Sound effects library: I

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These are some effects I have recorded in recent projects. Feel free to download and use any sound in your own projects. They all are under a Creative Commons license.

Mug Crashing to the Ground:

I tried to avoid pre-amp saturation (I put the gain at 40%) but it wasn’t low enough. It’s still a good sound.

Low Woody Sound:

One of those rare sounds you record by accident. It was recorded a few seconds before the “action” while I was trying to boom the talent.

Boiling Water:

Pitch shifting is fun with this.

Crawling rock:

Interesting sound performed by a sidewalk piece and the ground.

 

Test: Pre-amp gain levels

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Spanish Version

With this test I want to try to solve a doubt that I sometimes have when I record.

It’s pretty obvious that when you turn up the gain you are also turning up the noise. But in the other hand you also pick more useful signal. So, the question is:

 Does the Signal/Noise ratio keeps constant as you rise the gain?

When you record you always tries to avoid signal peaks which could saturate the pre-amp. Then, should you force the pre-amp in order to get some dB’s more? Or it’s better to get those dB in post-production? 

Instead of making theoretical analysis I would try to dispel my doubts with some tests.

Crank up the volumen!

Test 1: Room Tone

I’ve used the Tascam HD-P2 with the Sennheiser MKH 416 recording with differents gains and the matching levels with Pro-Tools.

To my surprise the biggest difference is in the lowest gain take (the first). The sound has a clear 12 Khz tone that can be also heard (barely) in the second take and it’s indistinguishable in the other takes. Also, the highs are overemphasized and the birds, wich we can clearly hear in the other takes, sound distant, specially in the 3-5 KHz range.

In the other takes, as you rise the gain you get some clarity in the bird sound and I don’t appreciate that you lose any sound quality, although maybe is hard to tell since it’s just ambient noise.

In the Izotope RX’s analysis we can clearly see the 12 Khz tone plus two other high bands above. We can also see that the 7-15 Khz range is overemphasized compared to the other takes. Also there is a clear high emphasis in the take’s borders (fades) Why all these appears? Is Pro-Tools producing it when we rise the signal? I have turned up the takes using the Pro-Tools’ native equalizer. I have also made the same operation with other plugins with the same result.  Just to make sure I had made it with the Pro-Tools’ offline AudioSuite too. Same results. Thinking that maybe is a Pro-Tools thing I’ve tried the same in Logic. Exactly the same.

It seems like rising the signal digitally introduces errors in it or maybe this errors are due to record with low gains. However it looks like it’s cleaner to earn those dB’s with the pre-amp gain.

You can also see in the second take a clear DC Offset (or so i think). It appears anyway I turn up the signal so it seems that it is in the original take. An A/D converter fail? Studying the complete take I realized that in that exact moment I was still rising the gain which can explain that converter behavior. To the ear it’s barely noticeable. In the RX’s analysis you can see a low end increment while in the soundcloud’s waveform you can see a clear level amplification.

Test 2: Signal

For this test I’ve record a Youtube dialogue (quite noisy) played in the monitors and captured with the same recorder and mic. 

We hear again something similar to the previous test. In the 3 Gain take the highs are again emphasized and we can hear the 12 Khz tone. 

We can also hear a 7 Khz periodic tone with its armonics. You can hear it as well in the first test. It’s very strange. I don’t think is an ambient noise (like a bird) as its periodicity is very exact (2,4 s) and we can’t hear it in the other takes which were made immediately after. I don’t find any explanation to this sound. We can see it in the RX’s analysis. 

For the rest, aside from the little ambient noises that change in every take, the 3 other takes are quite similar. I don’t hear any sound deterioration as you rise the gain.

So it’s seems to me that the best option is to record at high gains (being careful not to saturate). The tests tell us that the signal/noise ratio keeps constant as you rise the gain.

I have recorded these test at 16 bits and 48 KHz trying to keep the same sound quality that I usually use in the set. Given that I have recorded at 16 bits and low gain and I haven’t used many of the disponible bits this could traduce in converter errors. It’s the best theory I can find now. I will try to confirm this with futures tests at high resolution.

In the other hand I don’t find any explanation to that periodic noise at 7 KHz neither to the 12 Khz tone. Maybe inherent recorder noise? I leave this questions here in case someone could answer them.