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User Name Thread Name Subject Posted
Alan of Australia Help: A440 in computer (17) RE: Help: A440 in computer 15 Dec 00

Are you able to tell us the exact frequency you get instead of 440 Hz?

In a MIDI system the controller (e.g. sequencer software) does not determine the frequency to be played. The software simply tells the MIDI device (sound card or synthesizer) which note to play and the MIDI device should play the correct frequency.

You can normally change the frequency using the pitch bend function in your software. This setting should be zero unless you're deliberately bending the pitch. Have you checked this?

If the setup software that comes with your card has a fine frequency adjustment that might be the problem. Or the solution depending on point of view. (I expect that this adjustment would change the same internal parameter on the sound card as the pitch bend function.)

As an experiment I recorded a MIDI file containing one note of A 440. I played this back on two sound cards and a MIDI file player, at the same time recording the audio outputs on another computer. One sound card appeared to have a frequency error of about 0.08%, the other two devices were less than 0.02%. The frequencies were 439.66 Hz and 439.92Hz, but there's some deliberate frequency randomness in MIDI sounds because that's what happens with real instruments, so that makes it difficult to measure the exact values. Still, I wouldn't expect to hear any of this as an error.


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