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Author Topic: Radio interference with CA-9100  (Read 2809 times)

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Offline stgomez91

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Radio interference with CA-9100
« on: March 29, 2011, 07:52:08 PM »
I have a show tomorrow that I need to record and in testing my new CA-9100 out I've noticed that I get a strong radio signal that makes the recording sound terrible. Here's what the situation is:

I set up the deck and the pre-amp on my bed about 5 feet from my stereo and turned up my turntable to test the levels. When I put the headphones on I heard the music as well as interference. To make sure it wasn't just the music, I stopped the record and listened: LiteRock 105 was playing (local radio station). To find out where it was coming from, I unplugged the preamp from the deck. Now I just had the headphones and the deck: no sound, as expected. I then connected my headphones to the preamp: LiteRock again. So it's definitely the preamp.


I've searched the forums and haven't been able to find an answer. Also, per iGene's advice, I tried wrapping the preamp in aluminum foil but I didn't notice a difference, though when I did put the aluminium foil into the input I got a real strong FM signal.

Am I the only one who has had this problem?? How can I stop this or combat this?

Offline Belexes

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Re: Radio interference with CA-9100
« Reply #1 on: March 29, 2011, 09:19:46 PM »
Are you running some mics from the 9100? There is a common problem with cell phone interference from poorly shielded cables that has been discussed at length here, but that is a mic issue and not a pre-amp issue and only deals with cellular signals.

Would you be near an FM receiver at a show that this would be an issue?
Busman Audio BSC1-K1/K2/K3/K4 > HiHo Silver XLR's > Deck TBD

CA-14 (c,o)/MM-HLSC-1 (4.7k mod)/AT853(4.7k mod)(c,o,h,sc)/CAFS (o)/CA-1 (o) > CA-9100 (V. 4.1)/CA-9200/CA-UBB > Sony PCM-D50/Sony PCM-M10

Offline stgomez91

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Re: Radio interference with CA-9100
« Reply #2 on: March 29, 2011, 09:24:37 PM »
I'm running a pair of CA-11's to the pre. Tbh, I don't know much of what shielding is. I wouldn't know if I'm going to be near any FM receivers at the show...I've never been to this venue.

Offline Belexes

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Re: Radio interference with CA-9100
« Reply #3 on: March 29, 2011, 09:31:00 PM »
You should be fine with CA-11 > 9100 > deck.  I run this all the time with CA-14's and other CA mics without issue of interference and that is in venues with lots of cell phones, wireless in-ear monitors, walkie-talkies (crew), etc..
Busman Audio BSC1-K1/K2/K3/K4 > HiHo Silver XLR's > Deck TBD

CA-14 (c,o)/MM-HLSC-1 (4.7k mod)/AT853(4.7k mod)(c,o,h,sc)/CAFS (o)/CA-1 (o) > CA-9100 (V. 4.1)/CA-9200/CA-UBB > Sony PCM-D50/Sony PCM-M10

Offline vanark

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Re: Radio interference with CA-9100
« Reply #4 on: March 29, 2011, 09:42:20 PM »
I've never seen this problem with my CA-11 > CA-9100 > R-09.

But, perhaps it is a poor/loose connector/cable?  Are you certain the cables are properly seated in the preamp?  What kind of cable are you using to go from the CA-9100 to the recorder?
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Mics: Microtech Gefell M21 (with Nbob actives) | Church Audio CA-11 (cards) (with CA UBB)
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Offline Seth01

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Re: Radio interference with CA-9100
« Reply #5 on: May 30, 2011, 07:57:54 AM »
You should be fine with CA-11 > 9100 > deck.  I run this all the time with CA-14's and other CA mics without issue of interference and that is in venues with lots of cell phones, wireless in-ear monitors, walkie-talkies (crew), etc..

Sadly, I can confirm that I've had a few masters ruined using the the above rig.

I've never seen this problem with my CA-11 > CA-9100 > R-09.

But, perhaps it is a poor/loose connector/cable?  Are you certain the cables are properly seated in the preamp?  What kind of cable are you using to go from the CA-9100 to the recorder?

When I use that set up Rory, I never have issues either but I did get cell phone RFI with my CA-11 > CA-9100 > H4n.  Picked up some just the other night as I was taping 4 channels all into the H4n.  Strangely, it came through my CA-11 cards but not my CA-11 omnis.  Thankfully it was only 4 seconds but still ruins a master and my cards were getting a better pull that night too.  :(

A loose connector or not firmly plugged in would produce more of a static sound, I think.  Last summer when I first noticed it the RFI, I started putting my H4n into a Camel-back type water bag holder.  It was plasticized aluminum foil and anecdotally seemed to work - although I didn't do any scientific testing to confirm.

Good luck!
Mics: Busman Audio BSC1-K1/K2/K3/K4, CA-14 cards, CA-11 omnis, CAFS, Naiant X-X omnis, AT853 cards (with 4.7k mod)
Pres: Naiant Bigbox, CA-9100, CA-UGLY, Naiant Tinyhead
Recorders: Sony M-10, Zoom H4n, Edirol R-09 (retired)
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Offline owainturner

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Re: Radio interference with CA-9100
« Reply #6 on: May 30, 2011, 09:24:21 AM »
I've had something similar... But when I changed to higher-quality connector cable between the CA-9100 and my M10 I never had the issue again... It seemed to be the unshielded cable I used.

Offline Seth01

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Re: Radio interference with CA-9100
« Reply #7 on: May 30, 2011, 03:44:15 PM »
I've had something similar... But when I changed to higher-quality connector cable between the CA-9100 and my M10 I never had the issue again... It seemed to be the unshielded cable I used.

I'm pretty sure that's where my "weak point" is too.  Thankfully, I've just ordered some new much higher quality cables from Ted just in time for the festy season.   ;D
Mics: Busman Audio BSC1-K1/K2/K3/K4, CA-14 cards, CA-11 omnis, CAFS, Naiant X-X omnis, AT853 cards (with 4.7k mod)
Pres: Naiant Bigbox, CA-9100, CA-UGLY, Naiant Tinyhead
Recorders: Sony M-10, Zoom H4n, Edirol R-09 (retired)
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dorrcoq

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Re: Radio interference with CA-9100
« Reply #8 on: June 01, 2011, 12:31:06 AM »
...it was only 4 seconds but still ruins a master

I wouldn't go that far!  Easily fixed with a small patch from the other source.

Offline Seth01

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Re: Radio interference with CA-9100
« Reply #9 on: June 01, 2011, 03:29:45 AM »
...it was only 4 seconds but still ruins a master

I wouldn't go that far!  Easily fixed with a small patch from the other source.

Hahaha   :P  Why am I not surprised that you said that.   ;D  Yes, you're right it's not the end of the world and is fairly easily replaced by my second source but the omnis didn't get as nice a pull as the cards so anyone with decent ears will hear the (short) difference.  Plus the master is impure with that RFI.  :(
Mics: Busman Audio BSC1-K1/K2/K3/K4, CA-14 cards, CA-11 omnis, CAFS, Naiant X-X omnis, AT853 cards (with 4.7k mod)
Pres: Naiant Bigbox, CA-9100, CA-UGLY, Naiant Tinyhead
Recorders: Sony M-10, Zoom H4n, Edirol R-09 (retired)
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