Vintage ALPS Full-Sized Tapped Potentiometer

Stereo 50K Linear | Dual Center Loudness Taps | Integrated SPST Switch | Japan NOS

👨‍🛠️ Bench Verification & Technical Condition

Up for sale is a rare, premium New Old Stock (NOS) vintage 1970s ALPS Japanese-Made full-sized dual-ganged stereo potentiometer with an integrated power switch. This robust audio component features a 24mm can architecture engineered with independent centre-tapped loudness tracks on both decks. Outfitted with an integrated rear 2-contact Single-Pole Single-Throw (SPST) main power switch and reinforced with an industrial die-cast zinc-plated top mounting plate hosting a built-in anti-rotation alignment locating pin. Personally stored in dry workshop drawers for over 50 years, this premium assembly remains entirely unused, unmounted, and has never seen a drop of solder.

Verified Linear Track Curve: Factory stamped with the classic ALPS 22-50KΩBX2 series identifier. Confirmed via comprehensive multimeter sweeping to provide a highly uniform linear distribution curve across both ganged tracks, ensuring perfect stereo tracking balance.
Dual Physical Loudness Taps: Features independent centre tap lugs positioned on the rear side of both pots. Direct bench diagnostics confirm that the physical loudness taps and mechanical midpoints sit perfectly synchronized right at the mechanical 50% half-turn mark.
Integrated SPST Safety Switch: The base houses a heavy-duty rotary main toggle (Model 24SB11) carrying an official Underwriters Lab USA listing label (Snap Switch F-615). Rated for 3 Amps at 125VAC; contacts are Normally Open (N.O.) and close immediately upon rotating past the initial off-detent click.
Die-Cast Structural Safety Pin: Built-in structural zinc alignment pin adjacent to the threaded collar. This key slots cleanly into panel sub-frames to completely eliminate tracking chassis rotational twist under torque.

🔹 INDEPENDENT BENCH DIAGNOSTICS & RESISTANCE RATIOS:

- Mechanical Operation: Smooth Continuous Rotation with Positive Off-Detent Snap Switch & Locating Pin
- Total Chassis Termination Footprint: 8 Active Lugs (6 Side Resistor Lugs + 2 Rear Switch Contacts)

- Front Resistor Section (Pins 1 to 3): Nominal 50 kΩ | Measures 43.600 kΩ Max | 50% Mechanical Midpoint & Loudness Tap: 19.510 kΩ (True Linear)
- Rear Resistor Section (Pins 1 to 3): Nominal 50 kΩ | Measures 43.100 kΩ Max | 50% Mechanical Midpoint & Loudness Tap: 17.350 kΩ (True Linear)
- Integrated Switch Base (Model 24SB11): Single-Pole Single-Throw (SPST) | Rated for 3 Amps at 125V AC Mains

📊 Factory Component Specifications

Brand / Manufacturer	ALPS (Made in Japan)
Full Manufacturer Part Number	22-50KΩBX2 (Series 24SB11 / F-615)
Taper Architecture Code	"B" - True Linear Taper Profile with Centre Loudness Taps (Japanese JIS standard)
Nominal Resistance Base	50 kΩ Nominal Base (Highly balanced matched tracking around 43kΩ Max)
Architecture Layout	Dual-Ganged / Stereo Coaxial Track Configuration with Centre Loudness Taps
Integrated Switching Block	SPST (Single-Pole Single-Throw) \| 2-Contact Rear Terminal Base (3A 125VAC)
Casing Footprint Diameter	24mm Full-Size Can Main Housing Profile
Mechanical Structural Security	Zinc Alloy Die-Cast Sub-Plate with Round Anti-Rotation Indexing Locating Pin
Shaft Interface Dimensions	6mm Diameter \| 30 mm (Inc. 8mm thread) Aluminium Split-Spline Layout
Era & Origin / Condition	Vintage 1970s Production \| Made in Japan \| New Old Stock (NOS)

📻 Vintage Solid-State Stereo Restoration

This robust 50K tapped control is an excellent resource for vintage solid-state stereo repair:

Premium Integrated Amplifiers & Tuning Stages: Direct drop-in match for active tone circuits (Bass/Treble attenuation layouts) or loudness-compensated volume stages inside classic 1970s **Pioneer, Sony, Sansui, Sanyo, or Marantz** solid-state lines.
Flawless Track Continuity: Pristine internal carbon tracks combined with a flat centre curve shield your circuit from the abrupt audio level shifts and scratchy tarnish jumps found in heavily degraded original units.

📮 Combined Shipping Policy

Clearing out multiple vintage assets from your workspace project bins? I will gladly manually combine shipping costs across all active listings to save you money on postage. Please add your items to your cart and request a final total before making your payment so I can issue an adjusted invoice based on the true package size and weight.

⚠️ Vintage Electronics Disclaimer

This item is a premium New Old Stock (NOS) component from an accumulation of classic workshop stock. While it has been cleanly bench-tested to confirm precise track resistance, switch continuity, and smooth tracking, vintage electrical hardware components are sold as-is without modern commercial warranties. Please review all dimensions and chassis shaft profiles closely before purchasing. Added this!!