PC sound card as volume control ==> Dac ==> Active speakers

Discussion in 'DACs' started by rooster2001, Jul 18, 2018.

  1. rooster2001

    rooster2001 AK Subscriber Subscriber

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    Are there technical reasons that the titled configuration would degrade SQ? Dac has no volume control. I'd be using a wireless keyboard as a "remote". Thanks.
     

     

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  2. AlTinkster92

    AlTinkster92 AK Subscriber Subscriber

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    Should work fine, my DAC has no volume control either.
     
  3. rooster2001

    rooster2001 AK Subscriber Subscriber

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    Thanks Al. Have been reading up a bit and am finding claims that when Windows output is reduced, that the bit depth is decreased. I've used dac's for a while but am now becoming curious if my setup is optimal.
     
  4. Poinzy

    Poinzy Super Member

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    This is the first time I've heard that claim, and I've been using Windows for audio projects since 2000. Do you have a link?
     
  5. rooster2001

    rooster2001 AK Subscriber Subscriber

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    Here is one I came across. Bear in mind that I may not be interpreting everything correctly given my current level of digital knowledge. Simply trying to educate myself.
     
  6. imral3

    imral3 Super Member

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    All I needed to read was the title of the article stating it was nonsense and that was enough for me!!
     

     

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  7. Yamaki

    Yamaki Not For Hire Subscriber

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    That article has some good info but it's relevant to sound level only, not actual processing of the digital signal. I much prefer a more direct path for processing digital files:

    PC/NAS ===USB===> DAC ===RCA/XLR===> pre-amp/receiver

    Let the DAC process the digital file codec. That's what it is designed and built to do.
     
  8. rooster2001

    rooster2001 AK Subscriber Subscriber

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    No article, simply a thread discussing the topic of my question. Additionally, the first sentence of the post states that the title was used for generating interest. Thanks anyway.
     
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  9. rooster2001

    rooster2001 AK Subscriber Subscriber

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    Thanks very much for the reply. As stated, trying to learn more about digital. Your chain of connection is exactly as I have now with the exception of a pre-amp.
     
  10. imral3

    imral3 Super Member

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    I am sorry if I came off as dismissive or disinterested. My entire music collection is digital and initially thought this was nonsense that the volume level would in some way change the bits streaming through a DAC. My comment was meant more in support of the fact it was nonsense and NOT your post!
    My path is external hard drive - windows PC - external USB DAC - RCA cables - integrated amp - speakers - my ears!!
     
  11. rooster2001

    rooster2001 AK Subscriber Subscriber

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    No worries. I'm probably reading too much into things with my limited grasp on some the basics. Like all of us, just looking for the best sound possible in all my systems. Thanks!!
     
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  12. E-Stat

    E-Stat AK Subscriber Subscriber

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    Digital volume controls are typically lossy. I still use that approach with the office system.
     
  13. Final_Baton

    Final_Baton Active Member

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    Well : I have been meaning to ask this for a while. But didn't want to start a thread just for that. So this is the perfect opportunity!

    When I adjust my PC's soundcard volume, the sound, to me, become different. not just quieter or louder. but very different character. I swear it does sound different, hopefully I haven't gotten mad, hahaha.

    My theory(which may be completely false, I'm not well versed in electronics), is that a lower volume from my PC sends a lower(voltage?) signal, and thus drives my integrated amp less. whereas a louder volume sends higher(voltage?) signal, thus drives the amp more. And this would explain a change in not only volume, but also sound. Since driving the front end of an amp produces overdrive(which changes the sound profile quite a lot).

    Am I right in thinking this?

    I've spent a lot of time fiddling with the volume slider, and I've pinpointed that 85% volume, in my setup, gives the most balanced sound. At 100%, everything is overblown (and this can't be the fault of my amp and speakers : all my other sources(blu ray player, turntable, cassette deck, game consoles) sound great through them). Could it be that this 85% volume value, is the one that closest matches the "line-level audio" standard in term of voltage sent from the PC? After all, all my other sources are line-level(except TT which is RIAA obviously, and goes in the phono preamp) and sound great. But the PC set at 100%, even through my pretty decent external DAC, sounds completely overblown and a bit crunchy...

    What do you guys think? Some truth to my observation/theory? or am I a loon :rflmao:
     
    Last edited: Jul 28, 2018
  14. sKiZo

    sKiZo Hates received: 8641 Subscriber

    Way I understand it, the winDohs! volume control is built into Direct Sound. Given a choice, WASAPI is the way to go as that's lossless and the next best thing to bit perfect, but no volume control. Direct Sound is lossy AND the only way to defeat it and get it out of the audio chain is to leave the volume at 100%. Under that scenario, you would see degradation in sound quality.

    Simple enough to add a hardware volume control if you're using the analog feeds. Just cut an RCA cord and insert a 50k linear pot in line.

    If you don't want to deal with DIY, Nobsound Little Bear MC1022 is kinda neat, with volume, mute, and it even comes with instructions for swapping internal resistors to tailor it to your setup. And bonus, you get two for one on inputs. Set you back around $20.

    [​IMG]
     
    Last edited: Jul 28, 2018
  15. Final_Baton

    Final_Baton Active Member

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    @sKiZo Thanks for the input! I am using digital out of the PC(USB). Interesting, I had a hunch that Direct Sound was not the best option. so WASAPI is a program for volume control that's lossless? I'll try that! thanks
     
  16. sKiZo

    sKiZo Hates received: 8641 Subscriber

    Yup ... WASAPI is built into Windows since v7 ...
     

     

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  17. Final_Baton

    Final_Baton Active Member

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    AH! so what I need to download then, is an ASIO that will interface between WASAPI and my DAC(Peachtree Dac-iTx)?

    Or do I need to configure the Dac-iTx to output via WASAPI, via it's accompanying device setting/driver?

    Sorry I'm really not up to speed on that stuff...

    EDIT : forget it, it's too complicated for me. I'll stick with the windows mixer
     
    Last edited: Jul 28, 2018
  18. cpt_paranoia

    cpt_paranoia Active Member

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    Digital volume control is performed by multiplying the samples by a scaling factor (0..1).

    If the PC only sends 16 bits in its output samples (to an SPDIF interface, or to its internal DAC), this will inevitably reduce the bit precision of the output. e.g. for a 0.25 volume control (one quarter), the 16-bit sample is effectively reduced to 14 bits; 0.25 scaling is essentially a 2-bit right shift, so the 2LSBs are lost.

    If your PC outputs 20 or 24 bits of SPDIF audio (and you have a DAC that can hanfle those samples), and your source is 16-bit (e.g. CD), then you have 4 or 8 bits of 'spare' precision to implement volume control before you start to lose the source precision. If your source is 20-bit or 24-bit, you will lose source precision.

    Then there's the implementation of the multiplication arithmetic. It's likely that the PC will use 32-bit words for sample and volume control, giving a 64-bit result. It then has to round that result to the required output width. There are many different rounding algorithms used in DSP, and it is possible you may be able to hear the effects of them. You are reliant on the volume control using the most appropriate rounding algorithm.

    And I haven't touched on the use of dither...

    All things considered, it is probably better to output raw samples from the PC, running a full scale, let the DAC convert at full scale, and use an analogue volume control on the output of the DAC. Then you retain the full precision of your source in the digital domain.
     
    Last edited: Jul 29, 2018
  19. JoeESP9

    JoeESP9 ESL's & tubes since 83

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    ASIO and WASAPI are two entirely different thing. If you have the option configure your device to use WASAPI. If you use Music Bee, Media Monkey or Foobar WASAPI is included. It's merely a question of configuration.
     
  20. Final_Baton

    Final_Baton Active Member

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    Thanks for the reply Joe.

    That's the thing though : I don't just want to bypass Windows mixer in certain programs/applications. I want to bypass it for the whole PC setup. so that when I listen to music in web browser, it is also bypassed.

    Now, I know that when using a mediaplayer, you can configure that specific program to use WASAPI. But how do you do that for a web browser? Or even more convenient : for the whole PC setup(so that both web browser and apps like Spotify, all use WASAPI)?
     

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