Quantum Boards: The New Alternative to COBs

The latest tech to get the LED growing community all riled up has been dubbed “Quantum Boards” by the fine folk who designed them over at the Horticulture Lighting Group. These things have created quite a buzz across the usual forums that growers frequent, and for good reason. If you haven’t heard of them yet, you’re likely wondering what exactly a Quantum Board is and what’s so great about them.

What’s a Quantum Board?

HLG’s Quantum Board is a large circuit board that has hundreds of mid-power LEDs mounted to it. The LEDs are connected together in series to form strings, and these strings are then combined in parallel configurations to make them compatible with common high-powered constant current drivers like the HLG 80-H-C, 240H-C, or 320-H-C series.

Board Configurations

The 2 models available right now are the QB304 and the QB288. The number in the model number refers to the number of diodes.

A Horticulture Lighting Group QB304, containing 8 rows of 38 LEDs. Each row has a voltage of ~100-110VDC and all rows are paralleled to split the current from the driver.

The QB288 model, with 16 strings, each containing 18 diodes. Each string has a voltage of ~48-53VDC and are all paralleled together to split drive current.

The Almighty Samsung LM561C LED

These boards are built around the impressive Samsung LM561C diode. Boasting efficacy approaching 200 lumens per watt at low power, these diodes are incredibly efficient. Typical forward voltage for each diode is ~2.7-2.8V at 65mA of current. Absolute maximum current is rated at 200mA per diode.

If you want to play with some values and see what kind of output you can get from these diodes, check out Samsung’s calculator.

What are the Advantages Over COBs?

Here’s the question most skeptics are asking – why should I go QB over COBs? Well, you can sort of think of each of these boards as one giant COB. A typical COB has hundreds of individual diodes mounted to its little board, packed very tightly together. There are hundreds of diodes in these QBs as well, but they’re spread much further apart. The principal of harnessing the power of several small lights to produce one powerful source of light is the same, but the QBs just do it on a larger scale.

The main advantages for QBs are:

  • Thermal management is much simpler. The board can be mounted to a thin piece of aluminum with no active cooling and the diodes stay nice and cool.
  • More uniform spread of light. Compared to a COB that blasts all of its light from a surface 1″ in diameter, these boards are producing even light over the span of a foot.
  • Greater efficiency. At 50 watts, these boards are getting 180+ lumens per watt. Highly efficient COBs like the Cree CXB3590 average 160-170 lumens per watt at 50W.

What are the Disadvantages?

A few of the disadvantages I can think of are as follows:

  • There’s currently only one supplier and right now they’re completely out of stock.
  • These boards are more difficult to DIY than COBs are (if you want to build the actual board yourself).
  • Though light spread is better than typical COB setups, overall intensity in some areas is bound to be lower.
  • Cost. The price of COBs has really come down lately and even factoring the cost of a heat sink per COB, you could get 3 decent COBs for the same price as one QB with a heat sink.


It’s great to see manufacturers innovating and trying new things – these boards look really promising and I’m very excited to try this tech out.  Since HLG was out of stock, last night I ordered 600 of these Samsung LM561C diodes from Digikey and I’m going to try and build something similar myself – we’ll see how it goes! Once I’ve had the opportunity to test these things out, I’ll be sure to share my results.

Edit 05/10/17: Here’s the link to my DIY Quantum Board Build!

Edit 06/04/17: HLG sent me one of each of their QB Kits to test.  Check out my 3-part video review.


  1. Very interesting, looks like the same kind of boards that chilled grow lights are using, the price isn’t too bad either. I wonder what the full kits will cost? They must not make much heat or the heat is so spread out due to not need any thermal paste like they claim. That’s going to be lots of soldering to build one of those boards from scratch, especially of your going to bread board it, unless you can etch your own board or something like that.

    • LEDGardener

      April 3, 2017 at 10:53 pm

      Yeah very similar. The Chilled ones are crazy dense. I ordered 25 of these LT-H282 foot long strips that come mounted to a board with connectors and everything, so no soldering for me 🙂 http://www.samsung.com/global/business/business-images/led/file/product/products/201608/Data_Sheet_H_Series_GEN3_US_Rev.0.3.pdf

      • That quantum kit that came back in stock tonight is a good deal, I might just have to order one if I have the funds left over after everything is bought for the outside garden this year. I wish the 135w kit came in a 3500 or 4000k spectrum though, but just 3000 or 5000

        • For sure, they look awesome and the price is definitely right for people in the States. I got my 25x 4000K strips from Digikey tonight.

          • LEDGardener

            April 6, 2017 at 7:23 pm

            Noel: I’m replying to you via this comment since I think you can only nest 5 deep. I think the key for the lack of heat sink is the fact that the diodes are spread so far apart and each diode has a max of only 200mA * 2.9V = .58W. Regarding your last question, are you referring to the strip modules I have? If so, there are little notches on the edge of the strip that you could put a screw through to fasten it to a piece of aluminum.

  2. Neat that you went over the info on these. I ended up building a few bars using the 22inch Samsung H-series modules in 4000k to light a grow shelf. I’d be interested in reading about your experience in your next post.

    • LEDGardener

      April 5, 2017 at 3:07 pm

      Very cool. I’m really excited about how versatile these will be, given their size and lack of heat sink requirement. How are your plants doing beneath yours?

      • Visually they seem to be doing fine but I wish I had a better way of measuring the light properly. I’m just using a light meter on my phone which I know is not ideal. I can’t remember if you have a guide on how to measure light and determine optimal distances? I’ll take a look.

        • LEDGardener

          April 12, 2017 at 9:10 pm

          I don’t, unfortunately, because I don’t know of a reliable way to convert lux to PPFD. The lux meter is still a good way to check for uniformity of coverage. Lux to PPFD calculators are out there as well, but they’re usually intended for HPS, MH, or sunlight as a light source. LED is trickier to convert.

        • Buy a luxmeter at least. I would either use as a rule of thumb a value of something like 2.1 μmol/J (should be there) or just go with “old” lux recommendations for the species.

  3. I wouldn’t mind seeing a couple of rows of 660nm red in those boards, but I guess I could always supplement with a red cob.

    • LEDGardener

      April 8, 2017 at 11:32 am

      Hey Noah. I wouldn’t be surprised if we start seeing 5630 chips in different color combinations on these boards. For now, your best bet is likely COB as you say.

  4. Hello! I want to buy 3 qb, ive been searching and iam confused about the driver that i should use to power 336 qb. My plan is to wire 2 qb 336 in series for a 3,5×3,5 or 4×4 flower tent and another 336 for veg. I contact two sellers, one say this about the board.
    1. Board size: 305*358MM.
    2. Circuits: 24S x 14P.
    3. Max current: 2100mA.
    4. Output: 69.6V.

    Otherseller says: max current 2800mah and 68v

    What you think 3000k for flowering and 4000k for veg ? And what driver should i buy ? Or perhaps other qb board ? Heeelp meee 🙂 thaanks

    • LEDGardener

      December 6, 2017 at 7:18 pm

      Hey Jessica, these must be custom boards from Alibaba, I take it? The ones you listed are pretty high voltage – running 3 in series would be over 200 volts so it’s not ideal. I’d look for boards that run at a lower voltage like 36V or 54V. The real QB288 boards run at 54V and are much easier to match a driver to.

    • I have eight of these coming. I’m going to run three of them off a HLG-480H-C1750B. That has a maximum output voltage of 274 so that will work. Running them at 1750ma will result in 117watts per board. I have another board with similar diode spacing and running at this level you don’t have to use a heatsink. With airflow through the tent I have had the board get above 110F.

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