It is made with 19mm MDF.Use a ACR/Fostex FE208 Sigma Driver. Diameter of the Driver is 230 mm. The
complete Horn has a efficency of 100 dB with 2,83 Volt input in 1 meter. The Driver has a Impedance of 8 Ohms so 2,83 Volts are exactly 1 Watt input power. The Dynamic is enormus. The plan was in the German Magazine "Klang und Ton" issue 2/96 and it is called the JERICHO HORN.
R2 and C2 are to smooth the impedance curve you don't need them if your amp is atransistor design R2= 10 ... 33 Ohm, C2= 15 uF L1=1,0mH - air coil, wire diameter 1,4mm or more C1=2,2uF MKP or MKP-SN or betterone R1= 10 Ohm / 20 Watt Metall, I use 10* 100 Ohm / 2Watt paralell