Ran into trouble today - Tube Condenser Mic on vocals

Erkan

Erkan

mr-walker.bandcamp
Jun 16, 2008
3,305
5
38
Uppsala, Sweden
mr-walker.bandcamp.com
I was trying out "Guy 1" again on vocals today (see this thread if you want to know what I'm talking about) and I ran into some serious technical issues.

I recently bought a Golden Age TC1 Tube Condenser microphone. As the name implies, there is a tube in the mic. The problem is that I'm too "modern" and too little experienced with old vintage analog gear so I don't really know what a tube mic behaves like. Anyway, it didn't take more than a couple of vocal takes for me to cringe. It sounded like there was some serious distortion going on and when I solo'd the vocal track I was shocked.

This is what I heard and saw:

http://dl.dropbox.com/u/585020/TC1 Issue/Scream.wav

Waveform picture: http://dl.dropbox.com/u/585020/TC1 Issue/TC1 Issue.JPG

I drew lines on the top and bottom of the picture so you can see the amount of dynamics on the positive and negative side of the wave. The negative side is totally squashed and clipped. I checked the cables, I tried the -10db padding and the high pass switches on the mic but it didn't help. I didn't have this problem with "Guy 2" because his voice level was much lower than "Guy 1". In other words, "Guy 1"'s SPL (Sound Pressure Level) seems to be too much to handle for the mic even though it says it handles up to 140db?

So to sum up my questions; Is this what a tube mic behaves like or is my mic broken? Is it possible that the singer is simply too loud?
 
Did you use phantom power on the mic?
I had such a waveshape once, when the batteries of my active bass were nearly empty... That was a power issue too, so maybe it has something to do with the phantom power?
 
Forceps said:
Did you use phantom power on the mic?
I had such a waveshape once, when the batteries of my active bass were nearly empty... That was a power issue too, so maybe it has something to do with the phantom power?
Click to expand...

Well, the mic has its own power supply which supplies it with the power it's supposed to have. No need for me to feed phantom power from my Profire 2626. There are no advanced controls on the power supply other than an On/Off switch and the pickup pattern selector and the Voltage selector. The voltage is set on 230V which is what I need to use since I'm in Europe.
 
what preamp are you using? because I've had that problem before as well and I found that it's the way my preamp was set. I can't say this for all preamps, only some lower-end ART and Behringer tube pre's, but if you have more mic GAIN, and less OUTPUT that awkward waveform goes away and the distortion turns into more of a saturated tone. i think that could be the problem. I hope this helps :)
 
I'm not running anything other than my Profire 2626. I had the mic plugged into one of the channels and there's really nothing special about it as far as gain goes. I have the gain set low enough for his screams not to peak so it's definately not the Profire 2626 distorting. It seems to be the mic itself because the distortion only happens after a certain "pressure" from his voice.

Keep the ideas coming guys, it helps nonetheless. I'm gonna go to the music store tomorrow and talk with those guys about it too.
 
ahjteam said:
did you use a popfilter?
Click to expand...

Yup! The popfilter does its job wonderfully, but the distortion still remains. I'm pretty sure it's happening inside the mic but I can't figure out what I can do about it. Which leads me to next reply...

PhilR said:
DC Offset, probably something to do with the way the tube circuit applies gain.

Most DAW's will have some way of correcting it. A hi-pass filter at 20hz can alleviate it to a degree also.

More info: http://www.harmony-central.com/articles/tips/eq_dc_offset/
Click to expand...

It doesn't look like a standard DC-offset to me. The negative side of the waveform is totally clipped, can a DC-offset do this? Seems like something is fucked up with the mic. At first I thought it was due to the vintage sound the tube is supposed to give me but then I realized a nice tube distortion surely does not look like this in the waveform? IF it is tube saturation, shouldn't it be clipping more or less equally on both sides?

About the high pass, the signal is already high passed at 100 hz but I can't remember if that's the one I rendered out. In any case, it does not help because the distortion is already recorded when it hits my DAW. No processing in the world can get rid of the clipped valleys of the waveform (or well, maybe there is SOME way to restore them but I don't think that is something one should rely on!). So if the distortion is already recorded when it hits my DAW, and if the Profire 2626 does not indicate clipping, then that means the distortion is happening waaaay before I can even do anything about it in the DAW. It's got to be happening inside the mic :(

Question still remains; are tube mics supposed to behave like this or do they apply a much more gentle saturation? This saturation is certainly not gentle :|
 
The manual says at least 15 minutes, but I've read on the net that some people prefer to have them on for an hour before recording starts so it's no bullshit I guess. But yeah, I had it warming up for about 20 minutes and the distortion certainly did not get better after an additional 20 minutes so I don't think it has much to do with the warming up.

Good question about the tube being OK or not. How do I know that? :) I'm a total newbie at tube gear but there is no hissing or humming going on and everything that has a lower sound pressure than Guy 1's screams sound great. The distortion only happens when you get up to a certain sound pressure and I find that very strange. Man, I'm starting to regret this so much now... I hope I get any wiser tomorrow after speaking to the local music shop.
 
Yeah, can't imagine anything else being the problem. God damn, everything I buy turns out to be shit. Guess I'll just have to "pray" for receiving help at the store tomorrow then. If they let me return it I'll do it in a heartbeat :) The damn thing was on a midnight sale so I had no chance to try it out because if I hadn't bought it, someone else would've shortly after.

I guess I should look at it from the bright side - at least I learned something I'm not going to do again in the future. Buying something you don't have a clue about that is.

Judging from the replies in this thread it does seem to be the mic that is broken since nobody has been able to give a straight answer as to why it sounds/behaves/looks (waveform) the way it does. Had it been a really common problem someone would've chimed in with info about it.

Anyway, thanks a bunch so far guys!
 
Sounds like the mic needs to be looked at, could be the diaphragm but how old is the tube?
 
Actually, that's something I did not think of! The mic is "new" but only God/FSM/Ziltoid the Omniscient knows how long it's been lying around in the shop. It could very well be that the mic and its tube is a year old, I have no clue. Good thing you brought that up, that's something I'll have to ask them tomorrow.

So, can tubes "get old" and cause this type of behaviour just by lying around unused?
 
The first thing I'd check would be the tube, definitely. It could be a bias error in the mic's circuit too, but that would be very strange.
 
Sounds the valve is not clipped in right. Generally if the cap was damaged you would get weird muddy s**t and drop outs from my experience of breaking LDCs...

It isn't going to be this but worth a go if you're all out of ideas. My mate ordered a Red5 and it was playing up on arrival so he called them and they said the mic could of got overly damp/cold during shipping so keep it in the airing cupboard overnight to dry out any moisture on the cap. Needless to say the mic was broken and they replaced it. This really is scrapping the bottom of the barrel ....
 
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