Hello, If I can add some useful information, I would recommend choosing a suitable speaker for horn use, you must have its Fs and Qes and then calculate : Fhm = 2.Fs/Qes It gives you the useable upper frequency limit of your speaker+horn assembly and this must coincide with the lower working frequency limit of your medium driver. Regarding the EVM12L, it's not only an excellent guitar speaker but gives very high efficiency and low distorsion in the low mid-band region, where it is the most important for your project. E-V people were the first to give the distortion figure of their speakers in data sheet, proof that they were in advance over their competitors. Unfortunately EVM12L is now phased out. Hoping this will help. Thanks to you all. EM