How to Diagnose Filter Keytracking That Rises on Both Sides of the Reference Note

With conventional positive tracking, cutoff rises as played notes ascend and falls as they descend. Yamaha explicitly describes this behavior for MONTAGE M’s Cutoff/Key parameter; negative sensitivity reverses both directions. A single positive or negative sensitivity therefore does not, by itself, describe a response that rises on both sides of its center. MONTAGE M Operation Manual — Element Edit

Tracking amount and tracking direction are separate questions. On Novation Peak, maximum Key Tracking, 127, produces a 1:1 relationship: moving up one octave moves the filter cutoff up one octave. At zero, cutoff remains independent of the played note. These values belong to Peak; use your instrument’s documented scale when setting an equivalent amount. Novation Peak in detail — Filter tracking

Before changing anything, decide what you want: steadily rising cutoff across the keyboard, a fixed cutoff, or an intentional minimum around one note. That choice determines whether the observed V shape needs correction.

Save a copy of the patch, then prepare a repeatable test. The following sequence is a diagnostic procedure derived from the documented controls, rather than a manufacturer’s preset recipe.

1. Isolate one sound layer and one filter path where the instrument permits it.
2. Use a simple low-pass filter for the test and place cutoff somewhere it can move audibly in both directions.
3. Temporarily zero filter-envelope depth, LFO depth, filter FM, and other cutoff modulation. Record the original values.
4. Enter five separate notes at the same velocity: reference minus 12 semitones, minus 6, reference, plus 6, and plus 12.
5. Use equal note lengths and compare the same point within every note. Repeat in reverse order.
6. Run the sequence with tracking enabled, then disabled.

These isolation steps matter because filter frequency can have several simultaneous inputs. Peak, for example, allows envelope, LFO, and oscillator modulation alongside keyboard tracking. Turning down one visible modulation control does not establish that every other route is inactive. Novation Peak in detail — Filter modulation

If your instrument displays the effective modulated cutoff, record it. Otherwise, compare a spectrum using a consistent broadband source, such as the instrument’s noise generator if available. Treat perceived brightness as a clue rather than a cutoff measurement: Native Instruments documents different frequency-control behavior for low-pass, high-pass, band-pass, and more specialized filters. MASSIVE X Manual — Filter

In KROSS, positive keyboard-tracking ramps increase the tracking output as you move farther from Center. On the lower side, that means moving toward lower notes; on the upper side, it means moving toward higher notes. With positive filter intensity, positive ramps on both sides consequently produce the observed valley. Center itself contributes no tracking offset. KROSS Parameter Guide, p. 26

For conventional ascending tracking, KROSS documents negative Bottom-Low and Low-Center ramps, with positive Center-High and High-Top ramps. Negative destination intensity reverses the curve’s effect. Diagnose the ramp directions and intensity together; changing intensity alone reverses the whole shape. KROSS Parameter Guide, pp. 26–27

Do not transfer those signs automatically to another synthesizer. Read whether its graph represents increasing note number, distance from a center, or editable values at individual breakpoints. The parameter’s definition determines what a positive number does.

Use equal distances from the reference to separate shape from overall amount. The following values are illustrative calculations, not measurements or settings for a particular instrument. Assume a reference cutoff of 1,000 Hz and a tracking rate of one cutoff octave per keyboard octave.

Note position	Conventional positive tracking	Symmetrical rise away from reference
Reference −12 semitones	500 Hz	2,000 Hz
Reference −6 semitones	About 707 Hz	About 1,414 Hz
Reference	1,000 Hz	1,000 Hz
Reference +6 semitones	About 1,414 Hz	About 1,414 Hz
Reference +12 semitones	2,000 Hz	2,000 Hz

The conventional column follows cutoff = 1000 × 2^(d/12), where d is signed semitone distance from the reference. The symmetrical column substitutes the absolute distance, |d|. This is a mathematical model for recognizing the response; it does not establish that the instrument contains an absolute-value processor.

The upper half is identical in both examples. Testing only notes above the reference therefore misses the problem. Compare both sides, and distinguish symmetry from merely having two rising branches: unequal branch amounts can produce an asymmetrical valley.

Look for editable keyboard curves, breakpoint offsets, or a note source passing through a modulation mapper. Inspect the output values below and above the reference rather than relying on the route’s name. A curve with its lowest value near the reference is a candidate for the behavior you measured.

Yamaha’s MONTAGE M provides a useful example of a separate control to inspect: its Filter Scale page assigns cutoff offsets to four note breakpoints. That deserves examination alongside Cutoff/Key sensitivity. Its manual also specifies constant endpoint values outside the outer breakpoints, which can explain a response that changes through the middle and then becomes flat. MONTAGE M Operation Manual — Filter Scale

Test one candidate at a time. Flatten an editable curve temporarily, or disable one route, then replay the five notes. If the valley disappears, restore that control and adjust its lower branch deliberately. If it remains, continue to the next route. This makes the diagnosis traceable instead of accumulating compensating settings.

Compare the attack and sustained portions separately. MONTAGE M distinguishes cutoff key follow from FEG Time/Key, which changes envelope speed according to note position. Its FEG Depth controls the amount of envelope-driven cutoff movement. Consequently, listening at different stages of different notes can confuse time-dependent motion with a static keyboard curve. MONTAGE M Operation Manual — Filter EG

For diagnosis, keep filter-envelope depth at zero while checking the keyboard response. Restore it afterward and repeat the same sequence. If the sustained relationship is correct but the attack impression differs, investigate envelope timing and depth before reshaping the tracking curve.

Also verify which filter model you are testing. MASSIVE X’s Comb uses pitch-oriented controls and Keytrack, Fix, and Ratio modes; its Creak frequency control shifts resonances rather than acting like a conventional cutoff. Use the selected model’s documented behavior when interpreting the result. MASSIVE X Manual — Filter

Match the correction to the result of the isolation test. Keep the reference cutoff unchanged while correcting the curve, so the comparison remains useful.

Test result	Next action
Both branches rise only with tracking enabled	Inspect branch directions, breakpoint values, and destination polarity.
The response remains with tracking disabled	Continue isolating other cutoff routes and layers.
Cutoff behaves correctly but brightness seems inconsistent	Compare the filter response with a consistent source and check the selected filter mode.
The difference appears mainly during the attack	Recheck envelope depth and note-dependent timing.
The curve changes shape outside the initial test range	Test around each breakpoint and inspect the outer segments.

Once the intended relationship is established, restore modulation routes individually and replay the test after each change. Then test the actual musical phrase across its full range. For conventional tracking, confirm that the lower branch continues in the intended direction through the reference. For an intentional valley, confirm its center and both branch amounts. You have finished when the response is repeatable, its controlling route is identified, and the patch follows the shape you chose.

• KROSS Parameter Guide, especially printed pages 26–27.
• Novation Peak in detail, filter modulation and tracking sections.
• MONTAGE M Operation Manual — Screens and parameters — Part Edit (AWM2) — Element Edit, Filter Type, Filter EG, and Scale sections.
• MASSIVE X Manual — Filter.