ES-2000 Biradial Wood Horn Introduction


The ES-2000 Biradial is a new size format that takes advantage of high flare rate compression drivers that are typically used for 2kHz and above.  The small format compression drivers have a wide throat angle (high flare rate) of up to 28 degrees conical.  

Dimensional Drawing for ES-2000 Biradial Wood Horn (Part No. 1135)

Front Isometric View of ES-2000 Biradial (Part No. 1135) 


Section view of ES-2000 Biradial Horn Showing latest curvature (Part No. 1135) 


The resulting ES-2000 is a much shallower type of horn with a higher cutoff frequency (Fc) than the current ES-1200 Biradial.   The smaller size format shifts the frequency bandwidth comfortably into the upper treble region and would be a great solution for a "super tweeter" in a mutli-way system.


Suitable Drivers 

The following is a preliminary list of suitable drivers 


Compression Drivers 


  • B&C DE360 (New)
  • B&C DE120, DE110, DE111
  • 18Sound ND1030
  • RCF ND-350

Dome Tweeters


  • SB Acoustics SB26STAC (remove faceplate)
  • Scan-speak Discovery H2606/9200 (remove existing horn)


New addition to Autumn Speaker Series 

The ES-2000 will be a new addition to the Autumn Speaker Series.

Assembly No. 1142 outlines a new 3-way design...

New Autumn Series 3-way Assembly (No. 1142)

Assembly Drawing 1142 for 3-way Autumn Series Addition 

This configuration meets the 1 wavelength rule for driver center to center distance spacing.  Often horn speakers will place the high frequency horn too far from the midrange horn resulting in a sound that is not coherent or integrated. 

1142 Assembly showing optimal driver spacing and listening height 


Other Features of the ES-2000

Since this is intended for hifi applications there is requirement to completely eliminate any edge diffraction off the horn mouth.  To facilitate this I’ve decided to allow the sound wave to propitiate even further around the mouth lip another 90 degrees.  This forms pocket on the backside of the horn which I’ve sized for a layer of 1/2” thick foam.  This foam is the last line of defense to fully absorb the back wave.  Testing will be conducted later in March 2020 on the effects of the foam.

Isomentric Rear View of ES-2000 Biradial (Part No. 1135)

Driver Mounting 

To facilitate various drivers I’ve created a mounting ring that accepts the standard mounting bolt pattern for all drivers in this size format.  In an effort to keep the horn throat as smooth as possible, the mounting ring does not form part of the horn flare.(Ring not shown in pictures)


Acoustical Test Measurement

I will be testing the ES-2000 later this month using an exciting new compression driver available from B&C.  The DE-360 is a new driver that uses a ring radiator made from keytone polymer.  I will also be testing the horn with the B&C DE120.  

New B&C DE360 Ring Radiator Compression Driver

Prototype ES-2000 sitting on top ES-1200 for size reference 


Expect the price of a pair of horns to be in the $600 CAD range with choice of hardwood.


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