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can 48v fry an internal soundcard?

Discussion in 'Recording' started by redbort, Mar 8, 2008.

  1. redbort

    redbort Active Member

    I wanted to run some cuemix tests with a motu 896HD & a mac
    but i needed a source audio
    so i used the output of my other computer, a default HP Realteck internal sounded

    now the realteck soundcard isn't working.... audio output is very very very quiet, right next to the noise floor
    the headphone output (which when plugged in turns off the default "out") gives me the same problem....

    any diagnosis ideas?

    The 48v on the motu may have been on.
    motu inputs were switched from +4 to line to mic

    the cable i used was basically an insert patch cable
    i tsr 1/8" connector at the realteck end (headphone stereo)
    which split into two ts 1/4" into two channels of the motu
  2. Space

    Space Well-Known Member

    You went from Realtech "output" to Moto "input"? Nothing off there...maybe the sound level of the realtech has been adjusted down during the test?

    48v doesn't come into the equation UNLESS you send this same signal "out" of the Moto to the input side of the realtech.
  3. redbort

    redbort Active Member

    i didn't change any settings on the PC & realtec card... i just needed signal, i was playing some beatles in itunes

    & I not following the 2ed half...

    48v usually feeds the microphone "source"
    but this time the realtec card was the "soruce"... same input jack
    that's why i'm assuming 48v was sent into my realtek card and fried it... yet It's very doubtful, since only TS connectors were connected to the motu, and i'm certain you need all 3 pins to send 48v (i may be mistaken)
  4. Space

    Space Well-Known Member

    So you had an output from the Moto going to the output of the realtech?

    That is what I am trying to gather.

    A trs plugged into the "output" of the realtech is OK. When you split this into mono pair, did this same "output" of each mono signal go to an input on the Moto?

    If you had an output from the Moto going to the output of the realtech your lucky all that is burnt is the soundcard.
  5. redbort

    redbort Active Member

    motu input.
    signal was going INTO the moto

    inputs send "out" 48v...
    that's how phantom power works.... no?
    mics are plugged into inputs, fed 48v from inputs

    (why is this seeming more complicated then it should be???)
  6. Space

    Space Well-Known Member

    Yes, you are correct and the card is most likely fried.

    The inputs are switchable mic to line level so if you cycled thru then you may have inadvertently sent the hot signal to a place that it should not have gone.
  7. redbort

    redbort Active Member

    thanks for the obvious.

    dolts on message boards sure can add to the aggravation of a bad day. it must be me.
  8. Space

    Space Well-Known Member

    Losing a realtech onboard soundcard is not the start of a bad day.
  9. RemyRAD

    RemyRAD Guest

    Yes, you have most probably fried the output of your sound card as the 48 volts appears on both pins 2 & 3 in relationship to ground on pin 1. So, all you need to fry your sound card is the ground and either connection. It's a 180° differential trick that makes the voltage disappear when you don't plug things in wrong and you did. So, like I've always said, TRANSFORMERS ARE OUR FRIENDS since they don't pass DC.

    So basically, what has happened here is that you neglected to use an electronic condom (unbalanced to balanced transformer) to protect yourself. It only takes onetime and you're dead. A Radio Shaft transformer would sound better than your blown up sound card and much less expensive.

    And remember, always put a condom on your microphone also.
    Ms. Remy Ann David
  10. Boswell

    Boswell Moderator Distinguished Member

    If you really used a cable with jacks on both ends, you will not have put 48V on your soundcard outputs, as the 48V appears only on the XLR pins of the combo connectors. That doesn't mean to say that the soundcard hasn't developed a fault, but since you say that the headphone output (which is independent of the line out) is also unusably quiet, it sounds more like a settings problem in the soundcard control panel. I'm not familiar with the HP Realtek card, but if it has auto-sensing of attached devices, it may have decided that you are using that socket as an input and so has disabled it as an output. Try going through the diagnostics of the sound card and see if you can at least get the headphone output working again.
  11. MrEase

    MrEase Active Member

    I agree with Boswell's comments but have one other question.

    Did you connect using a mini TRS jack in the realtec and a 1/4" TRS into the MOTU? If so you are feeding a stereo output into a single balanced input and the resulting recording will only be the difference between left and right channels which is normally much lower than either channel.

    This would not explain the low headphone output though and you should also check Boswell's suggestions.

    EDIT: Woops! I just re-read your post and you used a Y cable. As Boswell says though, no 48V goes to the TRS connector so that is not the problem.
  12. That's a butthole of a thing to say to someone who's trying to help you fix your disposable soundcard.
  13. Codemonkey

    Codemonkey Well-Known Member

    Disposable nothing, my (particular) realtek is on the mobo. Makes it worse I guess. Although my cheapass Trust PCI card sounds so bad, it's funny. Onboard audio beats something.
    Although, if I flip the phase on the right track, and mono it, the noise goes away. Too bad about the vocals or whatever is centred.
  14. redbort

    redbort Active Member

    check out his post history.... it speaks for it self

    i've booted the PC in XP instead (I can dual boot XP/vista) & i get the same problems, so i doubt it's a "settings" issue. :?

    I'll get a new soundcard, but i'm sad about loosing the ergonomics of the front bay headphone plug.
    & using the motu for my home PC in the mean time has come with lots of bumps in the road... funny that i can't listen to youtube & mediacenter at the same time anymore.... hope the replacement SC has all the appropriate drivers...

    Thanks Remy.
  15. Space

    Space Well-Known Member

    Forgive me for giving you the benefit of a doubt even when your "history" suggests that you need more hand holding then most and may not always understand overly simplified answers.
  16. HansAm

    HansAm Active Member


    Thats a great metafore.
  17. redbort

    redbort Active Member


    i've been bugging HP help all day
    and after uninstalling the MOTU drivers with "Windows Install Clean UP", it was working !!!!!!!!! :icon_exclaim:

    yet, i restarted the computer, and now it's not working anymore.
    drivers have been re-installed, bios audio detection has been reset, different drivers installed...
    what ever it was, it was the MOTU drivers that ^#$%ed it up, not the 48v
    problem still isn't resolved... maybe it's "jack detection"

    hopefully i've got patience to put up with these bozzos for another 6 hours of trouble shooting
    god damned VISTA!!!!! (that's where i think the problem lies)

    this sufferance cause by using recording gear with my wife's computer...
    i usually keep em seperated for my own protection, looks like i'm the one who busted her stuff in this situation.
  18. RemyRAD

    RemyRAD Guest

    For $15, you can purchase a set of emergency CDs from Hewlett-Packard. It will allow you to reload the operating system plus all of the ancillary Hewlett-Packard included software and drivers, etc., etc.. Of course you will have to reload all of your personal software as it will make your computers a virgin again. Ask your wife if she would like that? Having her computer fixed or being a virgin again?

    Twice a virgin
    Ms. Remy Ann David

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