In search of silent lights

L

LauraM

New member
I'm trying to find lighting for my isolation booth where I record voice over. My mic (an AKG c414 XLII) is picking up every light I've tried.

I've tried LED rope lights, LED tape lights, and LED puck lights. My mic picks them all up as a deep hum. I've made sure that the cord is nowhere near my mic cable, and I've tried different outlets. The hum disappears when the lights are gone... but unfortunately I can't read in the dark.

I heard that LED lights were best, because they don't give off much heat and booths can get hot. But would incandescents be quieter? Or some other type of LED, maybe a specialty LED light? I bought the ones I've tried at Home Depot.

Thank you for your help.
 
If you are picking up a hum, I have a feeling that lights are not the source of the problem.

Do you get a hum with no lights?

Have you tried a different lead for the microphone?
 
Well, he said the hum goes if he turns off the lights Gecks but I agree, there is likely some sort of "second order" cause here.

You can buy very cheap battery powered LED lamps. I have a couple, 24x3 LEDs powered from AAs, tenner iirc. Then there are 10W LED PIR security floods, again cheapish £15. These are 12V and power nicely from a car, leisure or SLA battery. You might be able to arrange solar trickle charging or use a 15V or so SMPSU line lump.

Dave.
 
If the lights are on the same power point as the rest of the gear, change the power source. Better still if the building has 3 phase power put the lights on a different phase to the studio gear.

Alan.
 
witzendoz said:
If the lights are on the same power point as the rest of the gear, change the power source. Better still if the building has 3 phase power put the lights on a different phase to the studio gear.

Alan.
Click to expand...

I am not a qualified "power" electrician but I would not bring another phase into the room unless it was just lighting and you used ceiling pull switches.

I agree the chances of a phase to phase HV shock are vanishingly small but I understand this is not best practice?

Dave.
 
Let's find out a bit more about the signal chain....

- Mic is an AKG C414 XLII.
- What is the mic plugged into? Interface, mixer, or other device?
- If using a USB interface, is it powered by USB plugged into the computer or does it have its own power adapter (wall wart)?
- You are not using a phantom power box connected out to the 'MIC' in of a computer.
- Are you using a 'preamp' ahead of an interface or mixer?
- All connections are using 'balanced' cables (XLR or TRS)?
- Is the house fairly new with wiring that is up to date and appears to be grounded properly? Get one of these > Outlet Tester (Walmart, Home Depot, Lowes, etc)
- If you touch the mic, its attached cables, or other gear in the signal chain does the hum change?

Just saw your post elsewhere > 'They cause a deep hum/buzz noise.'
Here you had said > 'My mic picks them all up as a deep hum'
Can you post a short clip of the sound? Straight hum may have a different reason than something with a buzz and a different fix. The USB cable with the ferrites suggested in the other forum might work if its buzz and is cheap to try, but may not work on a clean powerline hum

Edit....
- Forgot to ask if this is a laptop or desktop or perhaps other type of recorder.
 
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"If you touch the mic, its attached cables, or other gear in the signal chain does the hum change? "

We may never hear from him again!

Dave.
 
ecc83 said:
"If you touch the mic, its attached cables, or other gear in the signal chain does the hum change? "

We may never hear from him again!

Dave.
Click to expand...
I had had a similar problem where the mic/interface wasn't grounded via the USB power very well through a desktop computer for some reason unknown. Touching the mic yielded hum. Bandaid fix was to ground the interface to another piece of gear with a 'dummy' 1/4" cable to a piece of gear with a known good ground.

Note: the OP's name is 'Laura'. Thinking it may not be a 'him' :)
 
ecc83 said:
I am not a qualified "power" electrician but I would not bring another phase into the room unless it was just lighting and you used ceiling pull switches.

I agree the chances of a phase to phase HV shock are vanishingly small but I understand this is not best practice?

Dave.
Click to expand...

I was thinking hard wired circuits for lighting, not a different phase PowerPoint.

Alan
 
For my overseas 'mates' with the accent....
Pretty much 100% guaranteed no hum or buzz and ideal for reading of VO scripts in the dark :D. I introduce to you.......

 
arcaxis said:
Wasn't in front of me so I had forgotten about it. I've got one of these clipped to the top of a music stand and I can't say I've ever noticed a problem with it inducing noise into any recordings when running off the AC adapter. It can also run on batteries which I haven't tried.
https://www.amazon.com/SumDirect®-C...r=8-1&keywords=music+stand+led+lamp+sumdirect
Click to expand...

I use a little dual LED stand clip, not very expensive. Proline PLD4A Dual Head Gooseneck Music Stand Light with 4 LEDs and AC Adapter | Guitar Center
 
Much like DM's solution, I use the Mighty Bright HammerHead LED Music Light Black | Guitar Center on my copy stand, and have a cheapie, 40w LED https://www.walmart.com/ip/Great-Value-GVRLA4027ND-Great-Value-LED-Light-Bulb-5W-40W-Equivalent-Soft-White-20K/51497410?action=product_interest&action_type=title&item_id=51497410&placement_id=irs-106-m3&strategy=PWBAB&visitor_id&category=&client_guid=401e8114-f1ce-42d2-9792-044f2b070f8d&customer_id_enc&config_id=106&parent_item_id=40507614&parent_anchor_item_id=40507614&guid=1a7e0b4c-e877-4352-8019-f6e8bc0c48c1&bucket_id=irsbucketdefault&beacon_version=1.0.1&findingMethod=p13n, in my booth. On the same circuit as all of my gear, it is dead silent, as far as I can tell, and why I bought it. It is not a "Dimmable" LED bulb. But, I am not sure that would make a difference. I will test that theory tomorrow.
Dale
 
ecc83 said:
Yes, that of course would be perfectly safe but still might not pass "code"?

Dave.
Click to expand...

Its normal practice in commercial buildings, 3 phase coming in, Air Con on one, Lights on another, Power on a couple.

My Building has 3 phase, I have the studio on 1 phase, the air con on another and the kitchen & Lighting on the 3rd. No interference from the lights being switched, the fridge in the kitchen or the air con turning on/off.

There are some 3 phase outlets in the workshop which I don't really use but could be handy if we want to test a lighting dimmer.

Alan.
 
Remember that virtually all LED light sources use rectified mains AC - and smoothing is absolutely minimal because the size of the PCBs in the lights is so small. Add to it that plastic is common means that every LED source contributes to raising the noise floor. In many cases direct radiation, but quite a few will be passing their interference back into the mains supply. Worse still, some designs have their interference at double the mains frequency where it is more audible. 50 and 60Hz interference is bass - but 100/120Hz starts to be very mid range. There are a few LED units that use a diode, dropper and capacitor rather than a rectifier and these chop the waveform even more. Just another interference source to live with. All LEDs are not the same, so trying a few different brands might help - then buy spares because when one goes you'll have to do it all over again. Battery powered LED don;t flicker and don't cause issues - just the AC to DC conversion that makes the noise.
 
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