If you've spent any time in KNX forums or smart home communities, you've likely encountered complaints about a specific problem: a pinkish tint that appears at certain color temperatures when using Tunable White LEDs. In German-speaking communities, this is known as Rosastich. It's a real phenomenon, it affects many products on market — including standard wide-range LED products — and at TILLUME, we chose to address it directly rather than ignore it in a marketing brochure. This article explains the physics, what we built, and what's honestly still a limitation.
1 What Causes Rosastich?
Tunable White LEDs work by blending two light sources: warm white (typically 2700–3000K) and cool white (typically 5000–6500K) chips. By adjusting the ratio between these two, the system produces any color temperature in between. The problem occurs in the middle of this range — roughly 3000–4500K — where neither chip dominates, and the spectral gaps between their emission peaks create an imbalance that our eyes perceive as a pinkish cast (Rosastich).
2 Why Has This Problem Been Tolerated?
For years, the lighting industry has largely accepted this as a trade-off: wider color temperature range in exchange for some colour compromise at the extremes and middle. Marketing brochures promote 2200–6500K coverage as a feature, while the Δuv behaviour at 3200K or 3800K rarely appears in any data sheet.
Technically savvy users — electricians, integrators, KNX professionals — have noticed. Community threads about this topic generate significant engagement precisely because it's a problem that affects real-world installations.
3 The TILLUME Approach: One Real Solution, One Honest Trade-off
At TILLUME, we believe the right response to a technical problem is to solve it — not to repackage it with marketing language. Here's what that actually means for our two product lines.
✦ Strategy 1: TILLUME 2400–4000K — The Engineering Solution
For applications where colour neutrality is the top priority — living rooms, bedrooms, galleries, retail — we offer our 2400–4000K LED spots. By deliberately narrowing the colour temperature range, we gain a significant advantage in spectral management.
Through precise LED chip selection and binning, we match warm and cool white chips that are spectrally compatible across the target colour temperature range. This rigorous chip selection process is what keeps the Δuv deviation consistently low throughout the 2400–4000K span — resulting in a noticeably cleaner, more neutral white light compared to standard wide-range products.
The practical coverage is more than sufficient: 2400–2700K for cozy residential settings, 2800–3300K for general living and kitchen use, 3500–4000K for work areas and offices. Over 95% of everyday applications fall within this window.
△ Strategy 2: TILLUME 2200–6500K — For When You Need the Full Range
Some applications genuinely require the full colour temperature spectrum — hospitality environments with dramatic scene shifts between 2200K candlelight and 6500K daylight simulation, theatrical and architectural installations, or specialty retail with extreme contrast requirements.
For these cases, we offer our 2200–6500K LED spots. We want to be direct with you: the Rosastich phenomenon in the 3000–4500K mid-range zone is a physical property of two-chip Tunable White technology. Technically, it can be addressed — but only by adding dedicated compensating LEDs and integrating specialised software algorithms into the control system. In practice, this approach significantly increases both component cost and system complexity, requiring custom hardware, additional control channels, and careful commissioning. For the vast majority of real-world projects, this trade-off simply does not make economic sense.
What we do offer is honesty about the trade-off. The 2200–6500K range gives you maximum flexibility. The Rosastich at mid-range temperatures is a real compromise you are making in exchange for that flexibility. If colour neutrality at 3200–4000K matters for your project, the 2400–4000K range is the right answer.
4 Choosing Between the Two
Both products are genuine TILLUME quality. The choice depends on the project:
| Use Case | Recommended Product |
|---|---|
| Residential spaces needing full CCT range | 2200–6500K Wide Range |
| Home office, kitchen, work areas | 2200–6500K Wide Range |
| Showrooms, exhibition spaces | 2400–4000K Precision |
| Galleries, museums | 2400–4000K Precision |
| High-end residential (colour neutrality focus) | 2400–4000K Precision |
| Hospitality, stage lighting | 2200–6500K Wide Range |
| Retail display with dramatic scene shifts | 2200–6500K Wide Range |
| KNX/DALI smart home — flexibility focus | 2200–6500K Wide Range |
| KNX/DALI smart home — colour neutrality focus | 2400–4000K Precision |
5 Technical Comparison
| Parameter | TILLUME 2200–6500K | TILLUME 2400–4000K |
|---|---|---|
| Δuv worst-case (full CCT curve) | -0.0102 | -0.0023 |
| Rosastich (pinkish tint) in mid-range | Clearly visible | Barely perceptible |
| Colour temperature range | 2200–6500K | 2400–4000K |
| Typical application | Residential spaces needing full CCT range | Showrooms, galleries, high-end residential |
Note: Δuv values are measured worst-case across the full colour temperature curve. A lower absolute Δuv value means less pinkish deviation and more neutral white light.
6 What Customers Report
In KNX forums and Reddit communities, users who have tested TILLUME's 2400–4000K products consistently note that the Rosastich is noticeably absent compared to their previous wide-range LED experience. The improvement is visible and has been confirmed by independent Δuv measurements in the community.
See Erfahrungen Tillume Spot - KNX-User-Forum for detailed user discussions.
"After experiencing the Rosastich problem with another brand's wide-range product, I switched to TILLUME 2400–4000K. The difference at 3500K is immediately visible — no pink, just neutral white."
KNX Forum user, residential smart home project
"The 2400–4000K version is exceptional — for my living room, I don't need anything beyond 4000K anyway, and the colour quality is remarkable."
r/knx community thread, home office application
7 System Compatibility
All TILLUME Tunable White LED spots — both 2400–4000K and 2200–6500K — are controlled via 24V constant voltage controllers:
8 Frequently Asked Questions
9 Conclusion
Rosastich is a real problem in the Tunable White LED category — one that industry has largely swept under the rug. At TILLUME, we chose a different path: we built a dedicated engineering solution in the 2400–4000K range, and we're transparent about what wide-range (2200–6500K) products can and cannot do.
If you need 2200K candlelight scenes or 6500K daylight simulation, the wide range gives you that flexibility — with the same mid-range Rosastich trade-off that affects the entire industry. If colour neutrality at everyday temperatures is what matters, the 2400–4000K range delivers it measurably.
We think customers deserve honesty over brochure promises. That's the TILLUME standard.
Ready to Experience True Colour Neutrality?
Explore our Precision line for colour-critical applications, or browse the full LED Spot range for your project needs.
2400–4000K Precision Spots → View Full LED Spot Range