Induction cooking show = problem

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Yullover

New member
Hi all.

It's my first post here, but i read you guy's from long time.

I have a new contract for many many days of work, and after the first day of work i'm totally dissapointed of my work.

Let explain. It's a cooking show and the chef use a portable induction cooking machine, EVERY time he turn up the machine i feel big big interference in the wireless.
It's not glitsh, it's not lose of AF signal as my receiver show 100% reception... is like i put a big compressor and the sound is pumping, the voice pass well but is like the back ground sound is going up and down. this machine have 10 level of force... when he use it from 1 to 5 level the sound start to be ugly..... after level 6 to 10 is perfect, without any impact over my sound,

so guy's did you have any idea what can i do ???

I use Sennheiser G3 with MK2 gold and sound device 302.

Did you ever hear about this before ???

Thank's in advance for your answer.
 
If you post a sample, it will be easier to diagnose. However, there are a couple of things going on here.

One, every wireless system has a compander (compressor-expander). While some systems are more transparent than others, the compander can "breathe" or "pump" with dialog or loud sounds. In higher-end systems, it takes some pretty nasty noise levels to hear the compander. I have two G2 systems, and I've never driven them to where I can hear compander artifacts.

Also, the SD302 has two-stage, "unclippable" limiters. Depending on how you have the limiters set and whether you're riding the mixer gain, they may cause the breathing/pumping with the sound level gets so high.

I'm willing to bet that it's one of these issues. Possibly a little of each.
 
Yullover said:
Hi all.

It's my first post here, but i read you guy's from long time.

I have a new contract for many many days of work, and after the first day of work i'm totally dissapointed of my work.

Let explain. It's a cooking show and the chef use a portable induction cooking machine, EVERY time he turn up the machine i feel big big interference in the wireless.
It's not glitsh, it's not lose of AF signal as my receiver show 100% reception... is like i put a big compressor and the sound is pumping, the voice pass well but is like the back ground sound is going up and down. this machine have 10 level of force... when he use it from 1 to 5 level the sound start to be ugly..... after level 6 to 10 is perfect, without any impact over my sound,

so guy's did you have any idea what can i do ???

I use Sennheiser G3 with MK2 gold and sound device 302.

Did you ever hear about this before ???

Thank's in advance for your answer.
Click to expand...

How well is your cabling shielded? And how well is the oven 'shieled/grounded'... The Wife occasionally complains about picking up 60 Hz hum when in theaters, and near power transformers with her hearing aid (yes, she has taken her meds, no, the hum does not tell her to go on a homicidal rampage... yet...).

Can you use 'cable' rather than go wireless... It's not like one needs to see the cook's shoes is it?
 
Thank's guy's for your input... but no, i know i'm driving my SD302 well, with the gain at middle, and the pot at 0, drive peak at 0 and limiter set to +12, so close to never the limiter enter... and the limiter in the input channel are of... as i drive it, and not let it going to this level.

As for the cable, i use the cable that come with the G3 to connect to the SD302. YES for sure i can use a cable microphone... but i didn't have, so it will be a expense for me, and that the show is in her third season and the chef DIDN'T want to have cable as the kitchen is big and he move a lot.

Is not like i'm doing a small show, connection a G3 directly in a camcorder...i'm professional sound engineer and live of that..... but this season they decide to use this induction cooker because is a sponsorship of the show... and now i'm completly in the floor with this problem....
 
I had something like this happen on a show I did. Senn G2 with stock mic.....I could see the peak light going crazy on the TX without speaking into the mic. Voice sounded compressed.
Switched to Oscar Sound 802.. different kind of distortion. But some kind of interference coming right into TX... RX seemed fine. Had another guy having same problem. Only thing that worked... both of us switched to Lectrosonics.
 
It may be even worse than that. Do a test with a wired lav. The magnetic field from the induction heater may even be too much for that. If the induction gadget is that important, you may have to boom it.

From your description, it sounds like the cooker uses a simple phase-angle power control, almost exactly like most lamp dimmers. But theatrical dimmers use giant inductors to limit the rise-time (which causes the buzz). The interference is worst-case at exactly 50% and reduces to either direction. If the cooker is THAT important, have the manufacturer make you a special filtered "media version" with some good filtering in the phase-angle power control. If they want the media exposure, it will be worth it to them.
 
Did you try different frequencies on the wireless? If it's emitting RF at a specific frequency (plus most likely lots of harmonics) rather than truly broadband noise, you might be able to tune around it, or go for Sennheiser gear on one of the other bands. (In general, the higher the frequency, the better for evading appliance radiation, but not always.) I'd also try different lavs into your transmitter; the noise might be getting in at the unbalanced cable between the microphone and transmitter, and mics with a different type or length of cable or a slightly different impedance might not pick it up as strongly. Wired mics might or might not help; even most wired lavaliers have at least a short length of unbalanced cable ahead of the transformer and XLR connector that could be the source of the ingress.

This is a truly nasty problem that will probably take a fair amount of experimentation to solve. I wonder if the FCC would be interested in knowing about the uncontrolled radiation from that device -- they have standards for computers and other incidental transmitters, after all.

- Greg
 
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Listen to Richard my guess is he is dead on. Your best and cheapest fix would be with a boom mic with a "good" shielded cable.
 
phudsontx said:
Listen to Richard my guess is he is dead on. Your best and cheapest fix would be with a boom mic with a "good" shielded cable.
Click to expand...

Yes... or not run the convection oven during the program. Many shows with cooking segments use pre-styled food for the on-camera work. I wonder how important it is to have the oven running throughout the entire segment?

Obviously, your first choice is to isolate the power [?] issue at the oven if possible.
 
Richard Crowley said:
It may be even worse than that. Do a test with a wired lav. The magnetic field from the induction heater may even be too much for that. If the induction gadget is that important, you may have to boom it.

From your description, it sounds like the cooker uses a simple phase-angle power control, almost exactly like most lamp dimmers. But theatrical dimmers use giant inductors to limit the rise-time (which causes the buzz). The interference is worst-case at exactly 50% and reduces to either direction. If the cooker is THAT important, have the manufacturer make you a special filtered "media version" with some good filtering in the phase-angle power control. If they want the media exposure, it will be worth it to them.
Click to expand...

As soon as I saw the word "induction", this was also my thought.

Gotta love them dimmers, right, Richard?
 
It would be interesting if it's RF from the level control or the fact that it's a big old magnetic field being generated by the cook top, inducing current in the electronics. You could actually be putting electronic devices at risk around such a thing.

I suspect it's not the dimmer though because your not getting the buzz. I suspect that this thing switches like most electric stoves do on a full on - full off cycle. On the low settings your getting a lot of down time between "ON" cycles so it's really noticeable and at higher settings it's on most of the time so it's more of a steady effect.

By what you are describing my guess is that the inductor in inducing a voltage on the mic and that is hitting the compander in the wireless in a bad way.

You could probably "fix" that by running the mic line through a isolation transformer, but then you would have to find a way to power the lav since you would be blocking power in both directions. A wired system wouldn't have the compander that the wireless has but you would still probably want to block the induced voltage with an iso block.
 
By all means, post an audio clip of the issue.
If the induction cooking machine generates a lot of high frequencies, that will drive the G2/3's notorious HF challenged compander nuts. If that's the case, you or production should purchase a digital system.
 
I shoot cooking shows - 90% of what I do is cooking shows… and when we designed the sets for our kitchen studio, induction cooktops were off the list. They are just giant electro-magnets that generate heat in a steel pot by moving the atoms of the pot - take the pot away and put your hand over the 'element' and there is no heat (also no audible noise). Only steel pots will work, aluminium or other materials will not heat up.

In tests we found that this electro-magnet generated an effect with wireless lavs - so we ditched the induction cooktops. Explain this to the chef and ask him to switch to a portable gas or quartz element. Problem solved.

Or boom him with a top notch cable.

Also when the chef is lav'd there isn't any problem with noise from the fridges or convection ovens - it's environmental ambiance.
 
Thank you all for your input. So yes finally the solution is to boom the chef, with a good cable it's solve the problem.

Because the set is big, i set my boom over the induction cooktops and still use the lav for other place of the set... so channel one is my lav and on the second channel i use the boom.
 
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