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AirTech Matrix
by Bill Mills
June 2001

In 1999 the paintball industry was buzzing with rumors that a company distributing through Diablo Direct had a high end paintball gun in the works.  Named the Matrix, and produced by AirTech Industries, it was initially envisioned as available in both pneumatic and electropneumatic versions. 

Eventually, with the trend in paintguns heading for all electronics on the high end, the pneumatic version was set aside and the E-Matrix (because the pneumatic version didn't come out, most people simply call it the Matrix) headed toward production.  Prototypes began making selected appearances.  According to Diablo's Richmond Italia, the first time a Matrix saw tournament play it was fielded by Team Pigchat, a team made of regulars from WARPIG.com's chatroom, at Skyball 2000.  Through the rest of 2000, the Matrix was further refined until its "coming out" at World Cup in October of 2000 (see an interview with AirTech staff in the World Cup episode of PigTV at www.PigTV.net).  At its debut, it was not just shown in the vendor's tent, but put to use on the field, in the hands of the pro team Image, and a number of amateur teams.

A Spool Valve Design

Spool valve structured paintguns utilize a fixed volume airspace, and a regulated air source to (in theory) deliver a consistent amount of energy to the ball with every shot.  The valve is controlled by a spool that slides back and forth like a piston.  In one position it allows the regulated gas supply to fill the fixed air chamber, known as the accumulator.  In the firing position the spool empties the contents of the accumulator into the breech, firing the paintball. 

A fair amount of energy is required to move the spool back and forth - enough that linking a trigger to it would be very impractical.  In the Matrix, like other spool valve paintguns the spool is moved back and forth by compressed gas.  The gas moving the spool is controlled by a smaller valve, referred to as a pilot valve.  Because a small mechanical valve, or a small solenoid (electronically actuated valve) could be used as the pilot, the Matrix concept would have worked with a manual, or electronic grip.  What made it to the final product was, of course, the electronic version, with a small solenoid valve serving as the pilot valve.

The spool valve of the Matrix is integrated with the paintgun's bolt.  This means that the only major moving part in the upper receiver is the bolt/valve core.  As compared to designs of other paintguns, where the bolt is separately actuated, or parallel to a hammer, the inline arrangement is compact and lightweight, keeping the Matrix from being bulky. 

An intriguing feature to the Matrix valve assembly is that the gas feeding the pilot valve is completely separated from the gas feeding the accumulator.  More on this subject later.

If there is one drawback to the spool valve in the Matrix, it is the number of o-rings.  Between the valve itself, and the spacers and blockers which hold it in place there are 13 o-rings, roughly half of which slide against moving metal, making them wear items. 

Fortunately, access to the valve for repair or maintenance is very simple.  After three turns of a knob on the back of the Matrix, it can be removed along with the threaded rod to which it is connected.  The rod runs the entire length of the paintgun in the center, screwing into the breech in the front.  With the breech released, it slides off the receiver with the barrel.  Removing the rod out of the back, the rear cover plate drops off easily.  A 5/32 hex wrench unscrews the rear valve plug, and all of the valve components can then be slid out the rear of the receiver.  While there or no real tricks or pitfalls to watch out for when taking out the valve, it is important to note the order in which the parts were removed when the time for reassembly comes.

Removable Breech

The entire breech of the Matrix is completely removable.  The stock breech is threaded to accept WGP Autococker compatible barrels, and sports a pair of or rubber ball detents.  The detents can be pried out with an o-ring pick for cleaning or replacement and pressed back in place with a hex wrench and a little wiggling.  The stock feed neck on the breech features curved sides which mimic the stock barrel, and is a tight fit with a Revolution loader.  Some loaders may need to be sanded, or heated to fit.  The feed neck is of the high rise variety, with room for a stack of two paintballs between the ball in the breech and the hopper neck. 

The removable breech opens a door for aftermarket manufacturers.  Potential aftermarket breeches will likely include different ball detent systems, angled or powerfeed necks, different barrel threading patterns, or even a side feed (with a single mill cut on the receiver) for use with the Warp Feed or other forced feed loaders.  Another aftermarket breech possibility would be the inclusion of optical or infra-red sensors that would link to an aftermarket circuit board. 

Early Matrices (the plural of Matrix) shipped with cast metal grip panels, later to be replaced by molded grip panels.  The grip frame shares shape and screw placement with the Angel LCD, allowing LCD compatible grip panels to be installed on the Matrix. 

There is no data display to be seen on the Matrix circuit board.  It provides the semi-automatic operational functions needed on a tournament paintgun, with no extra frills.  A PIC16C54C microcontroller lies at the core of the circuit board.  PIC processors are relatively inexpensive, and programmable in a variety of programming languages including Assembler and C.  They combine the functions of a microprocessor with memory in a single chip, able to store their own software onboard.  The PIC used in the Matrix is socketed, meaning it can be swapped with a unit featuring different software very quickly.  Rather than an aftermarket company needing to supply an entirely new circuit board to add new features, they could be supplied by swapping in a custom programmed chip.

Four dip switches are read by the software in the PIC and interpreted to select timing values (though a PIC with different software could be set up to use the switches to select firing modes, etc.)  The first two switches select the delay time in which the bolt is held forward.  The second two switches select the delay time to wait before firing the next shot, to allow a ball to fall into the breech.  The two settings determine the maximum rate of fire for the Matrix. 
 
 

Switch
0=on  1=off
Function
delay in seconds
F=bolt forward
D=between shots
Max R.O.F
Shots per Second
0 0 0 0 F=0.035  D=0.025 16.7
0 0 0 1 F=0.035  D=0.035 14.3
0 0 1 0 F=0.035  D=0.045 12.5
0 0 1 1 F=0.035  D=0.055 11.1
0 1 0 0 F=0.045  D=0.025 14.3
0 1 0 1 F=0.045  D=0.035 12.5
0 1 1 0 F=0.045  D=0.045 11.1
0 1 1 1 F=0.045  D=0.055 10.0
1 0 0 0 F=0.055  D=0.025 12.5
1 0 0 1 F=0.055  D=0.035 11.1
1 0 1 0 F=0.055  D=0.045 10.0
1 0 1 1 F=0.055  D=0.055 9.1
1 1 0 0 F=0.070  D=0.025 10.5
1 1 0 1 F=0.070  D=0.035 9.5
1 1 1 0 F=0.070  D=0.045 8.7
1 1 1 1 F=0.070  D=0.055 8.0

A single switch on the circuit board is accessible from the rear of the grip frame.  Selectable between F (fire) and S (safe) this is the power switch for the Matrix.  A four conductor connector and wiring leads from the circuit board to the receiver.  Two wires lead to the 9 volt battery clip, and two to the solenoid valve.  The battery is stored in the rear of the receiver, and can be changed out by removing the central threaded rod and receiver back plate.

The easily accessible wiring connector means that the grip can be taken off without any difficulties by removing the two grip frame screws.  This is important, as it is a necessary step in adjusting the trigger.  The Matrix trigger is a two fingered trigger with a light pull that actuates a microswitch on the circuit board.  Two set screws in the trigger allow for simple "trigger job" adjustment by limiting both its front and rear swing.  The stock configuration provides roughly 5mm of trigger pull (measured at the bottom of the trigger) which can be tightened to under 1mm with only 5 to 10 minutes of adjusting and testing.  Matrix owners may want to remove the rear trigger set screw and reinstall it backwards, with the hex head down.  This allows it to be adjusted and tested while the grip frame is still attached to the receiver.

Because the arm of the microswitch is made of plastic, it is a good idea for Matrix owners to check their trigger adjustment when first setting up their paintgun.  The rear limit set screw should be adjusted to stop the trigger before it pushes the microswitch lever into contact with the body of the microswitch.

Mounted vertically to the front of the receiver, is the Matrix regulator.  This two piece unit acts as a foregrip while reducing the pressure of the propellant gas before it enters the paintgun.  The Matrix operates at very low pressures - about 140 psi - making the regulator a necessity.  Because the volume of gas used with each shot is fixed, velocity of the Matrix is adjusted by changing gas pressure.  Adjusting the regulator involves twisting the lower half relative to the top half, and it is locked in place with a set screw.  The low pressure operation means that the Matrix is not limited to compressed air as a power source.  CO2 can also be used, since cold weather, and decompression chilling will almost never drop a CO2 tank's output pressure below what is needed to run the Matrix.

The overall design of the Matrix is sleek and clean, lacking external hoses.  All of the gas is routed through passages inside the receiver.  Plugs in the front and rear seal these chambers airtight.  A factory option for the Matrix is the addition of a low pressure regulator.  Adapter plugs can go in place of two of the front plugs allowing the use of an Autococker compatible low pressure pneumatics regulator to supply the solenoid valve and move the spool valve.  This is where the separate gas paths for exhaust, and control come into play.  By lowering the pressure used to move the spool valve, the bolt can be moved with less force allowing the Matrix to be much more gentle on the paintball, preventing breaks if a ball is only half way into the breech.  Low pressure regulators built just for the Matrix (Shocktech and Aardvark have models available at the time of this writing) can also achieve this same operation without any external hoses.

One of the first things many players do when they purchase a paintgun us to rush out and buy a brand name aftermarket barrel, figuring the stock barrel must not be able to compare.  The Matrix ships with a 14 inch Custom Products barrel, in .689 inner diameter.  This is the "medium" bore size of the 3 offered by Custom Products in their one piece barrels.

To test the Matrix, it was loaded up and taken to Spacecoast Paintball, and Command Post's Cow Town field, and tested with Diablo and Great American paintballs.  Centerflag Products Hyperflow 201 adjustable and 420 screw in preset 4500 psi compressed air systems, as well as a Crossfire 3,000 psi preset screw in system, mounted on a Shocktech drop forward were used for testing.  Additionally test firing was done with a 20 ounce CO2 tank on remote.  CO2 should be run with a remote, or with an anti-siphon tank if mounted horizontally to prevent the feeding of liquid CO2.

The first impression the Matrix made on most players - even those who hadn't fired it themselves is that it is very quiet.  The low operating pressure, few moving parts, and venting pattern of the CP barrel combine to send a lot of paintballs into the air without making much noise.  At the 2001 Gettysburg NPPL a player commented that he was shot out from diagonally down the field - he hadn't heard the Matrix that shot him on the open, inflatable bunker field.  In the woods, brush muffles the sound even more, giving the Matrix a stealth advantage.

Speed - the Matrix has it

The Matrix trigger is easy to pull fast, and the paintgun and electronics keep up with the trigger.  Firing with consistent velocity, accuracy is a hallmark of the Matrix.  Due to the low amount of moving mass in the design, there is very little "recoil" or shake when the Matrix is fired.  This means that in practical shooting (not locked down on a bench testing, but use in the real world) it is easier for the player to rapid fire tight shot groupings, rather than having their aim thrown off by the paintgun shaking as they shoot.  It was no problem to consistently fire 5 round groups, and put the last three shots (using the first two to walk in on the target) 5" x 5" sheet metal targets at various distances on Space Coast's target range.

On the field, it's centerfeed design proved quite adequate when topped with e Revolution loader, to keep up, and the double ball detent system did it's job.  Zero ball breaks were experienced during testing - the Matrix, equipped with the low pressure front regulator, is definitely gentle on the paint it shoots.

When adjusting the velocity, it became apparent that the smooth sides of the regulator are not easy to turn by hand when under gas pressure.  It is much more efficient to carry a pair of small adjustable wrenches to the chrono station along with the hex wrench used to lock and unlock the regulator.  One adjustable wrench can hold the top of the regulator in place to keep it from backing out of the receiver, while the other is used to turn the lower half of the regulator, setting the velocity.  The regulator is very responsive, and only needs to be turned in small increments.

Impressively, the Matrix handles well on CO2.  The reduced cost of CO2 tanks compared to compressed air systems can make them an attractive option.  For more advanced players, compressed air still ads the very attractive feature of being able to know how full a tank is by looking at a gauge.  With the Matrix regulator handling the final pressure setting, less expensive fixed output "screw in" compressed air systems provide excellent performance for the dollar.

With all the good points of the Matrix there must be something that is not top-notch and there is - gas efficiency.  The lower the pressure of a gas, the less stored energy it carries.  Because the Matrix runs at such a low pressure, it needs a lot of gas to operate at proper velocities.  4500 psi systems are definitely advantageous for the Matrix, due to the greater amount of gas they carry for a given tank size.  700 to 800 shots on a 68 cubic inch 4500 psi system seems to be the norm found in this field test and informal polling of various Matrix owners.  Back players who plan to shoot more paint will definitely want to go with larger tanks, perhaps even 114s.  The use of high quality paint, and a precise barrel to paint match can also help bring up the number of shots per fill by increasing gas efficiency.

In testing, some players remarked that they noticed a slight velocity drop while rapid firing.  Others did not.  It could be that this was an issue or perception, or that some players simply had faster trigger fingers.

Another area of concern with the Matrix is the connection between its regulator and the receiver.  While damage here has not been seen yet, it is a slender connection and has the potential to be damaged after a heavy impact.  Structural support for this joint may well appear as an aftermarket accessory.

An Impressive Paintgun

While still relatively new the Matrix is already appearing in custom versions.  Airsmith Danny Love is producing custom Matrices under the Shockteck name.  In addition to cosmetics, and the Shocktech hoseless low pressure bolt regulator, spacers inside the accumulator reduce the volume of airspace, increasing the gas pressure used to fire the ball, and decreasing the recharge time.  This improves gas efficiency, while the separated control and exhaust gas systems allow the bolt to still move under the power of gentle, low pressure gas.  The decreased recharge time reduces the possibility of velocity drop when rapid firing.

All in all, the AirTech Matrix is a very impressive paintgun.  It has a slim profile, is very easy to set up, adjust and maintain, it is capable of high rates of fire, and has excellent accuracy.  The standard Matrix includes a high end barrel, and will operate on compressed air or CO2.  While it is making a name for itself in tournament circles, being used by pro and top amateur players, it will probably also gain popularity amongst scenario and big game players where the stealth factor of quiet operation, and its accuracy make it well suited to sniper-like play.  There are also new features down the road for the Matrix, planned around the electronics.  Prototype circuit boards at AirTech are working with some new features that are a generation past anything on the market today.

The author would like to thank the following:
Richmond Italia of Procaps, and Troy Sorenson of Diablo Direct for providing technical insite into the operation and development of the Matrix (especially to Troy for the pointers on reassembling the spool valve!)
The players and refs at Spacecoast Paintball who tried out the Matrix and gave their feedback on how it performed.
 


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