Automatic audio switch

[JackBrienLX]

Hi all, apologies if this has been covered before but I have looked all over google and the search on here and cant quite find an answer, probably because my electronics components knowledge isn't amazing!

 

So I was hoping someone would be able to tell me how to make a input sensing audio switch. For two uses really (and I presume they would need to be slightly different, because one has constant voltage on both inputs and the other doesn't):

 

A - For a sound effects system, so when audio drops out on the A machine output, it automatically switches over to the B machine output.

 

and B - For a system where you can have two inputs, one of which takes precedence over the other. I would like to be able to walk around with a set of in ears in, connected to both an IEM pack and a radio (via the small construction I'm hoping you can help me with). So I will hear audio from the IEM pack normally, until someone tries to contact me on radio, in which case that audio is sent to the IEMs...

 

Hope that makes sense?

 

I'm assuming it would work in a similar way to the auto sensing inputs on TV's, but I cant find any easily digestible information online (for the electronically slow..)

 

Thanks in advance!

 

Jack

[mervaka]

Hi all, apologies if this has been covered before but I have looked all over google and the search on here and cant quite find an answer, probably because my electronics components knowledge isn't amazing!

 

So I was hoping someone would be able to tell me how to make a input sensing audio switch. For two uses really (and I presume they would need to be slightly different, because one has constant voltage on both inputs and the other doesn't):

 

A - For a sound effects system, so when audio drops out on the A machine output, it automatically switches over to the B machine output.

 

and B - For a system where you can have two inputs, one of which takes precedence over the other. I would like to be able to walk around with a set of in ears in, connected to both an IEM pack and a radio (via the small construction I'm hoping you can help me with). So I will hear audio from the IEM pack normally, until someone tries to contact me on radio, in which case that audio is sent to the IEMs...

 

Hope that makes sense?

 

I'm assuming it would work in a similar way to the auto sensing inputs on TV's, but I cant find any easily digestible information online (for the electronically slow..)

 

Thanks in advance!

 

Jack

 

For the electronically slow (as you put it) there is no easy solution for what you want. The simplest idea would just be to mix the signals together without dropping each other out, which from the sounds of your application sounds more sensible anyway. Beyond that, you're looking at a very complex solution perhaps involving an envelope follower, a comparator and a relay or transistor assembly (to gate the audio). If you're interested in this then maybe I could sketch what I'm imagining.

[Paul TC]

and B - For a system where you can have two inputs, one of which takes precedence over the other. I would like to be able to walk around with a set of in ears in, connected to both an IEM pack and a radio (via the small construction I'm hoping you can help me with). So I will hear audio from the IEM pack normally, until someone tries to contact me on radio, in which case that audio is sent to the IEMs...

 

If we are talking PMR radio, then if you can sense the squelch line, then you can take this off and use it to switch a relay to move the audio source from IEM pack to PMR radio. Have done simmilar types of modifications in the past, although in this case the switching was for remote recorders, but it will most likely require getting into the PMR radio and making some internal modifications, unless the PMR radio presents an suitable signal via a facilites connector.

[pisquee]

Could you send the IEM feed to the left input of the IEMs, and the Radio/Comms to the right input, set mix levels accordingly, and then mono sum the system?

[DrummerJonny]

How about something similar to this?:

 

http://www.bhphotovideo.com/c/product/1573...ure_SCM262.html

 

A device designed to dip the background audio track when an announcement is made over the mic.

 

Feed The IEM Audio through the Main Audio Track, the Radio through the talkover mic Channel. May have to sort out the impedances depending on what products are available....

 

Obviously this is a shop-bought solution rather than an electronics project, but if it does what you want...

[Robin Pratt]

Could you employ the "ducking" function using the side chain input on a cheap compressor limiter to do this?

[JackBrienLX]

Hi all,

 

Thanks for all the replies so far.

 

I have read through them, I have thought about using a compressor but to integrate this properly I would also need a Keybase (or similar) base station for the radio TX and RX (which is likely to be a Motorola CP040 or GP300) and 2/4 wire converters etc, as well as then having to carry around a rack mount for all this..

 

I guess I was hoping someone would say I could use switch XYZ that has 2 inputs to 1 output, and switches to the highest input of the two.

 

As for having both played into my ears at once, that would be possible and a lot easier, however I would be worried I would miss an important call on radio by not hearing it properly over the actual monitor feed.

 

Cheers,

 

Jack

[Simon Lewis]

Automatic mic mixer with your important audio signal connected to the priority channel? Several manufacturers make them (Shure, Audio Technica etc.)

[Paul TC]

Automatic mic mixer with your important audio signal connected to the priority channel? Several manufacturers make them (Shure, Audio Technica etc.)

From my understanding of the OP's requirement, "I would like to be able to walk around with a set of in ears in, connected to both an IEM pack and a radio " I think the OP wants to carry the radio in order to respond from where he is at time, hence all the kit has to be bodyworn. :D .

 

However a second radio on same channel with its receive audio output connected to an auto mic mixer feeding the IEM transmission as suggested would work, and the user then responds on the radio they are carrying, but if the radio system is simplex or on T/T (Talkthrough), it would make it difficult to talk as one would have "foldback" of one's own outgoing radio transmission via the IEM transmission. Other issue may be any other person monitoring IEM transmission which I assume is program, gets radio traffic intruding.

[TimmyP1955]

For your first task: http://www.radialeng.com/re-sw8.htm

[BlueShift]

You are making this complicated!

 

the Radial SW8 will do this for your first task. Auto switchover based on a manual or automatic trigger can do an unlimited number of channels, in blocks of 8. I use this for critical playback jobs all the time. works wonders.

 

For your second job, such a thing exists! precisely for Stage Tech's or Monitor Engineers who need to use a GP340 or equivalent with a IEM pack or just want a great set of IEMs to use as a radio headset. Sorts out the gain matching between devices and accepts an external mic etc... Made by the same guy who makes the EarPlug cable tester - can't for the life of me remember the URL - will look it up... Standby...