Question Help with noise removal please

Discussion in 'Hi-Fi Stereo Systems & Separates' started by sosojerk, Jan 5, 2018.

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  1. sosojerk

    sosojerk
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    Hello,
    Recently I decided to upgrade my stereo system and I went for this config:

    1. Took the sound out of my PC through USB to a Creative Omni 5.1 sound card running in stereo mode.
    2. Picked up a Onkyo TX 8270 amp and hooked a pair of Dynavoice Challenger M105 EX V4.
    3. The link between Omni 5.1 and amp is done via RCA analogs. I wanted this because I plan to use Zone 2 in the future and Onkyo's Zone 2 is only analogic.

    But I have an issue. If the system does not play any sound and I crank up the volume from the amp, I can hear some background noise coming from the speakers. It's in the treble domain (high frequency).

    So I assumed first that maybe my speakers\amp are broken somehow and I did some tests.
    If I stream the music from NET source (Tidal for example), than put the system on pause and crank up the volume there is NO background noise at all. The same is valid if I use a toslink\optical connection of the same Omni 5.1. With these, it is dead silent, so the speakers/amp are not broken.

    So the noise seems to come from the Omni 5.1 analog outputs. The digital part of the Omni 5.1 is fine, but analogs seem to put out some noise.

    I went further and I removed the Omni from config and I took the sound out of my PC directly from my sound card to my 8270 amp analogical only through a 3.5mm headphone connection. The noise is still there, but the level is far smaller than with Omni 5.1 analogical.

    How can that be? Creative Omni 5.1 is a 2017 model and advertised as a high quality sound card while my motherboard sound card is 8 years old. Is it possible that DAC in Omni is of poorer quality than my PC?

    And one last question: can I get rid of the noise if I place a DAC between digital Omni 5.1 optical out and my Onkyo TX 8270 amp?

    I was thinking to get a Cambridge Audio DAC Magic 100 for this purpose but I am not sure that will 100% help me. I need to preserve my analog input to the amp for Zone 2 compatibility.
     
  2. Rambles

    Rambles
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    Is it a scratchy noise in the tweeter? Sounds a bit like interference, and possibly changes if other things electrical are happening in the house, eg washing machine is on a spin?

    If so, I have had similar issues when connecting PC's and power amps in the same system. Never with a USB link though, only HDMI / RCA / toslink / coax. A simple and cheap ground loop isolater does fix it, but absolutely ruins the bass, so I use a Behringer hum destroyer now.

    Don't know if your issue is the same though, so this may not help.
     
  3. sosojerk

    sosojerk
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  4. Mark.Yudkin

    Mark.Yudkin
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    This is normal behaviour from all but expensive equipment and expected behaviour for a typical sound card and amplifier. There is no need for concern if the noise is not audible at normal listening levels. A CA DACMagic might help to reduce it - if it's a real problem and not one you are provoking by cranking up the volume to produce a bit of low level hiss.

    A "hum destroyer" will do nothing in your case. Your noise is not a 50Hz hum and therefore you don't have the ground loop issue it fixes.
     
    Last edited: Jan 5, 2018
  5. Rambles

    Rambles
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    Yes, that's the one. Is the noise a steady hiss, or a scratchy variable noise?
     
  6. sosojerk

    sosojerk
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    It is a scratchy variable noise. it is a high frequency one.
    I need to crank up the volume to hear it.
    And its louder coming from my Omni 5.1 than from my PC.
    But it annoys me. I must have it in total silence when no signal is coming from any source.
    Will a ground loop isolator help than? And mounted where? Right after my sound card RCA-s before entering the amp?
     
  7. Rambles

    Rambles
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    Yes, possibly. It does sound like the noise I have when connecting any PC to any power amp, I thought it was because of the poor electrics in my house. I had a power amp with a ground switch on it for a while, and that got rid of the noise. A ground loop isolater also gets rid of it, but messes up the bass, well it did for me.

    You could try one though, and experiment with it at any point in your system, they are very inexpensive, and if it works, at least you know you are are on the right track at least!

    https://www.amazon.co.uk/Ex-Pro®-Ground-Isolator-Elminator-Humming/dp/B004K24OV0/ref=sr_1_12?ie=UTF8&qid=1515165213&sr=8-12&keywords=ground+loop+isolator
     
  8. grahamlthompson

    grahamlthompson
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  9. sosojerk

    sosojerk
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    Creative Omni 5.1 is an external sound card. Right from Creative. :D
     
  10. Khazul

    Khazul
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    I suspect its an issue with the PC's PSU. TBH I tend to avoid creative - never been impressed with their sound cards for other than gaming and these days on board sound on many motherboards from the likes of asus and gigabyte is as good if not better anyway. My PC and its onboard sound are completely silent (asus gaming motherboard from a couple of years ago).

    Using an optical cable to an external DAC should get rid of the noise. Otherwise maybe a cheap pro-audio interface. If possible however, I would plug the optical into an optical out on the motherboard if such exists and dump the soundblaster on ebay or return it. I often see people complaining about noise on them or driver problems etc.
     
  11. BlueWizard

    BlueWizard
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    This is the External Sound Card you are using?

    Sound Blaster Omni Surround 5.1

    Amazon.co.uk: Buying Choices: Creative Sound Blaster Omni Surround 5.1 USB Sound Card with High Performance Headphone Amp and Integrated Microphone

    The prices range between £65 and about £85, you can only expect just so much for that kind of money.

    How far do you crank up the volume?

    I have a Onkyo Stereo Amp on my computer, and for normal videos the volume of the amp is set to about the 10 o'clock position. Occasionally some videos are louder and some are quieter, but that position of the volume control works most of the time for most sound (music, video, etc...).

    Though I am using my Internal Sound Card with volume set to about 9 or 10 (full), and the play/application volume set to roughly 50%.

    Also ... HISS or HUM ... those are very different problems? Any Amp will hiss when turned up VERY Loud. That is just background noise in the circuits, sometimes called floor noise. It is usually undetectable at normal volumes.

    Hum is a different matter, that usually indicated some type of ground problem. Typically either a poor ground or a ground loop. Ground Loop noise is usually detectable at any volume level.

    Poor ground is usually poor cable. What is the type and quality of the RCA cable you are using?

    Do you get the same effect with the Headphone Out of the external sound card?

    One assume you computer has an Internal Sound Card, try that and see if the same thing happens. Also try the Headphone Out directly from the Computer. We are trying to determine if the noise originates at the Computer or in the External Sound Card.

    I understand that you are using RCA between the Creative Omni and the Amp, but what is the connection between the Computer and the Creative Omni?

    What connection options are available from your computer? Generally Optical is free of noise, and doesn't have ground issues, so if the computer has Optical Out, give that a try.

    Steve/bluewizard
     
    Last edited: Jan 5, 2018
  12. Deleted member 781788

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    There is nothing wrong with your system, unless the noise is really loud at max. volume.
    In fact it could be a good sign!
    Even at a 100db signal to noise ratio (SNR), if there is no music, and you crank up your volume to the max., there is some noise - it is electrons moving about, colliding and making that kind of noise.
    A lot of sound cards (DAC's) actually mute their outputs, once signal level goes beyond a certain low level - it is a cheat way to artificially register a higher SNR figure for reviewers.
    Apparently yours does not, which is actually good.
    If the noise was in the lower frequencies, there was room for concern.
     

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