Buzzing noise with Condenser Microphone + Phantom advice

Question

I'm using the Floureon® Condenser Microphone 3.5mm BM-800 Studio Recording Mic with the InnoGear® 48V Phantom Power Supply but I'm getting a buzzing noise in the background when I use the phantom power, and the only way I know to avoid that is to turn down the sound, making it hard to hear my voice.

I'm confused slightly because I'm being supplied with a in line to usb adapter, (or usb soundcard, i'm unsure), it seems the phantom power makes no difference if I don't use a external soundcard. When I do use it, the audio sounds fine except from the buzzing noise, is there anyway I can fix this or any more information? I'm fairly new to this. Thanks.

Answer 1

According to the information on the Amazon.UK page you cited, the Floureon® BM-800 microphone DOES NOT use phantom power. There is no reason to use the InnoGear® 48V Phantom Power Supply at all. Since you DO NOT need it, and since it adds extra noise, I can't see that there is any reason to use it at all.

Answer 2

The kind of "can run on a desktop computer" handwaving info suggests that this is an electret condenser capsule rather than a "true" unpolarised condenser microphone in need of phantom power.

The phantom power, if any, will likely only be used for the internal FET preamp instead of polarizing the membrane. While the microphone is apparently fine with 48V, it does not need it. Instead it can get along with "plugin power" supplied through its 3.5mm cable. It's also unlikely that the connection is balanced even when using a balanced XLR cable (rather than the delivered one) and an actual microphone preamp with phantom power.

That means you won't get the common noise rejection of a balanced connection, and the quality of your phantom power circuit might depend on it. Also, you'll likely become much more susceptible to the switching power problems of your laptop supply by having another power supply in the loop without using balanced connections. This is a classical ground loop problem.

Try working without the phantom power supply, using "plugin power" instead (it's usually available on most mic inputs of soundcards or laptops, possibly by using some utility for switching it on).

The microphone you are using is not as much budget equipment as cheap equipment. I am surprised they even specify an equivalent noise level in their data sheet, and it is not actually bad for a small condenser capsule of 16mm diameter. Too good to be true would be my guess. Maybe they have just reprinted the capsule's spec without bothering to measure the whole microphone including delivered cable and their own plugin power circuit. At worst they have copied the specs from an unrelated microphone.

Personally, I don't think separate phantom power supplies make a lot of sense for computer recording these days. External sound cards of some quality will readily supply phantom power and you don't have to meddle with batteries or ground-loop-susceptible additional power supplies.

You'll still be able to use your BM800 with one of those and it will likely get the best out of that mic that you can hope to get, but considering the price of, say, a Samson C02 pair of microphones (still on the cheap and thus noisier side of budget, but manageable with good placement), meddling with plugin power designed equipment and unbalanced cables is just not worth it.

Answer 3

Reading various reviews on this mic [including the ones underneath your source at Amazon], it appears that it can run on anything between 9v & 48v. It can just about get 9v through USB alone, so tbh, if it works like that, use it like that.

I suspect you're getting mains hum over your 48v phantom supply, which is very likely to be incurable without further cost, as the external 'wall-wart' is probably the cause - I guess you could bin it & get a better-rated unit, but that would probably cost more than you've already invested in the mic & phantom together... which has to be said, isn't a lot :/

^{As a complete aside, I wonder whether that shock-mount would hold a U87, as a real one would cost more than 10 times that entire package...}

Answer 4

Can you still return it? Then try that. Seeing that price, gee, this is an extremely cheap product. Great membrane condenser mics for 100 bucks are considered cheap already.. So it may be easy to simply get a defective device. Something not soldered properly. Bad material, like partially corroded copper that's supposed to have low resistance. (I've seen super cheap cables that had that). Especially bad when it's the shielding that's not connected properly.

• try different cables
• if you know someone who has good a quality audio interface with microphone preamps or other sort of recording gear, be it just a mixing console with headphones or speakers connected - try whether your microphone and/or cables work there, without all that usb stuff connected, to narrow down the problem
• you might have a ground loop somewhere
• If you can get the mic replaced for free, try that, before you can't anymore