Hi Everyone

I don't have a very good ear for audio yet and after doing some experiments with my microphones I can't decide which of my microphone combinations sounds the best. I will be recording audio for an amateur film and want to try and work out which microphone sounds better, in general, for the recording of dialogue. Can anyone offer an insight into which one sounds better regarding the inherent noise, clarity of speech and so on?

If you listen to the attached WAV file you will hear the tests in the following order:

1. MC-012 with omnidirectional capsule, "Mary had a little lamb..."
2. MC-012 with cardioid capsule, "Mary had a little lamb..."
3. At815b shotgun, "Mary had a little lamb..."
4. MC-012 with hypercardioid capsule, "Mary had a little lamb..."
5. MC-012 with hypercardioid capsule and -10dB pad, "Mary had a little lamb..."
6. MC-012 with omnidirectional capsule, "The rain in Spain..."
7. MC-012 with cardioid capsule, "The rain in Spain..."
8. At815b shotgun, "The rain in Spain..."
9. MC-012 with hypercardioid capsule, "The rain in Spain..."
10. MC-012 with hypercardioid capsule and -10dB pad, "The rain in Spain..."

The main thing I noticed is that the omni capsule on the Oktava has too much echo in the small room I recorded in, though this might prove useful in some instances. After a while I find it hard to tell the different clips apart so any help is much appreciated :)

Recording Conditions:
Recorded using a modded Oktava MC-012 and an Audiotechnika At815b plugged into a Sound Devices Mix-Pre audio mixer which was in turn connected to a Canon XH A1 camcorder as recording device. Audio recording was done in HDV mode. Distance from mic tip to subject was 20 inches and the mics had foam windshields on them. The Mix-Pre had its gain setting at maximum, this gave audio peaks of about 4dB for all capsules - except with the addition of the -10dB capsule where the peaking was at 0dB. The XH A1 gain/attenuation dial was set to max and line in was used. Recording was not carried out in a special chamber or in a sound proofed room but in my lounge which is a fairly small room, about 6 x 6 metres in area with about a 2.75 metre high ceiling.

Thanks in advance!

Hi Stuart - you may want to check out the good review that Dan Brockett did last year on Ken Stone's web site...

As I Hear It - Choosing the Right Microphone (http://www.kenstone.net/fcp_homepage/right_mic_brockett.html)

He reviews the Oktava, among others.

For your recording situation, I liked the hyper with the 10dB pad best. It sounded fullest to my ears.

1) Too much room echo. Unacceptable.
2) Thin sounding.
3) Thinner still. (Was the lo-cut filter on?)
4) Full, but too bassy. Lacks definition.
5) Still a bit too bassy, but can be EQ'd to taste. The pad would require more gain, which could add noise. (I wasn't listening for noise.) Depending on the context (web? tv? cinema?) the noise might or might not be a problem. If it is, choose #2 and EQ in a smooth bump at 200-300 Hz to add fullness.

Jon: Thanks very much for your insights :)

I'm glad you think that sample number 5 (Oktava with hypercardioid capsule and -10dB pad) is best. I thought that sounded best too! I thought I might be imagining it.

However, I also noticed that if you turn the volume up and listen through headphones the inherent noise seems more acceptable with the -10dB pad on the Oktava. With the pad on it's a gentle hiss, without it you get an unpleasant buzz. The gain is already at maximum with all the tests, can't set the Mix-Pre any higher I'm afraid.

All of the samples in the file have had their audio levels adjusted in Media Composer so that their peak levels are roughly the same, but still the -10dB pad seems to have more acceptable noise.

The low cut filter wasn't switched on with the At815b, I just double checked.

I guess the ideal thing to do now is compare the inherent noise from 2 and 5 to see which is worst? I will be entering my next film in competitons, the one after that will be more for DVD.


Eric: Thanks for the link. I've already read it, but it's a great review.

If pads are actually changing the amount of noise and it's not just the volume difference fooling you, or the stages after it that are noisy, then something's wrong with the mic design.

Pads are simply resistive loads that knock the level down. They shouldn't change the signal to noise ratio.

note: HDV audio is pretty compressed; 384 kbps versus 1500 kbps for 16-bit, 48 kHz. Could be the noise is happening in compression, but it should be straight across the board on all mics.

Regards,

Ty Ford

Pads are simply resistive loads that knock the level down. They shouldn't change the signal to noise ratio.
Ty, as you know (and just to be clear for others who might read this), while it's true that the S/N from the mic won't change with a pad, you have to raise the gain downstream by 10dB to compensate for a 10dB pad. If you do this in post, the noise from the preamp and the rest of the recording chain will be 10dB higher.

The odd thing isn't that there's a bit of hiss with the pad, it's that there is buzz without it. My guess is that the mic was picking up some A/C power noise without the pad. Maybe the cable is cheap and way laying on a power cord. When he added the pad, he moved the cable away from the noise source. Or maybe the refrigerator or some other subtle noise source was running during one test and not another.

I recorded all the samples, except the At815b ones, in one sitting. And there wasn't an intermittently noisy appliance switched on nearby that would account for the change in background noise.

It could be that when I fitted the pad I tightened it more making a better connection or accidentally moved a cable that was receiving interference. Everything was running on batteries, so I guess there shouldn't have been AC interference?

My cables should be fairly decent as they are Canare ones with Neutrik connectors. So maybe it was a dodgy connection somewhere. Either that or the -10dB pad has mystical powers.

Stuart,

My studio is in the basement of my home. Dimmers in floor lamps and mounted in the wall one floor up, on the main floor, on different circuits, can quite easily "broadcast" a buzz that's picked up by my audio gear. Your audio problems may have been caused by something similar.

Regards,

Ty Ford