This case documents a conference room tunable white led strip package for a 42 m² board-and-training room in Graz — 14 seats, an Approx. 28 m closed plaster reveal, and a tenant whose complaint about the outgoing 4000K downlights was that every afternoon client meeting felt “like a dentist.” Part of our commercial office LED lighting work.
Two Channels Do Not Land on the Blackbody Curve
We have no native tunable-white COB, so this conference room tunable white led strip is two single-colour runs — Approx. 2700K and Approx. 5000K — mixed behind one diffuser. That works, with one consequence worth stating plainly.
Mixing two white points draws a straight line on the chromaticity diagram, while the blackbody locus is a curve. Every intermediate mix sits slightly below that curve, which the eye reads as a faint green cast on skin. That is geometry, not a defect, and no dimmer setting removes it. The first run measured Approx. 3600K at 50/50 with that cast on faces. The options are to accept it or buy a native tunable part with a third channel — we make none, so the tenant took the compromise knowingly, in writing.
Products Used, and the Profile That Could Not Exist
| Channel | SKU | Specs | Approx. Use |
|---|---|---|---|
| A — warm, Approx. 2700K | ES-COB-480-24V-8MM | COB, 480 LEDs/m, 8 mm, 12V/24V, CRI 90, IP20 | Approx. 28 m |
| B — cool, Approx. 5000K | ES-COB-320-8MM-12V | COB, 320 LEDs/m, 8 mm, 12V/24V, CRI 90, IP20 | Approx. 28 m |
An 8 mm strip beside a 10 mm strip cannot share a 12 mm dual-slot channel: two slots plus the web need over 18 mm internally, and the reveal is 22 mm wide in total. Both channels therefore use 8 mm parts in a 20 mm twin-slot profile, inside the existing reveal with no new joinery. The density difference, 480 against 320 LEDs/m, is deliberate — the warm channel carries most of the output at Client. Both are CRI 90 and IP20 — a dry cove, nothing more claimed, ratings defined in IEC 60529. Profile and diffuser are contractor-supplied to our specification, not catalogue SKUs; pairing logic sits on our warm white COB LED strip page.
What We Could Not Supply, Said Before the PO
The integrator needed two 0–100% channels from a Crestron front end. No conference room tunable white led strip assembled from our own controllers does that, and the arithmetic says so before any datasheet.
- Current first. Approx. 28 m of warm channel at roughly 12 W/m is Approx. 336 W — near Approx. 14 A at 24V. ES-LC-DIM-004 is a 2A/6A inline part, short by more than twice.
- Interface second. Every controller we make is an RF or touch handset. None accepts 0–10V or DALI, so none joins an AV system at any wattage.
- So dimming is not our scope. The integrator supplied two 24V dimmable drivers with 0–10V inputs; we supplied strip, mix curve, injection layout and bin specification. Saying so before the PO costs less than at commissioning.
- Every circuit is 24V SELV per IEC 61140, connected load Approx. 620 W.
- One bin per CCT across all Approx. 56 m, bin IDs in the handover file. A closed rectangle puts both ends of a run in one sight line, so a bin change reads as a corner fault — colorimetry settled on the PO.
Camera Banding, and Why Voltage Drop Shifts Colour Here
- PWM frequency follows the shutter, not the room. At 1/125 s the sensor integrates for 8 ms, so banding appears when the PWM period is a meaningful fraction of that. The drivers run above Approx. 3 kHz — roughly 24 cycles per exposure — verified on the actual camera at both shutter speeds.
- The low end is where a two-channel mix breaks. Below roughly 10% duty the drivers stop tracking each other and the mix drifts warm. No preset takes either channel under Approx. 15%; below that both drop together rather than re-mixing.
- Drop moves colour, not just brightness. Single-end feed round the rectangle measured Approx. 6.4% at the far corner, and because the channels sit on separate feeds it showed as a warm corner, not a dim one. Two symmetrical injections brought it to Approx. 2.5%, holding mixed CCT within Approx. 150 K.
- Maintained illuminance Approx. 320 lx on the table at Workshop, indirect from the cove.
- Three presets handed over as channel pairs — Presentation 5/95, Workshop 55/45, Client 90/10 — with a wiring diagram inside the AV cabinet. The host presses one button, never a dimmer.
Four Notes if You’re Specifying Tunable White
- Expect the mid-mix off the blackbody curve. A two-channel conference room tunable white led strip trades a green cast for stock parts; put that on the quote.
- Check the dimmer’s current rating and its input type. A handset with no 0–10V or DALI input cannot join an AV system at any wattage.
- Set PWM frequency from the camera shutter, then verify on that camera.
- Feed a closed perimeter symmetrically. On two channels, drop shows as a colour shift in one corner — see our dimmable COB LED strip notes.
Senfey is a Chinese LED strip manufacturer established in 2013, based in Shenzhen, with in-house SMT and silicone extrusion lines producing Approx. 1.2 million metres per month across COB, SMD, neon flex and addressable. See our commercial application range or request a tunable white quote.
