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Joseph Crowe

3D CAD Files for No. 1861 & 1862 — Biradial for RAAL Lazy Boy 210-10 Flat Foil

Regular price $45.00 USD
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By purchasing these plans you will automatically recieve via email the zipped folder containing the required files to either 3D print or CNC machine horn No.1861 or 1862.


1861: Open air horn version with complete wrap around geometry to the back of the horn, including rear pockets for sound absorbing foam 

Click here for dimensional drawing. (open air version)

1862: Baffle mount version allows mounting directly to cabinet. Horn must be mounted using wood screws from inside of cabinet. This means the cabinet must have a removable rear panel for installing the wood screws into the backside of the horn. 

Horn 1861 and 1862 are specifically designed to work with the RAAL Lazy Boy Ribbon 210-20. The horn has been carefully optimized to create a perfect horn flare geometry starting at the diaphragm. This requires a throat adapter that also acts as a mounting plate for the driver. (see photos). 

Click here for dimensional drawing. (baffle mount version) 


  • 3D file formats in STL and .iges 
  • Plastic throat adapter to ensure smooth horn flare transition 
  • 1.2kHz Fc 
  • Assembly drawings (PDF format) 

    Acoustical Measurements 

    The below measurement is a comparison between the 1155 Horn (Green) and the driver mounted to a regular speaker baffle (Red).  

    Off-Axis Performance (for smaller ribbon tweeter, shown for reference only) 

    The 1861 and 1862 horn drastically improves the off-axis performance providing much wider coverage in the upper treble and also controlling the coverage in the midrange so that it matches the power response into the room.  This drastically improves the natural sound of instruments giving them better musical timbral accuracy.  Edge diffraction is completely eliminated with the 1155 horn which improves transient detail.  

    Shown below, example photo of smaller RAAL tweeter. 

    How it’s made video click here.