Skip to content

Metallica Premium Monsters (Stern 2013)

Four-year build (2020-2024) spanning pre-toolkit v1.x through toolkit v2.0 conversion. Led by apophis79 with iaakki (physics/SSF/flashers), sixtoe, passion4pins (real machine measurements), tomate80 (Blender), flux5009 (toolkit debugging), primetime5k (testing), and majordrain (NIB Premium reference). Notable for the flash fadedown event stacking catastrophe, SAM system GI via lamp matrix discovery, magnet GrabCenter timing, Newton cube chamfers, and the apron angle revelation.

Build Story

Metallica was one of VPW's longest-running builds, exposing numerous Stern SAM system quirks that differ from WPC/DE conventions. The build uncovered that SAM GI strings are driven by lamp matrix indices (not GI callbacks), SAM ROMs cannot use AltSound, and the magnet board has its own onboard processor that PinMAME does not emulate. A progressive insert failure bug in the mtl_180h ROM (PinMAME issue #311) was filed but remains a SAM emulation issue that table developers cannot fix.

Table-Specific Details

Mechanisms & Hardware

Stern magnet board has its own processor: PinMAME only sends binary logic (on/off) to the magnet board -- it does NOT emulate PWM control. The board's firmware handles grab/release timing, strength ramping, and randomization. VPX magnet behavior must approximate what the real hardware does, not what PinMAME reports.

Magnet GrabCenter timing: GrabCenter should default to False and only be enabled after a 500-1000ms delay once the magnet activates. Enabling immediately causes an unnatural "wiggle" effect. The delay simulates the real magnet's gradual pull -- the ball first slows and curves toward the magnet, then locks in place.

Snake jaw dual solenoid with latch: Uses two solenoids -- jaw and jaw latch. The jaw solenoid fires True/False rapidly (sometimes multiple cycles per activation) while the latch controls the actual hold. The ROM sometimes sends extra events before the latch engages.

Coffin lock pin is cone-shaped: Not cylindrical. The cone shape prevents ball pinching against the playfield surface -- a cylindrical post would create a wedge point. The taper allows the ball to slide off naturally.

Captive ball rubber band fix: The captive ball was registering hits from table nudges alone. Fix: add a rubber band in front of the captive ball switch that absorbs small movements from nudging but allows legitimate ball hits through.

Art & Visuals

Flash fadedown event stacking: Flash fadedown speed set too low caused catastrophic FPS drops (54fps to below 30fps). When fadedown is slow, rapid flasher fire events stack -- each new flash starts before the previous fade completes, creating compound rendering load. Fix: increase fadedown speed or implement logic to cancel pending fades when a new flash arrives.

GI bloom technique: Dual-layer flasher textures -- one oriented bottom-up and one flipped 180 degrees -- both fading with GI intensity. Creates more realistic ambient glow than a single flasher layer.

"Mayo" lights with exponential falloff: iaakki refined the mayo technique to use level^2 or level^3 so bloom disappears faster as distance from the light source increases. Made optional in F12 menu.

Apron angle is NOT parallel to playfield: passion4pins measured his real machine: front edge of apron sits approximately 3" below playfield, back edge approximately 2" below. Most VPX tables incorrectly model the apron as parallel.

Stern "orange peel" playfield reflections: Stern playfields have a textured surface, not mirror-smooth. Reflection probe roughness of 1-2 looks more realistic than the default mirror-like setting.

Plastic bottom reflections: Toolkit-baked plastics only render the top surface. iaakki added separate white primitive meshes under the plastics that follow GI color combinations and brightness levels, providing correct reflections.

Physics & Gameplay

Newton cube chamfers: Invisible physics collision boxes need chamfered/beveled edges to prevent fast-moving balls from penetrating through sharp corners between physics frames.

Playfield is 20.25" x 45", not 46": passion4pins measured his real machine. This 1-inch difference affects ball travel times, physics scaling, and camera setup. Several tables assumed to be 46" are actually 45".

SAM GI via lamp matrix: On Stern SAM tables, GI strings are driven by lamp matrix indices (130, 132, 134, 136) rather than the standard GI callback. This caused dim lightmaps with VPMModSol=2 because lamp matrix intensity values were too low (PinMAME issue #312). apophis79 had to multiply intensity by 5x.

Sling threshold tuning: Both threshold AND hit threshold must match. Threshold 2.5-3.0 optimal for Metallica -- too low (1.5) causes Super Skill Shot and right orbit return balls to trigger sling kicks unintentionally.

Borg inlane danger zone: majordrain (NIB Premium owner) identified this as the most dangerous spot on the real machine -- shots to piston without enough momentum roll back off the metal inlane guide and bounce to the left outlane.

Known Issues

ROM emulation bug (mtl_180h): Progressive insert light failure during extended gameplay (PinMAME issue #311). Inserts stop responding after approximately 30 minutes, often triggered after Crank It Up mode. SAM board emulation issue -- not fixable by table developers.

SAM cannot use AltSound: SAM ROMs have a different audio architecture than WPC/DE. Workaround: use a PUP pack with ROM music muted.

BDL negative values break rendering: Setting blenddisablelighting to negative values causes inverted or washed-out colors. Always clamp to the 0+ range.

Stern ROM naming: "H" suffix indicates LE/Premium edition (e.g., mtl_180h). Without H = Pro. Different editions have different solenoid assignments and lamp mappings.

Techniques Developed Here

See Also

  • Iron Maiden -- another Stern table with similar physics challenges
  • Monster Bash -- sling threshold tuning comparison
  • Iron Man -- Stern-era playfield friction calibration