Improving Recording Quality

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Note: the mentioning of equipment brands in this article is not meant as an endorsement, but rather represents the experience of the author(s).

The built-in soundcard that comes with many PCs is quite poor. It may be okay for playing sound effects, but it's not good enough for doing high-quality recording. Often the worst ones are the built-in sound on your motherboard, or any audio device on a laptop. Note that you don't always get what you pay for: a $20 basic sound card could sound great, and a $100 sound card might have lots of problems. Here are some things to consider if you think you have hardware problems:

Your current system

  • Mute other devices that you don't use for recording - such as MIDI Synth, CD Audio, TAD-In, Auxiliary, Microphone, Line In. Only "un-mute" devices to be used.
  • Ensure you update your sound drivers: Find the website for your computer manufacturer or sound card manufacturer and see if they have a new driver for you to download (on Windows you can also try Device Manager first).
  • If possible, insert your soundcard into a PCI slot which has a dedicated "Interrupt Request (IRQ) Channel", as described in your motherboard handbook. Except for dual processor motherboards, there will probably be 4 electronic IRQ channels used to assign IRQs. (This is not the same thing as the 16 virtual IRQs we usually talk about.) For example, on my ASUS CUV4X mobo, Interrupt Request channel "A" is shared by AGP (reportedly noisier than PCI video cards) & PCI-slot1 (leave blank if AGP is in use) & PCI-slot5 (empty). Int-"B" is shared by AGP & PCI-slot2 (NIC - noisy). Int-"C" is a dedicated electronic channel, taking hardwire interrupt pulses generated solely by the device installed in PCI-slot3 (soundcard). Int-"D" is shared by PCI-slot4 (SCSI - noisy) and USB-controller (mouse, keyboard, etc. - very noisy). If I install my soundcard in any slot other than PCI-slot3, the result is a scratching sound, like a loose connection at an input jack. But, it comes from the mouse pulses (slot controlled by Int-"D") or from video rewrites (slot controlled by either int-"A" or "B").
  • Even if you are using a 'silent PC' (one with passive cooling rather than a fan) you will still need sound insulation between it and your mic (a piece of felted board will do) as the hard drives are not silent.
  • If you are using any outboard (externally powered) audio hardware, make sure all the equipment is plugged into the same power strip. Grounding issues can cause ground loops, which will appear in your recording as a hum. For more info, see Reducing noise.

Equipment upgrades

  • Buy a new soundcard - especially if you were using your computer's built-in audio capabilities before.
  • Consider buying a USB audio device. The main advantage is that the A/D converter is outside of your computer's case, which keeps electrical noise to a minimum - only the digital signal gets transmitted back to your computer. Another advantage is that you don't have to open up your computer to install anything, just plug it in and go (maybe after installing the software driver). It's easier to share it between multiple computers, too. Make sure other USB devices are unplugged if not being used, as especially USB 1 has a limited bandwidth. Even things like network cards can interfere with USB audio so disable them. Something like the M-Audio Duo puts most sound cards to shame and can be had on eBay for a couple hundred bucks. The Griffin iMic  can be a good and very affordable choice too as it does work nicely with Linux as USB audio device. Behringer  also has a compact unit that does a nice job for around $30.
  • Cheap sound hardware, anywhere in the analog chain, will result in poor quality recorded sound. Consider upgrading your audio hardware:
    • Microphones, more than any other single piece of hardware, will impact the quality of your recorded sound. This is one area that you indeed get what you pay for. Professional microphones can be had for $40 and up (way up). If you're just getting started in home recording, you can't go far wrong with products from Shure . Models SM58 and SM57 are workhorse microphones of the professional audio world, and as long as you don't mistreat them terribly their resale value holds up quite well. Check out this article on connecting a pro microphone to a sound card - Shure Technote - Interfacing Mics to Computers .
    • If you use a pro microphone, you'll need a good preamp. The "mic" input on a sound card has a preamp behind it, but it's usually not very good quality and lacks versatility. Consider using a mixer board with microphone and line inputs (useful for electric guitars and keyboards) and a line output that you can connect to the line input of your sound card. Behringer  makes quality low-end mixing boards that are a good starting point for beginning home recordists. Consider the Behringer UB802  as an entry level unit - street price usually well under $100.
    • Don't forget accessories like microphone stands and cables. Decent stands and some cables can be had from Radio Shack, but these cables will likely start to hum and buzz after a year or two. Professional microphones use XLR  cables that you might be better off getting from a store that caters to audio professionals. For a sure bet, you could choose Digiflex Tourflex cables . These wires are a bit more expensive, but connections wont get loose, and if they do, the cables are guaranteed 10 years.
    • The last step in your analog audio chain is the A/D converter on your sound card. As mentioned above, sound hardware from M-Audio or Echo can make a world of difference in the quality of your recordings.