Microphone sensitivity and recording distance

A

Adrian Lopez

New member
I've recently purchased an MXL 990 condenser microphone along with a Behringer UB1002 mixer so I can record my violin playing onto my computer. When I received the package from Musician's Friend I noticed the shipping box had been exposed to water (it was wet and had developed a tear along the length of one of its top edges). The boxes inside were mostly okay, although perhaps a little humid in small areas. Having never used such equipment, I have no way to judge whether it's working properly.

With a level of 0 on the "mic in" and "main mix" faders, I find that I have to raise the gain on my UB1002 to around 50dB to get the signal level indicator to peak at 0 when playing my violin from a couple of feet apart (which is closer than I'd like). Should the microphone really require that much gain? The MXL 990 has a sensitivity of 15mV/Pa, and according to Harvey Gerst's post on microphone sensitivity a sensitivity rating of 10mV/Pa would require 40dB gain while a sensitivity of 20mV/Pa would require 34dB gain. It seems that I shouldn't have to set the gain to 50dB in order to obtain a reasonable recording level.

I am concerned that either the microphone or the mixer may be malfunctioning because of the damage to the shipping carton, but I can't be sure whether that is the case (the equipment itself didn't get wet, as far as I could tell). If the equipment is not malfunctioning it would seem the microphone isn't very good for use in distant miking applications. I've seen how orchestras suspend pencil mics from the ceiling, and I don't think the MXL 990 could function at such a distance (from ground-level, of course).

This brings me to the matter of microphone sensitivity and its relationship to recording distance. I've been considering an MXL 603s as an alternative to the MXL 990, but I noticed its sensitivity is 15mV/Pa, just like the MXL 990. I am concerned that if I purchase this microphone I'll experience similar problems with gain and distance.

Is it possible for two microphones with identical sensitivity ratings to behave differently in terms of possible recording distances? Would the MXL 603s be more appropriate for distant miking than the MXL 990?

Aside from my awful playing I don't really like the sound of the MXL 990 on my violin and some people recommend the MXL 603s for such an application. If I'm going to spend $280 dollars on a stereo pair, however, I'd like to know whether it's able to perform at reasonable gain levels in distant miking applications.

I would appreciate any input on how to judge whether my equipment is working properly and whether the MXL 603s is better for distant miking than the MXL 990.
 
A violin is not a loud source compared to many other sources. Two feet of distance makes a difference too.

I record solo fingerstyle guitar. When recording at two feet or so, I'm typically running 48-51 dB of gain when recording. That's using Schoeps mics and a Pendulum Audio tube pre, some of the finest gear on the planet. I wouldn't worry about needing to use 50 dB of gain in your situation.
 
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Adrian Lopez said:
With a level of 0 on the "mic in" and "main mix" faders, I find that I have to raise the gain on my UB1002 to around 50dB to get the signal level indicator to peak at 0 when playing my violin from a couple of feet apart (which is closer than I'd like). Should the microphone really require that much gain? The MXL 990 has a sensitivity of 15mV/Pa, and according to Harvey Gerst's post on microphone sensitivity a sensitivity rating of 10mV/Pa would require 40dB gain while a sensitivity of 20mV/Pa would require 34dB gain. It seems that I shouldn't have to set the gain to 50dB in order to obtain a reasonable recording level.
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Those gain figures are with a 94dB source at the mic. A violin can easily be 94dB or more, but you are not right up against the mic, so 50dB of gain isn't unreasonable. How loudly do you play?

If you don't like the sound of the violin at two feet, move back to three or four feet. At four feet, you will only need another 6dB of gain.

Anyway, you won't find mics much hotter than those that are suited for your application.
 
If you check out the 2fiddles.com page on microphone examples you'll notice one of the samples was recorded with a stereo pair of MXL 603s mics. According to the author, "Sample 2 (95k) is a string trio (two violins and a cello), using the Marshal MXL 603s, as a stereo pair, angled out from each other at 110 degrees, near the ceiling, across the room. The microphones are plugged into a Behringer mixer; the recording was done directly on the computer. The piece is March in C by Scarlatti. This recording was made in our living room."

The sound levels on that distant recording are close to what I'm getting on the MXL 990 just a couple of feet away from the microphone. I don't know about the levels used to produce that recording, but the distance between the microphone and the source is significant, similar to orchestral recording setups. I'm not sure the microphone I purchased could produce the same results, but perhaps I'm wrong.

Do different microphones with identical sensitivity produce the same recording levels as the distance from the source is increased?
 
mshilarious said:
Those gain figures are with a 94dB source at the mic. A violin can easily be 94dB or more, but you are not right up against the mic, so 50dB of gain isn't unreasonable. How loudly do you play.
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I wish I had a dB meter. While testing the microphone I was playing just a little louder than I would normally play.

I guess I shouldn't be too concerned about the 50dB gain, but I am concerned about the recording levels as the distance increases.
 
Adrian Lopez said:
Do different microphones with identical sensitivity produce the same recording levels as the distance from the source is increased?
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With both mics at the same distance? Yes, both will lose 6dB when distance is doubled.

If you are unhappy with your setup, I'm guessing it's because you don't like the performance of your mixer with the gain at 50dB. Consider using an outboard preamp; there are units that produce 66 or 70dB of gain with good sound quality.
 
I suspect that you should be worried more about signal to noise ratio, than sensitivity.
You can always crank a weak signal up....but it raises the noise at the same time.
 
At like 4 feet, I've sometimes cranked the trim on my pre's (built inones on a tascam us-428) almost all the way with loudly played acoustic guitar, so I wouldn't worry about it.

The sound levels on that recording aren't necessarily the ones they got coming into the mixer... coulda turned up the gain all sorts of places, or even compressed the heck out of it (I haven't listened or checked out the site, so maybe they say something important about it, I dunno, just doing a quick post before I finally make myself go to bed so I can get up, learn how to do line and surface integrals a lot better, and pass a test on it! =D YAY!
 
mattamatta said:
At like 4 feet, I've sometimes cranked the trim on my pre's (built inones on a tascam us-428) almost all the way with loudly played acoustic guitar, so I wouldn't worry about it.

The sound levels on that recording aren't necessarily the ones they got coming into the mixer... coulda turned up the gain all sorts of places, or even compressed the heck out of it (I haven't listened or checked out the site, so maybe they say something important about it, I dunno, just doing a quick post before I finally make myself go to bed so I can get up, learn how to do line and surface integrals a lot better, and pass a test on it! =D YAY!
Click to expand...

Surface integrals - thats the devils mathematics!
 
Adrian,

I own both the MXL 990 and a 603s pair, and have used them through Mackie, Presonus Bluetube, and Great River pre's. The mic's have been almost identical in sound in my use on classical guitar, in fact there's more difference between my two 603s's than between them and the 990.

Both types of mic's have had a pretty hot signal going into the pre. My Great River pre is the only one with a dB scale marked incrementally and on it I don't think I've ever used more than 45 dB of gain with these mic's with distances of 2 to 15 ft from source. And your instrument is generally a little louder than mine.

So unless the mic has been facing backwards it may be that the mic, or the mating between mic and pre, are getting a bit lower output than ideal, but you're not really far off. More importantly though, the sonority characteristics of the mic might not be what you'll be happy with for violin. Unless you get a very dark tone or are using a large room w/high ceiling, they can be a bit bright and edgy on the high end. For an inexpensive mic that handles the high end a little more smoothly, and that might mate well with a preamp like the Behringer, you might try an MXL V67.

Or give your violin a thrill and rent a really good mic and preamp for a weekend just for fun.

Best of luck.

Tim
 
Adrian,

I just read your original post more thoroughly and have another comment. Regarding levels, it's not necessary to get your mixer output levels to peak at 0 on the meter. In fact some mixers, like the Mackie 1202 sound best when you keep the level much lower at the mixer output. What does matter is that the wave or aiff file, when you play it back, has a clear take of your instrument with low enough noise floor (hiss, etc.) that you don't notice it. It's OK to boost the playback or processing gain a lot in whatever software you're using as long as the noise floor stays unnoticeable. If the noise floor is too high, then you need to tweak your levels a bit at the preamp trim, channel fader, and/or mixer output faders. Does your soundcard in the computer have a software mixer that sets input levels? If so, check that too. The 990's a pretty quiet mic though, so noise floor problems aren't likely from there.

tim
 
Timothy Lawler said:
My Great River pre is the only one with a dB scale marked incrementally and on it I don't think I've ever used more than 45 dB of gain with these mic's with distances of 2 to 15 ft from source.
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This leads me to beleive that perhaps I'm not reading the gain levels correctly. The gain dial on my Behringer mixer ranges between 10dB through 60dB and is divided into equally spaced segments. So far I've assumed that each segment represents a 5dB increment, but now it occurs to me that perhaps the dial is nonlinear (is it?). If that's the case then the levels I've quoted are inaccurate.

Regarding your second post, having the levels reach 0 on the meter is what Behringer recommends for setting the gain, but I suppose that's more appropriate for close-miking situations than for distant miking. Perhaps I'm making a big issue out of nothing.

Regarding the character of the sound, I've assumed the 603s may be more appropriate for violin than the 990 because its response is much flatter around the lowest frequencies and slightly flatter around the higher freequencies. Then again, I think much of my dissatisfaction with the 990 has to do with the quality of my playing, so I think I'll give it another chance.

By the way... thank you all for your feedback.
 
The 990 is not the first mic that would come to mind for recording violin like that. I just think it's not sensitive enough.
 
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