2 at the maximum and minimum values of the LFO2 curve at the "differently filtered" sound (with higher depth) is difficult to pinpoint since I haven't found a set of standard parameters (cutoff, resonance, or even gain) that mimics these.

Whatever it is the "filter" is changing - it's cool. Trying to say reproduce the same sound using a motion sequence proves difficult - at least thus far.

This gives plenty of credence to the question of what exactly it does. For now I'm not sure there's a single explanation offered that provides a complete answer.

Jason, I agree, there's something odd at the extents of the LFO 'waves', and in the way they modulate the Filter's cutoff, too, before we get to the fact that there seems to be other things and/or aspects of the Filter being modulated.

I'm somewhat abusing some of these oddities and getting interesting, though not entirely predictable, results. It's when I want to do something exactly, or have exact expectations of what might occur at given values, that oddities show up most glaringly.

And some subsequent testing, at extremities, has sometimes revealed asymmetric results that are far past where they should be in one direction.

Other testing has me more than a little curious about the sequence of (and priorities of) operators (plus, multiply - the formula etc) that determines the cutoff when there is more than one thing changing it.

I'm with Bill. This whole area is low hanging fruit for much more informative and better insight and documentation, and it's long overdue that Yamaha inspire (pay) some artists to explore and explain the quirks and goods/bads of the MANY Filters in conjunction with FM-X and its effects, and Motion and Control dynamics.

Some of this fruit is so low hanging and ripe it's in danger of falling to the ground and going unpicked and uneaten.