terskelton

Hello. The Canon EOS T3i has a 3.5 mm jack to allow an external stereo mic to be connected. That jack also provides "mic power" for electret mics. There doesn't seem to be any way to get a live output to monitor audio as it is being recorded. I interface to inputs like this all the time. However, with this camera, the recorded audio seems very noisy (hiss) whether recorded with the internal mic or my feed from an external mixer. I've used several different mixers that either have a microphone level output or line level through an external pad to get the signal to the correct level for a electret mic input. Every approach has way too much hiss. The only way that has "worked" is to take an aux output from a mixer (about -10 theoretically) and set the master for the aux out to about -25. That should be resulting in about a -35 output...on the high end of the correct range. The camera is in the manual level mode and set to about one mark above nothing. But when I get that signal level via a resistive pad the recorded signal has too much hiss. And in that case the camera input manual control was about midway. The problem seems to be two-fold: 1/ the camera's record audio is just too noisy and 2/ why doesn't it like being fed from a resistive source? I don't want to get hiss by lowering the aux master so much in the method that "works". That's not the right way. And I may want to use other mixers. I could re-do these tests with test equipment instead of my ears but think the practical results will be the same. Has anyone had issues feeding mixers into camera analog mic inputs? Thanks.

larryepage Loc: North Texas area

I am not familiar with the EOS T3i, but my D850 has a menu selection that allows me to turn off AGC from the mic inputs, whether the internal microphones or external inputs, and manually select a record audio level. Can you find such an option somewhere among your menu choices?

TriX Loc: Raleigh, NC

That’s a good suggestion. If you input a low level to the camera with AGC enabled, it will increase the gain (and noise) to attempt to increase the low level.

terskelton

Larryepage: thanks for the response. I am aware of that but we don't want the very apparent effect of the AGC (pumping and sucking) in the music we're recording. And it does pull up any noise as well.

larryepage Loc: North Texas area

I am saying to make sure the AGC is off if possible...avoids pumping and turning gain up too high during quiet periods.

terskelton

Thanks. You are correct problems could arise. It is in manual, as I said: "The camera is in the manual level mode..."

larryepage Loc: North Texas area

I missed that when reading. Getting old, I guess. So it sounds like there is too much electrical gain somewhere in the chain. Any way to use more sensitive microphones, or mics with higher output, so the electrical gain can be reduced? Or maybe use a low pass filter to block or reduce the hiss?

terskelton

We need to feed the camera with a mixer as multiple mics are being used. And in the process of creating an electret level signal from a mixer to go into the camera...done in textbook, technically accurate method we get too much noise. I don't know if it is a function of the pad between the mixer and the camera or if the camera is just noisy. I'm looking for other folks who have had this issue. Or who have successfully interfaced mixers to this camera.

TriX Loc: Raleigh, NC

If you have a scope or a RT spectrum analyzer ap for your laptop, you might consider looking at the signal out of the mixer / pad to see if the noise is present at the input to the camera or generated in-camera.

terskelton

larryepage. You are correct of course that a higher source signal allows you to reduce the input gain (of the camera) and the internal noise as a result. That is basically what we are doing but the method of creating the proper level from the line level mixer output and the camera input isn't working as it should apparently. It seems as whenever the camera manual level is set above the first notch there is excessive noise.

terskelton

triX. A possibility, but we don't hear the noise at the mixer output and we have used several different mixers. My thoughts are that 1/ something funny happens with certain mic input circuits that provide "mic power" when they see a resistive source of a particular configuration. There are a couple of other tests I could do...removing the dc with a capacitor or using a transformer after the pad instead of before it (but I hate feeding a dc voltage into a transformer). But rather than test eternally I'm hoping to find someone who knows the answer.

TriX Loc: Raleigh, NC

You might send a PM to Bill Burk (Burkphoto) - he does a great deal of external recording with mixers, but not specifically with a T3.

terskelton

Thanks. A better camera would have a more professional interface but we're trying to make this work...and it should...unless the camera has a design issue no one talks about.

BebuLamar

Perhaps make the audio recording independently and put sound and pictures together in post?

terskelton

BebuLamar Thanks. We are also doing that so as to have digital multitrack recordings to re-edit later as needed. But that results in several days of work as opposed to having a mixed recording on the camera ready for immediate use. The plan is to have both resources.