118 • November 2014 • Lighting&Sound America

TECHNICAL FOCUS: PRODUCT IN DEPTH

The product up for review this month is the Rogue R2 Spotfrom Chauvet Professional. A number of companies thathave produced this class of units combine a white-only LEDsource with dichroic filters for color changes. There are prosand cons to this approach as I see it; on the plus side, whiteLEDs are very efficient. Most of the R&D from commerciallighting manufacturers is focused on them, so they lead theway for efficacy. They also tend to have better color render-ing than RGB LEDs, and you don’t have to worry abouthomogenizing all the colors together into a single beam. Othe minus side, however, as with any luminaire using a whitelight source, you inevitably lose light, and thus efficacy,when running them through a deeply saturated color filter.

Enough of thetheory; the proofis in the numbers.How did theChauvetProfessionalRogue R2 Spotperform on thetest bench? Asusual, I’ve tried totest and measureeverything I can,from power inputto light output,and report the rawdata so you haveinformation tohelp you makeyour own determi-nation. The results presented here are based on the testing,with the fixture operating on a nominal 115V 60Hz supply, ofa single Rogue R2 Spot unit supplied to me by ChauvetProfessional (Figure 1).

Light sourceAs I’ve already mentioned, the Rogue R2 Spot uses a whitelight LED source. This is formed from a chip-on-board arrayof 49 phosphor white emitters. I didn’t dismantle the unit toaccess them, but you get a good view of the array throughthe lens of the unit when you have it on at a low dim level.In Figure 2, you can clearly see the individual dies, as wellas the small bond wires joining them together. You can alsosee the combination of blue LED light and yellow phosphor

in that same pho-tograph. Chauvetrates this array at240W. As you’veheard me mentionmany times, allLED ratings arenominal. Whatmatters is howmuch you coolthe LEDs and howyou get the heataway to keepthem at their rated

operating temperature. Chauvet has mounted the arraydirectly to a large aluminum heat sink that has embeddedheat pipes to spread the heat load over a larger surfacearea. Figure 3 shows the edge of the heat sink and the sixembedded heat pipes that pass under the LED array. Theheat sink, in turn, is cooled by two speed-controlled axialfans.

Dimming and strobeBecause this is an LED unit, all dimming and strobing isdone electronically. Chauvet runs the LEDs with 16-bit dim-ming and this, coupled with a measured PWM rate of2.2kHz, produced excellent smooth control. Figure 4 showsthe dimming curve, which is very close to linear. Linear dim-ming is not my personal favorite, but you know where youare and the control is smooth enough to allow you to super-impose whichever curve you want from the desk. As youwould expect from LEDs, strobing was also crisp and clean,with a measured range of speeds from 0.8Hz to 22Hz.

The first item in the optical train, after the LED array, is a

Chauvet Professional Rogue R2 SpotBy: Mike Wood

Figure 1: Fixture as tested.

Figure 2: LED array.

Figure 3: LED array and heat sink.

Copyright Lighting&Sound America November 2014 http://www.lightingandsoundamerica.com/LSA.html

www.lightingandsoundamerica.com • November 2014 • 119

lens group. This presumably serves to collate the light out-put and direct it through the remainder of the device. We’llreturn to that and the optical performance later in thereview.

Color systemsAs I mentioned earlier, the Rogue R2 Spot is a white lightdevice that uses dichroic filters for color. There are two colorwheels, each fitted with seven non-replaceable, wedge-shaped dichroic filters, plus an open position. Both wheelsare operationally identical, although the color choice is dif-ferent, of course. Normal functionality of quick path opera-tion, split colors, and continuous wheel spins are providedon both wheels. (Perhaps split colors are another plus pointfor a hybrid solution using color wheels?).

COLOR WHEEL 1Color Yellow Light Blue Green Red Magenta Blue OrangeTransmission 98% 24% 61% 4.7% 5.5% 3.2% 23%

COLOR WHEEL 2Color CTO CTO Green UV Orange Pink Light Blue

3200K 5600KTransmission 72% 65% 36% 0.4% 39% 23% 5.7%

COLOR WHEEL SPEEDColor change speed – adjacent 0.1 secColor change speed – worst case 0.4 secMaximum wheel spin speed 0.65 sec/rev = 92 rpmMinimum wheel spin speed 132 sec/rev = 0.45 rpm

Figure 5 is a view of one of the wheels showing the gluedtrapezoidal colors and the narrow spokes. Figure 6 showsan example of a split color in use. The two wheels can alsobe used in combination to provide mixed colors and effects.

I measured thecolor temperatureof the unfilteredwhite light fromthe unit as 8197Kwith a CRI of 72and CQS of 69;with the CTO3,200K filter inplace, it was3,912K, and withthe CTO 5,600K, itproduced 4,566K.

You mightnotice in theabove table forColor Wheel 1 thatthe first yellow fil-ter appears tohave an unbeliev-ably efficienttransmission of98%. Why is thatso high? It lookslike quite a satu-rated yellow, sowhy wasn’t thelight outputreduced more?This is a result of acombination of thetechnique used toproduce whitelight—a blue LEDwith a yellowphosphor—andthe inadequaciesof the currentstandard used inlight meters.Figure 7 showsthe spectrum ofthe Rogue whiteLED with no filters,

Figure 5: Color wheel.

Figure 4: Dimmer curve.

Figure 8: Spectrum with yellow filter.

Figure 6: Split color.

Figure 7: Spectrum in open white.

PRODUCT IN DEPTH

while Figure 8 shows the spectrum with the yellow filter inplace. You can see that pretty much the only differencebetween the spectra (ignore the rescaling) is that the yellowfilter cuts out the large blue spike from the LED, leaving justthe emission from the phosphor. As you may have heardme rant about in previous articles, the current CIE standardused in light meters is deficient in the amount of blue it rec-ognizes. In fact, it can’t really see that blue spike at all!Thus, when it is removed with a yellow filter; the light meterdoesn’t notice it’s gone! In reality of course, the human eyecan see that blue perfectly well; if we couldn’t, the lightwould never look white, and it contributes significantly morethan the 2% of the output that the measured transmissionpredicts. This is in no way Chauvet’s fault; it’s a problemwith our established measuring standard for light output.

Gobo wheelsThe Rogue R2 Spot has two gobo wheels, one fixed andone rotating. The rotating gobo wheel has seven replace-

able metal pat-terns and an openhole. Followingthe current indus-try trend, thegobos are mount-ed in carriers thatcan be easilysnapped in andout of the mount-ing slots on thewheel. Figure 9shows one of thegobo patterns inits carrier, whileFigure 10 showsthe access panel(top—panel inplace, bottom—panel removed)

Figure 9: Rotating gobo.

Figure 10: Gobo access panel.

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that can be snapped open on the outside of the unit, allow-ing easy changing of the gobos without having to fullyremove the head covers.

ROTATING GOBO SPEEDSGobo change speed – adjacent 0.2 secGobo change speed – worst case 0.8 secMaximum gobo spin speed 0.47 sec/rev = 128 rpmMinimum gobo spin speed 51 sec/rev = 1.2 rpmMaximum wheel spin speed 1.1 sec/rev = 55 rpmMinimum wheel spin speed 71 sec/rev = 0.8 rpm

FIXED GOBO SPEEDSGobo change speed – adjacent 0.1 secGobo change speed – worst case 0.5 secMaximum wheel spin speed 0.98 sec/rev = 61 rpmMinimum wheel spin speed 112 sec/rev = 0.5 rpm

Positioning and rotation of the rotating gobo wheel werea little slow and jerky in some spots. I measured the posi-tioning accuracy/hysteresis at 0.28° which equates to 1.2"at a throw of 20' (50mm at 10m). Both wheels use a quick-path algorithm to minimize change times.

Figure 11shows the typicalfocus qualityachievable withthe rotating wheel.There is minimaledge-to-centerdifference (spheri-cal aberration)and color fringing(chromatic aberra-tion). The fixedwheel was verysimilar, although itexhibited a littlemore sphericalaberration. Figure 12 shows the effect of changing focusfrom one gobo wheel to the other, or morphing.

IrisThe last focusable component is the iris. The fully closediris reduces the aperture size to 13% of its full size, givingan equivalent field angle of 2.0°. I measured the open-ing/closing time at around 0.4 seconds.

Figure 11: Image sharpness.

Figure 12: Gobo morph.

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PRODUCT IN DEPTH

Prism and frostThe moving focus lens is immediately after the iris, followedby the prism and frost flags. The three-facet glass prismcan be inserted or removed from the beam in approximate-ly 0.5 seconds. Once in place, it can be rotated at speedsfrom 0.33rpm (180sec/rev) up to 3.8rpm. The image separa-tion is shown in Figure 13, which also shows that the imagefocus quality isfairly well main-tained through theprism, with theintroduction of asmall amount ofchromatic aberra-tion. (This isusual; I don’tknow of any man-ufacturer whouses an achro-matic prism foreffects.)

The frost flag is actually more like a piece of diffusionbreakup glass than a frost filter, thus it provides an overallwash effect rather than softening gobo edges. This is an all-or-nothing frost, with no intermediate positions. Frost inser-tion or removal again took 0.5 seconds.

Lenses and outputThe final element in the optical train is the large output lens.There are three lens groups in total: the collimator just afterthe LED array, a moving focus lens group (0.6 seconds endto end in movement time) after the iris, and the outputgroup. I measured the output of the Rogue R2 Spot at8,279 lumens with a field angle of 16°. With a measured292W of consumed power this equates to an efficacy ofjust under 30lm/W. The output profile is extremely flat,

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Figure 13: Prism separation.

Figure 14: Output

www.lightingandsoundamerica.com • November 2014 • 123

which is great for gobo projection, but not so good if youwanted to blend adjacent beams. This perhaps points tothe intended use as an effects unit. Figure 14 shows thevery flat output curve.

Pan and tiltI measured the pan-and-tilt range of the Chauvet Rogue R2Spot at 540° and 230°, respectively. A full-range 540° panmove took 2.7 seconds to complete, while a more typical180° move finished in 1.2 seconds. Tilt took 1.5 secondsfor a full 230° move and 1.3 seconds for 180°. Both panand tilt movements were smooth, with no jumps or steps.This is a mechanically stiff system, so movement was quickand hysteresis was low. I measured hysteresis on both panand tilt at a very low 0.05°, equivalent to 0.2" at 20' (8mmat 10m). The downside of a stiff system is that there is sig-nificant bounce when the head comes to a halt. Both axeshave optical encoders to reset position if the unit isknocked.

NoiseThe cooling fans were by far the noisiest item, with only thetilt exhibiting some resonance at some speeds and raisingthe noise floor any significant amount.

SOUND LEVELSNormal Mode

Ambient <35 dBA at 1mStationary 45.5 dBA at 1mHoming/Initialization 51.2 dBA at 1mPan 46.4 dBA at 1mTilt 49.4 dBA at 1mColor 45.5 dBA at 1mGobo 45.6 dBA at 1mGobo rotate 45.6 dBA at 1mFocus 45.6 dBA at 1mIris 45.7 dBA at 1mFrost 45.6 dBA at 1mPrism 47.2 dBA at 1m

Electrical parameters and hom-ing/initialization timeI measured power consumption with the LEDs at full powerat 2.42A from a nominal 115V 60Hz supply. Power was282W, with a power factor of 0.96. Quiescent consumptionwith the LEDs off was 0.43A, 48W at a power factor of0.92.

Full initialization from either a cold start or a DMX512reset command took approximately 25 seconds. Homingwas partially well-behaved and partially badly behaved, inthat the fixture fades out smoothly, then resets, but fadesup again before final positioning is complete.

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TECHNICAL FOCUS: PRODUCT IN DEPTH

Construction and electronicsThe Rogue R2 Spot follows current conventional techniquesand uses a distributed control system with the main motorcontrol board mounted in the head and power supplies in

the base. Figure 15 shows thetwo yoke arms with the pan-and-tilt motors, and Figure 16 themain motor control circuitry.Construction isn’t really modular,but it looks simple enough todisassemble and work on.Interestingly, Chauvet has cho-sen a ”soft feel” finish for theoutside of the molded compo-nents which has a very goodmatte, non-reflective finish. It willbe interesting to see how thissurvives the application, as I’venot previously found those finish-es to be very durable. If it is,then it’s a good choice. Both panand tilt are fitted with locks fortransport.

The ChauvetRogue R2 Spothas both five-pinXLR DMX connec-tors and three-pindata connectorsas well aspowerCon in andout to allow fordaisy-chaining ofunits. Figure 17shows the con-nection panel.Local control is

through a color LCD screen and menu system that containsthe usual setup, self-test, and maintenance functions.

That just about finishes it for the Chauvet ProfessionalRogue R2 Spot, a spot luminaire that combines the efficacyand control of LEDs with the saturated colors of dichroic fil-ters. As I mentioned earlier, this combination has both prosand cons. However, it’s your job, not mine, to weigh thearguments for your specific situation. As ever, I’ve tried togive you the raw facts and figures to help you make a deci-sion but, ultimately, that decision must be yours.

Mike Wood provides design, research and development,technical, and intellectual property consulting services to theentertainment technology industry. He can be contacted atmike@mikewoodconsulting.com

Figure 15: Yoke arms.

Figure 16: Motor control board.

Figure 18: Display.

Figure 17: Connectors.

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