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Author Topic: bit perfect setup for Mac  (Read 4474 times)

AM_DCS

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bit perfect setup for Mac
« on: November 12, 2015, 03:55:26 pm »

Hi all,

I am trying to set up jriver on a MacBook to send bit perfect audio through asynchronous USB to my DAC (dcs puccini player and U-clock). However, even when jriver tells me that it is playing in a bit perfect way, the volume control (the slider) is still operational, which means that the bits are potentially altered by jriver (at least when volume is less than 100%). Does someone know of a way to completely avoid volume control and to ensure that the original bits are always sent to the DAC without any modification, no matter how the volume sliders are set? I would like to leave volume control to the stereo amp.

Another thing that confuses me is that  the DAC sometimes reports 24/44.1 and sometimes 16/44.1 for the same redbook CD wav files. I have no idea what makes it switch between the two bit depths for exactly the same audio file. Sonically, there seems to be no difference, but I wish I could make the choice myself instead of letting jriver choose the one or the other in a rather arbitrary fashion. 

Any kind of help and suggestions is appreciated!
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blgentry

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Re: bit perfect setup for Mac
« Reply #1 on: November 12, 2015, 04:22:01 pm »

MC's authors apparently consider volume changes to be sonicly transparent, as the blue indicator for "no alteration" stays lit up, even when volume control is being applied in some way.  If you disagree with that, then you probably shouldn't trust the blue light in MC and you should look at the audio path to make sure no changes are being made.  Hover over the blue light and it will show you the audio path.  Or choose Player > Audio Path and it will show you the same stuff.

To your specific questions:

To disable volume control of the slider:  Tools > Options > Audio > Volume > Volume Mode > Disabled Volume
The slider won't move from 100% in this position.

Of course make sure you're not applying any DSP effects like Volume Leveling, Adaptive Volume etc.  All of that is OFF by default; I'm just mentioning it for completeness.

Your report of 16/44.1 versus 24/44.1 on the same tracks is new to me.  But I haven't paid a lot of attention either, as my current DAC doesn't have a display to draw my attention.  I would start by making sure that the Audio Device in MC is set up to go to the specific name of your DAC.  Not "default".  That may make a difference; I'm not sure.  On the other hand, locking the volume control (disabled) may affect this also, and might fix the problem by itself.

Let me know how this works for you and we'll see if there is anything else that needs to be changed.  Good luck.

Brian.
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AndyU

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Re: bit perfect setup for Mac
« Reply #2 on: November 13, 2015, 12:31:48 am »

The 24/44.1 display on your DAC for a 16/44.1 file might be because you have not quite set the JRiver volume control to 100%. If so, this issue should vanish when you fix the volume.
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AM_DCS

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Re: bit perfect setup for Mac
« Reply #3 on: November 13, 2015, 12:44:54 pm »

Hi Brian and Andy,

thanks a lot for your comments. I think I got it now.

When system and internal volume control are at 100 % and I hover over the blue light, the system tells me that no changes are being made to the audio. In this case, the DAC displays 16/44.1. When I reduce the internal volume and then hover over the blue light, jriver tells me by how many dB the volume has been decreased. In this case, the DAC displays 24/44.1. This switching between the two modes (16 and 24 bits) even happens when music is played continuously and the volume slider is moved. At 100% it now always returns to 16/44.1, which I see as an indication of bit perfect reproduction.

Alfred
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AndyU

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Re: bit perfect setup for Mac
« Reply #4 on: November 13, 2015, 12:56:50 pm »

As I thought. Easy enough to avoid the issue by setting MCs volume mode to Disabled Volume. Tools > Options > Audio > Volume Mode: Disabled volume. Or right click the loudspeaker icon next to the volume slider.

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AM_DCS

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Re: bit perfect setup for Mac
« Reply #5 on: November 14, 2015, 02:30:40 am »

It seemed so easy that I could not understand why I had these volume troubles in the first place. So I made a few more tests.

I switched the audio device from the DAC to Default. Music then came out of the internal loudspeakers. I played with the volume slider. It worked for both system and internal volume. When system volume was turned down and I hovered over the blue lights, jriver reported that no changes are being made to the audio, which was not true. Disabling volume control allowed me to lock volume to any attenuation that was used before. It did not jump to 100%.

I then switched the audio device back to the DAC.  Music was played through the stereo system again, but at a very low level. The DAC consistently reported 24/44.1, no matter which settings I used for system and internal volume. It seemed like the additional 8 bit were appended at the wrong end of the codewords. Disabling volume control also had no effect. When hovering over the blue light, jriver reported that no changes were being made to the audio, which was not true. Detaching the USB cable and restarting the entire Mac had no effect either. I still could hardly hear something out of the stereo system’s loudspeakers. I then went through the different option menus of jriver, including the volume settings within these menus and not only via the loudspeaker button left of the volume slider. I cannot tell which click was the right one, but apparently, volume control was operational again, and turning up the volume with the slider to 100% led to music being played through the loudspeakers at normal level. The DAC showed me 16/44.1 again. Disabling volume control now switches volume straight to 100%. Also, the slider no longer works to adjust system volume, it is only operational when internal volume is selected.

My conclusion is that the system seems to have some kind of memory. At least for me, the behavior depends on the sequence in which audio devices have been selected and menu buttons have been pressed. I am happy that I brought it back to a stage for which I believe that it really does not alter the original bits.

Alfred
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