DAC Newbie. Help!

Discussion in 'DACs' started by rromeo, Dec 4, 2017.

  1. slow_jazz

    slow_jazz Lunatic Member

    Messages:
    13,310
    Location:
    SE Michigan, Downriver....
    I wound up buying a Surface Pro 3 with a cracked screen that still works great but touch screen doesn't work for cheap.

    Put the free Windows 10 upgrade on it.

    Hooked up USB hub - USB audio with optical out feeding DAC.

    Run my music off USB memory stick filled with FLAC songs.

    Sounds good with no fan noise.
     
  2. adri2000

    adri2000 New Member

    Messages:
    12
    I do not recommend use tablet or laptop as music player. All parts (CPU, RAM, USB controllers) are squeezed in small space and from my experience that always will have bad effect on digital signal quality. PSU is also a compromise.
    Better use older small form PC with good quality PSU. SSD is a must, HDD drives keep farther away (in server or NAS). Also RAM quality (speed, latency) have effect on sound.
     
    Last edited: Dec 7, 2017
  3. cvt01

    cvt01 New Member

    Messages:
    25
    I read in a discussion on Comupteraudio that a HDD is just like a CD but the rpm is higher... that same source also dissed SSD and stated that a USB stick is the way to go... I don't remember the reasoning sorry.
    I have a Raspberry pi (2b i think - this has no built in wifi - one less potential source of RF nosie) which i got for 35 bucks and hardwired it to my router. I use the the Ifi Audio power supply ( https://www.bhphotovideo.com/c/product/1275641-REG/ifi_audio_0306007_5v_ipower_5v_for_all.html ) to feed the Raspberry based on recommendation I found on computeraudio forums. I added a 256 Gb USB stick with my music and just for the fun of it I duplicated that library to an HDD which I connected to the router's USB port. The Raspberry can map that as an external network drive. I did this to see if there was any difference in the SQ between the stick and the HDD on my system. I can't hear any but I'm not a seasoned audiophile so YMMV...
    The raspberry is running RuneAudio build and I can use MPDroid on my cell or any computer/tablet connected to the same router to remote control it. It is feeding a Topping D30 ($99) through an (async) USB connection.

    I'm very very happy with the SQ.

    I also tried a beaten up old Laptop with JRiver and foobar but I had issues with drivers as that thing would not take win10 and the Vista drivers were giving me hell...

    My solution is cheap enough for anybody to try (people spend more on interconnects..). I'm dying to try a high pricetag DAC to see how it would improve the SQ but can't make myself spend a grand on that only to find out I can't hear any difference...
     
    cpt_paranoia and ldatlof like this.
  4. cpt_paranoia

    cpt_paranoia Member

    Messages:
    84
    Unless you are using the analogue output from a device, the digital processing will have little bearing on the sound, provided there is adequate processing and memory to ensure an uninterrupted stream of data. RAM speed and latency can only have an effect on processing speed, nothing else.

    If you are using a USB or coax S/PDIF interface to a DAC, there is a small possibility that conducted noise might get into the DAC audio, but a well-designed DAC should provide effective isolation of the input.

    If you are using an optical S/PDIF interface, there is no electrical path to conduct noise from PC to DAC via the signal path; it would have to be radiated from PC to DAC, or conducted via the mains supply. If you provide a sensible physical separation, and the DAC is adequately protected against radiated and conducted susceptibility, you should not have problems.

    The last mechanism by which noise might be passed to the DAC is due to jitter in the signal timing of the USB or S/PDIF. Such jitter should be removed by the clock recovery, data sampling & FIFO buffer in the DAC. It is the sample clock to the DAC chip that determines the DAC sample timing, not the digital input stream. This DAC sample clock should be provided by a low phase noise source, such as a crystal oscillator.

    The fact that there is no flow control between source and destination in the simple protocols means that it is possible for data overflow or underflow to occur, due to the use of different oscillators at each end; data is sent at one rate by the source, and consumed at a different rate at the DAC. But this will be mostly dealt with by use of a FIFO buffer in the DAC, and the fact that crystal oscillators have a pretty good tolerance. Data overflow or underflow would result in a missed sample, or a duplicated sample; for instance, the VoIP protocol provides a mechanism to drop, or repeat frames as necessary, since the source and destination clock rates may be more significantly different.

    If you are using an analogue output from a PC, laptop or tablet, you might consider using a lead fitted with an RF suppressing filter, to prevent RF noise being conducted along the signal cable. The audio circuits should also be designed such that they will not respond to RF, usually by a simple low-pass filter on the signal input. They should also be designed to prevent radiated susceptibility, preventing RF injection into the circuit.

    RF injection can cause problems if it hits a rectifying element in the design, which will perform amplitude demodulation to baseband (audio frequencies), the classic being mobile phone injection (GSM will give a 216.6Hz buzz due to the TDMA frame rate), or even more classic; dental fillings that receive radio stations...

    If you are using WiFi or Ethernet streaming, there is almost no chance of conducted noise from the 'player' computer; the media stream is transported as a CODEC format, and reconstructed by the DMR. A badly designed DMR might be susceptible to WiFi or Ethernet noise, and noise generated by the processor performing the rendering.
     
  5. botrytis

    botrytis Trying not to be a Small Speaker Hoarder Subscriber

    Most Processors and ram are powerful enough. processing music can be done with w/ 386-32 bit CPU w/o any issues. It takes very little processing power to deal with music.

    Timing error on USB are in nano- to femto-second amounts. Our ears cannot hear that.
     
  6. cpt_paranoia

    cpt_paranoia Member

    Messages:
    84
    Timing error on the USB is immaterial; it does not propagate to the DAC sample clock.

    Femtoseconds is pushing it... it will be in picoseconds (USB3 being 5Gb/S, so 200ps period).
     
  7. JoeESP9

    JoeESP9 ESL's & tubes since 83

    Messages:
    14,806
    Location:
    Philadelphia PA
    Every DAC that operates asynchronously has a fairly decent internal clock.


    Okay, lets agree that he wrote the first code that can do that. (IIRC he got a patent for it). It's an indisputable fact Wavelength Audio DAC's were the first commercially available DAC's to operate asynchronously via the USB port.
     
  8. cpt_paranoia

    cpt_paranoia Member

    Messages:
    84
    Any system where the source and destination are not clocked by the same clock are 'asynchronous', although in this context, more accurately described as plesisochronous. The concept has been around for a very long time, and is in use practically everywhere where source and destination cannot be perfectly synchronous, because there is no direct clock connection.

    I don't know when the patent was granted, but I do know that the patent process is a rubber-stamping 'sort it out in court' process at the moment, with no real assessment of prior art or merit of the claim.
     
  9. botrytis

    botrytis Trying not to be a Small Speaker Hoarder Subscriber

  10. cpt_paranoia

    cpt_paranoia Member

    Messages:
    84
    Can you find one that has relevance to audio?
     
  11. botrytis

    botrytis Trying not to be a Small Speaker Hoarder Subscriber

    Don't need to All USB information is digital and usually harder than music to deal with. DATA is DATA.
     
  12. JoeESP9

    JoeESP9 ESL's & tubes since 83

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    Location:
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    None of that changes the fact that Gordon Rankin of Wavelength Audio was the first to write code that enables audio DAC's to operate asynchronously.
     
  13. botrytis

    botrytis Trying not to be a Small Speaker Hoarder Subscriber

    I am not saying it does. I was just pointing out that data is data in the digital world. We like to think music is different but in reality it is not.
     
    GChief likes this.
  14. JoeESP9

    JoeESP9 ESL's & tubes since 83

    Messages:
    14,806
    Location:
    Philadelphia PA
    My apologies. My comment was not aimed at you.:no:
     
  15. botrytis

    botrytis Trying not to be a Small Speaker Hoarder Subscriber

    No worries :D
     
  16. olderroust

    olderroust AK Member

    Messages:
    117
    Location:
    286 miles south of arcata
    I don't see it mentioned here, but the OP would do well to listen to the Ayre Codex before making a purchase. I think it lands at the top end of his price range - I think the MSRP is 1999, but I also have seen it discounted. It's a component I listened to recently, and I was very impressed.

    Not "more than my share of the mortgage this month" impressed, but if I'd heard it a year ago when I was more flush, I'd have bought it in a heartbeat.
     

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