Clay Paky | Alpha Spot HPE 1200 | The Clay Paky Alpha Spot HPE 1200

Copyright January 2006 Lighting&Sound America
The Clay Paky Alpha Spot
HPE 1200
Fig. 1
by Mike Wood
Fig. 2: Lamp and reflector
Clay Paky has been manufacturing moving lights for just about as
long as anyone; the company’s original GoldenScan (actually, I
think the first model was the RubyScan in 1985) was seminal in
establishing the acceptability of scanner fixtures in professional
markets outside of discotheques and nightclubs.
More recently, Clay Paky fixtures have become synonymous
with the use of condenser-based optical systems. This choice
meant that their image quality and field flatness was exceptional;
however, fixture brightness wasn’t always quite up to the
competing ellipsoidal units.
The Alpha Spot HPE range diverges from this philosophy and
utilizes the now almost completely ubiquitous short-arc
lamp/dichroic ellipsoidal reflector combination. Has this change
been a good one for Clay Paky and how does the Alpha Spot
HPE 1200 measure up to the competition at the top end of the
market? This review seeks to find out.
As usual, the review works through the light in a logical order,
from lamp to lens, and tries to present results in an objective
manner. All reported results are based on multiple averaged
readings taken from one specific fixture supplied to me as
representative of the product by Clay Paky America—thus, your
tests may differ slightly. I don’t tweak or recalibrate the units; I
want the test results to represent the reality of a standard fixture
as it is shipped to the customer. (Figure 1: Unit as tested)
Although the Alpha Spot HPE 1200 is fitted with an electronic
switching lamp power supply and can run on voltages between
100-120V or between 200-240V, it doesn’t auto-sense and the
user must select the voltage via a switch on the outside of the
unit underneath the carrying handle. The unit was tested at both
voltage ranges and measurements were taken when run at 116V,
The unit was supplied and tested with the Osram HMI 1200 W/S
double-ended discharge lamp rather than the HTI 1200 W/D7/60
lamp, which the literature talks about. Both the HTI and HMI
versions are nominal daylight lamps rated at 6,000K color
temperature, with almost identical specifications; both are fitted
January 2006
Lighting&Sound America
Fig. 3: Dimmer flag showing frost glass
with the XS “Extreme Seal” plated pinch-foil technology we’ve
discussed before in these reviews. This development facilitates
shorter arc gaps and, thus, high optical efficiencies. All these
lamps require forced cooling.
The double-ended lamp is mounted on a lampholder plate,
which is retained by two quarter-turn fasteners; once released, it
pulls out and down for lamp access. Lamp change is very easy
and straightforward, with all parts remaining captive. (Figure 2:
Lamp and reflector)
Figure 2 also clearly shows the faceted cold-mirror reflector
with its large slots to accommodate the double-ended lamp; this
arrangement is very common in modern fixtures and inevitably
causes the beam to be somewhat asymmetrical, although Clay
Paky has done an excellent job of controlling this through the
design of the reflector facets.
As mentioned earlier, lamp power comes from an electronic,
square-wave, “flicker-free” ballast. The supply itself is a very
familiar component, supplied by Schiederwerk. That company’s
supplies are used by many manufacturers in our industry and are
known to be solid and reliable.
The lamp is well-cooled and I saw no evidence of overheating
or other problems during my tests. The whole of the rear lamp
house is sealed off with a hot mirror and Clay Paky does a good
job of compartmentalizing the heat and keeping it away from
downstream components.
The dimmer flags are mounted immediately after the first hot
mirror (Figure 3: Dimmer flag showing frost glass). The Alpha Spot
uses standard “serrated-teeth” cut flags, but with the addition of
frosted glass attached to the fingers, to improve the dimming
softness and avoid dimming artifacts. The photograph shows one
flag with the attached glass inserted into the beam—the system
uses two of these flags when dimming.
The dimming system also uses the capabilities of the electronic
ballast and simultaneously reduces the lamp wattage down from
1,200W to 600W as the blades close. This combined system
worked extremely well and the dimming was possibly the best I’ve
seen in a discharge spot unit—very clean and smooth, with no “jaggies,” or artifacts,
even at the lowest levels. Unfortunately, this excellent optical system is somewhat let
down by a very poor choice of dimming curve (Figure 4: Dimmer curve), where
everything useful happens in the top 20% of the dimmer. The unit is down to under
10% output when the control channel is still at 60% and is essentially out when the
control channel is at 40%. This is a real waste of resolution and means that the Alpha
Scan will dim differently from everything else in the rig, unless the user creates a
custom dimmer curve on the control desk. This is something Clay Paky could improve
on very easily with a software revision to really show off and capitalize on this excellent
As mentioned above, the fixture reduces the lamp power to 600W when the unit is
dimmed or blacked out through the strobe flags for more than three seconds, reverting
to the full 1,200W as the strobe flags open or the dimmer channel returns to 100%.
The lamp recovered very quickly and no color shift was apparent.
Fig. 4: Dimmer curve
Next in line is the color-mixing system. The Alpha Spot uses a linear “pair-of-curtains”
system with etched dichroic blades in each of four colors—cyan, magenta, yellow, and
CTO. Each color uses two blades, which move into the beam from opposite sides.
The resultant color-mixing is acceptably smooth, with little visible aberration in the
beam. You can see some color-fringing on the sides of the beam when focused on a
gobo and mixing pastel colors (Figure 5: Color fringing) but nothing worse than
competitive units. This is one area where Clay Paky has inevitably had to compromise
slightly from the almost perfect flat mixing of its units with condenser optics.
Color mixing
Transmission 36%
Color change speed – end to end
Fig. 5: Color fringing
0.6 sec
The transmission data above shows that Clay Paky has chosen fairly saturated
colors for its mixing colors with 4-6% transmission when mixed to the full primaries.
The variable CTO system performs well and can be used as a color modifier with the
color-mix system, if desired, to help make some pastel colors.
Unusually, the Alpha Spot has a second hot mirror, mounted immediately after the
color-mix assembly—I’m sure this is to keep the gobo system as cool as possible.
There is a lot of hardware mounted in a very small space, and cooling these systems
must have been difficult (Figure 6: Fixture optics). It certainly works well and the
downstream optics are kept very cool.
Fig. 6: Fixture optics
Next in the optical train are the strobe flags, it is getting unusual to find strobes
separate from the dimmer these days, but it does make sense. The needs of both are
different—the dimmer needs to be as far out of the focal plane as possible and,
preferably, somewhere where the beam is large, to give you smooth dimming. The
strobe system, on the other hand, can be positioned where the beam is much smaller,
allowing for short flag movement and, thus, high speeds. The Alpha strobe system was
excellent—using two opposing flags for maximum speed, it was solid and smooth with
a measured range of 1-12Hz.
Color wheel
Completing the Alpha Spot’s color system is a fixed color wheel (six colors + white).
The manual talks about these being removable; however, in the test unit provided, the
colors were glued in (Figure 7: Color wheel) and would be difficult to change. (Note:
Clay Paky tells me that this has been changed in current production units and the
colors are now fitted without glue and are fully replaceable.) The system allows half
Fig. 7: Color wheel
January 2006
Fig. 11: Fixed gobo wheel with
magnetic hub attachment
Fig. 8: Half colors
Fig. 9: Fan flips up for access to gobos
colors, but, because of the offset positioning of the wheel in the
packed optical compartment, the transition line between colors is
slightly oblique and varies a little as you rotate the wheel (Figure 8:
Half colors). The dichroics are close together and there is little or no
black transition bar between the colors.
Color Wheel
Transmission 7.2% 62%
Gobo change time, adjacent apertures
0.65 sec
Gobo change time, max (Gobo 0 to 3)
1.5 sec
Orange Blue
Maximum gobo rotate speed
0.5 sec/rev = 120 rpm
Minimum gobo rotate speed
1080 sec/rev = 0.056 rpm
0.3 sec
Color change speed – worst case 0.6 sec (quick-path enabled)
Maximum wheel spin speed
0.3 sec/rev = 200 rpm
Minimum wheel spin speed
410 sec/rev = 0.15 rpm
Through the menuing system, you can select various modes of
operation for the color wheel—for example, you can choose if the
wheel can rotate continuously or if it will “jump” between full and
half-colors. Noteworthy here is the very slow wheel-rotate speed
possible—it’s so slow as to be almost imperceptible. Another menu
option is to use quick-path, so the direction of wheel movement
always gives you the fastest change possible.
The Alpha Spot 1200HPE has three gobo wheels—the first and last
contain six rotating patterns plus open hole, while the center wheel
contains eight fixed patterns. Clay Paky has tried to make it as easy
as possible to access and change the gobos. For example, one of
the lamp fans flips up on a spring to give clear access to the
rotating gobo wheels (Figure 9: Fan flips up for access to gobos)
and the rotating gobos snap in and out very easily with no
requirement for tools (Figure 10: Snap-in gobos).
Most noteworthy is the system used for the fixed wheel—to
change the gobos, you need to remove the whole wheel. This could
be a real problem, so Clay Paky has tried to make it easy by
attaching the wheel with a magnetic hub (Figure 11: Fixed gobo
wheel with magnetic hub attachment). To remove the wheel, you
just snap it away from the center magnet and slide it out. Putting it
back is a little trickier, as you need to ensure the ident hole is
Lighting&Sound America
Rotating Gobos (Gobo 1 and Gobo 2)
Color change speed – adjacent
correctly installed over the locating pin on the hub. It takes a little
practice to get right, but, once mastered, it’s a neat technique.
There is a good choice of colors, with a nice clean red and a
good orange—always a tough color to get with a mixing system.
Color change speed was good—not the fastest I’ve seen, but
crisp and definite.
Color Wheel
January 2006
Fig. 10: Snap-in gobos
Indexing and wheel-positioning accuracy on the rotating gobos
was a little weak. Measured hysteresis error was around 0.4°, which
is approximately 1.5” at a 20’ throw. Wheel positioning was not
quick-path-enabled, resulting in the relatively slow, 1.5 seconds of
movement from Gobo 1 to Gobo 6.
As with the fixed color wheel, it is possible to select an extremely
slow gobo-rotation speed—this rotation is smooth and clean. Clay
Paky has chosen to populate Rotating Gobo Wheel 2 primarily with
effects glasses—however, it is possible to use and focus on
standard patterns as well. I did have a problem with Rotating Gobo
Wheel 1—if you are in narrow zoom (less than 20%) then you can’t
focus on this wheel at throws less than 20’. Wheel 2 does not have
this problem, so this might help determine which wheel you should
use depending on your particular rig layout.
Fixed Gobo
Gobo change time, adjacent apertures
0.25 sec
Gobo change time, max (Gobo 0 to 4)
0.5 sec
Maximum wheel spin speed
1.5 sec/rev = 40 rpm
Minimum wheel spin speed
65 sec/rev = 0.9 rpm
The fixed gobo wheel had a little bounce when coming to a halt
but otherwise performed well. The open aperture on this wheel is a
little too large, as you can see a sliver of it when positioned on the
adjacent Patterns 1 or 8. You can work around this by closing the
iris slightly. [Note: Clay Paky reports that the software has been
adjusted to address this problem in current production units.] Fixed
gobo change is quick-path-enabled ,helping achieve the very
respectable gobo change times reported.
The big change here for Clay Paky with ellipsoidal optics is the
ability to effectively morph between gobos. The Alpha spot performs
this effect well—Figure 12 shows a morph sequence between the
Fig. 12: Gobo morph sequence
Fig. 13: Graphic disk with
magnetic hub
Fig. 14: Graphic wheel worm drive
two rotating gobo wheels transitioning from Gobo 1 (left) to Gobo
2 (right).
Next in line is a standard multi-leaf iris, which reduces the beam
size to 19% of the full size when fully closed—i.e., 2° when at
minimum beam angle and 6° when at maximum beam angle.
Movement time from fully open to fully closed is a very
respectable 0.2 seconds.
Graphic disc
This is a new feature in moving lights—it’s not the same as the
animation wheel used in some competitive units. Essentially, the
graphic disc is a large diameter pattern or effects glass (Figure 13:
Graphic disc with magnetic hub) which can be moved in or out of
the optical path through a worm-drive gear mechanism (Figure 14:
Graphic wheel worm drive) and rotated across the beam. I’m not
sure what the intended benefit of this wheel is over the more
conventional effects glass mounted in Gobo Wheel 2 or the
effects wheel. The normal reason for a large-diameter pattern is
so that you can change the center of rotation, giving vertical or
horizontal motion to the image (or anything in between). However
the Alpha Spot mechanism doesn’t allow for altering this axis and
thus has a fixed direction and pattern of movement—nor can you
index the wheel to accurately position a pattern. This all seems
rather limiting to me.
It does however allow a good range of rotation speeds, ranging
from 120rpm down to an almost imperceptibly slow 4.4rph and,
as such, could be useful for some subtle background effects.
If the graphic disc does do what you want, then you’ll love the
disc change. It uses the same magnetic hub system as the fixed
gobo wheel and, because it doesn’t have the locating pin, it is
simple to remove and install.
Prism/lens wheel
We haven’t finished with effects; this unit is very comprehensively
equipped—in addition to the wheels already mentioned, the Alpha
Spot has a separate dedicated rotating prism/lens wheel. This
contains both two- and nine-facet prisms, as well as a
supplementary wide-angle lens, which increases the maximum
field angle from 31° to nearly 40°.
The prisms are conventional and, unfortunately, are another
victim of Clay Paky’s move to ellipsoidal optics. The image
separation is small and
image-focus quality is
reduced. It’s not the fixture’s
strongest point.
The field-angle increase
from the supplementary lens
is useful for color washes but
does have its limitations—you
inevitably lose a little focus
quality with the lens inserted
and, more significantly, you
are able to focus only on
Fig. 15: Light frost
Gobo Wheel 2 at throws less
than 25’. Chances are, you
need the wider angle,
precisely because you are on
a short throw—but then, you
can’t use either Gobo 1 or the
fixed gobo wheel. This lens is
fine for ultra-wide color
washes but not for short
Fig. 16: Focus versus frost
throw gobo washes. Consequently, if gobo projection is important
to your plot, then plan your rig around the standard 31° field angle
without the supplementary lens.
Prism Wheel
Prism change time
1.5 sec
Supplementary lens insertion time
1,8 sec
Maximum prism spin speed
0.53 sec/rev = 112 rpm
Minimum prism spin speed
3 rph
The final effect in the chain is a frost wheel. This contains three
grades of frost: light, medium, and heavy—and is a truly excellent
system. Figure 15 shows the light frost disc, with its characteristic
center hole (Figure 15: Light frost). Frost change time was 0.6
This is a good opportunity to show the difference between
what a good frost system can produce as compared with simply
taking an image into soft focus—the results can be very different.
Figure 16 shows two side-by-side images; on the left is a
defocused image and on the right is the same pattern,
January 2006
focused but with medium frost (Figure 16: Focus versus frost). The difference is
apparent—the defocused image shows multiple edges, with some color fringing
caused by increased chromatic aberration when out of focus, and it still retains a high
contrast ratio between peak black and peak white; in contrast, the frosted image
shows uniformly soft, diffuse edges, no color-fringing, and an overall reduction in
contrast ratio across the whole image. To my mind, the frost gives a much more
pleasing soft effect.
Frost systems in automated lights are often neglected and don’t always work as
well as they should—the Alpha Spot shows what can be achieved when it’s done right.
Lenses and output
Fig. 17: Output at narrow angle
Fig. 18: Output at wide angle
The Alpha Spot 1200 HPE uses a three-group system: Groups One and Two move,
providing zoom and focus, while the final group is the static front lens.
The optical performance is excellent, with almost no apparent chromatic and
spherical aberration. Lens-movement time, from end to end, was 1.5 seconds for zoom
and 1 second for focus. Measured field angle, as the fixture was zoomed field, ranged
from 10-31°, with corresponding total lumens of 18,082 lumens at narrow angle and
16,795 lumens at wide (Figure 17: Output at narrow angle; Figure 18: Output at wide
With the supplementary lens inserted, the maximum field angle increased to 40°,
while total field lumens dropped very slightly to 16,570 lumens (Fig 19: Wide angle with
supplementary lens).
The 3:1 zoom range and output are on par for a fixture in this class, comparing well
with the competition.
Pan and tilt
No surprises here—the pan and tilt has a reasonable range of 450° x 250° and the
movement speed was acceptable. A full-range, 450°-pan move is complete in six
seconds while a more typical 180° move takes four. For tilt, the corresponding figures
are 4.3 seconds for a full range 250° move and 3.8 seconds for a 180° move. The
mechanism uses a mildly unusual construction, in that the pan motor is mounted in the
yoke and drives itself, and the yoke, around a stationary pulley in the base. It’s all good
and solid and has the customary Clay Paky yoke locks on both pan and tilt.
Positional repeatability accuracy on pan and tilt was good at 0.1° and 0.2°
respectively—that’s around 0.4-0.8” at a 20’ throw. There was a slight settling bounce,
particularly noticeable on tilt, when coming to a rest from a high speed move of about
double this amount.
Fig. 19: Wide angle with supplementary lens
Overall, sound levels for the Alpha Spot were on the low side for fixtures of this size
and power. I noted a couple of resonances but nothing too unpleasant and no
“whining.” Pan and tilt were the noisiest motors and this is reduced by using slower
speed moves. The graphic wheel has a mild but apparent “clunk” as it comes into
position, not loud but noticeable.
Sound Levels in Normal Mode
Fig. 20: Sealed lead-acid battery
January 2006
Lighting&Sound America
<35 dBA at 1m
Graphic Disc
48 dBA at 1m
Prisms / Effects
50 dBA at 1m
56 dBA at 1m
Gobo rotate
50 dBA at 1m
56 dBA at 1m
52 dBA at 1m
55 dBA at 1m
51 dBA at 1m
50 dBA at 1m
49 dBA at 1m
50 dBA at 1m
Electrical Parameters
Power consumption at 116V, 60Hz
Current, RMS Power, W Power Factor
Normal running – stationary 13.3A
Normal running – all moving 13.6A
Homing/initialization time
This is 27 seconds when the fixture is powered up and “reset”
command sent.
Electronics and control
A new feature with the Alpha Spot 1200HPE is the provision of an
internal battery for the menuing system, allowing the user to preset
the DMX512 address and menu options while the unit is still in its
road case without power. It’s a large LED display and so needs
quite a lot of power—thus, the substantial sealed lead-acid battery
shown in Figure 20 (Figure 20: Sealed Lead-Acid Battery).
The electronics is a distributed system with a single master
circuit board in the top-box and multiple motor driver boards
throughout the unit, all connected through a high-speed serial bus.
Figure 21 shows two of these boards mounted at the front of the
head, above the zoom lens
system (Figure 21: main
head motor drivers). The
motor-drive circuitry is a
well-established design,
using standard drivers, and
should be reliable.
The menu system
includes the options and
Fig. 21: Main head motor drivers
selections one has come to
expect and the fixture offers both five-pin and three-pin XLRs for
DMX512, as well as a currently unused RJ45 socket labeled
“Future Ethernet.”
The Alpha Spot 1200 HPE shows some new features and some
old favorites in a solid package. It also shows a move by Clay Paky
into ellipsoidal optics. Was that the right decision for them to make
and is the product right for you? As usual, I leave you to draw your
own conclusions and hope this review helps you make that
Mike Wood provides technical and intellectual property consulting
services to the entertainment technology industry. He can be
contacted at
January 2006
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