Zoom Q3 may be heading back to the store ...

[lpa53]

Fran, could you educate me on the meaning of AGC and why the lack of it is good? I think your blog said something about it pulling in background noise?

[Fran Guidry]

Ooops, AGC = Automatic Gain Control, also called lots of other things. Basically a really aggressive compressor/limiter. These things wreck the sound - when the source is quiet they raise the gain and bring up both the ambient and early circuit noise, when the source is loud they clamp down generating distortion.

Fran

[lpa53]

Thanks. Got it. Does the Zi* you use have that natively, and if so, does using the external mic (an H2?) bypass that?

[Fran Guidry]

Originally Posted by lpa53

Thanks. Got it. Does the Zi* you use have that natively, and if so, does using the external mic (an H2?) bypass that?

Now you're into the hard-to-answer questions.

The first thing I have to say is that my Zi8 had audio problems evident on the built-in mic and has been replaced by Kodak. These issues may have also affected the external mic input, I just have no way to know. And my replacement unit is in California and I'm in Hawai`i until March. So I don't know how my new one (and one you would purchase) compares to my old one.

With that in mind ...

My Zi8 definitely had a not too terrible AGC on the built-in mic.

Using the mic input, I went back and forth between thinking I heard an AGC in action and thinking it was not there. I contacted Kodak and asked for any information they could give me - they were unwilling to tell me anything that wasn't in the existing product literature. Very very frustrating, and hard to understand, but that's the way it goes.

The external mic input does have a sensitivity setting in the menu, which allows you to adjust for different sources. With my unit I had a hard time finding a consistent result.

I will say (once again keeping in mind that my unit was replaced for audio issues) that when I plugged in my H2 as an external mic (by running a cable from the headphone jack to the Zi8) and made three recordings at the same time - 1 inside the H2, 1 in the Zi8, and a second copy of the headphone output in my home recording rig, the Zi8 recording was noticeably lower in quality than the other two. It had more noise and less accurate frequency response.

I'm quite interested in repeating this test with my new Zi8, but it makes sense if you think of it. The audio function of these cameras (and this is true of much more expensive cameras as well) is relegated to a few cents worth of integrated circuits. Serious videographers record their audio separately and sync in post, even when they're using multi-thousand dollar camcorders.

Fran