Gmi Pro
Gmi Pro

CB Mic Wiring to Phono Plug?
i've got an old shure 100 series cb mic that i want to use for recording and am having trouble.
there are four wires, 2 of them are for the PT and not necessary for use, so i've got 2 wires, 1 hot and 1 ground i assume.
i've wired it up to a phono plug, but it doesn't work unless i actually touch the mic element. it's like it's using me as a ground. i'm testing out of the case, which is metal.
not sure what's happening, but, herer's a pdf. that shows the circuit diagram at the bottom.
http://www.shure.com/stellent/groups/public/@GMS_GMI_WEB_UG/documents/web_resource/us_pro_101c_ug.pdf
any help is greatly appreciated.
You didn't say if you were recording into a computer, or into audio gear.
According to the pdf, that mike has a carbon granule microphone element, which is commonly used in old telephones and older radio equipment. See:
http://www.aerialpursuits.com/comms/mikes.htm
Now, computers use electret condenser mikes, and Pro Audio uses condenser or other more advanced mike designs, which will put out very low levels of sound, typically in the few-millivolt range or less. They require a pre-amp for most applications - a computer Sound Card has the preamp built in. However, the carbon mike requires an external voltage to power it, a little like an electret, and its output voltage is a significant percentage of the input voltage (so, if you put 5 volts through the carbon mike, your output signal will be about 5 volts max). This means that the CB mike you are using needs an external power source, and its signal will be way higher than your average microphone.
Check out this guy's article. He used a mike from an old telephone, but it's the same type of mike you have from your CB:
http://www.instructables.com/id/Telephone-Handset-Microphone/
His solution involves adding a single battery (1.5 volts), adding a few resistors to bring that voltage down, and feeding the resulting signal to the line-in jacks rather than the mike jack (since the signal will be about 1 volt or so from the mike, and that's closer to line levels than mike levels. I think if you added his solution to your mike, it should work.
As for why it works When You hold it... I think your body may have been supplying a few millivolts to the mike, and this was enough to let the mike generate an output of a few millivolts, which is fine for a mike-Input Jack, but probably less than what you need to get sound from that mike. Maybe you can experiment with the mike-power that comes from the PC sound card, or tap a USB cord to get 5 volts, apply that voltage to the mike, and use resistors to bring it down to line levels. If you have access to phantom power, you can try the same thing. The pdf mentions the current specs that the CB mike takes, so use that as a guide to powering up the mike.
![]() |
NEW GMI PRO 1 SPACE POWER LIGHT MODULE W 9 OUTLETS | US $38.40 | 38m |
![]() |
GMI PRO 18 SPACE CARPETED AMP RACK CASE WITH CASTER | US $201.30 | 57m |
![]() |
TWO GMI PRO 8 CLOTH EDGE BULLET MIDRANGE WOOFER | US $99.10 | 1h 21m |
![]() |
GMI PRO CARPETED COFFIN CASE 2 TURNTABLES 19 MIXER | US $169.95 | 1h 39m |
![]() |
GMI PRO 1U PROFESSIONAL AM FM DIGITAL TUNER REMOTE | US $101.95 | 3h 43m |
![]() |
2 GMI PRO 1 1 2 TITANIUM TWEETER 1500 WATT NU 2010 | US $74.80 | 5h 49m |
![]() |
GMI PRO CARPETED CLASSIC PRO 320 CD CASE W WHEELS NEW | US $163.70 | 5h 51m |
![]() |
GMI PRO 28 SPACE AMPLIFIER MIXER COMBINATION CASE WHEELS REMOVABLE LID | US $239.47 | 6h 32m |
![]() |
14 SPACE GMI PRO CARPET AMP RACK DJ CASE WITH 4 CASTERS ALL PLYWOOD CONSTRUCTION | US $166.37 | 21h 39m |
![]() |
18 SPACE GMI PRO CARPET AMP RACK DJ CASE WITH 4 CASTERS ALL PLYWOOD CONSTRUCTION | US $201.57 | 21h 42m |
![]() |
TWO NEW GMI PRO DJ HORN DRIVER 800 WATTS PAIR | US $35.75 | 1d 7h 46m |
![]() |
TWO PRO SCREW COMPRESSION DRIVER 290 oz 4390 WATT PAIR | US $125.00 | 1d 7h 47m |
![]() |
BELL HOWELL GAF KEYSTONE KODAK CAROUSEL EKTAGRAPHIC SLIDE PROJECTOR LAMP | US $25.00 | 1d 16h 41m |
![]() |
DEK DFW LAMP for BELL HOWELL BUHL GAF KODAK KEYSTONE SEARS SINGER Projector | US $25.00 | 1d 16h 58m |
![]() |
GMI PRO HYBRID HB3750 3750w 72 CHANNEL RECEIVERUSBSD CARD REMOVALE EARS | US $255.02 | 1d 18h 27m |
![]() |
GMI PRO 1 SPACE STEREO PREAMP AMPLIFIER W IPOD MP3 INPUT | US $144.36 | 1d 20h 49m |
![]() |
GMI PRO 30 BAND GRAPHIC DJ EQUALIZER EQ w LOTS INPUTS BLACK OR SILVER | US $121.70 | 1d 21h 46m |
![]() |
THE DOOBIE BROTHERS LIVIN ON THE FAULT LINE TAPE S8 | US $15.78 | 2d 26m |
![]() |
EBC FA158 BRAKE PAD KAWASAKI ZX 600 ZX6 R NINJA FA 158 | US $21.99 | 2d 1h 37m |
![]() |
EBC FA159x POLARIS RANGER SPORTSMAN Brake pad FA 159x | US $15.99 | 2d 2h 55m |
![]() |
NEW GMI PRO 14 SPACE AMP MIXER DJ ROAD RACK CASE | US $140.77 | 2d 5h 16m |
![]() |
GMI PRO CARPETED CLASSIC PRO 320 CD CASE WITH WHEELS | US $166.95 | 2d 7h 16m |
![]() |
GE Projector Lamp DFW DEK 120V 500W LCL 445mm MOL 927mm | US $12.00 | 2d 13h 9m |
![]() |
2 GMI PRO 10 CLOTH EDGE BULLET MIDRANGE WOOFER | US $119.25 | 2d 18h 12m |
![]() |
TWO GMI PRO 3 SUPER TITANIUM TWEETERS 3000 WATTS PAIR DIE CAST FRAME | US $179.30 | 2d 18h 27m |
![]() |
GMI PRO 30 BAND GRAPHIC HOME EQUALIZER EQ w IPOD INPUT | US $122.00 | 2d 19h 11m |
![]() |
NEW GMI PRO DJ POWER LIGHT MODULE W 9 OUTLETS | US $38.30 | 2d 19h 30m |
![]() |
GMI PRO DJ 42 BAND GRAPHIC EQUALIZER 19 RACKMOUNT NEW | US $132.10 | 2d 19h 34m |
![]() |
GMI 3 1 4 ALUMINUM BULLET HORN WITH 1 SUPER TWEETER | US $42.90 | 2d 19h 53m |
![]() |
TWO GMI 1 1 2 TITANIUM SUPER TWEETER 1500 WATT PAIR | US $74.86 | 2d 19h 54m |
![]() |
TWO GMI PRO SUPREME 1 WIDE RANGE TWEETERS 1200 WATT | US $54.55 | 2d 20h 12m |
![]() |
NEW GMI PRO DJ POWER LIGHT MODULE W 9 OUTLETS 2011 | US $38.80 | 2d 21h 10m |
![]() |
2 GMI PRO 15 2200 WATT 7 WAY PA SPEAKER SUB SYSTEM | US $299.95 | 2d 21h 49m |
![]() |
GMI PRO NEW STEREO PRE AMP AMPLIFIER W IPOD MP3 INPUT 19 RACK MOUNT | US $144.00 | 2d 23h 23m |
![]() |
GARMIN GWS 10 NMEA 2000 MARINE WIND SENSOR | US $510.72 | 3d 3h 26m |
![]() |
NEW GMI PRO DJ SYSTEM W TWENTY SUPER DOME TWEETERS | US $99.70 | 3d 8h 17m |
![]() |
GMI PRO 30 BAND GRAPHIC DJ EQUALIZER EQ w IPOD INPUT | US $123.75 | 3d 8h 19m |
![]() |
2 GMI PRO 15 3400 WATT 8 WAY PA SPEAKER SUB SYSTEM | US $398.95 | 3d 19h 42m |
![]() |
GMI PRO 3200 WATT 2U POWER AMPLIFIER DUAL FANS NEW | US $179.90 | 3d 21h 28m |
![]() |
GE DEK DFW DHN Kodak Carousel Ektagraphic Slide Projector Lamp Bulb | US $9.95 | 3d 23h 5m |
![]() |
GMI PRO 30 BAND GRAPHIC DJ EQUALIZER EQ w IPOD INPUT | US $124.10 | 4d 30m |
![]() |
GMI PRO AUDIO XOVER 3 WAY STEREO 4 WAY MONO CROSSOVER | US $119.50 | 4d 1h 49m |
![]() |
NEW GMI PRO 3100 WATT 3 SPACE DJ POWER AMPLIFIER 2 FANS | US $229.00 | 4d 1h 50m |
![]() |
GMI PRO 1010 BAND GRAPHIC SPECTRUM DJ EQUALIZER w IPOD INPUTS ANY COLOR | US $108.30 | 4d 1h 53m |
![]() |
NEW GMI PRO 1U 19RACKMOUNT POWER SUPPLY W 9 OUTLETS | US $38.10 | 4d 1h 59m |
![]() |
NEW GMI PRO 2100 WATT 3 SPACE DJ POWER AMPLIFIER 2 FANS | US $188.00 | 4d 2h 31m |
![]() |
NEW GMI PRO 2100 WATT 2 SPACE DJ POWER AMPLIFIER | US $163.00 | 4d 2h 36m |
![]() |
NEW PAIR GMI SOUND BOOKSHELF STUDIO SPEAKERS 400 WATTS | US $69.95 | 4d 16h 40m |
![]() |
GMI PRO KARAOKE AMPLIFIER 2125 WATTS BRAND NEW NEVER OPEN | US $157.64 | 4d 17h 30m |
![]() |
Universal Learning Remote For All Satellite Brand Below | US $11.62 | 5d 6h 2m |
![]() |
NEW GMI PRO COMBO STYLE CASE 366 PLYWOOD CARPET CASE LID COMES OFF | US $174.95 | 5d 17h 4m |
![]() |
GMI PRO 30 BAND GRAPHIC EQUALIZER w I POD MP 3 INPUT NEW BLACK | US $125.40 | 5d 18h 10m |
![]() |
2GMI PRO SUPREME 1 1 2 WIDE RANGE TWEETERS SPEAKER | US $74.91 | 5d 18h 17m |
![]() |
CARLISLE POLARIS ATV BELT MAGNUM DIESEL ATP PTV 3211069 | US $41.99 | 5d 22h 52m |
![]() |
CARLISLE POLARIS ATV BELT SPORTSMAN BIG BOSS 3211069 | US $41.99 | 5d 23h 5m |
![]() |
KODAK Carousel Ektagraphic Slide Projector Lamp 500W 120V DEK DFW Priority Mail | US $25.50 | 6d 2h 52m |
![]() |
2 GMI PRO 1 1 2 TITANIUM TWEETER 1500 WATT PAIR NEW | US $74.83 | 6d 19h 45m |
![]() |
2 GMI PRO SCREW ON TWEETER DRIVER 60 OZ MAGNET 2010 | US $83.75 | 6d 19h 47m |
![]() |
GMI PRO 18 SPACE AMP MIXER RACK CASE ALL PLYWOOD NEW | US $168.63 | 6d 19h 50m |
![]() |
GMI PRO NEW14 SPACE AMP MIXER RACK CASE ALL PLYWOOD | US $140.64 | 6d 20h |
![]() |
NEW GMI PRO 4200 WATT DJ POWER AMPLIFIER WITH SECURITY FEATURE | US $199.92 | 6d 20h 15m |
![]() |
NEW GMI PRO RX 3200 WATT DJ POWER AMPLIFIER 19 RACK MOUNT SECURITY FEATURE | US $179.99 | 6d 20h 17m |
![]() |
2 NEW GMI PRO 25U AMP TRIPLE RACK MOUNT COOLING FAN | US $99.88 | 6d 20h 42m |
![]() |
GMI PRO 1U 19RACKMOUNT POWER SUPPLY W 9 OUTLETS 2011 | US $38.70 | 6d 21h 1m |
![]() |
2 GMI PRO COMPRESSION HORN DRIVER 1500 WATT NEW 2010 | US $58.20 | 6d 22h 10m |
![]() |
2 GMI PRO COMPRESSION DRIVER 120 oz 2000 WATTS THIS IS FOR HORNS THE PAIR | US $83.92 | 6d 22h 17m |
![]() |
2 GMI PRO COMPRESSION DRIVER 76 oz 1500 WATT 2010 | US $58.69 | 6d 22h 20m |
![]() |
1 GMI PRO HORN COMPRESSION DRIVER 750 WATTS NEW 2010 | US $35.67 | 6d 22h 39m |
![]() |
Wilson Pro Staff Largehead Original Tennis Racquet | US $99.99 | 7d 27m |
![]() |
2 NEW GMI PRO HORN COMPRESSION DRIVERS 5850 WATTS FOR THE PAIR FREE SHIPPING | US $139.95 | 7d 5h 49m |
![]() |
2 GMI PRO COMPRESSION DRIVER 240 oz 4000 WATT 2010 | US $119.95 | 7d 6h 36m |
![]() |
1 GMI PRO COMPRESSION DJ HORN DRIVER 750 WATTS 2010 | US $35.43 | 7d 6h 38m |
![]() |
4 GMI PRO SCREW ON DRIVER TOTAL 1600 WATT 2010 | US $49.75 | 7d 6h 40m |
![]() |
2 NEW GMI PRO 16 X 6 PLASTIC HORN ONLY FOR DJ SPEAKERS | US $69.63 | 7d 6h 42m |
![]() |
GMI PRO 18 X 9 PLASTIC HORN FOR DJ SPEAKERS NEW | US $49.40 | 7d 6h 59m |
![]() |
2 GMI PRO 12 X 5 PLASTIC HORN FOR DJ SPEAKERS NEW | US $51.95 | 7d 7h 1m |
![]() |
4 GMI PRO 7 x 3 PLASTIC HORN 1200 WATTS NEW 2010 | US $39.91 | 7d 7h 10m |
![]() |
2 GMI PRO BRAND NEW COMPRESSION HORN DRIVERS 4390 WATT BRAND NEW | US $122.95 | 7d 7h 12m |
![]() |
NEW GMI PRO 15 1350w POWERED ACTIVE USB 5 BAND EQUALIZER SPEAKER SYSTEM | US $328.95 | 7d 19h 53m |
![]() |
NEW GMI PRO 12 1120w POWERED ACTIVE USB SPEAKER 5 BAND EQUALIZER SD CARD MORE | US $248.95 | 7d 19h 55m |















































































