Wayne Parham Messages: 18758 Registered: January 2001
Illuminati (33rd Degree)
I've noticed that different horns and motors are sometimes optimal with slightly different top-octave compensation. All the ones I commonly use are pretty similar, but there are subtle differences. For an example, using a PSD2002, the Peavey CH-3, Eminence H290 and Martinelli 17" horns all need about 10dB, if memory serves. Using 12dB or more attenuation/compensation gives a little too much energy in the top octave and less than 8dB isn't enough. But the Altec 811 is best with 6dB or 8dB, and any more starts giving you too much in the top octave. It provides some acoustic EQ because of collapsing directivity, so if you equalize power response flat, then on-axis response rises into the top-octave.