Topic: picking up radio station with CA mics???

[SBW]

Has anyone ever had a problem with the wires on the CA-14 mics acting as antennas and picking up a radio station?  Unless I have the wires totally bundled up, I can distinctly hear a radio station in the background. 

I'd like to try recording w/ the omnis but I have to spread the wires out to to get stereo and the radio station shows up.  Is there any kind of shielding I can use???

Any suggestions welcome

SW

[jagraham]

Were you using mics directly into recorder or a pre/battery box?  This came up sometime recently in a thread.

[John Willett]

This is something that can happen with unbalanced microphones, especially if the unbalanced cable is long and especially in areas with a strong RF signal.

This is why professional microphones are balanced.

[LikeASong]

I would like to hear a sample, if possible

[SBW]

I had the mics plugged into the CA 9100 preamp.  I can't change the mic wires because they're permanently connected to the mics. 

This sounds crazy but if I plug in some grado labs SR60 headphones directly into the output of the preamp, crank up the gain, it sounds like I have a walkman.  However, if I wrap the microphone wires around the preamp itself, then the radio station goes quiet.

[ilduclo]

google is your friend here, there's a lot of discussions out there on the subject. I used to pick up a neighbors HAM signal over my speaker wires, when I upgraded to heavier more shielded wires it went away...

[DigiGal]

The FCC requires radio stations to perform a station identification every hour, which will help you identify the station and thus its frequency.  Additionally there are still low power analog television transmitters in operation and again they are required to perform a station identification.  HAM operators could be tougher to identify.

Balanced mics/cables perferably StarQuad with Neutrik EMC XLR connectors would do wonders to eliminate it.

[SBW]

I don't know if you've ever seen CA mics but I think the wires are soldered straight on to the mics and the cable is tiny - like 20 guage or so.  Would these cables be balanced or unbalanced?  I have no idea.

[adrianf74]

I don't know if you've ever seen CA mics but I think the wires are soldered straight on to the mics and the cable is tiny - like 20 guage or so.  Would these cables be balanced or unbalanced?  I have no idea.

1/8" connectors are unbalanced... at least in the case of any of these small mics.   The only way to try and avoid this is to run three-wire mics (such as a mini-XLR terminatre pair of AT853's) or to not use a preamp and stick with a battery box.

[LikeASong]

I don't know if you've ever seen CA mics but I think the wires are soldered straight on to the mics and the cable is tiny - like 20 guage or so.  Would these cables be balanced or unbalanced?  I have no idea.

1/8" connectors are unbalanced... at least in the case of any of these small mics.   The only way to try and avoid this is to run three-wire mics (such as a mini-XLR terminatre pair of AT853's) or to not use a preamp and stick with a battery box.

Why would using a BB instead of a preamp solve the problem? I have no real opinion towards or against that - just curiosity

[adrianf74]

Why would using a BB instead of a preamp solve the problem? I have no real opinion towards or against that - just curiosity

I say this because I'm basing it on a similar issue some people have had with cellphone interference being picked up during recordings on a preamp.  I believe it has to do with a battery box providing a fixed voltage and as soon as a preamp (with variable voltages being introduced) is involved, these secondary problems can creep up when using unbalanced gear.

I've had cellphone hits on various preamps using 1/8" connections and *NEVER* had an issue when using the battery box.

[LikeASong]

Why would using a BB instead of a preamp solve the problem? I have no real opinion towards or against that - just curiosity

I say this because I'm basing it on a similar issue some people have had with cellphone interference being picked up during recordings on a preamp.  I believe it has to do with a battery box providing a fixed voltage and as soon as a preamp (with variable voltages being introduced) is involved, these secondary problems can creep up when using unbalanced gear.

I've had cellphone hits on various preamps using 1/8" connections and *NEVER* had an issue when using the battery box.

Aha, I understand you. There must be some serious Physics explanations behind this issue but I'm a chemist

[absnj]

Why would using a BB instead of a preamp solve the problem? I have no real opinion towards or against that - just curiosity

I say this because I'm basing it on a similar issue some people have had with cellphone interference being picked up during recordings on a preamp.  I believe it has to do with a battery box providing a fixed voltage and as soon as a preamp (with variable voltages being introduced) is involved, these secondary problems can creep up when using unbalanced gear.

I've had cellphone hits on various preamps using 1/8" connections and *NEVER* had an issue when using the battery box.

Aha, I understand you. There must be some serious Physics explanations behind this issue but I'm a chemist

So could an alchemist change unshielded cables into shielded without having to re-wire the mics?

[capnhook]

Yep.

The alchemist in me sez you should use lead pipe. 

[SBW]

Sweet, I will try the ferrite bead trick and see if it works.  Also, what exactly is the difference between the CA9100 and a battery box?  Also, do you know where to buy them? 

Thanks