Need help identifying type of noise

[nfshp253]

Hi there. I need some help with reducing the noise present in all my current recordings. Let me first start off by saying that I'm quite a newbie in all matters recording and with Audacity so forgive me for not knowing a lot of things, including some basics.

I'm currently using some Chinese-branded Takstar SM-8B, which according to them, is a studio condenser microphone. It's hooked up to their own 48V phantom power supply that inputs into my computer via a 3.5mm jack through the line-in port on my laptop.

Now here's my problem. I'm trying to record from my upright acoustic piano and no matter what I do physically to try to remove the noise, the same type of noise gets recorded. I've uploaded a sample of the noise so that you guys can perhaps get a better idea what type of noise this is.

The microphone is already wrapped with some foam thing and on top of that, I've added a soundproofing pyramid type foam between the microphone and the piano. But despite all these, my recordings are still full of noise. My room is about 24dB at average unless the laptop fan is running on high which brings the room to 26-28dB. This should be considered quiet enough for a good recording, but I just can't understand why there's always this hiss. I've read that electrical interference usually comes in the form of a hum, so I don't think the noise comes from that source.

I know I can use the Noise Removal effect included with Audacity but this distorts the recording quite a bit when it successfully removes all noise. Turning the effect down causes noise to remain whenever a key is struck and a tone is produced.

Can someone please enlighten me on how I can try to solve this dilemma?

[flynwill]

That noise is definitely electronic, not acoustic in origin. You say "line in" on your laptop, but I
assume you mean "Microphone In". The Phantom Power Injectors I found on Takstar's website
were all XLR in and XLR out (as I would expect), but those only provide power for the preamp
in the microphone, no additional amplification. So I presume you have some sort of XLR to
mini-phone cable?

Most likely the noise is from your laptop's microphone preamp, and the best solution is
going to be some sort of external Microphone preamp and USB audio A/D D/A converter
(many of which can provide phantom power for your microphone as well.)

There is a sticky post for sound card reviews in the "recording equipment" forum that
might be of help. There is also a current discussion started by a fellow looking
to replace his EMU 1616 -- the sort of thing you'd be looking for.

Finally do you realize that microphone is of the "side address" type meaning it is most sensitive
from each of the sides, not from the end? Would not be my first choice for recording
a piano, but can be made to work. I would not try to put anything to muffle
the sound between the piano and the mic. Better to open the top of the piano
and get the active side of the mic (on it's own mic stand) aimed at the opening
and a foot or two away. If you can get the program sound level up a bit you may find
the noise is now at an acceptable level.

[nfshp253]

Hi, there is both a line-in and a microphone port on my laptop. The cable I'm using to the microphone is the one that has three pins arranged in a triangular manner and the one to my computer is similar, just that on one end is the 3.5mm connector.

Is there a way to reduce the electronic noise without having to buy extra equipment since I'm not really that into professional recording, but rather I just want a fairly good recording with the equipment I currently have?

I did not know that about the microphone. I'll try to position it better. So what you are saying also means that if I lower the recording volume, I can reduce noise but I'll have to make sure the piano sounds louder?

[flynwill]

Yes the big connectors with three pins in a triangle are known as XLR connectors.
(There are also 4, 5, 6 & 7 pin versions of XLR connectors, they look the same just more pins).
They are pretty much the standard for professional audio connections.

If you are in fact using the "line in" connection on your laptop, that could well be the
problem. Microphone signals are about a factor of 100 weaker than what is normally
considered a "line level" signal. (Even though your condenser mic has a small preamp
built into it, that is only to boost the incredibly weak signal of the condenser element up to
the level of a typical dynamic mic, but still far weaker than "line level".) So if you
are using the line input you are probably having to turn the input gain way up which
makes the noise all the louder as well. So if that is what you are doing, try the
microphone input.

So what you are saying also means that if I lower the recording volume, I can
reduce noise but I'll have to make sure the piano sounds louder?

Correct. What matters is the ratio of the signal (in engineering parlance) to the noise.

Is there a way to reduce the electronic noise without having to buy extra equipment?

Probably not. Generally once the noise has been mixed with the music it is impossible to separate
it out again. As you discovered the "noise removal" effect has side effects.

If the problem is with the microphone inputs on your laptop (most likely) then you need to make
the signal stronger before it gets to your laptop (ie a small mixer or microphone preamp), or
to digitize the signal before it gets to the laptop (ie a USB audio interface). I recommend the
latter as it will be about the same cost and will take the laptop's questionable analog circuits
out of the equation entirely.

If the problem is the microphone itself, then the only fix is to make the piano louder
or get a different microphone.

[nfshp253]

Thanks for taking time to explain in such detail. I've tried using the microphone input as well and I'm getting much louder record volumes but the noise is still as bad. To make sure that it's the sound card giving me problems, I've tried using another microphone which is small enough to fit inside the piano through the top cover, and guess what, exactly the same amount of noise. Of course, this was just a small clip-on microphone which needed no power supply of its own but it's strange how the exact same noise level and type is heard in the recordings.

I've thought through some of your advice and figured why not try a USB mixer? Would you recommend the Behringer XENYX 302USB? That model seems extremely reasonable price-wise but I've no idea if it'll allow me to record with significantly less noise. And how would I go about setting up the recording peripherals? Would I still need my current phantom power supply and do I use the XLR to 3.5mm to plug into what looks like a microphone input on the mixer?

[kozikowski]

Whenever you buy something, Google "complaints."

In general I like Behringer products, but this one has one shortcoming that would prevent me from buying one.

Microphone Phantom Power

The label on this product makes you think you're getting true 48v power, and it takes, in my opinion, too much searching to find out that you're really not - it's actually something in the range of 11v to 15v. This seems almost like false advertising.

There is a "standard" version of Phantom Power designed around 12 volts rather than 48.

He's right. Most product lists announce in big letters "48 VOLT PHANTOM POWER." Not this one. This product list has Phantom Power as "Yes." This will not work with all microphones and worse, you can't turn it off, which can make recordings slightly more noisy than you want.

The 1202 has the real thing and I think this is the smallest one that will do this (attached).

I use a Peavey PV6 which has all the adjustments and switches and in the USB version, costs right about in the same ballpark (attach 2).

That's not an unalloyed recommendation, either. My mixer is the analog version. I didn't certify the USB version.

Koz

[kozikowski]

this was just a small clip-on microphone which needed no power supply of its own

Is it a "computer microphone?" Part numbers are good.
http://kozco.com/tech/audacity/pix/comp ... ophone.jpg
It takes no batteries and plugs right into the soundcard?

You can't plug one of them into a mixer. They do take power but they get it from the computer through special wiring. Some tie-tack microphones like the Radio Shack 3013 do have their own batteries and if you have the right adapters, will connect to a mixer or anything that will accept a microphone.

Koz

[kozikowski]

Wait. Are we still talking about the Takstar SM-8B? That's an XLR microphone and will plug into almost any larger mixer. If you use the larger Behringer or the Peavey, you won't need the extra phantom power supply. They both supply phantom power directly.

Koz

[flynwill]

I've tried using the microphone input as well and I'm getting much louder record volumes but the noise is still as bad.

By "as bad" I assume you relative the program. (ie after you've turned the input gain down to compensate for the higher level). Not terribly surprising. I would bet that the Mic input is just the other 1/2 of the same opamp chip setup for a higher gain.

Wait. Are we still talking about the Takstar SM-8B? That's an XLR microphone and will plug into almost any larger mixer. If you use the larger Behringer or the Peavey, you won't need the extra phantom power supply. They both supply phantom power directly.
Koz

He's saying he used the small clip-on mic to test the mic inputs and found the same noise level, implicating the laptop's sound card as the noise source, a reasonably good test.

You could also try recording with nothing connected to the mic input, or with the XLR to mini-phone cable plugged in but with the XLR disconnected. If you get the same noise at the same level then the laptop is the culprit. (Unfortunately the inverse is not true, if you get no noise or a lot more noise you have learned nothing).

Also the Behringer 1202 does not come in a "USB" version, that's just a straight mixer. The next up USB unit is the 1204, which is somewhat more expensive than the PV6-USB.

[nfshp253]

I've tried recording with that mini microphone off and yep, there's some noise caused by the onboard audio. I guess it's time to buy an external mixer. Regarding the 302USB and the phantom power supply issue, would using the current phantom power supply instead work? Like this setup: Computer-->USB-->302USB-->XLR to XLR-->Microphone out on Phantom Power Supply-->Microphone in on Phantom Power Supply-->XLR to XLR-->Takstar SM-8B? Or would it just be easier to get the Pevey as Koz recommended? Ultimately, what I need is something cheap that does the job.

Thanks again for taking so much time to answer my queries.