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Choosing a USB Sound Card/Device

Discussion in 'Sound, Music, and Intercom' started by bobbyt2012, Sep 27, 2008.

  1. bobbyt2012

    bobbyt2012 Member

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    Dear Fellow Sound People,

    I am looking into buying a USB Sound Device in order to bypass my crap sound device that is internal in my laptop. I will be inputting it into an Allen and Heath GL2800 via RCA. Is it better to buy a USB sound device that has RCA right on it, or would it be okay to get one with only a 3.5mm jack that I would have to convert again with a 3.5mm to RCA cable. Any Suggestions? I don't want to spend too much money on this.
     
  2. jkowtko

    jkowtko Active Member

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    My experience with USB devices has been with M-Audio, so my suggestions are --

    * The M-Audio FastTrack USB has stereo RCA outputs ... you should be able to find one used in the $50-100 range.

    * However if you want cleaner sound you might consider using balanced connectors to the board and using two input channels or a stereo return on the board instead of the CD inputs. For that, an M-Audio FastTrack Pro will give you balanced outputs.

    If you don't used balanced connectors, then I'm not sure that you'll hear much of a different with an outboard USB device over just using the laptop headphone jack. I have a Dell Latitude 620 and the sound out of the headphone jack is pretty decent compared to a CD player with RCA cables.
     
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  3. bobbyt2012

    bobbyt2012 Member

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    I have an HP Pavilion DV6000 and when I have it plugged into external power, I get a 60 hertz hum. I have numerous filters on the cord, but they don't work. The M Audio Fast Track seems decent. I will be using whatever device I buy for the Accompaniment songs and sound effects for the show.
     
  4. jkowtko

    jkowtko Active Member

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    Unfortunately the only solution I've heard of (and used) for the laptop hum is to unplug the power cord ... the hum will stop. I think it has to do with the laptop power supply not being a grounded plug. However that means you have to rely on battery power to last through each act.

    If the laptop wasn't plugged into the same power outlet as the sound board, try doing that first to see if it helps. Otherwise, desktops don't seem to have this problem ... and therefore I use desktops in the theater.
     
  5. NicktheEvil

    NicktheEvil Member

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    For my playback i personally own an M-Audio MobilePre. its a good sound for the price. i think i picked it up brand new for about 130... i've seen them much cheaper since then. There aren't any RCA jacks on it, but its nothing an adapter from radio shack can't fix. but if you don't need to go through RCA it does give you 2 1/4" jacks along with a normal 35mm head phone jack.
     
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  6. howlingwolf487

    howlingwolf487 Active Member

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    I would recommend a Whirlwind PCDI (my favorite) or a ProCo iFace. Both will be very handy for balancing anything RCA or 1/8" related. They both have ground lifts and sum to mono, but the PCDI has pads whereas the iFace does not (unless they've upgraded it).
     
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  7. museav

    museav CBMod CB Mods Departed Member

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    The PCDI and iFace are both good choices if you want to stay with your internal sound card. An external interface may provide an improvement but that all depends on the laptop sound device, I've seen some where just about anything would be an improvement and other where you would have to spend some money to improve on the internal sound. If you do go the external interface route, I think it is worth it to get a device that has balanced inputs and outputs, if nothing else that allows for a lot more flexibility in application. Balanced inputs are also nice should you ever want to use the interface for recording.
     
  8. bobbyt2012

    bobbyt2012 Member

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    The iFace is a good price for me, but I am a little confused about it. How is it powered? The only reason I really want an external USB device is to get rid of the 60 hertz hum. When I have the power cable out of the laptop, it sounds really good.
     
  9. SHARYNF

    SHARYNF Well-Known Member

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    does your laptop have a two or three prong ac power connector?
    Sharyn
     
  10. howlingwolf487

    howlingwolf487 Active Member

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    The iFace is NOT a USB device. It is simply a passive direct box of sorts with transformers that balance the unbalanced signal and pad it down to an acceptable level for microphone inputs. It also has a ground lift switch on it to help deal with that 60Hz hum you want to get rid of. Also, very handily, it has a mono sum switch to save on channels.

    From the Website


    SharynF's questions might help us understand what the problem is so we can tell you how to fix it, not band-aid it (if at all possible). If your power supply has 3 prongs, I think there might be a solution for you. Ebtech has a cool little product out there called the Hum-X. You plug your power cord into it and it (somehow) eliminates the nastiness you are hearing from the AC.
     
    Last edited: Oct 1, 2008
  11. lieperjp

    lieperjp Well-Known Member

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    The HUM-X works great, but NOT FOR LAPTOPS! Had this same problem... We tried 4 different laptops (Three PCs and a Mac) with varying degrees of success, but the Hum-x did not completely remove the "buzz" from any of the laptops. So we got a PCDI, but I haven't had a chance to test it yet. :( However, the Hum-x is a great product and completely worth the $65.
     
  12. Thefoxygranpa

    Thefoxygranpa Active Member

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    I would first go with the PCDI, but if you are on a budget then try this Behringer model...

    Behringer UCA202 USB Interface from zZounds.com!

    I've owned one for a year and have had no problems....plug in and it installs. It sounds just fine, but then again, if I had the budget I would go with the PCDI.
     
  13. bobbyt2012

    bobbyt2012 Member

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    The the AC adapter that plugs into the wall is three pronged. The one going into the laptop itself is 1 prong.

    Power Supply: Input: 100-240V~ 1.6A 50-60Hz Output: 18.5V 3.5A LPS
     
  14. museav

    museav CBMod CB Mods Departed Member

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    It would be nice for the manufacturer to identify how it works. Anyone please correct me if I am wrong, but here are a couple of points I have heard noted regarding this product. It is rated 15A, which is probably fine for many applications but most commercial circuits are 20A. I don't believe the Hum-X is UL listed, at least it is not so noted on the product data, which can be a significant concern for some applications. And according to others, the Hum-X uses power diodes such that in normal use there is effectively no connection to ground but if the potential gets high enough then the path is made, thus you theoretically have safety ground path only during a fault. The concern with this is whether the voltage that would trigger the safety ground path or that might pass through the device during a fault might also blow the diodes, thus breaking the safety ground path.
     
  15. bobbyt2012

    bobbyt2012 Member

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    Let me know if you get a chance to test the PCDI. I can re-create the problem when i connect via 3.5mm to RCA on my TV. I also use an S-Video cable in that configuration, but the hum will come with either.
     
  16. SHARYNF

    SHARYNF Well-Known Member

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    I know there will be screams of NEVER do this etc, BUT th risk is very slight and I have found that there just seem to be problems in the design of three pin power supplies for notebooks.

    First I would try and make sure that the notebook is plugged into the SAME outlet as the sound board, and then I would test to see if by using one of the usually dangerous three pin to two pin adaptors on plug will solve the problem

    I know I know never remove the ground, but on these adaptors where the actual notebook is dc powered and the power supply is not isolated as a typical 2 prong ac connection is the audio from the notebook picks up the hum problem

    Worth a try this is the ONLY case where I have ever recommended not using the ground connection on an ac device

    Sharyn
     
  17. bobbyt2012

    bobbyt2012 Member

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  18. Chris15

    Chris15 CBMod CB Mods Premium Member

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    These ground lifter hum eliminator what have yous use a pair of opposing bias diodes between plug and socket earth pins. This should mean that anything under 0.67 volts will get blocked whereas supposedly faults greater than that should get through. But if it fails, well you're up the creek without a paddle...
    On that basis I would be rather hesitant...
     
  19. bobbyt2012

    bobbyt2012 Member

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    Could you elaborate a little bit. I'm not quite sure what you are talking about. Thanks.
     
  20. howlingwolf487

    howlingwolf487 Active Member

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    The ground cable in electrical gear is meant to conduct any stray voltage and return it to the AC source and not YOU. The diodes that are apparently included in the HumX device block any voltage below a set level (like the threshold in a gate). Once that level is exceeded, the stray voltage is passed to the outlet's grounding plug.

    Corrections welcome!
     
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