The answer is no, the Sennheiser MD 421 does not require phantom power.
Does Sennheiser 421 Need Phantom Power?
It does have an integrated preamp and does not need to be connected to external sources of power. The microphone is self-powered, so you can just plug it in and start recording without worrying about additional power supplies.
With this great mic, you can easily capture professional-sounding recordings without any fuss or extra equipment! So if you’re looking for a reliable and easy-to-use mic that doesn’t require phantom power, the Sennheiser MD 421 is a great option!