The final truth about DSP Volume Control in Roon

[Propheticus]

Rhetorical question, Ray. If he did, he'd known it would be... very applicable.

 

[LTig]

Analogue volume attenuates the noise noise of the DAC, digital volume doesn't.
As long as digital volume is higher bit than the actual effective bits of the DAC, it will not add anything bad. There will be no better digital volume.

The volume control in the RME ADI-2 series is a mixture of both worlds, to keep dynamic range as high as possible.

 

[JohnYang1997]

The volume control in the RME ADI-2 series is a mixture of both worlds, to keep dynamic range as high as possible.

That's why it's a hybrid system not purely digital.

 

[PeteL]

The volume control in the RME ADI-2 series is a mixture of both worlds, to keep dynamic range as high as possible.

I like that approach, we should see more, not expensive to acomplish neither. Even the Bluetooth system on chip cs8675 works like that.

 

[DualTriode]

Hello All,

If I recall correctly we collectively have had this conversation previously a few times already. Excuse the redundancy.

If you start out with 32 bits you may figure that you have a few bits to burn. By the time you attenuate to 24 bits you may want to start taking a closer look at your bit budget. Add in several dB’s of equalization you may have fewer than 16 bits in your piggy bank. That means that you are running at less than CD quality. Oh Dear what to do about that now? You have run out of spare change.

Take a look the JBL M2 with Crown amplifiers and Digital Signal Processing. Tucked inside the enclosure there is a hardwired L-Pad in series with the D2 Dual Voice Coil Compression Driver. The L-Pad provides 9dB’s of attenuation to the output of the Crown Amplifier noise floor. Who would think; power to burn?

Thanks DT

 

[JohnYang1997]

Hello All,

If I recall correctly we collectively have had this conversation previously a few times already. Excuse the redundancy.

If you start out with 32 bits you may figure that you have a few bits to burn. By the time you attenuate to 24 bits you may want to start taking a closer look at your bit budget. Add in several dB’s of equalization you may have fewer than 16 bits in your piggy bank. That means that you are running at less than CD quality. Oh Dear what to do about that now? You have run out of spare change.

Take a look the JBL M2 with Crown amplifiers and Digital Signal Processing. Tucked inside the enclosure there is a hardwired L-Pad in series with the D2 Dual Voice Coil Compression Driver. The L-Pad provides 9dB’s of attenuation to the output of the Crown Amplifier noise floor. Who would think; power to burn?

Thanks DT

What matters is the residual noise instead of the bits. If the noise come out at the speaker output is lower than audibility then why it matters.
As long as the volume control has the same or higher bit than the actual measured DAC output, it introduces less noise in the system than the DAC's own output at all times.
So the key to get acceptable digital volume control result is to get a better DAC.

 

[phoenixdogfan]

Do you know how a digital signal is attenuated?

Yeah, you throw away bits with each bit thrown away providing 6 db or attenuation. And since JRiver has a 64 bit master volume control, it should be perfect since it has plenty to throw away. But would be nice if that could be verified.

 

[JohnYang1997]

Y

Yeah, you throw away bits.

No.

 

[RayDunzl]

Yeah, you throw away bits with each bit thrown away providing 6 db or attenuation.

That would suffice for 6.02dB increments, just shift the sample bits one step to the right, losing the LSB.

What is done is multiply the sample values by a factor of attenuation.

Example:

Higher precision might occur with more bits to play with, but that's the basic method, however implemented.

 

[anchan]

I totally get how digital volume works, and when 16-bit audio is upsampled you suddenly have millions of steps of resolution to do division not just 65,536. This is how the volume control on my old Sonos player works. You can really hear a difference in an attenuated signal on the Sonos vs Airplay for example.

But I have a question. Let's say I'm not using Roon or anything fancy. What if I'm playing Spotify on my Macbook through let's say a Topping E30 dac with it's volume control. Would the dac automatically upsample to 24bit so as to gain the resolution for proper digital volume control? Or might it just be digitally attenuating a 16-bit signal?

 

[RayDunzl]

Would the dac automatically upsample to 24bit so as to gain the resolution for proper digital volume control? Or might it just be digitally attenuating a 16-bit signal?

My DAC (ESS chip) takes an input of 16 bits and converts to 32 bits for volume control, then rounds that to 24bits for conversion to analog, if I understand it correctly.

 

[anchan]

Related question: What happens if I'm using a dac connected to a PC or Mac, and I use the computer's volume control to turn down the volume, while playing a 16-bit file. Does Windows or Mac internally attenuate at 16-bit resolution, or are things upsampled by the OS?

 

[JohnYang1997]

Why so much bullshit still being tossing around?

 

[preload]

Does the Roon volume control go to 11?

 

[enricoclaudio]

I use Roon DSP with all my Roon Ready devices but all of them have volume set as fixed. A bit of EQ is always good to fix room modes or to fix a not perfect designed speaker and Roon EQ is just too good to not be used.

 

[xema]

[QUOTE="

The noise floor remains at -178dB, regardless of which attenuation is set for the DSP volume. This means that even at volumes down to -50dB the dynamic at the output is higher as the signal to noise ratio of the best DACs and power amplifiers. [/QUOTE]

That's .... not right. Here we have 128db SNR still, but to dac or amp, all the signal AND noise of a DSP are SIGNAL!
So, the dac will receive a -50dbfs signal and the SNR will be indeed degraded.

 

[xema]

And the measurement setup is not correct, the thdn fft of a digital signal is nosense.
If you do this measurement with a dac, you'll find the degradation.

 

[xema]

The test is from definiteAudio GmbH, my blacklist +1

 

[192kbps]

Analogue volume attenuates the noise noise of the DAC, digital volume doesn't.
As long as digital volume is higher bit than the actual effective bits of the DAC, it will not add anything bad. There will be no better digital volume.

I love u so fucking much.

 

[H-713]

So where do PGAs fit into this mess? TI has the PGA2311 chip, there's one from Cirrus Logic, and then there's the technique that's been used for decades:
https://www.analog.com/en/analog-dialogue/articles/high-resolution-multiplying-dacs.html#