Velodyne DF-661 loudspeaker A Little Boost Can't Hurt
As the DF-661's lean sound quality appears to be due to a simple equalization problem, I tried boosting the region below 500Hz with an Audio Control Richter Scale bass equalizer. Though a slight glare remained in the mid-treble, the EQ both eliminated the speaker's intrinsically lean quality and produced usable bass extension to 60Hz or so. The price paid, however, was that the woofer was now working much harder than the other units. High-level kickdrum was accompanied by significant wind noise from the port, for example, as were low-frequency warble tones at spls of around 90dB. Some distortion could also be heard on pure tones below 100Hz at this level. Nevertheless, I felt this tradeoff to be worthwhile: Orchestral music was more neutrally balanced and became quite listenable as a result. Vocal music, in particular, allowed me to hear how clean the speaker's upper midrange and treble sounded (though with the lower midrange and upper bass at a more natural level, the tweeter now sounded too shelved-down).
As a complete solution, however, boosting the woofer's output without compromising the distortion specification is probably not viable. Assuming that Velodyne sticks with the fixed coil in the woofer voice-coil gap, this could only be achieved with a passive crossover by padding down the midrange unit and perhaps the tweeter. This would drop the Velodyne's sensitivity by 6dB or more, bringing it in line with such miniatures as the BBC LS3/5A. I'm sure this would be a no-no in commercial terms.John Atkinson