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4 String 2+2 Bass Ratio Y-Style Button (PRB-4220, Select Finish)

4 String 2+2 Bass Ratio Y-Style Button (PRB-4220, Select Finish)



Regular price $114.99 USD
Regular price Sale price $114.99 USD
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RATIO® patented gear technology
RATIO® - Calibrated Machine Heads incorporate different string gauges into the tuning equation.

From Low E to G - 36:1, 30:1, 20:1, 18:1.

We balanced the gear ratios to each string simplifying the tuning process.

With RATIO®, a half-turn is a semi-tone!

Every string reacts the same to any tuning adjustment. Predictable, precise tuning, on every string. 


Bass Ratio animation

The PRB-4220 is a right-handed set of RATIO® Calibrated Machine Heads for BASS that use a 2 x 2 configuration.


In order to achieve the higher gear ratio's, Ratio's are the world's first machine heads using a double envelope gear design with a hardened steel gear. Amazingly smooth and super strong.


Headstock Configuration 2 x 2  Ratio Tuned Machine Heads: The New Standard In Tuning Technology


Gear ratio: unique for each string position - one turn-one tone
Peg holes diameter required: 35/64" (14mm)
String post diameter: 0.547" (13.9mm)
String post length to string hole: 1.030” (26.1mm)
Weight per single machine head: 1.86oz (53g)
Weight per set of four: 7.44oz (212g)
String diameter up to 0.98 gauge (or larger if taper-wound)
Includes 4 machine heads, mounting screws, and bushings


Staggered Ratio Measurements.pdf Ratio Installation Guide.pdf Ratio Installation Guide Video


Our Bass Ratio rated 5 stars on Sweetwater.

Sweetwater Rating 5.0


Rated 5.0 stars
Based on 1 review
Total 5 star reviews: 1 Total 4 star reviews: 0 Total 3 star reviews: 0 Total 2 star reviews: 0 Total 1 star reviews: 0
100%would recommend this product
1 review
  • TA
    Thad A.
    Verified Buyer
    I recommend this product
    Rated 5 stars
    2 months ago

    As a retired Engineer turned musician, I will never touch another Bass without them. From an engoneering point of view, they make perfect sense, and with the heavy Bass strings, they turn tuning from 'close is OK' to 'E'!

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