Audio hiss

[Evan Mann]

I'm running my HV20 in full auto mode, which gives me no control over the mic as far as I know. I've listened to about 50% of my clips from the past 2 hours of footage and noticed the hiss throughout. It does seem to be fairly constant. I will have to go back and listen to the rest of them.

I'll try and covert 10-20 seconds of some clips in different locations and get them online to listen to.

Originally Posted by Steve Boutin

The mic is usually never the cause of hiss. Try a cheap DYNAMIC mic (any non-powered mic) , borrow one or whatever, and see if you still have the hiss. If you do then it's purely electrical, and the mic is not the problem. I don't know how the HV20 is configured without the schematic. I don't know if you can bypass the internal preamp. If your just pluging a better preamp into the same noisy preamp, you're not going to solve the hiss problem.
I have not experienced any hiss problems with my HV20. If you are using proper recording levels, and bypassing the compressor, and still getting hiss then you might just have a bad circuit in your HV20. It's hard to troubleshoot something like this without seeing/hearing it.

Does the hiss stay at the same level all the time, or does it appear to rise if there is low or no incoming audio. If it rises, this would indicate the compressor gain too high.

[Don Palomaki]

The mic is usually never the cause of hiss.

Generally true for dynamic mics, but not always the case for condensor mics. Condensor mics have internal amplifiers, and some can be rather noisy (lot of hiss), especially the economical mics.

You can sometimes infer the noise level from the mic specifications, if they give you a meaningful signal-to-noise ratio figure (not always the case). The better shotgun mics commonly used for video like the AT-879 or NTG-2 have S/N on the order of 77 dB at 1 Pa sound level. A good studio condensor mic will have a S/N on the order of 84 dB or better.

The lesser shotgun mics such as in the the Azden line range form 70db to a very poor 40 dB depending on the model.

BTW, 1 Pa is a measure of sound level, fairly loud, corresponding to about 94 dB SPL, or roughly 6 dB below the sound level you get standing 3 feet from a jack hammer. Thus 40 dB S/N is a pretty loud hiss.

[John Hotze]

What about making sure the audio level indicator shows and use the jog switch to select audio level and try to adjust it down to where it shows no ambient noise being picked up by the onboard mic. You could at the same time record a test for a short period of time & listen to the playback.

For me, it's quite surprising at how much ambient noise is around us that our mind seems to filter out most of the time. I was just testing and putting a little blank space at the beginning of a tape this morning before an upcoming taping. I was amazed when I played it back how much noise just the air conditioner blower was recorded and heard when played back.

You could also watch the audio level indicator display and tape some cotton or material over the onboard mic to see if it the audio level goes way down. I know that the onboard mic is pretty damn sensitive and can easily pick up a lot of ambient noise we don't normally even hear.

[Don Palomaki]

The arguably best approaches include:

1. Get the microphone close to the talent, within a few feet or closer. Having the mic inside a camcorder is the worst possible location for recording any sound other than ambient background sound. Mounted on top of the camcorder is the next worse location
2. Use a quality microphone with high output and that usually means a powered condenser mic. For quality sound forget just about anything that has a price below around $250, and many would set that limit at $500 or more.
3. Avoid using automatic level control or maximum audio gain settings on the camcorder - get a higher output mic, or closer to the sound source, if you can.
4. Hiss will always sound worse with headphones due to tight coupling to the ears and isolation from other ambient background sound in the listening environment. Judge your end product in a viewing/listening environment similar to where the end user will view it.
5. Field recording is not the same as studio recording, it is difficult to impossible to control ambient noise in the field, but that can also mask the noise in your system.
6. Does it make sense to spend $2000 or more on audio gear (quality mics, preamps, etc.) for use with a $700 camcorder? Only only you can answer that question.

[Paul Nixon]

I've been experimenting with an external mic and different recording devices.

1) external mic with a Sony D8 cam for audio and wide shots, and the hiss is something fierce!

2) same mic with my Sony HC1 HDV cam and the hiss is still there but not nearly as bad (though now I am tethered - don't like that)

3) same mic hooked into my laptop - similar hiss to the HC1 - can hardly hear it.

4) same mic with a digital voice recorder - JUST SAY NO - sounded like a good idea at the time, but the quality of the recording is very poor.

Regardless of which device the mic is connected to, do NOT use any AC adapter - you will get 60hz hum. Perhaps if I had a more professional mic setup the results would be different, but I'm near the bottom of the food chain with regards to shooting/recording and will upgrade as I climb the ladder.

[Don Palomaki]

D8 = Digital8? If so is consumer, will likely have poor audio due in part to AGC.

What make/model external MIC are you using? Some have much more self-noise than others, and some may not be a good match for camcorder.

Digital voice recorder, if intended for voice only may end up about ye-olde-time telephone quality. For decent recordings witjh an external recorder a MiniDisc or a recorder similar to the M-Audio MicroTrack (ther are several similar products on the market) is what you should consider.

[Paul Nixon]

Originally Posted by Don Palomaki

D8 = Digital8? If so is consumer, will likely have poor audio due in part to AGC.

What make/model external MIC are you using? Some have much more self-noise than others, and some may not be a good match for camcorder.

Digital voice recorder, if intended for voice only may end up about ye-olde-time telephone quality. For decent recordings witjh an external recorder a MiniDisc or a recorder similar to the M-Audio MicroTrack (ther are several similar products on the market) is what you should consider.

Yes, D8 = Digital 8.

Microphone is a modest Audio Technica unidirectional. It provides much better sound than the built-in mics, but the results seem to depend a lot on what the mic is connected to. Camcorder = lots of hiss, laptop = very little hiss (actually less than the HC1, contrary to what I said previously).

Digital Voice Recorder - yes, it actually does sound something like a telephone, and it makes sense when all things are considered. I had hoped to use such a device instead of wireless, but the audio results are - well, you know.

Funny you should mention an external recorder like the Microtrak - I had come to the same conclusion but had only just started wondering what was available and for how much. The Microtrak II looks like a very good match for what I'm needing.