For the two identical not master/slave A500, this goes well beyond a digital crossover to include compensation for resonances and nonlinear dispersion. Each driver was measured at 2'700 different microphone positions to be analyzed in-depth then corrected for "many acoustic phenomena which our software can distinguish to a very high degree for strategic corrections on each. This includes identifying which effects are natural so we don't compensate those."
Don't call it loudness! Also integrated is ear/brain-compensated amplitude response. This updates basic loudness notions whereby with diminishing SPL, our ears' sensitivity becomes nonlinear relative to frequency. The more quietly we listen, the less bass and treble we perceive. Now the midband as the bandwidth critical for speech intelligibility becomes most dominant. Buchardt decided to leverage modern processing power to correct for this in DSP. Now even whisper sessions deliver the correct tonal balance. This part of the correction algorithm only activates for playback levels below 70dB.
MO. But that wasn't the end yet of the A500's IQ. Not by iOS/Android app but from the configuration library on the German distributor's website, the intrepid hifi adventurer can download various tuning profiles onto FAT32-formatted USB stick. That new firmware then uploads to each powered-down speaker's USB port. It's there exclusively for that, not to connect external hard drives or computers. Regardless of your preset profile, there's still separate room calibration which I seriously recommend to at least try. It relies on the hub, however. That stores the measurements to calculate then transmit the correction code to the speakers. Here you need the app's iOS version. That's because the built-in microphones of Android phones aren't calibrated strictly enough like iPhones are. Only the latter guarantee consistent and reliable data capture. Buchardt thus insist that for a few minutes, Android users borrow a friend's iPhone just to conduct their room-correction measurements.
Sensibly the bandwidth which room calibration concerns itself with falls below 500Hz. That's where the most deleterious speaker/room interactions occur. Interestingly, during the about 1-minute test-noise phase, one is called upon to go walkabout to capture all of a room's resonant modes. Buchardt call this CSS for continuous soundfield sampling. The details thereof exceed this review's purview so interested parties should reference Buchardt's relevant web presentation. Whilst the app is currently focused on just room correction, a parametic EQ plug-in is already on the books.
