Distortion - AAAARRRGGHHHH!!!!

Y

Yonatan

New member
Greetings to all,

I have a home studio I am using Pro Tools 6.4 with a Digi 002, I am using 4 Shure KMS-27 Microphones and I am constantly running across issues with Distortion. My input levels are around 5 and the microphones are set to the sraight line switch on the back. (there are 3 settings and this is the only one that does not drop the decibles to the point it sounds like we are singing into a pillow).
I am recording 4 part singing with all male voices. In several cases individual tracks have no distortion, but the piece as a whole sounds like there is distortion.

thanks for your time,

Yonatan
 
This sounds like you simply are clipping the master when all the tracks are playing at once. Tried turning it down?
 
Forgive my ignorance but I am not familliar with the term "clipping the master"
as far as volume goes, when all parts are involved - there is the sound of distortion even at quieter lavels
 
What DbFS rating are the individual tracks recorded at? What is the DbFS of the master buss playing back the 4 tracks?

In a typical digital audio chain distortion can appear in any of the following links:

1.) Overloaded or broken microphone diaphragm.
2.) Bad cable.
3.) Input gain too hot for the preamp.
4.) Gain set too high on the preamp.
5.) Exceeding 0 DbFS on the AD converter.
6.) Improper setting of a plugin input/output or settings.
7.) Exceeding 0 DbFS on individual track playback.
8.) Exceeding 0 DbFS on the master buss by the sum of the tracks.

Keep in mind that subtle amounts of distortion can be present in *all* of the signals that is difficult to detect (depending on listener skill and quality of monitors) that doesn't become apparent until you listen to multiple tracks (where the distortion is added up) with the distortion present. The concept of noise is similar--a single track with a little noise may not be very apparent but when you have 24 tracks with a little noise it all adds up to be a ton of noise....
 
Yonatan said:
there are 3 settings and this is the only one that does not drop the decibles to the point it sounds like we are singing into a pillow
Click to expand...
This is just wrong. (Not your observation, just the effect you're describing.) There is something wrong with the way the mics are connected to the preamps, or maybe a mismatch between the mics and the preamps, or ...

You don't by any chance have the mics pointed in the wrong direction, do you? The side with the "SHURE" name on it should face the performer.

I doubt very much you're overloading PT's mix bus. If I recall correctly it's a 56-bit bus, and should be very difficult to drive to clipping.

Gain staging is something you should learn about if you haven't already.

Make sure a full 48 volts of phantom power is getting to the microphone. You can measure it with a voltmeter. Pins 2 and 3 should both read +48V with respect to pin 1 at the mic connector. The docs for the KSM27 say it works as low as 11VDC, but with decreased headroom and sensitivity.

Also, be sure to follow the 3-to-1 rule of thumb. The mics should be spaced at least 3 times as far from each other as they are from the sound source they're intended to pick up. If you're distant miking four voices in a small room, you may be hearing interactions between the microphones. If you can, try recording the group with just 2 mics, in a close X-Y configuration. You may be more pleased with the results you get that way.

That's all I can think of for now.

Don
 
Don,
Thanks for all of your advice, I have indeed (once or twice) had the microphone pointing the wrong way, but we have caught it each time and we have taken measures for it not to happen again :D. It is interesting you should mention the room. That is part of my suspicion (the room is smallish with a low ceiling). The 4 of us are about 4 feet away from each other and facing towards one another (think of it like an X with each of us at a point facing inward). I will check the voltage and using 2 voices at a time instead of all 4. I am also going to try a little better sound proofing on the room I am using.

Cloneboy,
Thank you for your posting as well. I will check this weekend for the things you mentioned. Forgive my ignorance (I have been working in a home studio for almost 15 years but never in a professional studio so there are HUGE gaps in my knowledge) but, how do I check the following things you asked?
- What DbFS rating are the individual tracks recorded at?
- What is the DbFS of the master buss playing back the 4 tracks?
I am positive I should know how to check these things (and may already be doing so) But I am unfamiliar with how. Also what you were saying about noise makes sense and is something that had not occurred to me.

I am very pleased with the feedback I have received so far, this is a very cool forum.

Yonatan
 
Yonatan said:
how do I check the following things you asked?
- What DbFS rating are the individual tracks recorded at?
- What is the DbFS of the master buss playing back the 4 tracks?
Click to expand...

Look at the meters, wherever they may be. Judging by your system they are going to be in software and thus on your computer monitor.
 
Yonatan said:
The 4 of us are about 4 feet away from each other and facing towards one another (think of it like an X with each of us at a point facing inward).
Click to expand...
Three questions: (1) How far are the mics from the performers' mouths? (2) How far are the mics from each other? (3) Is the room treated at all?

If the answer to question 1 is, say, 1 foot, you might try moving the mics closer to the performers. With the mics closer, you may need to use pop screens in front of the mics, depending on the ability of the singers to control plosives (mainly the "P" sound). Close miking reduces the influence of the room on the recorded sound.

If the answer to question 2 is not at least 3 times the answer to question 1, you're breaking the 3-to-1 rule I mentioned above. At any rate, in a small, untreated room, even 3-to-1 may be insufficient.

One thing that would be helpful is if you could get a small sample (maybe 20 - 30 seconds) of the distortion that you're hearing into a high-bitrate .mp3 file, and put it somewhere where we can download it and listen. If you don't want the world to hear it yet, PM me with the link.

Don
 
probably not related, but i spent a bunch of remix time trying to eq out some trebly-vocal spikes, clips whatever you call it..in a word=distortion....
turned out it was my compressor settings.
 
Hi Don,

Andwes to the three questions:
(1) How far are the mics from the performers' mouths? - I have tried from as little as a foot to as much as 3

(2) How far are the mics from each other? 4-5 feet

(3) Is the room treated at all? not as much as I think it should be - the ceiling has no accoustical foam - it provides a lovely flat surface - which might be part of the issue
 
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