The "bitperfect" way to adjust volume using Equalizer APO..?
Dec 12, 2020 at 5:52 PM Thread Starter Post #1 of 7

Kjy7199

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Hi all! I just got xduoo ta-30. I really like it but there is one problem.... It is so powerful that the volume knob is nearly useless (I can't make it above 9 o'clock. It's too loud!)

I don't want to change the computer volume because I heard that changing the digital volume level changes the bits in the file and reduces the maximum bit depth.

So I googled a bit and found that using Equalizer APO, I can just set a preamp of -10 dB or -20 dB so that I can get some more fine control over the analog volume while setting the computer volume 100%.

Is this a "bitperfect" way to adjust volume? It seems right since the computer volume is max but I am not quite sure because I am not familiar with Equalizer APO and don't really know how it works. Maybe it degrades other sound qualities..?

Any help would be appreciated!
 
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Dec 12, 2020 at 10:21 PM Post #2 of 7

SilverEars

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Hi all! I just got xduoo ta-30. I really like it but there is one problem.... It is so powerful that the volume knob is nearly useless (I can't make it above 9 o'clock. It's too loud!)

I don't want to change the computer volume because I heard that changing the digital volume level changes the bits in the file and reduces the maximum bit depth.

So I googled a bit and found that using Equalizer APO, I can just set a preamp of -10 dB or -20 dB so that I can get some more fine control over the analog volume while setting the computer volume 100%.

Is this a "bitperfect" way to adjust volume? It seems right since the computer volume is max but I am not quite sure because I am not familiar with Equalizer APO and don't really know how it works. Maybe it degrades other sound qualities..?

Any help would be appreciated!
Bit-perfect is if the music stream is going straight to the DAC unmodified by any software or mixer in the OS. If you are EQ'ing, you are modifying the streaming going into the DAC, therefore, it's not bit-perfect. EQ is a sort of a mixer in between that is modifying the digital music content.

You will notice when something is in bit-perfect mode, you cannot EQ. APO EQ can only be utilized through OS direct sound, therefore the music is going through the OS mixer. When the music is going through OS mixer, it's not in bit-perfect mode.

There is no bit-perfect way to digitally adjust volume. Bit-perfect is output at maximum digital volume, and only volume control is at the pre-amp or amp in the analog stage. If you are changing volume digitally, that means that digital signal is not bit-perfect, or the output is not in bit-perfect mode.
 
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Dec 13, 2020 at 2:26 AM Post #3 of 7

Kjy7199

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Bit-perfect is if the music stream is going straight to the DAC unmodified by any software or mixer in the OS. If you are EQ'ing, you are modifying the streaming going into the DAC, therefore, it's not bit-perfect. EQ is a sort of a mixer in between that is modifying the digital music content.

You will notice when something is in bit-perfect mode, you cannot EQ. APO EQ can only be utilized through OS direct sound, therefore the music is going through the OS mixer. When the music is going through OS mixer, it's not in bit-perfect mode.

There is no bit-perfect way to digitally adjust volume. Bit-perfect is output at maximum digital volume, and only volume control is at the pre-amp or amp in the analog stage. If you are changing volume digitally, that means that digital signal is not bit-perfect, or the output is not in bit-perfect mode.
I see. I thought Equalizer APO limits the total output power of my computer and doesn't modify any actual digital music content. Now I should get a preamp....😅

Thanks!
 
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Dec 13, 2020 at 5:19 AM Post #4 of 7

Roseval

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3000 mW is way to much indeed.
Maybe the manufacturer can lower the gain?

The loudest a DAC could play is called 0 dBFS, say all bits are on.
If we lower the volume digital we ‘shift’ to the right in the register

If we play 16 bit program material on a 16 bit DAC and lower with 48 dB, we have only half of the number of bits left.
MSB LSB

1111111111111111
0000000011111111

Yes, we do loose resolution and with each bit chopped off, 6 dB of the dynamic range.

If we play 16 bits program material on a 24 bit DAC and lower with 8 bits (48 dB) we sill have all 16 bits in the register of the DAC.

111111111111111100000000
000000001111111111111111

When using 24 bits program material on a 24 bit DAC we do loose resolution but in case of a 48 dB reduction, we still have 16 bits of resolution left.

111111111111111111111111
000000001111111111111111

Today you have DACs working internally with 32 bits and even have a 32 bit data path over the USB....

Anyway as most of our program material is 16 bit and our DAC's 24, you can apply a substantial digital volume reduction without audible degradation.
 
Dec 13, 2020 at 8:47 AM Post #5 of 7

Kjy7199

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3000 mW is way to much indeed.
Maybe the manufacturer can lower the gain?

The loudest a DAC could play is called 0 dBFS, say all bits are on.
If we lower the volume digital we ‘shift’ to the right in the register

If we play 16 bit program material on a 16 bit DAC and lower with 48 dB, we have only half of the number of bits left.
MSB LSB

1111111111111111
0000000011111111

Yes, we do loose resolution and with each bit chopped off, 6 dB of the dynamic range.

If we play 16 bits program material on a 24 bit DAC and lower with 8 bits (48 dB) we sill have all 16 bits in the register of the DAC.

111111111111111100000000
000000001111111111111111

When using 24 bits program material on a 24 bit DAC we do loose resolution but in case of a 48 dB reduction, we still have 16 bits of resolution left.

111111111111111111111111
000000001111111111111111

Today you have DACs working internally with 32 bits and even have a 32 bit data path over the USB....

Anyway as most of our program material is 16 bit and our DAC's 24, you can apply a substantial digital volume reduction without audible degradation.
Thank you for the good explanation.

So you mean that most of the time, I have the room of 48 dB therefore I can lower the digital volume without audible degradation? Like setting Windows volume 100% and Foobar volume -40 dB wouldn't degrade the audible resolution of music, so I can adjust my amp volume.

I kind of understand your explanation but it is little difficult for me... thanks again for your explanation!
 
Dec 13, 2020 at 3:52 PM Post #6 of 7

Roseval

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Yes, you can substantially lower the digital volume before you gonna hear a degradation.

You can simply try it yourself.
Set Win 10 100% and Foobar to 100% and your amp to "loud".
Now lower e.g. Foobar and at the same time boost the volume of the amp trying to keep what you hear at the same level.
I bet it will take a substantial amount of digital volume reduction before you hear any degradation.

If you are using Direct Sound, check the WIn audio panel, choose the max bit depth supported by your audio device.
https://www.thewelltemperedcomputer.com/SW/Windows/Win7/AudioPanel.htm

If you have not already done so, try Foobar with WASAPI in exclusive mode: https://www.thewelltemperedcomputer.com/SW/Players/Foobar.htm
 
Dec 13, 2020 at 9:11 PM Post #7 of 7

Kjy7199

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Yes, you can substantially lower the digital volume before you gonna hear a degradation.

You can simply try it yourself.
Set Win 10 100% and Foobar to 100% and your amp to "loud".
Now lower e.g. Foobar and at the same time boost the volume of the amp trying to keep what you hear at the same level.
I bet it will take a substantial amount of digital volume reduction before you hear any degradation.

If you are using Direct Sound, check the WIn audio panel, choose the max bit depth supported by your audio device.
https://www.thewelltemperedcomputer.com/SW/Windows/Win7/AudioPanel.htm

If you have not already done so, try Foobar with WASAPI in exclusive mode: https://www.thewelltemperedcomputer.com/SW/Players/Foobar.htm
Awesome! Problem solved. Thank you so much.

Windows 100% and Foobar -20 dB. It's just perfect now.

Maybe I would be able to tell a difference if I have golden ears but I could't find any differences with my HD800S.
 

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