The audio quality is absolutely crucial for good video productions. Here are some guidelines to help you improve the sound in your recordings.
The best way to transfer the audio signal to your Mac
We recommend transferring the audio signal from the audio source (microphone/audio system) directly into your video camera. This ensures that audio and video will be synchronous, even if you do not use the camera's built-in microphone. More expensive camera models offer an XLR input interface for best sound quality (see image above).
A short lesson about audio cables
XLR is mostly used in professional equipment and offers the best transfer quality, because it uses balanced audio transfer. This method cancels out most effects of electromagnetic interference and is thus better suited for long distances.
Recommendation: Use XLR cables whenever possible. They have typically a male plug at one end and a female plug at the other end. However, all combinations are available on the market. Make sure you buy the right cables for your environment.
Although one cable contains 3 wires, it will only transmit a mono signal.
RCA Jack (=Cinch) is commonly used both in consumer and semi-professional devices. The two mono cables together provide a stereo signal:
Red - Right audio channel
White - Left audio channel (sometimes also grey or black)
Some cables have Cinch connectors at one end and Jack or Mini Jack plugs at the other end.
Jack is the equivalent of an RCA Jack with a larger form factor. They are still quite popular on mixing desks.
Be aware that there are plugs with only one black isolator ring. They are used for mono signals. Plugs with two black isolator rings can transmit stereo sound through the same cable.
Mini Jack plugs are used in consumer devices like portable audio players, cell phones and also the MacBooks.
If you don't have the possibility to send the audio from the HiFi to your video camera and then through FireWire into your computer, use the Mini Jack plug. As a converter you could use the ART DTI Dual Transformer mentioned below.
If your cable is too short, use an extension piece to prolong it. Please do always keep in mind that you should keep the cables as short as possible.
Also, there are plenty of adapters, connectors and adapter cables available on the market to convert between Cinch, Jack and Mini Jack.
You don't have got the right audio cable?
In many cases, you need to be flexible and support many combinations of the cable technologies mentioned above. We recommend you to extend your basic material with a generic audio converter box. As you can see in the picture below, the converter allows you to mix the different kinds of audio cables.
Here is an example: In the HiFi system of the auditorium you only have the possibility to insert an XLR cable and on the other end (in your Mac) you can only insert a Mini Jack:
In this case connect the XLR cable to the converter (IN) and on the other side of the converter (OUT) you can insert a cinch to Mini Jack adapter cable into your computer.
ART DTI Dual Transformer/Isolator
Do you have a buzz noise in your audio?
When you set up your recording equipment at a new location, you might get a bad surprise concerning the audio quality. It may happen that the sound is disturbed by some static buzz noise ("Brummton"). Commonly, this situation occurs when you use mobile recording equipment. One cause could be the electrical installation of that room or some devices (e.g. installed HiFi system).
It is difficult to find the reason for audio problems because there are typically many components involved. As first measure, try the following steps to get rid of the problem:
- Regulate the audio "output" at the room's HiFi system
- Regulate the audio/XLR "input" on your video camera or on your Mac running the Recorder
- Plug all your devices to the same power outlet in the auditorium. Avoid using multiple socket outlets if possible.
As second measure you can integrate a device called "DI-Box active" in you setup, which is responsible for reducing possible hum noise. The main task of the device is to perform a "ground lift", resolving the ground loop between input and output.
BSS AR 133 DI-box active
In this case activate follow settings on your video camera:
- 48V Phantom powering
- Input 1 has to be set on "Mic-Level"
Now connect the HiFi system to the "DI-Box" (Input) using an XLR cable and the "DI-Box" (Output) using an XLR or Cinch cable to your video camera or to your Mac.
As mentioned before, the cause of a humming noise is often not easy to find. Also, the use of the DI-Box is not a guarantee that you can solve the audio problem. Anyway, it is useful to have the device in your assortment. Maybe it helps you in another situation.
If you need some specific help in this matter don't hesitate to contact our helpdesk.