AT4053b mic, Sound Devices MM1 and Tascam DR-40 combo audio question

I

IndiePaul

Hi

Was testing our new sound gear for the first time today.

  • Boomed Audio-Technica AT4053b Hypercardioid Condenser Microphone
  • Sound Devices MM1 pre
  • Tascam DR-40
Most of our feature (our first) will be shoot inside (in our apartment).

The issue is that the Tascam input level tells me the average is -30db but I'm trying to get it to -20db (average) with a peak at -12db - as I have read that's a good indie audio level goal.

But with headphones plugged into the Tascam the signal sounds okay at -30db but noisy at -20db.

I set the pre-amp gain on the MM1 to 45db. At higher dbs I get noise and clipping.

Note the AT4053b mic has a -10db pad but I have that switched off. The AT4053b is being boomed to within 3 feet of the talent.

If I increase the Input Level of the Tascam, I can get closer to -20db but the Tascam (through my headphones) sounds increasingly noisy. I presume it's much better to use the gain available on the MM1 as opposed to the Tascam since the pre on the MM1 is so much better than the pre on the Tascam.

I read the whole Tascam manual and have carefully set it up following that read. As far as I am aware it is set-up correctly.

I have the Limiter on the MM1 set off.

The Tascam input switch is set to Line Input. Tascam has phantom power OFF.

MM-1 has phantom power ON and is supplying the correct 48v to the AT4053b mic.

Cabling is all XLR.

Am I doing something seriously wrong? Is my -20db (average) with a peak at -12db goal ill advised? Any suggestions would be hugely appreciated.

This is my first time using film audio gear - but I have read dozens of audio posts here on IT and elsewhere (Roland Comfort etc).
 
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Keep trying different level combinations.

Start with the headphones plugged into the MM-1. Get the levels close to clipping the MM-1 and back it off a bit. Then plug the headphones into the DR-40 and slowly bring up the volume on the DR-40 to the desired levels. After that make minor adjustments until you are happy.

Gain-staging is a real PITA until you've got some serious experience under your belt. Take your time and keep experimenting; you'll get there.
 
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As Alcove said! Ideally you want the input level on your Tascam to be as low as possible, as it's mic pre-amps are considerably inferior to the MM1's pre-amps, but you don't want to peak your MM1 much above about -10dB or so.

IndiePaul said:
But with headphones plugged into the Tascam the signal sounds okay at -30db but noisy at -20db.
Click to expand...

This is largely irrelevant. If you record both the -30dB average signal and the -20dB average signal and then in your NLE/DAW reduce the -20dB signal by 10dB, is it still noisier than the -30dB signal? you can do it the other way around of course and raise the -30dB recording by 10dB in your NLE/DAW and compare the noise levels. This is the real test of which setting is less noisy but be careful with this test, obviously your two different recordings are not going to be identical (in addition to the 10dB pre-amp difference) so your results are not going to be accurate. Just try to get the 2 different recordings as identical as possible (excluding the 10db pre-amp difference) and be aware they are not identical when comparing the results.

G
 
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Just an update in case anyone does a Search.

After some additional testing I found out that even in a silent room, I could not increase the gain of my MM1 past 45db. Basically the MM1's red light would come on and there would be constant clipping.

As an audio newbie I did not know what was going wrong... But after some internet searching and talking to Sound Devices support...

Turns out the reason was due to a problem with the MM1 and compatibility issues with my AT4053b mic.

Sound Devices are aware of the issue:

Oscillation with Transformer-Balanced Inputs
Condition
Depending on several conditions, chiefly the microphone, the transformer-balanced inputs, such as those on the 302, 442, MixPre, MM-1, MP-1, and MP2, can get into an oscillating condition with a microphone that renders the audio unusable. This oscillation is often described as a “motorboating” condition since this low frequency oscillation sounds like a motor boat.
Click to expand...
For details see:
http://www.sounddevices.com/notes/mixers/oscillation-xfmr-inputs/

They have a fix which was to engage the MM1's high-pass filter. That cured the problem for me.

Sound Devices list the microphones know to exhibit this problem as:
  • AKG Blue Line Series
  • AT 4073
  • Sanken CUB-01, CS-1
They should add the AT 4053b to the list. They said they would - just sent them a chaser.
 
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