lui@CS.UCLA.EDU (03/30/88)
I have a Radio Shack Realistic mixer which has 3 microphone inputs that I
never use. I want to convert these microphone inputs to line level inputs.
Does this involve inserting a simple resistor in series? How do I
calculate the value of the resistor? Do mic inputs perform any type of
equilization similar to phono cartridge inputs?
Stephen Lui
ARPA: lui@cs.ucla.edu
UUCP: ...!{cepu,ihnp4,trwspp,ucbvax}!ucla-cs!luipokey@cpocd2.UUCP (Todd Wayne) (03/31/88)
In article <10742@shemp.CS.UCLA.EDU> lui@CS.UCLA.EDU (Stephen Lui) writes: >I have a Radio Shack Realistic mixer which has 3 microphone inputs that I >never use. I want to convert these microphone inputs to line level inputs. >Does this involve inserting a simple resistor in series? How do I >calculate the value of the resistor? Do mic inputs perform any type of >equilization similar to phono cartridge inputs? I hacked an IBM PC telephone interface card once when I was back in school. I converted a mic level input to a line level input by swithching a transconductance amplifier OUT of the circuit. After I figured out what the gain of the amplifier circuit was, I discovered that the next section was set up for line level voltages. What you want to do depends completely on the circuit and the impedences involved on either side of the amplifier circuit for a particular input (I assume that any reasonable mixer would have some kind of amplifier or at least some form of isolation for each input). You might require clipping out the amplifier AND adding some resistors - but I think the section after the input stage should be high impedance. I personally think having your addition switchable in/out, such that out leaves the original circuit, is a very good idea. > Stephen Lui > UUCP: ...!{cepu,ihnp4,trwspp,ucbvax}!ucla-cs!lui Hope this helps, Todd -- "Here, this will cheer you up. The martian moves when you flip the pages! Watch, you can see him eat an astronaut!" - Calvin, 1/28/88 ATT: (602) 961-2399 DOMAIN:pokey@cpocd2.intel.com UUCP:...!{decwrl|hplabs|oliveb}!intelca!mipos3!cpocd2!pokey
daver@felix.UUCP (Dave Richards) (04/07/88)
In article <10742@shemp.CS.UCLA.EDU> lui@CS.UCLA.EDU (Stephen Lui) writes: >I have a Radio Shack Realistic mixer which has 3 microphone inputs that I >never use. I want to convert these microphone inputs to line level inputs. >Does this involve inserting a simple resistor in series? How do I >calculate the value of the resistor? Do mic inputs perform any type of >equilization similar to phono cartridge inputs? Radio Shack also sells patch cords that have a built-in resistor to do this for you. There's a different one depending on whether the mic input is low or high impedance. With the right patch cord and adapters you should be able to hook everything up. Dave