Telephone To Amplifier

[audioguru]

I thought he was going to use the headphones output of the phone, not connect to the earpiece. An isolation transformer is needed to avoid hum.

A phone makes sidetone so that you can hear how loud or soft you are speaking. Then you will have acoustical feedback howling if the mic can hear the speaker.

 

[mvs sarma]

when we try a Mic and a amplifier system ina closed accomodation without proper accoustic arrangements, this howling effect is immennt- unless special care is taken . In case of telephones, i have rarely seen the mute facility when the MIC supply is cut. really very few instruments.

I had occassion to couple telephone istrument to a Public address system while inaugurating a LDD/ILD in the telececom deparment ,i was working for.

ther i had to do all the rehaursal to ensure smooth and clear broadcast of the speech contesnt of an inaugural call. In this case i can't mute the MICof the telephone.
Ofcourse , it went on well.

 

[audioguru]

Some PA systems in stores avoid acoustical feedback by using a recorder then playing it into the PA when the mic is turned off.

 

[shocking find]

Some PA systems in stores avoid acoustical feedback by using a recorder then playing it into the PA when the mic is turned off.

The local OSH hardware store equipped the managers with cell phones that also interfaced with the store p.a. What WILL they think of next?

 

[shocking find]

That's a bit harsh audioguru, how would he know what an audio isolation transformer looks like if he's never seen one before?

The kind of transformer used in a modem isn't as good as a high quality audio transformer, it'll only pass frequencies between 300Hz and 3kHz instead of 15Hz to 20kHz.

I've found a Radio Shack 1:1 isolation transformer for 3.99USD with 600-900ohms,300-5KHz response and 100 mega-ohms insulation resistance at 250vdc! Did I do good, boss?

 

[audioguru]

I've found a Radio Shack 1:1 isolation transformer for 3.99USD with 600-900ohms,300-5KHz response and 100 mega-ohms insulation resistance at 250vdc! Did I do good, boss?

You did very well, boss.
I hope it works (RadioShack parts have garbage quality) and I hope they say which wire is which.