Line Level and Mic Level

obi1jacobi

obi1jacobi

Active member
Hey guys - I picked up a Zoom H2 a couple of months ago and have been looking around at all the creative uses people have put it to.

I came across this site - http://www.hv20.com/showthread.php?t=2909
where they suggested connecting their zoom h2's to their hv20s for use as an external mic. (I'm not quite sure why since at best the zoom h2 is a 90-degree angle cardiod with dual mono)

Regardless, what confused me was the fact that they went from Zoom H2 line out, to HV20 mic in.

I've always been under the impression that you can't just go from line level to mic level without an inline pad or some adjustment for line level being too hot.

What is it that I am missing in this equation?
 
You can. It just usually won't come out as clear. Without looking at the thread or ever seeing an HV20 in person, are sure that's what they meant to be saying?
 
"The GOOD news is - YES you can use the H2 as a camera mic. I switched both the mic vol on the HV20 and the H2 Line Out vol to zero, switched on the Attenuator and connected up. The volumes were increased and the sound came through beautifully!! Switched OFF the Attenuator and the combination still worked well.
I do not propose to give any Vol figures for the H2 as this was not a thorough test, it was more of a "does it explode???" sort of test.
The H2 does work as an external mic."


They don't seem to report any distortion which is what I thought would happen if you go directly from line level to mic level:
 
Apparently volume at zero reduces the output to close enough to mic level to not have any issues to deal with, at least with what I guess would be the second preamp set to its lowest. Also not sure why one would want to... I guess it would allow you to get a track in the camera as well as on the recorder, depending on how the machine's built. Which can be nice.
 
The gain staging sounds pretty dodgy, in that setup. If the gain structure on the H2 is optimally set (nice, fat levels going to "tape"), then running its line out into another device's line in without a pad is going to give you a real mess of distortion.

If, on the other hand, the mic gain is set so lown on the H2 that the meters barely wobble, then you may be able to pass its line out into a mic input without incurring massive distortion.

"Beautifully", in this case, may well mean "without sending the meters shrieking into the red". I would not recommend this type of gain staging if you're looking to maximize your signal-to-noise ratio.

Perhaps a better solution would be to record double-system onto the H2 using an optimum gain structure, while using its line out and a 30dB pad (easy enough to build) to record a guide track into the camera (assuming it won't accept a line input). The H2 recording will likely be significantly cleaner, but the camera's version may well be acceptable.
 
(Sorry, Casalen. You're latest post showed up while I was slowly typing away).

The way preamps often work is to apply a fixed-gain amp followed by a variable attenuator. If dropping the input level setting to 0 brings the signal back into an acceptable level, what's likely going on is the camera's adding a lot of gain, then stripping most of it away. You're likely going to still pick up more noise and analogue distortion (which will sound far less apocalyptic than digital distortion) than you would with a 30 dB pad.

Of course, this is all just conjecture on my part. A quick google will yield the circuit plans for a DIY line-to-mic pad. They're awfully handy to have in your kit. Slap one together, and see which gain structure gives you optimal results.
 
Thanks for the responses.

Yeah, again, I'm not sure why I would bother doing this since if I were to use my Zoom H2, for production audio, I'd go double system. People have even made their own shock mounts and boomed with it. http://www.youtube.com/watch?v=TCn28Ke1tm0&feature=PlayList&p=82C4F070182B31CD&index=4

But, mostly I just couldn't understand how two consumer pieces of equipment were working together without any adjustments. Now I can see what you mean, SMuir. Maybe these people just haven't noticed a problem because it still sounds better than using the HV20's built in mic?
 
That is a common myth. It depends on the input circuit. Modern electronics are often--but not always--designed to handle a wide range of input sources. The classic example is the single audio ports on laptops and computers--these used to have separate line in/mic in etc. Now it is almost always one jack, sometimes switchable, sometimes "one size fits all". The Canon input is pretty good, but it isn't like having semi-professional audio gear, like a Fostex FR2LE and two good mics. Or pro gear. And if you want long cable runs, that is going to be an issue with the unbalanced lines. Of course, you will do better with your Zoom H2--a fine box for the price--recording in 24 bit to the Zoom.
 
A bit more on the FR2LE....having tested all the available flash recorders, I would call it semipro; the quality of the converters is excellent. The quality is also as good or better as many products that are advertised or even regarded as professional. I prefer the preamps to those of Sound Devices. Compared to the SD the sound is slightly less artificial and slightly more open. In addition, the opamps can be modded if you want to tweak the sound towards neutral, warm or transparent. The customization of the input stage gives a very high end sound, but the stock box is fine as is. The only downside is the output stage, but I only use that for monitoring anyway. If you are going to daisy chain the output to the cam input, there is a bit of noise from the output stage. But I always use the 24 bit flash recorder sound for post. An added plus, the FR2LE power the Schoeps and Sennheisers beautifully due to the way the stages are matched. Both the MK41 and MKH40 give superb results; in fact, one of the great strengths of this box is the sound with high end mics and solid phantom power. High end batteries allow it to run all day as well. A sleeper.
Why semipro as opposed to pro? The output stage is really not professional quality, but the rest is good, and I don't normally need the output stage. I would not use it to record a concert, but in a pinch it would do :)
 
You must log in or register to reply here.
Back
Top