Sound mixer 664 and Boom Issues

[GMandyG]

Hi guys, I'm having issues with the 664 mixer where when recording, I hear a static sound like a hum throughout the shots. I feel like its an issue with the 664 mixer and not the boom op because I tried using another zoom mic on the boom and that worked fine.
I also had another question. I would like to know how to make the boom wireless because have cables from the boom connected to the 664 is inconvenient. I would love to speak with a sound expert regarding these issues.
If you were filming a silent film, how would one record the sound to be as clear as possible? And also what type of equipment would one use for this?

 

[Maura N.]

Hi GMandyG,

Static/Hum Issue with the 664 Mixer​

The static hum you're experiencing might be caused by one of the following:

1. Ground Loop Interference: If the mixer and other connected equipment share different power sources, it can create a ground loop, leading to a hum. Try isolating the power source or using a ground loop isolator.
2. Cable Issues: Faulty or poorly shielded XLR cables can introduce noise. Test with known good-quality cables.
3. Mixer Settings: Check the gain staging on the 664. Excessively high input gain can cause issues, especially if the microphone is close to the noise floor.
4. Phantom Power: Ensure the phantom power (48V) is correctly enabled/disabled based on your microphone's requirements.

Since your Zoom mic worked fine, the issue could very well be with the mixer’s input ports or configuration. Testing the boom mic on another channel of the 664 can help isolate the issue. If nothing works, it may be worth contacting Sound Devices support for hardware troubleshooting.

Making a Boom Wireless​

A wireless boom setup can significantly improve mobility on set. Here’s what you’ll need:

1. Wireless Transmitter/Receiver System:
   • Brands like Sennheiser (e.g., G4 systems) or Lectrosonics are reliable options.
   • Attach the transmitter to the boom pole and connect it to the microphone via an XLR cable.
   • The receiver will connect to your 664 mixer.
2. Lightweight Power Solution: Ensure your transmitter is lightweight for the boom operator. Some setups use rechargeable battery packs.
3. Quality Considerations: Use a system with high-quality transmission to avoid interference or loss of audio fidelity.

Recording Clear Audio for a Silent Film​

Even though it’s a silent film, the sound will still play a key role, especially for ambiance, Foley, or post-sync dialogue if necessary. Here’s how to ensure the clearest recordings:

1. Location Considerations:
   
   • Choose a quiet location with minimal background noise.
   • Use acoustic treatments (blankets, baffles) to minimize reflections.
2. Microphones:
   
   • Use a shotgun mic (e.g., Sennheiser MKH 416 or Rode NTG series) for focused sound capture.
   • Pair with a high-quality omnidirectional or cardioid mic for ambiance.
3. Equipment:
   
   • Recorder/Mixer: Your Sound Devices 664 should be fine once the hum issue is resolved.
   • Wind Protection: Use proper windshields or blimps to reduce noise from environmental factors.
   • Headphones: Use reliable monitoring headphones like Sony MDR-7506 to identify and isolate issues early.
4. Workflow:
   
   • Use boom placement techniques to maintain consistent sound levels.
   • Monitor sound actively to catch any interference or noise on set.
   • Record room tone for every location to help with post-production.

If you’re looking for specific recommendations for your setup or more advice on sound design, feel free to ask!

Good luck with your project!

Maura

 

[Kim Welch]

"We should definitely get Fred involved in this one. When it comes to production sound, he’s our go-to expert. His knowledge is unmatched!"

 

[Maura N.]

@FredGinsburg