VO-BB - 20 YEARS OLD!

Dayo · Cinquecento Joined: 10 Jan 2008 Posts: 544 Location: UK

Hi everyone

I've been lurking around this board for ages and I think this could be my first post.

I've almost finished building my new voice booth and so far so good, with one minor problem. My TLM 103 which previously behaved like a dream has now developed a huge problem with RF. Fine if you want to listen to top 40 radio, but not conducive to clean v/o recordings! My other mics work fine.

I'm guessing I'll need to re-wire the XLR but wanted to get some input from you guys before I go ahead. Anyone else had RF problems with the TLM?

Oh and if I'm going to re-wire the cable, it could be a good time to replace it. Something esoteric perhaps? Does anyone have any recommendations or favourites that actually make a sonic difference beyond hype?

Thanks all!

Colin

Mike Sommer · Posted: Mon Jan 19, 2009 6:16 pm Post subject:

Could be a grounding problem.

Condenser mics are very sensitive to to RF, hence why they are in such heavy bodies and caging. Check the screws on the housing are all tight. I had this problem with a Gefell once, as soon I locked it down all was right.

Check the cables and pins. If there is a dimmer in the area this can be a problem, along with appliances and breaker boxes. Make sure your electrical outlet/s are grounded all the way to earth. If you are in a dry area water your grounding post -- Not Kidding.

Try moving the mic around the room to see if there is any change also. If there is you should be able to find the source.

An audio sample will always help.

Frank F · Posted: Mon Jan 19, 2009 6:25 pm Post subject:

Have you changed cables?

Ockham's Razor strikes again. (Most times the easiest solution is the right one).

Toodles

F2
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Ed Gambill · Posted: Mon Jan 19, 2009 7:33 pm Post subject:

Look at your microphone cable. Try to determin if it is Quad or Star Quad. If not get some. Razor 1
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Deirdre · Posted: Mon Jan 19, 2009 7:46 pm Post subject:

"It's always the cables."
--George Sanger, the Fat Man
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Philip Banks · Posted: Tue Jan 20, 2009 3:19 am Post subject:

You are probably aware that there is true north, magnetic north and compass north. Due to the way the earth behaves magentic north is constantly moving. Condenser microphones are charged and "excited" across the diaphragm electrically in a bi-polar manner. This manically depressed +/- movement (magnetic true north/south) may be subject to waves generated by RF (radio frequency) interference. Electro/radio physical properties combined with natural polar magnetic fields are impossible to combat so my suggestion would be to buy a new cable (shielded).

Dayo · Cinquecento Joined: 10 Jan 2008 Posts: 544 Location: UK

Thanks for the input everyone. I should have mentioned that I've tried 3 different cables (all shielded Philip cool

). The problem persists. Will update you when I get it sorted. Got a feeling it's the way the XLR needs to be earthed for a Neumann.

Widening the discussion for a moment, does anyone have any thoughts regarding high end mic cables vs regular off the shelf?

Ed Gambill · Posted: Tue Jan 20, 2009 7:27 am Post subject:

NaNa Dayo.

You said shielded, you didn’t say Quad. The difference is night and day. I had a video shoot within 4 miles of an antenna farm with 4 TV stations. The wireless microphones would not cut it, so I use cabled mics. All the cables were Quad and yes it knocked out the RF.

How did I learn about Quad Cable, from a location sound engineer who also knew his stuff.

Read more about Quad here http://www.belden.com/pdfs/prodfaq/faqpqdmc.htm

You have been given good advice by folks who know. I taught production sound for Film, Video and Radio. I held 1st Class Radio License and still consider myself a Broadcast engineer.

Frank is super sharp on this stuff as are some others on this board. DB and Philip know from first hand experience that using the right quality of cable is essential to defend from RF and other naughty things in the ether.

Canare, Mogamie and Belden make fine product that are used in the recording industry. Good Luck
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Dayo · Cinquecento Joined: 10 Jan 2008 Posts: 544 Location: UK

Thanks for all your input everyone.

I invested in star quad mic lead, it made no difference. Then tried another mic amp and the RF went away. Turned out to be a problem with the power supply to my TC Konnekt mic amp. Switched that from bus powered to mains and the RF has (almost) completely gone.

Mike Cooper · Posted: Mon Jan 26, 2009 9:52 am Post subject:

Ah, the old ground loop problem again! Mike S was right, and wins a cookie… Laugh

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Mike Sommer · Posted: Mon Jan 26, 2009 8:25 pm Post subject:

When all else fails go to earth.

Sounds like your need a power scrubber. I'll also bet the outlets in you home/studio are not truly grounded. Someone may have done one of those quickie home improvements and didn't attach a pigtail to the grounding post and metal box.

In the last studio I wired for a friend we twisted the all the wires before pulling through the conduit which had it's own grounding post. Dead quite power supply.

Dayo · Cinquecento Joined: 10 Jan 2008 Posts: 544 Location: UK

Thanks for the tip Mike. I'll look into a power scrubber today. Is that the same thing as a power conditioner? I'm in the UK. Anything I should be looking for in particular?

Mike Sommer · Posted: Wed Jan 28, 2009 1:15 am Post subject:

Google under Line Conditioner

Here's a good start:
http://www.google.com/products?client=safari&rls=en&q=line+conditioner&oe=UTF-8&um=1&ie=UTF-8&sa=X&oi=product_result_group&resnum=1&ct=title

Dayo · Cinquecento Joined: 10 Jan 2008 Posts: 544 Location: UK

Looking into the grounding problem. I've recently moved here so I'm not sure how good the earthing is. My small rather old TV in the kitchen tends to buzz loudly when a caption comes on screen. I'm wondering if that might be bad earthing. Hmmm - looks like a call to the electrician is on the cards.

Mike Sommer · Posted: Wed Jan 28, 2009 7:06 pm Post subject:

The reason for the Buzzing on you Telly when the captions come on, is because ( assuming you're using an aerial) is that the antenna may be misaligned, especially if the broadcasting antennas are not at the same location and are not being received equally; the vision to sound ratio to prevent "Buzz" should be close to 10:1 on each channel. If it isn't, you'll get 'buzzing' on captions, interference patterns on pictures, as well as errors on captions or teletext. In extreme cases, it may not be possible to obtain acceptable reception of all channels using a single antenna. If it's happening on all channels then all you need to do is adjust the antenna. If you have cable call the cable company.

As for your ground problem. Do you live in a Home, Condo or Apartment? If you're in a condo or apartment you could be on a common ground and maybe getting feed back from another unit, which could mean bad earthing. Hopefully you're not grounded to a water pipe.

Here in the States, there is an inexpensive device you can plug into the outlet to check polarity and for open grounds (less then $20), it would be worth looking into.