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100.2.133.74
If you use a second DAC (volume control DAC) to control the Vref of the main DAC, you get a lossless digital volume control. However this will add hardware cost.
What other modern methods are out there?
Follow Ups:
Can you explain? How do I connect the 2nd dac?
Cut to razor sounding violins
It is about circuit/chip design. It is not something you can achieve using two retail DAC boxes.
Whew. I was struggling trying to understand how to do it.
Also digital vc these days is like 53 bits anyhow.
Cut to razor sounding violins
An actual answer would be cool, instead of some mysterious bullshit.
If you don't understand, you do not need it.
Edits: 04/22/25
FOS.
Could you please check the link provided by Mr. Kal Rubinson so you could have an idea?
...to talk to the recording studios that do their recording, mixing and processing in the digital domain. They've ruined your recording before you've even turned your stereo on!
For me, I've never had a problem with digital volume control. But, I'm probably a cloth-eared neanderthal who shouldn't be enjoying music in the manner I do. ;-)
When I first got a streamer I switched back and forth between CD and streamer using the same music on CD and streaming, using the same external DAC through a preamp. I used the output level control on the streamer and couldn't hear any difference.
I'm still enjoying my 50-year-old party speakers (JBL L100's) at the snow bird house. Cloth-eared Neanderthals rule!
Regards,
Steve
I usually live with an equipment for sometime. For example I lived with my class D amp for about a month or so. Then I switched back to my class A amp. I can immediately tell what was missing.I usually do not switch back and forth. In that way I will get tired very soon.
Edits: 04/15/25
I try to use a similar approach. My aural memory is short enough that I switched back and forth between streaming and CD after a couple of songs to get an immediate sense of any differences. Then I spent weeks with each one to get a longer term feel. Eventually I boxed up the player and got rid of my CDs. There was more to the decision to go streaming than sound quality.
We all have our methods and preferences. I'm not a purist audiophile, I just like listening to music.
Regards,
Steve
long term listening. That's my approach, too.
Instantaneous Cowboy switching just doesn't tell the whole story to these ears. :)
The internal architecture in most modern DACs is 32-bit so if you're playing 24 or 16-bit material you have 'lots of extra bits' to spare with no perceptible impact on resolution, dynamic range, or THD+N.That being said, my DAC actually incorporates a digitally controlled relay stepped attenuator using discrete PCB mounted resistors in it's volume control. I can set volume in 0.5dB or 1.0dB steps. 100% repeatable volume levels and more accurate stereo tracking than the typical dual-gang analog potentiometer. That's another way to do it, since you asked.
Edits: 04/14/25 04/14/25
With respect, your DAC is 32 bits. But it uses relays to do the volume control. Is the volume control analog or digital?
Digitally switched analog. Relays are digitally controlled. Discrete resistors in the stepped attenuator are analog.
My CJ Premier 17LS2 preamp has the exact same style volume control as yours, i.e. digital controlled (switched) relays with analog resistors.On the order hand, my Benchmark DAC3 HGC has a pure digital volume control. I do wish they could have a better design.
Edits: 04/14/25
How Digital Volume Control Works:
1. Digital volume control typically works by multiplying the digital audio samples by a factor less than 1 to reduce the amplitude of the signal.
2. This process can lead to a loss of bit depth, which in theory reduces the resolution and dynamic range of the audio signal. For example, reducing the volume of a 16-bit audio file by 6dB effectively reduces it to a 15-bit file.
I can't stand the sound quality of the digital volume control on my Benchmark DAC3 HGC at low volumes. I always bypass it or set it to the maximum. Most digital volume controls lose bits of resolution. I would avoid using it unless there is no other choice or it is lossless.
Of course a digital controlled analog volume control like the one on my CJ Premier 17LS2 is excellent.
How soft are you listening to the music at?
The digital volume control (which only applies to the digital inputs) is 32 bit, so with 24 bit data you have 48dB to play with before any bit truncation and with 16 bit data, you have a full 96dB.
-48dB is already pretty quiet even as background music so why would you be worried about bit truncation in that scenario? The ESS 9028Pro is already giving you essentially perfect linearity down to the very limits of measurement.
If you are hearing distortions, it is possible that you have another problem somewhere else in the system.
Regards Anthony
"Beauty is Truth, Truth Beauty.." Keats
CD is 16bits. Unless you upsample to 32bits. How can you get 24bits after you turn down the volume?
Bit padding or dither - that is usually done in the SRC or digital filter and so what is output to the DAC is going to be at a higher bit depth and has been done that way for decades ever since DACs were capable of 18 bit or higher .
The PMD-100 HDCD digital filter which was available in the late 90s was able to add different levels of dither and output 16, 18, 20 or 24 bits depending on the capability of the downstream DAC irrespective of the input data word length.
Music is normally mastered assuming a listening level of about 90dB. Reducing the listening level by 48dB (assuming 24 bit word length) will alter the frequency balance away from the mastering and will be sufficiently quiet anyway that I would be surprised if you could hear the music program properly let alone the effects of the bit truncation. With Redbook conversion, you will get no bit truncation. In other words,for normal listening habits, no bit truncation will be going on with high resolution digital audio unless you insist on playing back at extremely soft levels specifically to look for a problem which is why the digital volume controls are designed the way they are.
You can trust that the engineers at ESS and Benchmark actually knew what they were doing when they designed their respective systems.
Regards Anthony
"Beauty is Truth, Truth Beauty.." Keats
Padding a couple of 0s doesn't add any information more than 16bits. Dither will introduce distortion. There is a thing called bit perfect.You mentioned Benchmark. Yes my Benchmark DAC3 HGC is in storage. I usually put something in storage when they sound particular bad.
If you enjoy software volume control, go ahead enjoy it. I will stay with hardware volume control or analog volume control.
Edits: 04/22/25 04/22/25
Just out of interest, what is your background exactly? Your statements suggest that you don't have any background that involved learning about signal processing.
I would suggest studying a bit more before asserting what is simply an uninformed opinion.
Regards Anthony
"Beauty is Truth, Truth Beauty.." Keats
I have a master degree in EE. 35 years ago I was teaching postgraduate student "Digital Random Signal Processing". I have two Plinius AMPs and I am selling them. No more Plinius AMP. Do you have an issue with that?As a loyal Plinius customer of 25 years, I am disappointed to say you have lost my business. Congratulations.
Edits: 04/22/25
It adds a little bit noise that removes the quantization distortion from small signals.
Why you guys can't just use hardware volume control? Cost reduction? Every cent counts?
Leo, I do volume control in the digital domain. For my purposes I only change the volume by, maybe, 3dB between songs/pieces. My system gain is adjusted so I am always working near the top of the range. I would contend that in my application this volume control is as good as, or better than I could achieve with any stepped attenuator working in the analog domain.
I think it perfectly fine for you to prefer the latter. However, when I correct an error in your post you make an ad hominem suggestion that I am somehow cheap for not adding an analog attenuator. I would contend there is less evidence in my posts on AA that I am cheap than there is evidence in your posts of idiocy. And yet I do not call you an idiot!
You might misunderstand me.
"Why you guys can't just use hardware volume control? Cost reduction? Every cent counts?"
you guys = chip design/manufacture company
Cost reduction = manufacture cost reduction
Every cent counts = manufacture every cent counts
Aren't you a director of IC design?
What do you mean by "hardware volume control". Do you mean an analogue volume control or additional electronic hardware to do the volume control external to the DAC? Neither is likely to be as good as doing the volume control internal to a DAC that internally converts and processes the incoming data at full 32 bit resolution because extending the signal path and routing the data to another circuit can only increase the noise floor.
In the case of the Benchmark DAC and other DACs using the ESS DACs (I'm not sure about the AKM DACs but I believe they are the same), they can achieve a full range of volume adjustment because they are using the full capability of the 32bit DAC so the 16 bit or 24 bit word is converted to 32bit and processed at that word length, therefore the volume can be adjusted with full precision down to the limits of the DAC itself. An analogue volume control can only be better than the -135dB range of the ESS DAC if it has lower noise...which is highly unlikely.
So the answer to your question is that it depends on the DAC and overall system design. Your concerns apply to older DAC designs from the early 2010s such as Cambridge Audio DACs (DacMagic plus) which had an 8 bit (-48dB) range of volume adjustment before bit truncation on a 24 bit word. NAD had a -66dB range which was very usable for "typical" listening behaviour.
Regards Anthony
"Beauty is Truth, Truth Beauty.." Keats
Hi Leo, I didn't intend to be offensive so apologies. I don't find your posts idiotic but I do find them idiosyncratic, which is not a bad thing. I am an engineer, and good engineering means better = doing the same job for less cost or doing a better job for the same cost. That is pretty much the opposite of audiophilia where better = more expense, more stuff, more boxes, 'special' components. Maybe digital volume control is a good example. When I bought my CD player, a long time ago, it had bespoke filtering and a digital volume control. Back then that was expensive to implement as it needed a special DSP chip and software. That made it an expensive product but was hailed as audiophile. Later other companies jumped on the bespoke filtering bandwagon to set themselves apart and justify high prices. These days multiple filter options and digital volume control are now integrated into DAC chips making the whole solution much, much cheaper. The solution is still as good but because the price is now low those products are looked down on. This is sad because a lot of effort and talent went into making those features affordable whereas, the technical bar for entry into high end audio is not as high as the prices. If you have access to a CNC machine then you can sell a product and how often do you see the first product spec line being how thick is the face plate?
"2. This process can lead to a loss of bit depth, which in theory reduces the resolution and dynamic range of the audio signal. For example, reducing the volume of a 16-bit audio file by 6dB effectively reduces it to a 15-bit file."Not quite right. You have 32-bits to work with internally (in many modern DACs) so you're not reducing the 16-bit music file by 1-bit. You're reducing the 32-bits you have to work with by 1-bit.
Not liking how your Benchmark DAC sounds at low levels likely has more to do with its Analog+Digital volume implementation and its anemic analog output stage.... not the number of bits being manipulated.
Edits: 04/14/25 04/14/25 04/14/25 04/14/25
In the past, some have used a DAC "backwards" by connecting the input to Vref and using the R-2R ladder as a stepped analog attenuator. This was the basis of the old R-SRC (Acoustic Research System Remote Controller)
Any particular reason you want to do volume control in the digital realm rather than in analog?
Digital takes samples of the signal, digitizes the samples, and after it is done processing it converts the signal back to analog. Inherent in this sampling are approximation errors (limited bit count), with approximation errors also stacking up in the processing and reconversion.
Perhaps digital works nicely in computers, where life is 0 or 1, but that is not an analog music signal. I am surprised about how nice a good CD system can sound (with top flight components), but I certainly would not send the signal through a chain of 'digital processors' and expect anything useful to come out.
Consider a TVC, where the signal remains in the analog realm and it is effectively lossless.
Now days, many streamers and DACs and AMPs have digital volume control. I just want to bring this to owners attention so they know what is lossless.
Edits: 04/14/25
Merely because technology can create something does not mean it has merit. My comments above are still valid. The digital volume control acceptability depends on budget and what can be tolerated.
Technology often does translate to 'cheap' rather than desirable. Having worked in Silicon Valley for a couple of decades, it became obvious that some tech is useful, and a lot is not so much so.
Volume control works well in the digital domain, especially if you optimize system gain to work at the top end of its range. I know it is easy to assume price equals quality in the audiophile world so be reassured there are audio companies who will charge a lot for their implementation of digital volume control.
I am sure that the control of volume works well in digital volume control, it is the fidelity of the signal I am commenting on. I am making the assumption that signal fidelity is important.
When the signal goes into the digital volume control, it is digitized, processed, and reconverted to analog no matter what the volume setting is. Back to the fidelity of the digital volume control.
I think it is fine if people want to use a digital volume control. Just be aware of what it is and how it works. Everyone has their priorities and listening preferences.
With regards to fidelity, if the signal is already in the digital domain then a properly implemented digital volume control should equal, or better, any method of volume control once the signal is converted back to analog. Of course, YMMV, and comparisons would be necessary just don't throw the baby out before the bath.
And if you're purely analog, there is a whole host of imperfections to deal with so volume control is the least of your worries:)
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