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02-13-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,337
Joined on 05-28-2004

Post #: 1
Post ID: 6642
Reply to: 6642
Digital Volume Control self-assessment

I propose a very simple but extremely effective method of audio evaluation of you and your playback

Take any devise that has a digital volume control. If might be a CD player, DAC, Sound Card, Preamp or a power amp. Connected it to your system and set the digital volume control in unity gain at 0dB. If you have a chance to bypass it then do it. Play the system as is; get a reference of the result. Change the attenuation of the digital volume control for any amount, .5db for instance. Observe that the sound of playback become immediately unworthy in term of musical values (use my 6-level evaluation scale)

If you come to the opposite conclusion and if you feel that there was no change with sound when a digital attenuator is engaged and disengaged then there are ONLY two possibilities:

1) Your playback is very dull and inflicts too much masking effect. Go to Circuit City, buy yourself a good table radio, get life and trash the garbage audio that you use currently.

2) You are completely deaf or have listening techniques of Ordovician lizard. Stop doing audio.

I am not kidding - there are no other options... well, perhaps you try to educate yourself

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
11-05-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,337
Joined on 05-28-2004

Post #: 2
Post ID: 12158
Reply to: 6642
A digital volume control is a bitch
fiogf49gjkf0d

The last two weeks I have no preamp in house. I have great vintage EVS attenuators but I can’t use them with Melquiades as they talk with Milq’s input filters absolutely killing sound. The only way I can play music those days is only from my DAW, roiling off volume by digital volume control from the Lynx 16 mixer.

Holly shit!!! I did not use the digital volume control for years and forgot how horrible they might be - it is an absolute nightmare! I always was disgusted to hear the digital volume control in other playbacks but here is first time in 15 years I had it in mine – it was a good reminding how many deaf people out there…

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
11-08-2009 Post does not mapped to Knowledge Tree
Amir
Iran
Posts 131
Joined on 02-11-2009

Post #: 3
Post ID: 12180
Reply to: 12158
Digital and it's volume both are shit
fiogf49gjkf0d
me and armen were testing dcs scarlatti digital volume control with vitus amplifier and kharma midi speaker.

it's effect on sound is removing life from sound, less emotion, flatter sound, less bloom, less color.
digital volume kill micro information of sound that make sound beautiful.

i think there are many digital records that are fundamentally lifeless and digital volume has less effect on them but with a good records we see difference more.



I Love My Mom
11-08-2009 Post does not mapped to Knowledge Tree
tuga


Posts 173
Joined on 12-26-2007

Post #: 4
Post ID: 12182
Reply to: 12158
Digital Volume explained
fiogf49gjkf0d
 Romy the Cat wrote:

The last two weeks I have no preamp in house. I have great vintage EVS attenuators but I can’t use them with Melquiades as they talk with Milq’s input filters absolutely killing sound. The only way I can play music those days is only from my DAW, roiling off volume by digital volume control from the Lynx 16 mixer.

Holly shit!!! I did not use the digital volume control for years and forgot how horrible they might be - it is an absolute nightmare! I always was disgusted to hear the digital volume control in other playbacks but here is first time in 15 years I had it in mine – it was a good reminding how many deaf people out there…

The Cat


Here's an explanation by Slim Devices' Sean Adams:

"I think the easiest way to understand this is to forget about numbers, decibels, and bits per sample for a minute, and just think about what's coming out of the DAC.
To oversimply only slightly: there are two things always coming from the DAC. 1) signal and 2) noise.

The level of the noise output stays the same no matter what signal level is being produced. That is really important to understand!

When the DAC is making a loud signal, there is a lot of signal and a little noise. That's a high SNR, which is good.

However, when the DAC is making a quiet signal, you have a little signal and a little noise. If we now consider the noise level in relation to the signal level, the noise is now louder. The noise level hasn't gone up in absolute terms (eg volts), but relative to the signal it has, so you now have a bad SNR.

Now consider a simple resistor attenuator being fed by a loud (good SNR) signal from the DAC. When the voltage passes through the resistor divider, everything gets attenuated - the signal and noise together. You have the same* SNR coming out of the divider as you had going in, i.e., the DAC's optimal SNR is preserved.

OK, now back to bits per sample. As you can see, the above effects really don't have much at all to do with bits per sample. We could send a million bits per sample, and it would still be the same. So why does bit depth matter? What is the significance of 16 vs 24 bit?

What matters is that we send enough bits per sample that the DAC's full dynamic range is utilized. It is important to realize that the DAC's dynamic range is finite, and is less than its input word size - more like 20 bits, since it is limited by its output noise level.

By "expanding" a 16 bit signal to 24 bit, all we are doing is saying "these 16 bits go in the most significant slots of the 24 bit word". We haven't improved the SNR of the signal, any more than you can "enhance" a digital photo the way they do on CSI.

If we attenuate the 16 bit signal, yes, the zeroes and ones will migrate down into the least significant bits of the 24 bit word, and yes, if we still "have all the bits" we could then mathematically go in reverse and get back to the same data. But that is not what the DAC does with the signal! The bits represent a smaller signal now than they did before. We still have exactly the same decreasing SNR effect. Sending 24 bits into the DAC just means we aren't making it any worse than it already is. We haven't "bought more headroom"... it does NOT mean that those first 8 bits of attenuation are "free".

To prove this, you could play a sine wave through the DAC and measure the SNR at each volume step. We would expect to see the SNR decrease as the volume is decreased. If there were anything special about the point where we start "losing bits", or if we were really getting "extra headroom", then the plot would decrease slowly (or not at all) until it reaches that point, and then there would be an inflection.

However, that is not what you'll see. The SNR will simply decrease with the signal level, all the way down."

Cheers,
Ric


"Science draws the wave, poetry fills it with water" Teixeira Pascoaes
11-08-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,337
Joined on 05-28-2004

Post #: 5
Post ID: 12183
Reply to: 12182
The bad explanation.
fiogf49gjkf0d
tuga,
 
I do not like this explanation, it is very confusing and self-contradictive. The Digital Volume controls (with a few very seldom exceptions) do bits-depth conversion and toss the bits with each new volume setting. This is as bad as it could be. 

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
11-08-2009 Post does not mapped to Knowledge Tree
Lbjefferies7
Southern California
Posts 49
Joined on 01-11-2008

Post #: 6
Post ID: 12187
Reply to: 12183
Digital Volume Control-Daniel Weiss
fiogf49gjkf0d
http://www.weiss-highend.ch/computerplayback/Digital_Level_Control.pdf

Here's Weiss's paper on the subject.  It features a cat, so it must be right Wink  All of the explanations are beside the point, however, as there really is no reason to use digital volume control under operational circumstances.

LBJ


I'm not interested in having an orchestra sound like itself. I want it to sound like the composer. Leonard Bernstein
11-08-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,337
Joined on 05-28-2004

Post #: 7
Post ID: 12191
Reply to: 12187
The shameful Daniel Weiss’ paper.
fiogf49gjkf0d

 Lbjefferies7 wrote:
http://www.weiss-highend.ch/computerplayback/Digital_Level_Control.pdf

Here's Weiss's paper on the subject.  It features a cat, so it must be right   All of the explanations are beside the point, however, as there really is no reason to use digital volume control under operational circumstances.

This Weiss’ paper is very stupid one. I really do not like when the professionals of the Weiss’ caliber trade their reference opinion about the subjects just to promote mendicancy, selling the half-true or juts deceptions. Daniel Weiss know much better than this but in this case he chose to express only 5% of true, leaving the rest in comfortable silence. What Mr. Weiss said is true and there are shity digital controls and there are better controls. If people go for higher rates or use dither to mask out the problems when they loose bit-resolution then it does not support the notion that digital volume controls are “good” but juts indicate that the different masquerade methods are affective to impress the Morons who do not understand better results.

Saying all of it I have to note that it is possible to have a digital volume control that is problem-free and that will have even at -90dB the full bit-death resolution. To my knowledge it was implemented in one DAC and in there the entire conversion algorithm is recalculated based upon the setting of the volume control. Ironically in that DAC the volume control still sound very bad but because of VERY different reason.

Anyhow, the Daniel Weiss’ half-ass explanation do not do honor to the designer of his competence.

The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
11-09-2009 Post does not mapped to Knowledge Tree
Amir
Iran
Posts 131
Joined on 02-11-2009

Post #: 8
Post ID: 12193
Reply to: 12191
Weiss paper
fiogf49gjkf0d
I think 99% of audio designers try to solve problems on paper (objective model).
Mr.weiss try to loss less when design a volume control but non of them pay attention to musicality of sound.
market do not like to say what new approach loose and they just say what they gain in new design.
in 99% they do not know what really loose because their method is not subjective (like replacing low feedback single ended triode with  high feedback ss design).
audio industry never guide with smart and wise designers and reviewers.





I Love My Mom
11-09-2009 Post does not mapped to Knowledge Tree
tuga


Posts 173
Joined on 12-26-2007

Post #: 9
Post ID: 12195
Reply to: 12183
Digital Volume by software
fiogf49gjkf0d
 Romy the Cat wrote:
tuga,
 
I do not like this explanation, it is very confusing and self-contradictive. The Digital Volume controls (with a few very seldom exceptions) do bits-depth conversion and toss the bits with each new volume setting. This is as bad as it could be. 

The Cat
Hi Romy,I should have added that this explanation refers to volume control by software and it's probably the worst case scenario.Cheers,Ric


"Science draws the wave, poetry fills it with water" Teixeira Pascoaes
11-09-2009 Post does not mapped to Knowledge Tree
coops
London, United Kingdom
Posts 115
Joined on 02-16-2007

Post #: 10
Post ID: 12198
Reply to: 12191
Honestly
fiogf49gjkf0d

L
 Romy the Cat wrote:
 Lbjefferies7 wrote:
http://www.weiss-highend.ch/computerplayback/Digital_Level_Control.pdf

Here's Weiss's paper on the subject.  It features a cat, so it must be right   All of the explanations are beside the point, however, as there really is no reason to use digital volume control under operational circumstances.

This Weiss’ paper is very stupid one. I really do not like when the professionals of the Weiss’ caliber trade their reference opinion about the subjects just to promote mendicancy, selling the half-true or juts deceptions. Daniel Weiss know much better than this but in this case he chose to express only 5% of true, leaving the rest in comfortable silence. What Mr. Weiss said is true and there are shity digital controls and there are better controls. If people go for higher rates or use dither to mask out the problems when they loose bit-resolution then it does not support the notion that digital volume controls are “good” but juts indicate that the different masquerade methods are affective to impress the Morons who do not understand better results.

Saying all of it I have to note that it is possible to have a digital volume control that is problem-free and that will have even at -90dB the full bit-death resolution. To my knowledge it was implemented in one DAC and in there the entire conversion algorithm is recalculated based upon the setting of the volume control. Ironically in that DAC the volume control still sound very bad but because of VERY different reason.

Anyhow, the Daniel Weiss’ half-ass explanation do not do honor to the designer of his competence.

The caT


Lets examine the facts on the one hand a very well respected engineer who has spent his life working in the digital domain, who has just been voted a member of the AES, on the other a puffed up ,over opinionated buffoon. Who are you going to believe!
Keith.
11-09-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,337
Joined on 05-28-2004

Post #: 11
Post ID: 12201
Reply to: 12198
Here we go again.
fiogf49gjkf0d
 tuga wrote:
I should have added that this explanation refers to volume control by software and it's probably the worst case scenario.
Tuga, any digital volume control is software based. This defines the nature of the digital volume controls

 coops wrote:
Lets examine the facts on the one hand a very well respected engineer who has spent his life working in the digital domain, who has just been voted a member of the AES, on the other a puffed up ,over opinionated buffoon. Who are you going to believe!

Keith, I know it is difficult to understand for the people like you – for whom the objectives of audio concentrated only upon the efforts to create a publicity noise and then to sell goods while the people are  still affected by the noise. No one deprives Daniel Weiss from his position of authority however. I know the man personally, met him, very much like him and do respect his views. However, you need to understand that Daniel Weiss like anyone in this world has a mortgage and has a need to buy food. His ability to make leaving is contingent upon the people of your trade sell his devises.  But the people like you are too primitive to understand the subject or invent the subject – there are a lot of damn sale people around there – so the hi-fi industry relay upon the network of reviewing idiots who develops for sale personnel and mostly ignorant public some rudimental tailing points, pre-selling the notions, concepts and assessment results. Pay attention that they do not pre-sell the rightness but they pre-sell what is imidetaly beneficial for them to move. It would be like you explain to your 5 year old son the notion of gravity – it will be BS but good enough in order to satisfy his curiosity  now and until he will ask next time when grow up.

However, Daniel Weiss is not too deep in hi-fi industry; he is mostly in pro-audio industry. He does not relay too much upon the public reviews – the pro-audio has own distribution method.  For the hi-fi consummates Daniel Weiss personally is quality outspoken and he perfectly capable to stratify/partition his knowledge and to delegate it in the format that he feel is necessary for him.  In your case - the lightweights with not too much own integrity or familiarity on the subject it is all the necessary to make you motivated.

Anyhow, to propose you to listen youssef is not a good idea as you have no interest about sound. If you would like to print the given Daniel Weiss papers as your marketing material, as the “prove” then go ahead – it was written for YOU with this exact objective. Still, if you would like to go to a core of the subject then look further. It might not be too beneficial for your sale but at least going to internet chartrooms and demonstrating you wisdom you will not sound so idiotic.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
11-09-2009 Post does not mapped to Knowledge Tree
coops
London, United Kingdom
Posts 115
Joined on 02-16-2007

Post #: 12
Post ID: 12202
Reply to: 12201
Faintly ironic
fiogf49gjkf0d

Perhaps you would be kind to teach us all how attenuation should take place in the digital domain. The world holds it breath.

 

11-09-2009 Post does not mapped to Knowledge Tree
perrew
Posts 30
Joined on 10-06-2009

Post #: 13
Post ID: 12210
Reply to: 12202
Weiss Passive Volume
fiogf49gjkf0d
If you do not like digital volume by Weiss there is always the passive alternative: http://www.designwsound.com/dwsblog/?p=1699
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   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  Horns and digital crossovers...  Disregard...  Horn-Loaded Speakers Forum     16  113053  03-20-2005
  »  New  Dream Hi-Eff Speakers for an “inmate”...  Re: An average audio person has no opportunity......  Horn-Loaded Speakers Forum     3  34129  07-03-2006
  »  New  Digital crossovers self-assessment..  Digital crossovers self-assessment...  Audio For Dummies ™  Forum     0  14549  07-09-2006
  »  New  Weiss Engineering DAC202..  Attenuation...  Didital Things  Forum     5  26766  06-21-2010
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