This is my third video of the week because people keep asking good questions, and I can't wait to answer them. Over the past few weeks, I have received countless comments asking if adding a phantom power supply to your cheap mic setup can improve your microphones audio. To put it simply, yes and no. Let's look more at this.
The Test
For this test, I ran the Excelvan BM-700 directly into the Sabrent USB Audio Adapter as well as the Gino Stereo USB Audio Adapter for a base quality test. Then as a comparison, I ran the microphone into the Neewer Phantom Power Supply, and then ran the output from the phantom power supply into each adapter. I include comparisons of me talking, and then samples of the background noise.
Results
The initial audio from the Sabrent Adapter was pretty good. My microphone input gain was set at 7% on my computer and there was very little background noise. When I added the phantom power supply to this set up, I was able to drop my input gain from 7% down to 4%. You can hear a slight bump in clarity and high end once phantom power is added, but you also hear a slight increase in background noise (a new hiss).
The first test with the Gino Stereo USB Adapter is horrible. The audio sounded digital, quiet, and I had to set my microphone input gain to 72% which yielded a ridiculous amount of background noise. Once I added the phantom power supply, the audio for this adapter improved considerably! The sound was clearer, crisper, and less digital sounding. We were able to drop the input gain from 72% down to 35% and this led to a significant decrease in background noise.
Conclusion
If you have a Sabrent audio adapter, or an audio adapter that gives you plenty of gain, and you don't have much background noise, I do not think that it's justifiable to purchase a $20 power supply. On the other hand, if you have a cheap piece of crap USB adapter that forces you to crank your input gain, causing ridiculous background noise, the phantom power does seem to improve that.
However, keep in mind that regardless of what accessories you get, you are running a microphone into a cheap USB Adapter. Your audio quality will always be limited by this. The pre amps in these USB Sound Cards are nothing special, and quite frankly, kind of suck. If you really want to improve your audio, I recommend looking into an audio interface that was designed to record microphones. An audio interface that has real preamps in it. But if that option is out of your price range, this solution seems to work just fine.
Neewer Phantom Power Supply: http://amzn.to/1llLK3a
Sabrent USB Audio Adapter: http://amzn.to/1llLGR6
Gino USB Audio Adapter: http://amzn.to/1IkwCIQ
BM-700: http://amzn.to/1InMPgb