Benchmark, seriously, volume control in DAC3 L, how does it work?

[tensor9]

I can't make heads or tails of your description because it's so steeped in marketing language nonsense.

HGC™ Hybrid Gain Control HGC™ is Benchmark’s unique hybrid gain control that combines analog and digital gain control into a single volume control knob. The HGC™ system uses an active analog gain control for analog inputs and a 32-bit dithered volume control for digital inputs. Both types of inputs leverage the low-impedance passive Manual for DAC3 HGC and DAC3 L with 2.X Firmware - Rev. D Page 7 analog attenuation system at the XLR outputs. The dual-domain HGC™ system combines the high dynamic range of Benchmark’s HDR™ analog control (used in the DAC1 HDR) with the low distortion and accuracy of a digital control. HGC™ outperforms traditional analog or digital volume controls, including the twostage DAC1 HDR™ system. Musical details are preserved over a very wide range of output levels. Analog inputs are controlled in the analog domain. Digital inputs are controlled in both domains. The volume control is a servo-driven analog potentiometer. This control rotates in response to commands from the remote control while providing the convenience of manual adjustments with a physical knob.

How does the device attenuate output from a digital input (other than the XLR attenuators)? Is it strictly digital volume control? A combination of digital and analog? If analog, how does it work? Resistors? Stepped attenuation? Relays?

Does anyone have a plain sense answer or am I missing something? Is it really just a pot?

 

[RayDunzl]

Is it really just a pot?

Two pots under one knob...

One signals the DAC to attenuate digital data.

The other (stereo pair) is a likely voltage divider in the all-analog path.

Unless I'm mistaken.


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The DAC2 ad copy maybe has a reasonable explanation:

"The DAC2 features our unique Hybrid-Gain-Control™ system which separates analog and digital inputs into two entirely different volume control systems.

We use 32-bit digital gain control for digital inputs, and an analog potentiometer for analog inputs.

We do not convert analog inputs to digital, nor do we pass the output of the D/A converter through an analog volume control.

Nevertheless, both types of inputs are controlled by a single motor-driven potentiometer.

Analog input signals pass directly through this pot while digital input signals follow a shorter analog signal path that bypasses the pot.

For digital inputs, the position of the pot determines the multiplier for the 32-bit digital gain control that feeds the 32-bit input of the ES9018.

This hybrid system provides two signal paths; one that is optimized for analog inputs, and one that is optimized for digital inputs. This hybrid system delivers the lowest possible noise and distortion for each signal type."

 

[Mtbf]

The volume control is a servo-driven analog potentiometer.

As a nice touch it has a -20dB button on the remote, which rotates the servo-driven analog potentiometer to -20dB. Prefer that to mute.

 

[GrimSurfer]

which rotates the servo-driven analog potentiometer to -20dB.

Or a reasonable guess of -20 dB...

 

[restorer-john]

Like everyone these days, they are pandering to their market. Audiophiles like knobs, they want their pristine digital sources to stay digital and they want their analogue sources to stay analogue.

So Benchmark gave them the best of both worlds to silence any potential complaints.

If it is indeed a servo driven pot, there is positional feedback of the control rotation.