Changing tempo affect sound quality?

[guitar roy]

If I use Soundforge or Audition to change the tempo of the song without changing the pitch, will this affect the quality or fidelity of the recording?

Does it matter whether I'm speeding up or slowing down the song?

Should this tempo change be applied after all of the mastering is complete?

Thanks

[SPINSTERWUN]

Originally posted by guitar roy
If I use Soundforge or Audition to change the tempo of the song without changing the pitch, will this affect the quality or fidelity of the recording?

Does it matter whether I'm speeding up or slowing down the song?

Should this tempo change be applied after all of the mastering is complete?

Thanks

Drastic tempo changes will definitely affect your recording.

[ryanlikestorock]

Theoretically, slowing the song down should affect the quality more than speading it up. When you speed a song up, it will take up less time and is therefore taking information away from the existing file. When you slow it down (and therefore increase the amount of time), you have to somehow make up information to fill in the new time.

Little changes shouldn't hurt, but I'd suggest doing it before mastering so the mastering process will work as somewhat of a mask of any obvious sound differences caused by the time change. However, I've never done this so I could be way off.