Gearslutz.com - View Single Post - Building an effects microphone out of an old telephone

shifty · 21st September 2007

hello all,

I am wanting to build an effects microphone out of an old telephone receiver, circa 1970-1980. I would like to drive it off of phantom power since I believe that 48 VDC is comparable to line voltage of most (older) phones.

Here come the questions:

Since the microphone elements of these phones where a two wire system, can I simply tie one of the legs carrying the phantom power to the neutral pin through a significantly large resistor 100k?? 1M??

(I know this unbalances the system, but this is to achieve a low fi sound anyway.)

Next what would be the protocol for impedance matching. I dont have the thing on the bench so I am unsure of the impedance?

Would it need to be an more complex than a series resistor?
Would I need anything else?
Remember that simplicity is better in my opinion as long as I can be relatively sure that I would destroy my board or its phantom power.

Does anyone have any ideas?

Thanks

-E

21st September 2007	#1
shifty Gear interested Joined: Jul 2007 Posts: 13 Thread Starter	Building an effects microphone out of an old telephone hello all, I am wanting to build an effects microphone out of an old telephone receiver, circa 1970-1980. I would like to drive it off of phantom power since I believe that 48 VDC is comparable to line voltage of most (older) phones. Here come the questions: Since the microphone elements of these phones where a two wire system, can I simply tie one of the legs carrying the phantom power to the neutral pin through a significantly large resistor 100k?? 1M?? (I know this unbalances the system, but this is to achieve a low fi sound anyway.) Next what would be the protocol for impedance matching. I dont have the thing on the bench so I am unsure of the impedance? Would it need to be an more complex than a series resistor? Would I need anything else? Remember that simplicity is better in my opinion as long as I can be relatively sure that I would destroy my board or its phantom power. Does anyone have any ideas? Thanks -E