DEQX hdp-express mkii music processor

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The DEQX HDP-Express MkII Preamp Processor is an excellent addition to your 2 channel home studio.

DEQX processors correct the distortion that all speakers make—electro-mechanical devices that they are—and offer room compensation as an added extra. While righting frequency-response errors as other units do, they also uniquely fix critical timing errors by adjusting thousands of frequency groups so that they arrive on time.

*If you use a music server, add the Digital Input Board below called the DEQX XS-1 - its an Asynchronous USB Audio option and this is the best way to get higher quality sound into your DEQX!

Now includes DEQX XS-1 USB Audio Board For Macs or PCs

Other ‘room correction devices’ simply adjust amplitude response (uneven output at different frequencies) to offset room modes. But they can’t address the fine details of phase coherence; the group-delay timing issues that manifest in all real-world speakers.

The results are startling; two-channel and surround systems open up in a dramatic way when timing, phase, and amplitude accuracy are restored to the speakers, with judicious room compensation added.

The DEQX Calibrated™ mark guarantees a frequency response, phase response and time alignment accuracy in speakers that's comparable to the rest of your audio components.

The DSP(Digital Signal Processing)-based technology also provides detailed room measurements and the tools to compensate for room acoustics problems.

For active loudspeakers DEQX Calibrated™ correction includes the integration of a high order linear phase digital crossover, radically reducing distortion, improving power handling and creating a wider soundstage, even in low-cost loudspeaker systems.

Please welcome the latest addition to the DEQX line up, the all new/revised DEQX HDP-Express Mkii pre-amp correction processor. There has never been a better time to leap into the system correction realm.

There’s never been anything like DEQX’s reference HDP-4 DSP pre-amp correction processor. And it’s still the only audiophile component capable of delivering a four-fold improvement (that’s 400%, not 40%) in almost every parameter that helps make your audiosystem sound ‘real’. And the DEQX HDP-Express MKii offers an affordable way for all to benefir from the benefits of DSP speaker and room correction.

It directly corrects your system’s weakest link—your loudspeaker’s native (anechoic) performance, where over 90% of the distortion and inaccuracies in timing and coloration originate.

The HDP-Express: for only $2950 (plus cal mic and freight), the HDP-Express MKii™ retains the HDP-4’s key performance features, using the same DEQX-cal setup software for Windows (or Mac with Windows).

DEQX™ HDP-Express MKii™ sets a new price/performance benchmark by allowing you to enjoy the sonic benefits that naturally flow when your speaker's inherent errors are corrected in timing, phase and frequency-response. HDP-Express™ provides the same basic features as DEQX's premium HDP4™ processor preamp, utilizing the same DEQX-Cal™ PC software for measuring and setting up your speakers.

The improved sense of realism we experience after our speaker's native (anechoic) timing, phase and frequency-response errors are corrected is always surprising. For example our speaker's frequency response is typically only accurate within a 6dB window, or nearly 6dB worse than the signal driving them. DEQX reduced to about a one dB window or error. With regard to musical coherence; timing and phase errors in speakers cause critical mid band frequencies to typically lag behind others in the order of a millisecond. DEQX reduces these typically fivefold.

When the speaker itself is working accurately, HDP-Express MKii™ provides room correction that focuses on bass and the lower midrange without the danger of corrupting its native performance by using room measurement to correct midrange and high frequency phase information.
However, since neither speaker or room correction can actually increase speaker's resolution, reduce breakup and crossover distortion, nor improve dynamics and dispersion, HDP-Express MKii™ provides the option to upgrade your speakers to a new generation of 'active' configuration – where high-order crossover filters can be implemented yet maintaining true linear-phase and individual driver correction!

Speakers become 'active' when individual power amps are provided for each type of driver: bass, midrange and tweeter, whose amplifiers are driven by typically a 3-way active crossover, or 2-way plus subs. The steep linear-phase crossover filters that HDP-Express MKii™ provides properly quarantines frequencies sent to each driver to their 'comfort zone', so they deliver best-case distortion, resolution, and dynamics.

To avoid unnecessary conversions, HDP-Express MKii™ provides preamp features so that when using digital input sources no additional DAC conversions are required that could compromise source signal integrity. Analogue inputs are also provided.

Active linear-phase crossover features:

Steeper than 6dB/octave crossover filters required to reduce distortion don’t maintain linear-phase using traditional crossovers. Now they do.Traditional active Butterworth and Linkwitz Riley, mild to steep crossovers and four ‘Profile’ presets lets you directly compare linear-phase advantages.Using 48dB/octave or steeper linear-phase crossovers distortion vanishes, resolution increases, while volume can double or quadruple, 3 to 6dB.When used with speaker correction, stereo 3D imaging, volume and dispersion improve markedly, making a centre speaker usually unnecessary.

Speaker correction features:

Anechoically measure and correct your passive or active speakers using a simple measurement technique, even in your listening room.Corrects anechoic (native) speaker frequency-response from typically plus/minus 3dB to plus/minus 0.3dB*Corrects Group-delay (phase/timing errors at different frequencies) about tenfold* e.g. 2ms reduces to 0.2ms —especially noticeable in midrange.Room Correction features and preference EQ:One or more room measurements displayed graphically, allow manual, real-time, 7-band parametric EQ settingsTime-domain correction of subwoofers/bass speakers measured in-room.Adjust delay between main speakers and subwoofers in real-time.

Media correction—forensic tone control:

Remote controlled Low-shelf, Midband-fully parametric and High-shelfLow, mid and Hi frequencies adjustable in octaves and semitonesAdjustable Q from one semitone to four-octave wide99-memory storage for instant recall.

Pre-amp and processing features

Four profiles for instant selection of crossovers, correction and EQFour inputs: S/PDIF, AES3, analogue unbalanced and balanced.Integrate one or two subwoofersRemote controlled Input and profile selection.Six unbalanced outs: Stereo low, mid, Hi (mid used for passive speakers)Optional balanced outs (6 x XLRs) transformer or active.Dual 32-bit SHARC DSPs provide minus 140dB THD digital transparency.

Features Express HDP-4
Remote Controls: Standby, Profiles-select, Volume, Input Yes Yes
Front Panel controls: Standy, Profile-select, volume Yes Yes
Digital Volume control Floating 32bit DSP Yes Yes
Analogue Volume control No No
32 bit DAC Yes Yes
Mains (manually switched) analogue power supply No Yes
Mains (auto switching) switch-mode power supply Yes No
Front Panel 12mm Brushed aluminium Black or Silver No Yes
Front Panel 6mm black anodized Yes No
Balanced output option (6 x XLR) No Standard
Ditital output option No Standard
Digital DSP input pass output No Standsrd
24/176.4 & 24/196 digital input Yes Yes
DEQX-Cal Software & Firmware Yes Yes
USB Option input Yes Yes
SPDIF (RCA) Digital input Yes Yes
SPDIF (BNC) Digital input Yes Yes
AES/EBU (XLR) Digital inout Yes Yes
Toslink (optical) Digital Input No Yes
Balanced Analogue Input (XLR) Yes Yes
Single Ended Analogue Input (RCA) Yes Yes
DC coupled analogue outputs No Yes

DEQX XS-1 USB Audio Board

DEQX XS-1 24/192 Asynchronous USB board.

This digital input board allows you to connect your DEQX directly to your Windows or Mac based music servers.

If you use a music server, this is the best sounding way to get sound into your DEQX!

USB Board Features:

16/44 - 24/192 Asynchronous

No 5v power connection to computer; powered internally from ultra clean DEQX power supply.

I2S interface to eliminate conversation to SPDIF and reduce jitter.

Interdependent regulated clocks.

No drivers required for Macintosh OSX.

Windows Drivers supplied for XP, Vista, Windows 7, Windows 8 32 & 64 bit.

DEQX HDP firmware update supplied on disc.

Easy to install, just one plug.


  • Provides DEQX Calibrated™ speaker correction for passive speakers
  • Provides DEQX-HD™ speaker correction for up to 3-way active speakers
  • Audiophile grade analogue electronics
  • DEQX-HD™ active crossovers; 48dB/octave to 300dB/octave linear-phase
  • Frequency-response of speakers typically corrected from 6dB range to 1dB*
  • Traditional active 3-way crossovers from 6dB/octave to 48dB/octave
  • Automatically corrects phase and group-delay over typically 3ms window
  • 32-bit, floating-point, 240-MFLOPS processing with dual SHARC DSPs
  • Integrate one or two subwoofers with main speakers with time-correction
  • Audiophile op-amps typically 300V/uSec slew-rate with high output drive
  • Provides anechoic measurement and detailed display for speaker correction
  • Audiophile 24-bit 96kHz ADC-DSP-DAC processing and conversion
  • Patented low-latency FIR processing for speaker correction allows video use
  • Front-panel volume control and ‘Profile’selection
  • Provides room-measurement/display (non-anechoic) for room correction
  • Four, user-defined ‘Profiles’ allow different crossovers, room-EQ, preferences
  • Auto and real-time manual Parametric EQ over measurement display
  • Remote controls; Volume, Profile, Input select, and Lo, Mid, Hi tone controls
  • Remote tone control provides full-spectrum parametric EQ with 100-presets
  • DEQX integrated software measurement, correction and user-defined options
  • Calibration Kit provides DEQX-calibrated measurement microphone
  • Two analog inputs: Unbalanced (2 x RCA) and Balanced (2 x XLR)
  • Individual driver correction prior to crossover when actively implemented
  • Two stereo digital inputs: S/PDIF (1 x RCA) and AES/EBU (1 x XLR)
  • Microphone input has 48V phantom power for DEQX Calibrated™ mics
  • Anodized Black brushed or Silver brushed aluminum front panel
  • D115V-230VAC switched mains input; 30VA (100V-200V Japan only option)
  • 2U high chassis; 3.5" H x 17" W x 11.5"
  • Audiophile linear main power supply
  • Six analog outputs: unbalanced (6 x RCA)
  • Membership of DEQX Users Group (online)
  • Free downloadable software and firmware updates

Difference between HDP-4.0 and HDP-Express MKii

The Express is based on the HDP-4.0 2U chassis with a similar main board using a standard new Burr Brown op-amp OPA-1642 to keep production cost down. The 6mm front panel has no buttons (remote control or PC only to operate it) analog outputs are standard 6 RCA and no balanced option. No digital output option is available for the Express MKii. Higher grade parts are used through out the HDP-4.0. The HDP-4.0 uses an Analog Preamp stage, the HDP-Express uses a Digital volume control. Thevolume is controled in the digital domain of the DSP Processor, not the post DAC analog volume like the HDP-4.0. One thing that should be noted is while the volume is digital bit stripping, it only occurs below about –20dB on the volume slider. If the six analog output gain jumpers are set on the main board you can balance the output level to keep the volume above –20dB and avoid bit stripping. The HDP-4.0 has a Linear Mode power supply. The HDP-Express is a switch mode Power Supply. It is a wonderful piece for two thirds the price. We could not imagine living without a DQX in our system. And the HDP-Express is a great affordable way to get into DSP topology.


Stereo analog inputs, balanced (XLR) and unbalanced (RCA)

Stereo digital inputs, BNC & RCA S/PDIF and AES/EBU, USB (SOON)

Six analog outputs, unbalanced RCA

Mic input for optional DEQX Calibrated™ measurement microphone

Standard Calibration Kit includes:

DEQX Calibrated™ Behringer measurement microphone

Five-metre balanced microphone cable (XLR)

DEQX PC-based measurement, correction software on CD

Five-metre USB cable

Reference Calibration Kit includes:

DEQX Calibrated™ EARTHWORKS measurement microphoneFive-metre balanced microphone cable (XLR)

DEQX PC-based measurement, correction software on CD

Five-metre USB cable

Additional OUTPUT options (6 x RCA unbalanced outputs are standard):

No Balanced Analog output option offered ont he HDP-Express MKii