Products > Loudspeaker Correction

DEQX HDP Balanced Output Board Balanced output board with latest generation op-amps and DC servos for the HDP-3 and HDP-Express $455.00	DEQX HDP Jensen Transformer Balanced Output Board A plug in board to add six Jensen Transformer balanced outputs to your HDP-3 or HDP-Express. $988.00
DEQX HDP-3 The DEQX HDP-3 flagship speaker correction, room correction, dsp crossover and digital preamplifier. $3,995.00	DEQX HDP-3 Digital Output Board Plug in board to add digital outputs and an external clock sync to your DEQX HDP-3 $550.00
DEQX HDP-Express The DEQX HDP-Express speaker correction, room correction, dsp crossover and digital preamplifier. (1) $1,950.00	DEQX Reference Earthworks M23 Calibration Kit 'Better' DEQX calibration kit containing software, cables and Earthworks M23 measurement microphone. $645.00
DEQX Reference Earthworks M30 Calibration Kit 'Best' DEQX calibration kit containing software, cables and Earthworks M30 measurement microphone. $935.00	DEQX Standard Calibration Kit 'Standard' DEQX calibration kit containing software, cables and Behringer ECM8000 microphone. $199.00

DEQX HDP-3 and HDP-Express can reduce the frequency response and group delay errors caused by your loudspeakers, audibly improving sound quality.

Your speakers are the largest source of acoustic distortions after your room. The DEQX HDP-3 and HDP-Express, amongst other things, are powerful DSP correction processors that can reduce the intrinsic distortions to frequency response and phase caused by your speakers. DEQX corrects your speakers in three main ways:

Speaker frequency response. The performance of speakers, when considered in terms of frequency response, is an order of magnitude worse than that of the rest of the electronics within your reproduction chain. Typical best case (on-axis) speaker performance is +/- 3dB across the audio spectrum from 20Hz to 20kHz compared to +/- 0.1dB for the signal that leaves the amplifier.
Speaker group delay. The crossovers in most speakers create a frequency dependent delay or group delay which causes some frequencies to lag behind others in time. At 1kHz our detection threshold for group delay is around 2ms. A typical high end speaker can have group delays of 3ms in this critical frequency band! These group delays negatively impact our perception of musical timing and coherence.
Speaker time alignment. Whilst some speakers used sloped or stepped baffles to time align drivers many do not. Lack of time alignment causes a loss in musical coherence and timing similar to that caused by high group delay. DEQX can be used to correctly align the arrival time of the signal from different drivers within a loudspeaker. DEQX can also be used to time align subwoofers, which are often placed further away from the main speakers near a wall or in room corners.