Pro-95 Headphone Volume Mod

chaddiesel

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Hello everyone. I'm looking to stream my old Pro-95 scanner, but when I run the audio cable from the headphone jack to the Line-In on my soundcard, the volume level is very low even when the scanner volume is turned up and the line in is set to 100% (it's a stereo line cable...I'm not sure if that is an issue as well). I tried to do my research before posting and found several posts about this talking about a headphone volume mod which provided a link. The problem is, this link in all the posts doesn't seem to work (link is titled "Speaker Mod for external speaker Pro 95/96/106"). It somehow involves shorting out the ground to the jack with a piece of wire. If anyone has any tips, I'd appreciate it.

Thank You,

-Chad
 

gmclam

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Hi.

1) Use the "mic" input rather than the "line" input of your PC sound card.

2) I used an external 600 ohm to 600 ohm isolation transformer. This is typically done to mitigate ground loops. It may or may not help, but regardless it is not a total solution. The input side connects to the "hot" from the headphone jack and ground from the antenna BNC.

3) Some people have had good luck in just connecting the ground of the antenna BNC and hot audio of the headphone directly to the sound card input.

Since you're using the headphone jack in all the above scenarios, the scanner's volume will affect the level.
 

chaddiesel

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Dec 30, 2008
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Indiana
Hi.

1) Use the "mic" input rather than the "line" input of your PC sound card.

2) I used an external 600 ohm to 600 ohm isolation transformer. This is typically done to mitigate ground loops. It may or may not help, but regardless it is not a total solution. The input side connects to the "hot" from the headphone jack and ground from the antenna BNC.

3) Some people have had good luck in just connecting the ground of the antenna BNC and hot audio of the headphone directly to the sound card input.

Since you're using the headphone jack in all the above scenarios, the scanner's volume will affect the level.
I really appreciate the help. Moving from the line input to the microphone input really helped the volume level. I had a loud hum when the scanner was plugged into power. I tried a ground loop isolator I had and still had a hum but not as bad. I ended up taking a piece of speaker wire and attaching one end to a screw on the outside of the computer case and the other end to the BNC connector which quieted the hum. I think I'm in good shape now. Thanks again for all the help!
 

chaddiesel

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Premium Subscriber
Joined
Dec 30, 2008
Messages
12
Location
Indiana
I really appreciate the help. Moving from the line input to the microphone input really helped the volume level. I had a loud hum when the scanner was plugged into power. I tried a ground loop isolator I had and still had a hum but not as bad. I ended up taking a piece of speaker wire and attaching one end to a screw on the outside of the computer case and the other end to the BNC connector which quieted the hum. I think I'm in good shape now. Thanks again for all the help!
One additional piece of of information for anyone else reading. There were some noise reduction/cancellation features on my sound card that I turned off because of an echo and poor sound quality. Line in and the mic input seem to both work pretty well now using a stereo line cord and running the wire from the BNC connector to a screw on the computer case.
 
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