laptop headphone o/p to Mic input

pmgd · 24th November 2004, 07:15 PM

I am putting together a laptop/projectioh system for my church.
This is going fine -- but I want to be able to provide audio from the laptop as well as vision!

The only input to my church sound system mixer is a microphone input.

(Very silly I know - but thats what is physically located where the laptop is ... and I cant change the other end easily).

So - I know very very little of the specifics of the spec of a typical laptop headphone output (not stated on data sheet of course) and also very little about microphone inputs.

Clearly I need to match levels and impedances (the distances are quite long).

I lookat the paticular mic I have and it is a Audio Technica AT857QMa.

I looked at the spec sheet and it appears to produce about half a volt and uses DC power from the mixer.

Anybody got a circut, or know of a piece of kit I can use to make this work easily?

pinkmouse · 28th November 2004, 08:30 AM

You need to buy or make what is called a DI box. This matches impedance and converts to balanced to enable long cable runs. Oh, and if you buy, you will need to make an adaptor to 1/4 inch jack as well, as that is the input on most DI boxes.

Check out project 35 on the ESP website

lowlevel · 6th January 2005, 11:40 AM

Yeah mate this is every day AV staging stuff grab a DI box & away you go.
If you want the content of both audio channels you will either need to run 2 di boxes & 2 mic channels or I would recomend using two 1k resistors i series with the signal conductors to mix properly to mono.
I wouldn't bother buliding a di box these days they are so cheap.
cheers

24th November 2004, 07:15 PM	#1
pmgd diyAudio Member Join Date: Nov 2004 Location: newcastle UK	laptop headphone o/p to Mic input I am putting together a laptop/projectioh system for my church. This is going fine -- but I want to be able to provide audio from the laptop as well as vision! The only input to my church sound system mixer is a microphone input. (Very silly I know - but thats what is physically located where the laptop is ... and I cant change the other end easily). So - I know very very little of the specifics of the spec of a typical laptop headphone output (not stated on data sheet of course) and also very little about microphone inputs. Clearly I need to match levels and impedances (the distances are quite long). I lookat the paticular mic I have and it is a Audio Technica AT857QMa. I looked at the spec sheet and it appears to produce about half a volt and uses DC power from the mixer. Anybody got a circut, or know of a piece of kit I can use to make this work easily?

28th November 2004, 08:30 AM	#2
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	You need to buy or make what is called a DI box. This matches impedance and converts to balanced to enable long cable runs. Oh, and if you buy, you will need to make an adaptor to 1/4 inch jack as well, as that is the input on most DI boxes. Check out project 35 on the ESP website __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

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6th January 2005, 11:40 AM	#3
lowlevel diyAudio Member Join Date: Dec 2004 Location: South of Brisbane Metro, Queensland.	Yeah mate this is every day AV staging stuff grab a DI box & away you go. If you want the content of both audio channels you will either need to run 2 di boxes & 2 mic channels or I would recomend using two 1k resistors i series with the signal conductors to mix properly to mono. I wouldn't bother buliding a di box these days they are so cheap. cheers