500MHz whine when G3/G2 powered off

[Les Wilson]

I've been using my Sennheiser wireless for a long time. I have G1, 2 and 3 units. However I've pretty much just been using them with a field mixer. I recently hooked a G3 up directly to my Sony EX1R XLR connector in mic level impedance and notices a slight whine when the receiver is muted. The whine is much louder if I power off the receiver. It goes away if I disconnect the XLR. Changing cables and camera channels doesn't affect the problem. If the receivers are attached to my Shure FP33 field mixer, there is no whine.

The whine is 500Hz and is familiar as a sound that previously was only in the headphones (only when the camera LCD was open) but not in the recording. Now it's in the recording.

Is this the camera block or something else? TIA

Here's a video showing the problem:

500hz whine in audio from Sennheiser G3 on Vimeo

[Steve Game]

Sounds more like 500Hz. :)

[Les Wilson]

Yes. SMH. Editing original post.

[Andrew Smith]

Dang. Was about to compliment him on his incredible hearing.

Andrew

[Richard Crowley]

Does it happen with the flip-out viewfinder CLOSED?

You can hardly fault the Sennheiser receiver if it happens when powered-down.

I have observed exactly such noise in other prosumer Sony camcorders when the audio cable(s) were in proximity to the flip-out LCD viewfinder screen.

Two remedies that I recall were helpful:
1) Don't use the flip-out viewfinder. Or at least route the audio cables as far away from it as possible.
2) Operate on battery. Significantly quieter than operating from the mains-connected charger/power supply.

[Les Wilson]

Thanks Richard. First thing I did was to close the flip out screen. No effect. Everything is running on battery. Cables are clear of flip out screen and moving them around doesn't affect noise. Noise abates when G3 powers on.

[Richard Crowley]

How confident are you about your cables? That is a classic symptom of a dodgy cable. Especially the one from the receiver to the camcorder.

[Les Wilson]

Cables are a good idea so I tried others but no joy. This is a camera problem.

By coincidence, the topic of audio interference from the EVF just came up in the Sony XDCAM forum: http://www.dvinfo.net/forum/sony-xdc...ml#post1921618

Turns out the EVF is what puts the 500Hz whine in the audio. In the past, it was faint, only in the headphones and only happened when the LCD was closed which turned on the EVF. Anyway, one of the things I did in recent years was to have the EVF powered on all the time. So when I went to directly connected radios, I hit the problem.

Powering the EVF in AUTO mode solves the problem of the 500Hz whine in the recording when a bodypack is connected but powered off. On a lark, I changed the audio block impedance to MIC+48 where the radio was connected and that solves the problem as well. Clearly a Sony design issue. Thanks for the help.

[Rick Reineke]

The G2/3 100 series portable receiver is unbalanced (don't know about the G1), so the cable and receiver is likely picking stray RF from the monitor. You could try setting the cam & receiver to line level input (G2/3 AF maxed out.. a much hotter signal), but the levels may be a little low if the cam has 'true' +4dB nominal line level.

[Ignacio Rodriguez]

Good point. Always prefer line-level when available. It's what I do with my Sony RXs; they have XLR connectors but are not really balanced. Also, by using line-level you defeat the crappy preamps on some prosumer cameras.