Samsung LM301H Evo

What it is

The Samsung LM301H Evo is a mid-power white LED package (3030 footprint) released by Samsung Electronics around 2022 as an update to the popular LM301H diode used heavily in horticultural fixtures ^[1]. Samsung's published datasheet rates the Evo at up to roughly 3.1 µmol/J of photon efficacy at typical drive currents, with a redesigned phosphor mix that adds more far-red and deep-red content than the original 301H ^[1][2]. Strong evidence

The Evo is a diode, not a fixture. Lighting brands buy reels of these diodes and assemble them onto boards with drivers, heat sinks, and lenses. The end-fixture's efficacy (PPE, in µmol/J at the wall) can be substantially lower than the bare diode number because of driver losses, thermal derating, and how hard each diode is pushed.

Why growers use it

Three honest reasons:

1. Efficacy. At equal wattage, a well-built Evo fixture produces more photons than older mid-power white LEDs. Samsung's diode-level data shows roughly 5-10% efficacy gain over the LM301B and a smaller gain over the original LM301H at typical horticultural drive currents ^[1]. Strong evidence
2. Broader red content. The Evo's phosphor blend pushes more output into the 660 nm and far-red (~730 nm) regions compared to the original 301H, which growers correlate with flowering response ^[2]. Whether this translates to measurable yield gains in cannabis specifically has not been published in peer-reviewed trials. Weak / limited
3. Marketing pull-through. Many growers buy Evo fixtures because review channels and forums recommend them — a real effect on purchasing, not on plants. Anecdote

What the Evo does not do: produce a different 'quality' of cannabinoid or terpene output that's been demonstrated in controlled trials. Claims of higher THC or terpene levels specifically from Evo diodes versus other modern white LEDs are not supported by published data. No data

When to start

Consider an Evo-based fixture when:

• You're buying a new light and the price difference vs. a 301H or 301B board is small (often <15%).
• Your existing fixture is older than ~2020 or uses non-horticultural diodes; the efficacy jump is real.
• You pay high electricity rates and run lights 12+ hours a day — efficacy gains pay back faster.

Do not rush to replace a working modern LED just because Evo is the new badge. The marginal efficacy gain over a 2-year-old 301H fixture is small enough that the embodied cost and e-waste of swapping is hard to justify.

How to evaluate and buy an Evo fixture (step-by-step)

1. Ignore the diode name on the box. Find the fixture's published PPE in µmol/J at the wall, measured at the rated wattage. Reputable manufacturers publish this. If they don't, treat the fixture as unverified.
2. Check the driver. Meanwell HLG, Inventronics, and Sosen are common reputable brands. A cheap unbranded driver can fail in 6-18 months regardless of how good the diodes are.
3. Count the diodes and divide. Total fixture wattage ÷ diode count = watts per diode. Mid-power 301H Evo diodes run most efficiently at 0.2-0.5 W each. Boards pushing diodes harder than ~0.7 W trade efficacy for cheaper builds.
4. Verify the photon map. Ask for a PPFD map at your intended hang height (typically 12-24 inches above canopy) showing average and min/max over your footprint. A high PPE means nothing if the spread is uneven.
5. Confirm warranty and parts. 3-5 years is standard. Ask whether driver and LED boards are individually replaceable.
6. Measure it yourself if possible. Borrow or buy an Apogee MQ-500 or similar quantum sensor and verify PPFD at canopy matches the spec sheet within ~10%.
7. Calibrate to your tent/room. Most flowering cannabis canopies target ~600-900 µmol/m²/s PPFD without CO₂ supplementation ^[3]. More light is not better past the plant's saturation point. See PPFD and DLI for Cannabis.

Common mistakes

• Treating 'Evo' as a quality guarantee. It's a diode part number. Fixture build quality varies wildly.
• Assuming higher diode efficacy = higher yield. Yield is gated by PPFD at canopy, environment (VPD, CO₂, temperature), and genetics. A 3.1 µmol/J diode in a poorly cooled fixture can hit 2.4 µmol/J at the wall.
• Overdriving. Running diodes at maximum rated current to claim higher fixture wattage drops efficacy sharply and shortens diode life ^[1].
• Ignoring spectrum claims. 'Full spectrum + Evo' is meaningful only if the manufacturer publishes the actual spectral power distribution.
• Replacing working fixtures. The carbon and dollar cost of swapping a functional modern LED rarely pencils out for ~10% efficacy gain.
• Buying clone diodes. Counterfeit Samsung-labeled diodes exist. Buy from manufacturers with verifiable Samsung distributor relationships.

Related techniques and topics

• PPFD and DLI for Cannabis — what photon density to actually target.
• LED vs HPS for Flowering — the efficacy comparison that actually matters.
• VPD Management — environmental control to capture the yield benefits more light enables.
• Far-Red and the Emerson Effect — context for Evo's expanded red content.
• Hang Height and Light Footprint — getting an even canopy.

Sources

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