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Do INTERNAL soundcards - pick up a lot of interference?

Discussion in 'Recording' started by Fer, May 20, 2004.

  1. Fer

    Fer Guest

    hello, people. This issue may have been addressed sometime before, but it is of dire importance to me.

    I´ve been recently reading a lot about sondcards, since I´m planning to get one in order to record with a korg synth, straight to the soundcard in-port. The thing is, I´m CURRENTLY using that framework, but may some day want to record with someone else, as in a band. I really don´t care about HOW MANY tracks I can record simultaneously, because I know I can record in different sessions with the different members of the band, but the matter here is:

    many people say that INTERNAL soundcards (i.e. those which do not have a breakout box) such as Audiotrack´s Maya MKII, or Waveterminal 192L, pick up a lot of interference from within the CPU, coming all the time from the different components inside the computer, thus, inserting NOISE into the recording signal, and ultimately reducing sound QUALITY quite considerably. What these people argue, is that EXTERNAL cards (with a breakout box) do not pick interference, since they have AD-DA converters "outside" the PC, in the box.

    - Is this true??? What I want is, chiefly, GOOD SOUND QUALITY. I don´t care about the number of parallel tracks I can record at one single time.

    - Can I achieve near-pro or pro quality with internal cards (the ones without the box)? or do I inevitably need an external one?

    -does sound quality vary a lot from external to internal cards, or do the former cost more due to the confort of having all plugs closer and more input ports to record?

    -or is it that the REAL difference is with those huge cards that cost over $1000 (at least in Argentina)?

    any advice or opinion, I´ll appreciate.

    thanks a lot

    Fernando
     
  2. krash

    krash Guest

    Yes there's a real difference, potentially, in analog noise. It all depends on many factors including the PC design, where the card is installed, etc., so it's hard to quantify. There are probably cases where, with all other things being equal, having the converters external to the PC is not noticeably less noisy than having them internal to the PC, but this would be the exception rather than the rule. One important thing is the power supply noise, and having the analog stage supplied by a power supply made for an analog device, rather than a switching power supply in a PC polluted with all kind of digital noise on the power bus is a real difference.

    However, I'd think a modern synthesizer would have a digital output (optical for example), and in which case, if all you are recording is the direct output of the synthesizer and you are concerned with absolute duplicate of that sound, then using the digital output on the synthesizer into a digital input on a sound card would make this whole question moot.
     
  3. Fer

    Fer Guest

    thanks krash. I didn´t get the part of the power supply though.
    Do you mean that I should supply power to the synthesiser from a different place than that which the computer takes power from?

    by the way, my synth hasn´t got a digital out-port, which is a nag, since I can only record through audio (or midi, but that´s not what I´m looking for)

    Fer
     
  4. krash

    krash Guest

    No, I meant the DC power supply... the computer has an AC/DC multiple-output switching power supply that takes in the AC from the outplet and puts 5V DC and 3.3V DC on the computer motherboard to run the PCI bus, and any PCI card in the system runs on this power along with the whole PC motherboard etc. Every device/part/active component (that would be RAM, PCI bridge, chipset, CPU especially, other PCI devices, you name it) that derives power from this bus can potentially feed back noise onto the power bus, and that noise will find its way into the other cards in the system. If the system runs at clock rate ranging from 33MHz to say 300 MHz (I don't know how fast PC buses are anymore) then the power only has to be "quiet" at those frequencies, but lower frequency noise (like audio band) does not affect the PC's digital performance nearly as much as it can affect the analog performance of a audio-band device in there.

    An outboard converter is going to have its own dedicated AC/DC power supply, likely a linear power supply (not a switcher) with much better regulation and much quieter power. The result in the noise floor, transient response, etc., can be huge. Power supply is probably the most important factor about the outboard vs. internal sound card converters, not necessarily electromagnetic noise.
     
  5. Fer

    Fer Guest

    thanks a lot for the time, krash

    fer
     
  6. Preben Friis

    Preben Friis Guest

    In short: Yes, you can. I don't know how they manage to get that kind of specs in such a noisy environment as a computer, but it is possible....

    http://audio.rightmark.org/test/lynx-two-new/lynx-two-b-2496.html

    /Preben Friis
     
  7. golli

    golli Active Member

    Exelent thread.

    I have an permanent/hardwired PSU, on 220-240v (Europe).

    It's an Enermax 350w.

    The fact that it is not switchable, does that mean its better in any way???

    BTW I bought this thing on a recomendation from a guy who has a thing about Enermax :lol:
     
  8. krash

    krash Guest

    "Switching power supply" is a AC/DC converter topology that's distinctly different from a traditional "linear" power supply and much more efficient.

    This is not a "switchable power input"... I guess this is the wrong forum to be getting into all of these details. Suffice to say, if it's a power supply in a PC, it's a switcher, and it's noisy (comparatively). If it's an outboard set of converters, it's almost definitely got a linear power supply that's much quieter. A 350W linear power supply would be nearly as big as your whole computer, and certainly as heavy.

    So in summary, no matter what, your PC power supply is a switcher, and relatively noisy compared with a linear.
     
  9. anonymous

    anonymous Guests

    [quote="Preben Friis]I don't know how they manage to get that kind of specs in such a noisy environment as a computer, but it is possible....[/quote]

    Lynxes are amazing cards. I don't know if my Lynx 2A would perform worse with a crappier PSU but it really is wonderful with the PSU I now have in the computer..

    Good sound and silent.


    Jaakko
     

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