This is the Gibson Les Paul model that the late great Terry Kath of the band Chicago played in the early 1970's.

This vintage guitar comes with a Guild non-original hardshell case and non-original transformer. The frets look to be original. They are low but definitely playable, no buzzing. It looks like someone used pliers to turn the bridge thumb screws and slightly gouged the top. I tried to get all the dings in the photos. There is some buckle rash on the back and there is very little checking in the finish, the wood has beautiful grain. The tuning machines are original. All the electronics in the guitar are original and in good working order. I recently cleaned out the electronics.

"The Gibson Les Paul Professional model, produced primarily between 1971 and 1973, has a standard 12-inch fretboard radius. This specification is a classic Gibson standard, providing a rounded feel for comfortable chording while still allowing for smooth string bends.   Details of the Gibson Les Paul Professional:

• Year(s) of Production: Primarily 1971-1973.   
• Body Dimensions: A 14-inch wide, 18 1/4-inch long, and 2-inch deep body.   
• Fretboard: Rosewood with a 12-inch radius.   
• Features: An economy model with Standard-style features, chrome parts, and a low-impedance electronics setup.    
• Why the 12-inch radius matters:

• Comfort for Chording:  The slightly rounder surface of a 12-inch radius is generally considered more comfortable for forming chords.   
• Bending and Soloing:  While a rounder neck is good for chords, a flatter radius is more beneficial for string bending and soloing. The 12-inch radius strikes a balance between these needs, offering classic Gibson feel for both. 

The Gibson Les Paul Professional, produced from 1969-1973, is characterized by its unique low-impedance electronics, heavy solid mahogany pancake body construction, and an angled pickup design. Key features include two low-impedance pickups, an 11-way decade rotary tone selector, a 3-way phase switch, a Tune-o-matic bridge, and a rosewood fretboard with trapezoid inlays. It differs from the more common Les Paul models by lacking a maple top, featuring a significantly heavier build (around 12-13 lbs), and having an unbranded truss rod cover with Les Paul Professional engraved on it.

• Body: Heavy, solid mahogany construction with a flat mahogany top and a "pancake" laminate layer.   
• Electronics: Two factory-installed low-impedance pickups, offering pristine clarity, a staple-style design, and a distinctive sound ideal for studio use.   
• Tone Controls: An 11-way decade rotary switch for discrete tone filtering, a 3-way tone selector, a master volume and bass/treble attenuation, and an in/out phase slide switch.   
• Hardware: A chrome Tune-o-matic bridge and stopbar tailpiece.   
• Neck & Fretboard: Mahogany neck with a rosewood fretboard, trapezoid inlays, and a standard Gibson scale length of 24 3/4 inches.   
• Headstock: A specific design with a peghead veneer, no Les Paul silk screen, and a truss rod cover engraved with "Les Paul Professional".   
• Weight: Notably heavy, often weighing 12 to 13 pounds.   

Unique Aspects

• Low-Impedance Electronics:  These pickups are a hallmark of the model, creating a very different sound from typical Les Pauls and often requiring an impedance line transformer for use with standard amplifiers.   
• Pancake Body:  The multi-layered mahogany body contributes to the guitar's substantial weight and unique sustain.  

Body & Neck:   

Body: Solid British Honduras mahogany. 

Neck: Mahogany, set-neck construction with a rosewood fingerboard. 

Frets: 22 frets. 

Scale Length: 24 3/4". 

Nut Width: 1-11/16".

Electronics & Controls: 

Pickups: Two low-impedance humbucking pickups.    

Output: Low-impedance output designed for direct connection to a mixing console.

  Master Controls: Independent bass and treble controls (EQ, not tone controls).   

  Pickup Selector: A three-position switch for front, rear, or both pickups.    

Phase Switch: Activates when both pickups are selected to provide a phase-out effect.    

"Decade" Control: A rotary pot with 11 positions to modify the harmonics of the guitar's tone.    

Volume Control: A dedicated volume pot.  

 Hardware:    

Bridge: Chrome Tune-o-matic bridge. 

Tuners: Chrome Schaller or Grover tuning keys.

Key Features & Innovations                                                                                           

Low-Impedance Output:  The main feature, allowing for a unique tonal response and direct               connection to recording equipment.    

  Comprehensive Tone Shaping:  The combination of bass, treble, decade, and phase control              provides a vast range of tonal possibilities, although it was considered complex for some players. 

The Gibson Les Paul Professional model has a 12-inch radius found on most modern Les Pauls. 

Key Features of the Les Paul Professional

• Fingerboard Radius: 12-inch.   
• Scale Length: 24.75 inches.   
• Electronics: Includes dual low-impedance humbuckers, a master volume, a treble control, a bass control, a phase switch, and a 3-way tone selector (middle position (2) is bypass, allowing treble and bass controls to operate. In position 1 or 3, there are preset tones for fast tonal changes."