Two SoundCards and Bleedover??

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kb0nly

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Ok interesting problem here that i'm not finding an answer to...

I have two soundcards in a dedicated computer, desktop running Windows 7, for my two scanner feeds. If i listen to my MN feed i can hear the SD feed at a very reduced level in the background noise, it also goes the other way as well but im just giving you an example.

Both soundcards, SB Extreme PCI Express and the computers onboard sound, are to the Line-In jack and the scanner audio is connected to them correctly. I tried with both Oddcast and Scannercast to see if it was a software problem but that doesn't appear to be it.

Any ideas why windows or the hardware would be doing this? Would getting a couple of those cheap USB soundcards off eBay and using them fix it? I saw some posts on here which would indicated using external USB soundcards seems to fix some problems with running more than one sound device.

Suggestions?
 

hvscan

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I have the same problem with one of my feeds and I am using the USB soundcards. I have tried some quick solutions without any luck. The bleedover volume is very low, but I hope to find the time to further troubleshoot it soon. Of the multiple feeds I have running in the same area, only one is doing this. I tried changing out the scanner, but that did not help. There have been a couple of other threads posted for this problem, but I don't recall if the problem has been fully resolved. Good luck with yours.
 

lexmedic157

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Mute all the microphone inputs and make sure only the line in's are active. I had a problem where my computer's mic was rebroadcasting what ever was coming over the speakers. Not sure if that's going to be the solution but it worked for me (had to go into the advanced options).
 

gmclam

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I've set up some computers using both internal sound cards and the $1 USB sound cards. I do not like to use the "default" sound card as a stream source. What I mean by default is the sound card which runs the speakers and has sound from typical Windows sources (when you receive an email, when a USB device is plugged in, when you click on certain things, etc).

I too mute all inputs for recording except the single inputs per sound card being used for the scanner audio. I mute ALL of the inputs including the one being used from the scanners for playback.

By setting things up in the above fashion, there should ZERO sound coming out of the speakers from any of the feeds. To test a sound I load a program such as WinAmp and play the local URL.

Any problems I have encountered have been related to "third party" sound drivers and utilities. These are programs that are not part of the standard MS Windows stuff and used for various functions. I just uninstall that stuff so I know I have a 'standard' system.

I hope this helps.
 
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kb0nly

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Ok... I went through it all again...

Everything is muted except for the two line inputs.

Its set so that the inputs are not played through the speakers, its a checkbox option on Win 7 and Vista seperate from the mixer.

I didn't even have speakers hooked up to this computer, so i plugged some in and no sound was heard because i disabled all windows sounds in the control panel since no speakers were connected, i fired up Winamp and played the demo, you know the one, it really kicks the lama's ass... etc.. Sounded fine.

I plugged in a USB soundcard and made that the default playback device just as a troubleshooting step, so that neither of the audio devices being used for streaming were the selected device.

I also went another step further and using the playback and recording devices control panel in Win 7 i disabled all devices but the two line inputs.

Oddcast and Scannercast now only show the two line inputs to choose from for the feed audio.

After doing all this i still get the bleed over between soundcards. So i'm stumped.
 

VK2GEL

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Crosstalk can be caused by not using shielded audio cables, ground loops and iron core transformers in power supplies.

Try ferrite beads, better cable, different earthing and a switch mode power supply on the scanners.
 
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kb0nly

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Crosstalk can be caused by not using shielded audio cables, ground loops and iron core transformers in power supplies.

Try ferrite beads, better cable, different earthing and a switch mode power supply on the scanners.
The cables are double shielded audio cables, no problems there. I put some snap on ferrites on both cables already to keep down the interference.. I also had to add some bypass caps to keep RF off the audio lines because of my RF dense shack and amplifiers. No more buzz or humm, still get a bit of bleeding between the two audio sources though.

The scanners are powered of the main power supply that feeds the whole shack and has battery backup, not using the stock wall warts for them. Everything is grounded and lightning protection in place as well.

Tried a ground loop isolator on both audio lines originally to clean it up a bit, put that back on them and the bleeding is still there.

So it appears to be a computer related problem, its mixing them over for some reason.
 

gmclam

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So it appears to be a computer related problem, its mixing them over for some reason.
I would agree with this diagnosis. And it is usually 3rd party sound software to blame. Otherwise there is no "path" from one sound card to the other.
 
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kb0nly

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There is nothing installed... The onboard is the factory driver and the soundcard i added i just used the windows driver for it...

I will see if updating the driver for the soundcard helps, got nothing else to lose at this point i guess!

Maybe get another USB soundcard and use two of them and see if it does it, i don't see any reports of people having this problem with the cheap ones on eBay. I remember seeing on here where one guy was using like a dozen of them.
 

gmclam

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$1 sound cards

I have done a few installations now using sound cards I bought from eBay for $1 each. I made some cables that had transformers in them to isolate the scanners and drop the audio level down, because the cards only have a mic input. But in the end they sound great.

Ironically, I am working on a different system for someone that has 4 PCI sound cards installed in his system. The cards are all different brands with different types of inputs. For example, one has a single input that can be mic or line, while another has 2 inputs for such.

The audio sounds horrible through the PCI cards by comparison. On one card I have the line input pot set to full and the level is still low. I can drive the input harder, but that just causes distortion and I still can't reach 100%.

One problem I have not had is cross-talk from one input to another, even if my transformers are all directly next to each other. To monitor my input directly I need to move my headphones or speaker from sound card to sound card. Otherwise I stream the signal and monitor it that way.

I am going to get more of the $1 sound cards and replace the PCI cards totally. I will note however that out of the 20 sound cards I bought, 3 were dead for one reason or another. That's a 15% failure rate. If the cards working now continue to work, I'll be happy with that.
 

VK2GEL

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I am having a similar problem with 2 scanners (UBC93XLT's), one tuned to UHF FM and one to VHF air, feeding via 'Y' lead to the stereo line in of an old IBM T23 laptop running Windows Media Encoder to stream.

For a few seconds every 30 seconds or so, one scanner's audio will bleed over in to the other stereo channel.

Any ideas please?
 

datainmotion

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Gentlemen,

FWIW, I had the same problem and after trying EVERYTHING, it turned out to be scanner #2 (VHF feed) was bleeding out audio and being picked up internally by scanner #1 (800 EDACS feed). Scanner #1 was a BC245XLT and scanner #2 was a SC-150.

Whenever scanner #2 was hooked up (to a 2nd PC BTW) and turned on, I could hear its audio on scanner #1s PC speaker AND its online feed. I swapped in my PSR-500 for scanner #2 and voila! no more audio bleedover.

Hope this helps. :)
 
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gmclam

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... it turned out to be scanner #2 (VHF feed) was bleeding out audio and being picked up internally by scanner #1 (800 EDACS feed). Scanner #1 was a BC245XLT and scanner #2 was a SC-150.
Very interesting. Were these two scanners sharing a common power supply? A common antenna? Were they so close to each other that this was inductively coupled? Or was it just a strong IF (or weak shielding in the other) that was being coupled?
 

datainmotion

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Very interesting. Were these two scanners sharing a common power supply? A common antenna? Were they so close to each other that this was inductively coupled? Or was it just a strong IF (or weak shielding in the other) that was being coupled?
Ran AC from another part of the house, tried all of my three antennas on the roof, shielded mono audio cables etc. etc. etc....

The scanners themselves, if within 10 ft. of each other, were the cause. I think a combo of IF from one and weak shielding on the other was the actual issue.
 

conve36

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All I did was run a simple single wire from the computer case (just loosened one of the case screws and slipped it around the screw) and then to the scanner. I just made a small loop and slipped it over the BNC connection.

I then had NO more problems with bleed over audio into my 2 scanners. But remember, only run the ground wire to ONE of the scanners.

Worked for me, and took less than 2 minutes!
 
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