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The DAC1 HDR is Benchmark Media’s  reference stereo pre-amplifier incorporating the renowned DAC technology used in the DAC1 Pre, and features such as the UltraLock^TM clock system, AdvancedUSB^TM computer audio playback (USB DAC) interface, and the legendary HPA2^TM headphone amplifier. There is also a remote control system built around Benchmark's new HDR-VC^TM (high dynamic range volume control).

Side-by-side comparisons of the DAC1 HDR’s circuitry and the DAC1 USB reveal numerous circuit and PCB layout similarities. The differences include the Xilinx XC3S50 FPGAs (Field Programmable Gate Array), this devices handles multiple logic functions. The HDR dispenses with the single BNC digital input in favour of 3x RCA digital inputs, as well as the USB and Toslink variety. Compared to earlier versions of the DAC1 circuit, the NE5532 op-amps used in the analogue stage are upgraded to the LM4562.

The HDR DAC is faces serious competition in the £1600 price range, the inclusion of high performance pre-amplifier goes some way increase product value. To improve performance of pre-amplifier and DAC we have developed upgrades for the DAC1 HDR to provide a serious boost in sound quality. The upgrades improve the quality of the AC supply, reduce jitter at the DAC, improve digital inputs (coaxial) improve signal propagation at the singled ended and/or balanced outputs.

We have a reference upgrade available with selectable optional extras depending on individual set-up and requirements.  The reference upgrade installs a pair of Bybee Large Quantum Purifiers at the AC input.  The Bybee Purifiers reduce in 1/f noise which if left unattended is transferred at the audio signal output. The resulting sound is more open and spacious; the noise floor is notably reduced so music emerges from a quieter background.

The Benchmark DAC1 uses the UltraLock^TM clock system and has effective jitter reduction at the digital inputs. The AD1583 DAC used in the DAC1 has a master clock input (MCLK) at pin 2, the benchmark enrols a TCXO oscillator for this purpose. Any phase noise (jitter) here will impact on sound quality, as will the quality of power supply for the TCXO. We upgrade the TCXO to a Superclock 4 resulting in a significant reduction in jitter at the DAC. Additionally, the 5V supply line for the DAC is now isolated from the clock system.

Next we move to the analogue outputs. We install a Bybee Slipstream purifier on the L/R analogue outputs for either RCA or XLR outputs where required. Installing the Slipstream purifiers here results in a marked improved in sound quality. Low frequencies have more depth, definition. The entire frequency range is cleaner, music has a greater texture and substance.  The overall presentation is more lifelike, believable.

Similarly, The Bybee Slipstream purifiers are installed on the RCA digital inputs as required. By default we upgrade digital input 2. To upgrade RCA digital inputs 3 & 4 please add multiples as required.

Another optional extra is Deep Cryogenic Treatment (DCT) for the entire DAC. Deep Cryogenic Treatment is a process that involves the cooling of metals and other materials to very low temperatures, typically around -190°C. When metals such as Copper or Silver are drawn they develop a distorted ‘grain’ structure which leads to tiny voids, disruptions and discontinuities in the conductor as the metal is compressed and contorted by the drawing process.

The DCT processing leads to the development of a more refined crystal structure of the metals, drastically reducing voids disruptions and discontinuities in the conductor. The result is a metal with reduced skin effect, lower resistance; improved electron flow.

The resulting sound after the DCT process results in a system with reduced background noise bringing to the surface detail and nuances previously unheard.

The lower frequencies have greater definition and accuracy. Vocals and instruments have a truer tonal balance, realistic timbre; the sound projects into the listening room with increased spatial qualities.

Benchmark DAC1 HDR Reference Upgrade

Bybee Large Purifier for AC input.
Superclock 4 ultra-low jitter clock.

Analogue Output Upgrades

Bybee Slipstream for RCA outputs.
Bybee Slipstream for XLR outputs.

Digital Input Upgrades

Bybee Slipstream for RCA digital input.*

*Selecting one digital input upgrade will upgrade RCA digital input number 2. To upgrade RCA digital inputs 3 & 4 please add multiples as required.

Deep Cryogenic Treatment.

DCT for DAC1 HDR***

***The DCT requires sending the DAC to a third party for the process. The DAC is fully insured and this cost is included in the price. The DCT process requires 1-2 weeks.