New AF100 Setup

if the pre amps work similar to dvx100, hmc151 then you will have no problems with rode ntg2, at4073a, oktava mk012 or ntg3 mics - these have all gotten great results for me. What Jan said initially threw me (panicked is probably a better description)
& i thought there must be something new in the way the af101 will record audio & all my mics would suddenly become useless on the af101, but if you are saying it is about the same as existing panasonic cameras then I don't see a problem
But have to say Jan's words did worry me.....
 
This is exactly what is necessary to make ntg1 work. I have it at -50db on my hpx170. And if af100 has it as Barry confirmed one post below the quote then we're in good shape. Thanks Barry

taubkin said:
So the AF100 doesn't have the option of choosing from -50dB to -60dB like the DVX had? -not that it matters so much, but still...
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eXe69 said:
I have the rode ntg1 and have been using it with fantastic results with an hpx170. My volume nobs are rarely past a quater.
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And this is what I am taking about. You never get the full fidelity of the microphone at 1/4 of a turn. Better to use a -15dB pad and run the mic a little at 1/2.

Best,

Jan
 
Barry_Green said:
All the Panasonic AG handhelds are designed to use -50 or -60 mics. If the NTG1 is similarly hot, then it will be so on the HVX, HPX, DVX, or AF100.

Do you ever turn the audio pots all the way up, or only halfway? If you're comfortable with the range you're getting, then you should be comfortable with the AF100 too. But if you can only use a limited range before the mic output overloads the system, then you'd want a 10dB pad in there (or 15dB).

Frankly, if you can live with the limited range of a hotter mic, there's a chance (I'd have to test) that you'll end up with slightly cleaner sound from the hotter mic. Because you'd be using less internal boost for lower volume levels, you might get a cleaner signal after the pre-amps get through with it. But if you're in a loud situation you may not be able to turn it down low enough.

I will admit I didn't look up the specs on the NTG2 before saying it'd be okay, and that was negligent on my part. I was just going off all the praise that I see heaped on it, and I don't think I recally anyone who has reported it being troublesome, so ...
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I'd say that this sounds about right.

Typically, we don't have the pots up much, usually at or below mid way. Never had an issue with poor quality sound. Excellent shotgun mic with a good muff on the end.
 
I approach an on-camera microphone differently. First off, you're never, ever going to want to depend on a camera-mounted microphone for your primary sound. You're always going to be dealing with handling noise from operating the camera, and if the camera is beyond five feet from your subject, the recorded audio is going to be less than ideal. No wonder then the on-board microphones shipped with big-ticket camera (Varicams, etc.) are never expensive, high-end mics; their purpose is generally picking up backround or backup audio.
So, better ways to spend your $$$$ than on an expensive shotgun type mic. However, if money is no object, and you want to open the wallet for a great mic, I'd suggest what my audio tech uses -- a Sanken CS-1 (about $800-). He says it matches the sound from a lavaliere really well; it's also short in length (7 inches) and that helps on-top of a smaller camera. Audio-Technica also makes a cheaper mic that works well -- the AT875 -- only a couple hundred bucks.
 
Jan_Crittenden said:
And this is what I am taking about. You never get the full fidelity of the microphone at 1/4 of a turn. Better to use a -15dB pad and run the mic a little at 1/2.

Best,

Jan
Click to expand...

So what exactly are the knobs doing in the audio circuitry on the AF100? My understanding was they controlled the gain of the pre-amps internally. I would ALWAYS prefer to use as little gain from the pre-amps as possible to reduce noise from the pre-amps. The less they have to do, the better. By padding the microphone, you are just reducing the input by 15dB and then putting back that gain by using the pre-amps in the AF100. Granted, if you cannot run the pre-amps low enough and your mic is too hot and you are getting clipping you NEED to pad, but if someone is running at 1/4 and getting great results, I would see NO need to change that setup. (which might be what you are getting at).

ANY time you push gain up on amplifiers, they continue to increase THD (total harmonic distortion) AND gain up the op amp noise that most pre-amps are made of. In addition, since the pre-amp is not gaining the signals as much, the affects of the frequency response of the op-amp on the gaining of the signal will be MUCH less pronounces since the delta gain is so much lower.

With the HVX200, we've never had an incident where I felt the ntg-1 was a problem. We could always lower the gain enough that even someone screaming near the boom mic wasn't clipping it. That's why we aren't worried with the AF100 :)
 
Form an audio perspective, the harmonics of the microphone, see the diagram for sensitivity on the brocure that came with it, that pickup pattern is only true when the mic is used and the output is about half way up the dial. That is where the device it self(read camcorder) going to also hit its marks. But if you are running the camera below that then you are not getting the best out of the mic or the recorder, you are not getting the full fidelity of the system. The Pots are not meant to be controlling the sensitivity but rather the input volume. Two different things. Yes it can work that way, but may I suggest that you put a pad in between the camera and that mike, you may very well get an even better result.

Best,

jan
 
Jan,

Thanks for the input but I don't fully understand the point you're making.

The volume nobs: pots or potentiometers are variable resistors that regulate the incoming line voltage. I don't quite understand how turning them to a lower number (adding resistance to the circuit) is any different than adding an external mic pad.

Perhaps I am not understanding something here.
 
Jan_Crittenden said:
Form an audio perspective, the harmonics of the microphone, see the diagram for sensitivity on the brocure that came with it, that pickup pattern is only true when the mic is used and the output is about half way up the dial. That is where the device it self(read camcorder) going to also hit its marks. But if you are running the camera below that then you are not getting the best out of the mic or the recorder, you are not getting the full fidelity of the system. The Pots are not meant to be controlling the sensitivity but rather the input volume. Two different things. Yes it can work that way, but may I suggest that you put a pad in between the camera and that mike, you may very well get an even better result.

Best,

jan
Click to expand...

No, that is not true, and I am not sure where you are getting that from. The sensitivity diagram that comes with your microphone is showing you the frequency response to the transduction of sound pressure to voltage. This has NOTHING to do with the gain staging after the microphone. I will repeat, turning down the gain on the pre-amps in the AF100 is a better solution than reducing the voltage (padding) the microphone output and then gaining it up with a pre-amp. ALWAYS. Most quality pre-amps even employ an isolation circuit, mostly optical in light weight systems, to isolate electrically both systems. (In studio gear, it is very common to use transformers to isolate and use magnetic induction to transfer the voltage).

A pad is not adjusting the sensitivity of the microphone either, it's reducing the volume of the microphone voltage.

What are the controls doing on the AF100? Are they a voltage divider just reducing the input voltage before they hit the pre-amps? Or, are they a gain control circuit designed to control the gain of the pre-amps in the AF100? In either of these cases, as long as you are not driving the AF100 to the point where you are getting clipping, then there is no need for a pad. In fact, I guarantee you that the frequency response of your pre-amps are not flat, I've never seen any that are, so gaining up a signal with the AF100 is going to introduce changes to the frequency response (although extremely subtle) which is why I agree with Barry that running in hotter is going to produce a better signal. This is true of almost ALL audio equipment.

Now, if you say that there is an issue with the pre-amps at 1/4 turn, that they are not working as flat as they'd be at 1/2 a turn, then I could see this as a problem with the AF100 gain circuitry, but I'd find that hard to believe.
 
Jan,

Could you please find out or tell us if you know if the volume pots are:

A) Upstream from the preamp: line-in TO volume pot TO preamp

OR

B) Downstream from the preamp: line-in TO preamp TO volume pot

If the camera is case A I wouldn't see a problem running a mic that is too hot but on the other hand with case B there could be.

Thanks!
 
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