Do I Have a Faulty Mic?

[brandont_h]

If it's not too much to ask, could I get some opinions on two audio files? I recently purchased both an MXL v67g mic and (about two or three weeks later) an MXL 2003. The first time I used the 2003, I was recording an electric at a moderate volume, so I didn't have to jack the preamp. The first time I tried it on acoustic, however. . .. Eeeew, what was that noise? I took the mic in to the shop I bought it from, and after an hour of testing and A/B comparisons with another mic, I agreed with the owner that it sounded the same. The next two times I tried the mic, though, it was SO noisy!

The noise seems to go away after 20 minutes or so, but I don't want to have to wait 20 or 30 minutes to use a mic. I have here two sound samples. I know this isn't too scientific, but. . .

Sample 1: http://www.projectionrecords.com/mxlv67gfullpreampgain.wav

MXL V67g mic through the left Mic/Guitar input on a MOTU 828mkII with the preamp at full gain.

Sample 2: http://www.projectionrecords.com/mxl2003fullpreampgain.wav

MXL 2003 mic through the left Mic/Guitar input on a MOTU 828mkII with the preamp at full gain.

Both wavs are 24/48.

Am I crazy, or is the 2003 ridiculously noisy? I know it's an "apples and oranges" test, but if the 2003 is behaving normally and is this noisy, I'd like a refund, because when it's noisy like this, I have to turn the gain on the preamp down to about 12:00 to get a clean sound, which means that the instrument itself peaks around -25 or -20 instead of -12 or -10, which I'd prefer.

Thanks for any input you guys can offer.

 

[scrubs]

That sound can occur if you have moisture on the capsule. Try this: Place the mic in a small sealed zip-top plastic bag with a few moisture desiccant packets in there. Leave it for at least a day. Then, retest. If the noise is gone, moisture was your problem. If not, send it back.

When using the mic, always use a pop filter (both to prevent pops and to keep moisture from your mouth from collecting on the capsule). Also, keep a desiccant packet in the bag where you store the mic when not in use.

 

[andyhix]

Dumb questions, but where you get those dessicant packets?

 

[scrubs]

Dumb questions, but where you get those dessicant packets?

I get them from shoe boxes, mic boxes, and many other mail-order shipments -- you probably have some around your house. Google "silica desiccant" and you should find some places to buy them -- though I've never had to do that. Periodically, you do need to dry them out, because they get saturated with moisture. Just put them on a cookie sheet in the oven at about 225 (F) for 15-30 minutes.

 

[PhilGood]

Oh, that noise!

That can be a bit of a mystery. I have found that can be caused by anything from moisture on the capsule (as mentioned), a bad capacitor, bad solder joint, or bad FET.

Its a roulette spin. Good luck.

 

[brandont_h]

Hi Guys,

Thanks for all your responses. I always store the mic in it's zippered pouch with the original package of dessicant. The guy at the mic shop had said he had a problem similar to the one I was describing (but couldn't replicate in his shop) with a Rode NT2 mic. He said just leaving it for a day was enough to let it dry out, but that clearly hasn't been the case with this one as it's been ongoing for over a week now. Furthermore, the fact that the noise decreases and eventually goes away makes me wonder if the moisture could really evaporate that quickly. . .

Anyway thanks for your help. I should also mention that I would have already demanded a replacement except for one small thing. . . I live in Korea, don't speak much Korean, and almost never get receipts when I purchase something at a market here. That means I kinda have to work on the shop owner's timetable as far as replacing, repairing or returning.

Thanks again!

 

[brandont_h]

Update. . .

So here's a quick update for anyone paying attention.

Today after work, I went back to the shop where I bought the mic. I played teh two above samples for the guy, and he was puzzled for a second. (They sell lots of active monitors there. . . a range of Fostex and KRK were plugged in through a Behringer device, but I'm unsure which of the speakers were playing back).

He understands a reasonable amount of English, and when he saw the filename (containing the words fullpreampgain) he said that the problem was that the 2003 has its own character and that the noise I was hearing must be from the preamp. I gently argued against him, saying that I understand that a cranked preamp will generate noise, but that the v67g generated much less noise, and certainly nothing close to the clipping that was created by cranking the 2003 (a 30db difference, in fact). He says that it's normal, but invited me to bring the mic in tomorrow for further testing, and said that he'd be willing to exchange the mic if there's a problem. Keep your fingers crossed for me!

 

[Melsi]

those samples sound like your in a very noisy room, may just be your pre amp settings, try and make the room as quiet as possible and use an expander or a gate, which will block out all other noises part from your voice when you speak, keep your gain down but the main output up.

Good Luck

 

[scrubs]

I always store the mic in it's zippered pouch with the original package of dessicant. The guy at the mic shop had said he had a problem similar to the one I was describing (but couldn't replicate in his shop) with a Rode NT2 mic. He said just leaving it for a day was enough to let it dry out, but that clearly hasn't been the case with this one as it's been ongoing for over a week now. Furthermore, the fact that the noise decreases and eventually goes away makes me wonder if the moisture could really evaporate that quickly. . .

I've never been to Korea, but I suspect it is a humid climate. If so, your desiccant packet could already be saturated with moisture. Like I said above, you may need to dry it out in an oven. Anyway, if the guy is willing to exchange it, just do that.

 

[PinkNoise]

Resistors, also!

" . . can be caused by anything from moisture on the capsule (as mentioned), a bad capacitor, bad solder joint, or bad FET."

Don't rule out resistors! I encountered a noisy amplifier once and located the noisy resistor and replaced it. That fixed the problem - - for a while, then it would recurr, elsewhere in the amp. After doing this painstaking location of the fault several times (I'm a slow learner!) I decided to replace ALL the resistors. Must have been a dud brand! That really did fix it "forever", or, rather, until the burglars took it!

 

[SRR]

I have never tried it myself but putting the mic 4-7 inchs over a 40-60 watt light bulb for 4-8 hours is supposed to dry it out as well. Certainly doesn't sound good from the sample provided.

 

[ausrock]

Actually, the light bulb method is probably much safer than baking in an oven, also, it is not necessary to have the mic "over" the bulb, it just needs to be in closish proximity to the warmth.

 

[SRR]

They were talking about baking the silca packs in the oven not the mic

 

[brandont_h]

Thanks for all the advice, guys. Here's what happened.

I went into the shop, and we hooked up my mic and a new one from his shelf. We tried all sorts of different gain levels, but repeatedly mine recorded much higher noise. He told me that I was lucky to have such a "sensitive" mic. I said no, I didn't think that was the case, because recording quiet music requires a quiet mic etc, etc, etc. We got a third mic, which proved to be slightly louder than the first reference mic, thus "proving" his point that not all mics are of equal sensativity, and that clearly mine was just at the top end of what MXL's Q/C would allow. I maintained that I needed a quiet mic, so after about two hours of testing and beating around the bush, he gave me the quiet mic and took the loud one back.

Here's where the story gets even funnier. He complained to me about exchanging the mic saying that he had no way to send it back to the distributor, and that he'd have to sell it cheap because it was used.

When I got home, I realized that the mic he gave me didn't have the part that screws on to connect to a stand. I went back to the shop, and told him this. What did he do? Went to the shelf, opened up two boxes, found the one that had the part on it (my old, loud mic) and gave it back to me. I'm not exactly surprised by this, but I thought it was funny that he gave me such a song and dance about not being able to resell it for full price, and then pulled it off the shelf to give me my piece back.

Ahhh, Korea.

 

[ausrock]

They were talking about baking the silca packs in the oven not the mic

Silica.................phew, thank gawd for that. Just shows what can happen when you speed read the posts

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